JPS638972Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to an overshift prevention mechanism for gear transmissions for automobiles, and particularly for transmissions equipped with a transfer that can switch between two-wheel drive and four-wheel drive, as well as between low and high speeds. It is something.

Conventionally, as an example of this type of overshift prevention mechanism, as the clutch hub sleeve moves during a shift operation, the inner spline of the clutch hub sleeve forms a protrusion in the radial direction with respect to the gear spline with which it engages. There is a means for regulating the shift stroke by having its end surface abut against the protrusion when the shift stroke is moved to its fullest extent. In this case, in order to accurately regulate the shift stroke, the end face of the clutch hub sleeve and the protrusion that contacts it must be accurately finished, which causes problems such as difficulty in machining and an increase in machining work. .

In particular, it is unreasonable in terms of space to employ the above-mentioned type of overshift prevention mechanism to regulate the shift stroke of the shift operation related to switching between two-wheel drive and four-wheel drive in the transfer.

In view of such conventional circumstances, the present invention divides the transfer case into a front case and a rear case, and in conjunction with this, the front case and front extension housing are integrally formed, and this front case and front In the case of a type in which a separate bearing retainer is fixed at the boundary with the extension housing, by using this structure, it is possible to accurately regulate the shift stroke by slightly changing the shape of the existing parts. It is an object of the present invention to provide an overshift prevention mechanism configured as described above.

Next, the configuration of this invention will be explained in detail according to an embodiment shown in the drawings.

FIG. 1 is a cross-sectional view of a part of a gear transmission equipped with a transfer capable of switching between two-wheel drive (rear-wheel drive) and four-wheel drive, as well as switching between low and high speeds. In FIG. 1, a transmission 1 is configured such that rotation from an engine (not shown) is controlled based on a gear ratio determined by operating a shift lever 2, or a change in rotation direction (reverse shift), as is well known. It is transmitted to the output shaft 3.

A transfer case 5 constituting the transfer is installed on the rear side (right side in the drawing) of the transmission 1. The transfer case 5 is divided into a front case 6 and a rear case 7 to enable die-cast molding. The two cases 6 and 7 are bolted together with a gasket interposed therebetween, and the front case 6 is attached to the rear wall 4a of the transmission case 4 with bolts. Due to this type division of the transfer case 5, the front case 6 and a front extension housing 8 extending from the case 6 toward the front side (left side in the drawing) are integrally molded. In addition, with the integration of the front case 6 and the front extension housing 8, a bearing retainer 27 for rotatably supporting a rear output shaft 16, which will be described later, is attached to the boundary between the front case 6 and the front extension housing 8. It is formed separately from 8. The bearing retainer 27 is integrally fixed to the inner periphery of the boundary portion from the rear side (right side in the drawing) by means such as press fitting. In addition,
The above-mentioned rear case 7 and the rear extension housing 9 extending rearward from this case 7
They are formed separately from each other and are bolted together with a gasket interposed between them.

The output shaft 3 of the transmission is guided into the interior of the transfer case 5 configured in this way and is rotatably supported, and a drive gear 12 is mounted on the axis of the shaft 3.
and gear 13 for power extraction to work winches, etc.
are arranged so as to be able to rotate together with the shaft 3, respectively. This drive gear 12 is always in mesh with an idler gear 15 rotatably supported on the shaft of an idler gear shaft 14 disposed parallel to the output shaft 3 described above. Furthermore, a rear output shaft 16 is arranged parallel to this idler gear shaft 14.
is rotatably supported by the bearing retainer 27 and a part of the rear extension housing 9 by tapered roller bearings 28 and 29, respectively. On the shaft of this rear output shaft 16 is the idler gear 1.
A high-speed gear 17 that meshes with the large-diameter gear 15a and a low-speed gear 18 that meshes with the small-diameter gear 15b are each rotatably supported. That is, transmission 1
The rotation of the output shaft 3 is always transmitted to the high speed gear 17 and the low speed gear 18 through the idler gear 15.

Also, on the shaft of the rear output shaft 16, there are a high speed gear 17 and a low speed gear 1.
8, a clutch hub 20 of the low/high speed switching device 19 is formed integrally with the shaft 16. A clutch hub sleeve 21 is splined to the outer periphery of the clutch hub 20 so as to be slidable in the axial direction. That is, the clutch hub sleeve 21 is slid along the axial direction by the movement of a shift fork (not shown) accompanying the low-speed switching operation, and the inner spline is connected to the spline 17a of the high-speed gear 17.
By meshing with the high speed gear 17, the rotation of the high speed gear 17 is transmitted to the rear output shaft 16. In addition, the clutch hub sleeve 21
By meshing the inner spline with the spline 18a of the low speed gear 18, the rotation of the low speed gear 18 is transmitted to the rear output shaft 16. A companion flange 22, which is connected to a rear propeller shaft (not shown) via a universal joint, is fitted to the rear end of the rear output shaft 16, centered from the outside of the rear extension housing 9. .

Now, inside the front extension housing 8, a front output shaft 23 is disposed coaxially with the rear output shaft 16. In other words, as is clear from FIG. 2, which is a partially enlarged view of FIG.
is rotatably supported by a needle bearing 24 on the inner periphery of a center hole formed at the front end of the rear output shaft 16, and the other end is rotated on a ball bearing 25 against the inner periphery of the front extension housing 8. freely supported. A companion flange 26, which is connected to a front propeller shaft (not shown) via a universal joint, is fitted onto the front end of the shaft 23, centered from the outside of the front extension housing 8.

Further, inside the front extension housing 8, a clutch hub 31 of a two-wheel drive/four-wheel drive switching device 30 is spline-fitted to the outer periphery of the front end of the rear output shaft 16. The clutch hub 31 is axially restricted to the rear output shaft 16 by a stepped portion 16a formed on the outer periphery of the shaft 16 through the inner race 28a of the tapered roller bearing 28.
This is also accomplished by a snap spring 32 fixed to the shaft 16. On the other hand, on the axis of the front output shaft 23 facing the clutch hub 31, there is a clutch hub 31.
A spline 41 having the same diameter is integrally formed.

On the outer periphery of the clutch hub 31, the clutch hub sleeve 33 is attached to the spline 4 of the front output shaft 23 from the state shown in FIGS.
1 and is slidably spline-fitted towards the end. A fork shaft 34 passing through the inside and outside of the housing 8 is disposed in a part of the front extension housing 8 so as to be slidable in the axial direction. Two detent grooves 34a and 34b are formed in the outer periphery of the fox shaft 34 in the axial direction, and the detent ball 37 is engaged in one of them by receiving the elastic force of the spring 38. , which also regulates the shift position of the forkshaft 34. The detent ball 37 and spring 38 are incorporated into a plug 39 screwed into the wall of the front extension housing 8.

Further, a shift fork 35 is fixed to the fork shaft 34 by a slotted pin 36, which grips the outer circumferential groove of the clutch hub sleeve 33 so as to be relatively rotatable inside the front extension housing 8. In this shift fork 35, an abutment part 40 is located near the joint with the fork shaft 34 and also on a straight line connecting the axis of the fork shaft 34 and the middle part of the forked part of the shift fork 35.
are integrally formed (see Figure 3). This contact portion 40 is located on the side opposite to the bearing retainer 27, and in the shifted state shown in FIGS. 1 and 2, the front side surface 27 of the retainer 27 is
It is in contact with a. This bearing retainer 27
The front side surface 27a of the bearing retainer 27 is connected to the transfer case 5 as described above.
Finished with high precision to maintain centering accuracy when press-fitting and fixing. Therefore, the position regulation of the shift fork 35 (shift stroke regulation to be described later) by the contact of the projection 40 with the front side surface 27a becomes extremely accurate.

In the above configuration, when the two-wheel drive/four-wheel drive switching device 30 is in the state shown in FIGS. 1 and 2, that is, the clutch hub sleeve 3 is engaged only with the clutch hub 31, the rear output shaft 16 and the front Output shaft 23
This is a two-wheel drive (rear wheel drive) shift in which torque transmission between the two wheels is cut off. Therefore, when the clutch hub sleeve 33 is shifted to the left in FIG. 1 and FIG. The spline 41 of the output shaft 23 is engaged with the spline 41 of the output shaft 23, and both output shafts 1
A four-wheel drive shift is obtained that allows torque transmission between the 6 and 23 wheels.

In this way, switching from two-wheel drive to four-wheel drive,
In addition, in the switching operation from four-wheel drive to two-wheel drive, each shift stroke is caused by both detent grooves 34a, 34b of fork shaft 34.
This is temporarily regulated by the action of the detent ball 37 which is pressed against these grooves by the force of the spring 38. However, if an excessive operating force is applied, the shaft fork 35 may be moved beyond a predetermined set stroke.

Therefore, when shifting from two-wheel drive to four-wheel drive, the front end surface of the clutch hub sleeve 33 is brought into contact with the convex portion 41a formed on the spline 41 of the front output shaft 23, thereby regulating the stroke in this case. (overshift prevention). In a shift operation from four-wheel drive to two-wheel drive, the abutting portion 40 of the shift fork 35, which is a non-rotating member, is applied to the front side surface 27a of the bearing retainer 27 to restrict its stroke (overshift). prevention). In this case, since the front side surface 27a of the bearing retainer 27 is originally finished with high precision as described above, it is possible to avoid a significant increase in additional machining and to perform accurate shift stroke regulation.

Note that instead of the shift stroke regulating means by the front side surface 27a of the bearing retainer 27 and the contact portion 40 of the shift fork 35 when switching from four-wheel drive to two-wheel drive, It is also conceivable to adopt a means similar to the shift stroke regulation in the switching operation, that is, a means to form a convex portion on the outer periphery of the clutch hub 31 and to apply the clutch hub sleeve 33 thereto. However, for this purpose, it is necessary to set the width of the outer peripheral spline of the clutch hub 31 to be larger than that shown in the drawings. In order to implement this in a limited space, the clutch hub 31, which is a rotating member, must be placed abnormally close to the bearing retainer 27, which is a fixed member, which is not preferable. It is also possible to regulate the shift stroke by, for example, touching the end of the forkshaft 34 to a part of the transfer case 5, but in this case, the end of the forkshaft 34 and the transfer case 5 side Finishing is required, and additional special machining is required to prevent overshifting.

As described above, the present invention allows the contact part of the shift fork, which is a non-rotating member, to come into contact with the side wall of the bearing retainer, which is a fixed member to the transfer case side and is originally finished with high precision. By configuring the shift stroke of the shift fork to be restricted, when the shift stroke is restricted (shift stopper), relative rotation occurs between the side wall of the bearing retainer and the abutment part of the shift fork. Not only can basic functional inconveniences such as those that occur can be avoided, but by slightly improving a part of the shift fork, which is an existing part, it is possible to avoid major additional processing or design changes in other parts. This has the advantage that the shift stroke can be regulated accurately without the need for.

Moreover, in the present invention, the abutment part is formed near the joining part of the shift fork to the fork shaft, and on a straight line connecting the axis of the fork shaft and the middle part of the forked part of the shift fork. This prevents biased forces such as bending force from being applied to the shift fork when the shift is stopped, thereby increasing the durability of the shift fork.

[Brief explanation of the drawing]

The drawings show an embodiment of this invention; FIG. 1 is a sectional view of a gear transmission equipped with a transfer, FIG. 2 is an enlarged sectional view of the main part of FIG. 1, and FIG. It is an external perspective view of a shift fork. 5...Transfer case, 6...Transfer front case, 7...Transfer rear case, 8...Front extension housing, 16...Rear output shaft, 27...
... Bearing retainer, 30 ... Two-wheel drive, four-wheel drive switching device, 34 ... Folkshaft, 35
...Shift fork, 40...protrusion.

Claims (1)

[Scope of utility model registration request] A gear transmission equipped with a transfer that can switch between two-wheel drive and four-wheel drive, the transfer case is divided into a front case and a rear case, and the front case and front extension housing are A bearing retainer that rotatably supports the rear output shaft of the transfer shaft using a bearing is formed separately from the transfer case, and is connected to the boundary between the front case and the front extension housing. The front extension housing is arranged so that it can be slid in the axial direction with respect to the front extension housing, and this sliding operation is used to shift between two-wheel drive and four-wheel drive. A shift fork, which is a non-rotating member, is fixed to the fork, and a straight line connecting the axis of the fork shaft and the middle part of the forked part of the shift fork is located near the joint of the shift fork with the fork shaft. An overshift prevention mechanism, characterized in that an abutting portion is formed on the upper side of the bearing arena to abut against a side wall of the bearing arena to regulate a shift stroke.