Motor vehicles – Special wheel base – Having only three wheels
Reexamination Certificate
1999-06-02
2001-10-02
Johnson, Brian L. (Department: 3618)
Motor vehicles
Special wheel base
Having only three wheels
C180S233000, C074S473240
Reexamination Certificate
active
06296070
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a transfer device in a four-wheel drive vehicle and more particularly to a transfer device in a four-wheel drive vehicle provided with a plurality of switching mechanisms to change the running condition of the vehicle.
BACKGROUND OF THE INVENTION
In certain conventional four-wheel drive vehicles (4WD vehicles), a transfer device is installed integrally with a transmission. The transfer device has a plurality of switching mechanisms such as a two-wheel/four-wheel switching mechanism for switching over between two-wheel drive (2WD) and four-wheel drive (4WD) and a high-speed/low-speed switching mechanism for switching over between high speed (H) and low speed (L). These switching mechanisms are operated with operation of each shifting shaft which is actuated, for example, by operation of a lever.
In the transfer device shown in
FIG. 11
, a high-speed/low-speed shifting shaft
304
with a high-speed/low-speed fork
302
fixed thereto and a two-wheel/four-wheel shifting shaft
308
with a two-wheel/four-wheel fork
306
fixed thereto are disposed side by side in proximity to each other. A high-speed/low-speed shifting groove
310
is formed in the outer peripheral surface of the high-speed/low-speed shifting shaft
304
, while a two-wheel/four-wheel shifting groove
312
corresponding to the high-speed/low-speed shifting groove
310
is formed in the outer peripheral surface of the two-wheel/four-wheel shifting shaft
308
. A shift lever
314
comes into engagement with the high-speed/low-speed shifting groove
310
and the two-wheel/four-wheel shifting groove
312
selectively by shift and select operations, whereby the vehicular running condition is switched over between two-wheel drive (2WD) and four-wheel drive (4WD) or between high speed (H) and low speed (L).
For conducting the switching operations by utilizing an actuator without going through the select operation of the lever, there has heretofore been adopted such a construction as shown in
FIG. 12
, wherein a shifting yoke
410
is fitted on both a high-speed/low-speed shifting shaft
404
with a high-speed/low-speed fork
402
fixed thereto and a two-wheel/four-wheel shifting shaft
408
with a two-wheel/four-wheel fork
406
fixed thereto. A high-speed/low-speed semicircular groove
412
is formed in the outer peripheral surface of the high-speed/low-speed shifting shaft
404
, while a two-wheel/four-wheel semicircular groove
414
corresponding to the high-speed/low-speed semicircular groove
412
is formed in the outer peripheral surface of the two-wheel/four-wheel shifting shaft
408
. Further, a ball
416
is disposed within the shifting yoke
410
and is brought into engagement selectively with the high-speed/low-speed semicircular groove
412
and the two-wheel/four-wheel semicircular groove
414
. Though not shown, when the high-speed/low-speed shifting shaft
404
and the two-wheel/four-wheel shifting shaft
408
are actuated for switch-over to high-speed two-wheel drive (2H), high-speed four-wheel drive (4H), or low-speed four-wheel drive (4L), by means of an actuator, there are used two types of actuators which are an actuator for shift operation and an actuator for select operation, or a three-stop position actuator is used.
Transfer devices of such a construction are disclosed, for example, in Japanese Patent Laid-Open Nos. 10-53045 and 8-156625 and Japanese Utility Model Laid-Open No. 6-80053. According to the transfer device disclosed in Japanese Patent Laid-Open No. 10-53045, a two-wheel/four-wheel switching shaft member and a high-speed/low-speed switching shaft member are disposed coaxially. The two-wheel/four-wheel switching shaft member operates in its axial direction independently of the high-speed/low-speed switching shaft member to effect switching between two-wheel drive and four-wheel drive, whereby it is intended to attain a reduction of size. According to the transfer device disclosed in Japanese Patent Laid-Open No. 8-156625, three shift positions four-wheel high-speed position (4H), four-wheel high-speed direct-coupled position (4HLc), and four-wheel low-speed direct-coupled position (4LLc)—are switched over from one to another using a single switching rail, thereby making the safety for on-road use and running performance for off-road use compatible with each other. The transfer device disclosed in Japanese Utility Model No. 6-80053 intends to simplify the construction thereof by switching in interlock with a lever.
However, in such conventional transfer devices, as shown in
FIG. 11
, a select operation of a shift lever is needed at the time of switching between two-wheel drive (2WD) and four-wheel drive (4WD) or between high speed (H) and low speed (L) with use of the shift lever, and this operation is troublesome.
Further, where the vehicular running condition is to be switched over to high-speed two-wheel drive (2H), high-speed four-wheel drive (4H), or low-speed two-wheel drive (4L), using an actuator, it has so far been necessary to use two types of actuators or use a three-stop position actuator. These actuators enhance the accuracy of stop positions (4H), particularly the accuracy of the middle stop position out of three stop positions. However, such an accuracy enhancing operation is troublesome.
SUMMARY OF THE INVENTION
The goal of the invention is elimination of the above-mentioned problems for a transfer device of a four-wheel drive vehicle. A preferred transfer device has at least two, first and second shifting shafts which actuate a plurality of switching mechanisms to change the running condition of the vehicle. The first and second shifting shafts are disposed side by side in proximity to each other. A first elliptic groove and a first semicircular groove are formed in an outer peripheral surface of the first shifting shaft in axially spaced relationship to each other and a second semicircular groove corresponding to the first elliptic groove and a second elliptic groove corresponding to the first semicircular groove are formed in an outer peripheral surface of the second shifting shaft in an axially spaced relationship to each other. An axially movable shifting yoke fits loosely on the first and second shifting shafts while embracing the shifting shaft portions corresponding to the first and second elliptic grooves and the first and second semicircular grooves. First and second balls are disposed within the shifting yoke and between the first and second shifting shafts. The first ball engages or disengages from the first elliptic groove and the second semicircular groove and the second ball engages or disengages from the first semicircular groove and the second elliptic groove, with axial movement of the shifting yoke.
REFERENCES:
patent: 3354741 (1967-11-01), Johnston, Jr. et al.
patent: 3529487 (1970-09-01), Dolan
patent: 3552227 (1971-01-01), Schroeder et al.
patent: 3747425 (1973-07-01), MacDonald
patent: 6-80053 (1994-11-01), None
patent: 08156625 A (1996-06-01), None
patent: 10053045 A (1998-02-01), None
Flynn ,Thiel, Boutell & Tanis, P.C.
Johnson Brian L.
Luby Matthew
Suzuki Motor Corporation
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