Motor vehicles – Having four wheels driven – With manually operated means for disengaging drive to one or...
Reexamination Certificate
2002-02-04
2004-01-20
DePumpo, Daniel G. (Department: 3611)
Motor vehicles
Having four wheels driven
With manually operated means for disengaging drive to one or...
C100S249000
Reexamination Certificate
active
06679348
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a vehicular two-wheel/four-wheel drive switching device for switching between two-wheel and four-wheel drive modes of operation.
BACKGROUND OF THE INVENTION
Heretofore, vehicles capable of switching between two-wheel and four-wheel drive modes of operation have been known.
FIGS. 4 and 5
show an example of such a vehicle. The vehicle
1
has a body frame
3
in the center of which an engine
2
is mounted. A pair of front wheels
4
and a pair of rear wheel
5
are arranged at the front and rear portions of the body frame
3
, and a steering handlebar
6
is arranged above the front portion of the body frame
3
for steering the vehicle via the front wheels
4
. A fuel tank
7
is located above the engine
2
and attached to the body frame
3
, and a seat
8
is attached to the rear of the fuel tank
7
.
As shown in
FIG. 5
, the front wheels
4
are supported by a suspension system
9
so that each front wheel can move vertically, and the rear wheels
5
are supported by a suspension system
10
so that each rear wheel also can move vertically.
A final reduction gear mechanism (differential)
13
for driving the front wheels
4
and a final reduction gear mechanism
14
for driving the rear wheels and connected to the engine
2
via respective drive shafts
11
and
12
are provided in the center of the front portion and the center of the rear portion, respectively, of the body frame
3
. The right and left front wheels
4
and the right and left rear wheels
5
are respectively connected to the final reduction gear mechanism
13
for the front wheels and the final reduction gear mechanism
14
for the rear wheels.
A two-wheel/four-wheel drive switching device for switching between rear-wheel drive and four-wheel drive by selectively transmitting and disconnecting motive power to the front wheels
4
is provided, for example, between the final reduction gear mechanism
13
for the front wheels and the drive shaft
11
. Alternatively, the two-wheel/four-wheel drive switching device can be provided between the rear drive shaft
12
and the final reduction gear mechanism
14
for the rear wheels.
The switching of the mode of drive is performed by the driver of the vehicle according to factors such as the state of the road surface and the type driving.
A two-wheel/four-wheel drive switching device having the structure shown in
FIG. 6
has previously been proposed.
The two-wheel/four-wheel drive switching device denoted by reference number
15
in
FIG. 6
is composed of two input shaft components
16
a
and
16
b
formed by axially dividing the input shaft
16
of the final reduction gear mechanism
13
for the front wheels into two shafts which are aligned on the same axis, and a switching device
17
for selectively connecting and disconnecting the shaft components
16
a
and
16
b.
In more detail, a cylindrical positioning protrusion
18
is provided in the center of the end face of the input shaft component
16
a
located on the side of the final reduction gear mechanism
13
for the front wheels, and a positioning concave portion
19
into which the positioning protrusion
18
is fitted in such a manner that the positioning protrusion can be turned is formed in the center of the end face of the input shaft component
16
b
. The two input shaft components
16
a
and
16
b
can be connected so that they turn together by positioning the input shaft components
16
a
and
16
b
so that the positioning protrusion
18
and the positioning concave portion
19
are interfitted.
Splines S
1
and S
2
are formed on the respective outer peripheral faces of the engagement parts of both of the input shaft components
16
a
and
16
b
. The switching device
17
is arranged such that it surrounds these engagement parts.
The switching device
17
includes a switching ring
20
provided on the inner surface thereof with splines fitted to the respective engagement parts of both input shaft components
16
a
and
16
b
so that the switching ring can be slid. With this structure, the splines of the switching ring can be engaged with or disengaged from the respective splines S
1
and S
2
of the input shaft components
16
a
and
16
b
. The switching device
17
further includes a drive mechanism
21
composed of a solenoid for selectively moving the switching ring
20
in the axial direction of the input shaft components
16
a
and
16
b
to a position in which its splines are engaged with only one input shaft component
16
a
or a position in which the splines are simultaneously engaged with the splines S
1
and S
2
of both input shaft components
16
a
and
16
b.
The two-wheel/four-wheel drive switching device
15
configured as described above can thus select between a two-wheel drive mode in which only the rear wheels are driven by moving the switching ring
20
in one direction by the drive mechanism
21
so as to engage it with only the input shaft component
16
a
to thereby disconnect the transmission of driving force to the front wheels
4
, and a four-wheel drive mode in which driving force is transmitted to both the front wheels
4
and the rear wheels
5
simultaneously by sliding the switching ring
20
so as to connect both input shaft components
16
a
and
16
b.
However, such a conventional type two-wheel/four-wheel drive switching device
15
has the following problems.
When there is difference in rotational speed between the front wheels
4
and the rear wheels
5
, in switching drive modes engagement between the switching ring
20
and the input shaft component
16
b
sometimes may not be possible, thus preventing switching between modes. Even if switching can be made, there is also a problem that the splines may collide in switching, creating a clashing noise.
To solve such a problem, a mechanism for synchronizing (aligning) the splines of the switching ring
20
and the splines of the input shaft component
16
b
may be provided, but the structure of the switching system then becomes complex, necessitating significant changes in the layout of the existing structure.
Moreover, as the interior chamber of the two-wheel/four-wheel drive switching device
15
and that of the final reduction gear mechanism
13
for the front wheels communicate, the same lubricating oil is required to be used to lubricate the two-wheel/four-wheel drive switching device
15
and the final reduction gear mechanism
13
for the front wheels. However, as the functions of the two-wheel/four-wheel drive switching device
15
and the final reduction gear mechanism
13
for the front wheels are different, it is preferred that different types of lubricants be used.
SUMMARY OF THE INVENTION
The invention has been made to solve the problems occurring in the conventional two-wheel/four-wheel drive switching device, and an object of the invention is to provide a vehicular two-wheel/four-wheel drive switching device the configuration of which is simple, which can be employed without changing the existing configuration of the vehicle, which generates scarcely any noise, and which can be lubricated separately from other actuating parts.
A vehicular two-wheel/four-wheel drive switching device according to the invention includes a driving shaft extending to a drive side of the switching device, a driven shaft extending from a driven side of the switching device, an inner ring and an outer ring having a generally annular clearance formed therebetween, one of the inner ring and the outer ring being coupled to the driving shaft and the other of the inner ring and the outer ring being coupled to the driven shaft, a plurality of connecting/disconnecting members provided in the clearance between the inner ring and the outer ring for selectively connecting and disconnecting the inner ring and the outer ring, a switching mechanism for selectively positioning the connecting/disconnecting members in one of a position in which the inner ring and the outer ring are connected and in a position in which the inner ring and the outer ring are disconnected, a casing rec
Handa Akio
Seki Bunzo
Takano Noriaki
DePumpo Daniel G.
Sughrue & Mion, PLLC
LandOfFree
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