Wheel

Details Wheel Wheel

2000-11-02

2002-08-13

Morano, S. Joseph (Department: 3617)

Wheel substitutes for land vehicles

Stepper type

C301S005230

Reexamination Certificate

active

06431664

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention relates to a wheel. More specifically, this invention relates to a wheel which can easily go up and down stairs.
The Japanese Unexamined Patent publication No. 301459/H1 (1989) discloses a wheel which is capable of going up and down stairs (hereinafter referred to as “prior art
1
).
FIG. 10
is schematic views of a wheel
100
of the prior art
1
. The reference numeral
110
is a cart. An axle
111
is secured horizontally to a lower part of the cart
110
. A wheel
100
is journaled on each end portion of the axle
111
so as to be freely rotatable.
The wheel
100
has a cross-shaped rotator
104
, which is journaled freely rotatably on the axle
111
. The rotator
104
has four rollers
108
A,
108
B,
108
C, and
108
D, each roller journaled on one of the four tips of the rotator
104
so as to be freely rotatable.
Accordingly, as the rotator
104
of the wheel
100
rotates on the axle
111
, the rollers
108
A to
108
D revolve around the axle
111
.
Referring to
FIG. 10
, the movement of the wheel
100
going up stairs will be described next.
The letter “A” indicates the riser of the first step of a stairway; “B” the tread; “C” the top corner.
As shown in FIG.
10
(I) , while the cart
110
is moving on the surface of a road, the rollers
108
A and
108
B roll on the road surface and the rollers
108
D and
108
C are positioned above the rollers
108
A and
108
B, respectively.
As shown in FIG.
10
(I), when the cart
110
reaches a stairway, the front lower roller
108
B comes in contact with the riser “A” of the first step.
As shown in FIG.
10
(II) , when the cart
110
is pulled up forward, the wheel
100
turns forward about the roller
108
B, which remains pressed against the riser “A” of the first step, for the rotator
104
is rotatable on the axle
111
. Accordingly, the front upper roller
108
C moves onto the tread “B” of the first step beyond its top corner “C”.
As shown in FIG.
10
(III), when the cart
110
is further pulled up forward, the roller
108
C rolls forward on the tread “B” and the roller
108
B rolls on the riser “A” upward.
Thus, the rotator
104
can be turned on the axle
111
and pulled up forward, and hence the wheel
100
and the cart
110
can be pulled up forward.
As shown in
FIG. 10
(IV), when the cart
110
is still further pulled up forward, the roller
108
B goes beyond the top corner “C” and gets onto the tread “B”. Thus, the whole wheel
100
and hence the cart
110
get onto the tread “B” of the first step.
As described above, the wheel
100
of the prior art
1
can go up a stairway by turning the rotator
104
on the axle
111
and rolling the front lower roller and the front upper roller on the riser “A” and the tread “B”, respectively, of each step.
The Japanese Unexamined Utility Model publication No. 191669/S57 (1982) discloses another wheel which is capable of going up and down stairs (hereinafter referred to as “prior art
2
”).
FIG. 11
is schematic views of a wheel
120
of the prior art
2
. The wheel
120
comprises a rectangular rotary plate
124
and four rollers
128
A,
128
B,
128
C, and
128
D which are supported by brackets at the four corners of the rotary plate
124
. Each of the four sides
125
of the rotary plate
124
is concaved in an arc-like shape.
In the same way as the wheel
100
of the prior art
1
, the wheel
120
gets on a step by putting the front upper roller
128
C on the tread “B” of the step and rolling it on the tread “B” forward and, at the same time, rolling the front lower roller
128
B upward on the riser “A” of the step. Although the rotary plate
124
is different from the rotator
104
of the wheel
100
in shape, the principle of the wheel
120
is the same as that of the wheel
100
.
The wheels
100
and
120
of the prior arts
1
and
2
have the following shortcomings (1) to (4).
(1) In case of the wheel
100
of the prior art
1
, when the rotator
104
turns about the roller
108
B, the roller
108
C comes in contact with the tread “B” at a relatively high speed, as shown in FIGS.
10
(I) and
10
(II). Accordingly, when the roller
108
C bumps against the tread “B”, it gives rise to a large shock. Thus, the cart
110
is exposed to large shocks and vibration while it is pulled up the stairway. The goods in the cart
110
may be damaged. In addition, the hands pulling the cart
110
are exposed directly to the unpleasant vibration of the cart
110
.
(2) The wheel
100
of the prior art
1
cannot be pulled up a stairway without risers “A” because it cannot be turned about the roller
108
B to put the roller
108
C on the tread “B”. Even if the roller
108
C can be put on the tread “B”, the roller
108
B cannot goes up toward the tread “B” because there is not a riser “A” for the roller
108
B to roll on.
(3) In case of the wheel
120
of the prior art
2
, because each of the four sides of its rotary plate
124
is concaved in an arc-like shape, the roller
128
B can be raised by leaning the side
125
on the top corner “C” of a step and turning the rotary plate
124
forward about the top corner “C”even if the stairway has no risers “A”, as shown in
FIG. 11
(II). However, in order to pull up the roller
128
B onto the tread “B”, the wheel
120
has to be moved by sliding the side
125
on the top corner “C”. Because the side
125
has no guiding function, there occurs large resistance between the wheel
120
and the stairway. Accordingly, although the wheel
120
can be pulled up a stairway without risers “A”, it requires large force to pull the cart up the stairway.
(4) In case that the wheel
120
of the prior art
2
is pulled up a stairway with risers “A”, a side
125
is slid on the top corner “C” of each step and the front lower roller
128
B comes in contact with the top corner “C” of said step. At this time, if the center of the front lower roller
128
B is lower than the tread “B” of said step, the front lower roller
128
B runs almost horizontally into the riser “A” of said step and its horizontal movement ceases. Accordingly, when the front lower roller
128
B runs into the riser “A” of said step, it causes a large shock. The goods in the cart may be damaged by the shock and vibration. In addition, the hands pulling the cart are exposed to the vibration of the cart.
Besides, the horizontal component of the pull force is wasted, just used to bump the front lower roller
128
B against the riser “A” of said step. Only the vertical upward component of the pull force is made use of for raising the center of the front lower roller
128
B above the tread “B” of said step. Thus, it requires large force to pull the cart up the stairway.
In accordance with the above, the object of the present invention is to provide a wheel which enables us to carry a movable body equipped with two units of the wheel easily up a stairway, even without risers, with small pull force, causing small shocks and vibration.
SUMMARY OF THE INVENTION
According to the first aspect of the present invention, there is provided a wheel comprising (i) an axle secured to a movable body, (ii) a rotator journaled on the axle so as to be freely rotatable and having at least three apexes disposed rotationally symmetrically around the axle, and (iii) rollers, each roller being mounted on one of the apexes of the rotator so as to be freely rotatable. Each side between apexes of the rotator is provided with a guiding surface which has small frictional resistance and is slidable.
According to the second aspect of the present invention, there is provided the wheel of the first aspect wherein each guiding surface is concaved in an arc-like shape.
According to the third aspect of the present invention, there is provided the wheel of the first or second aspect wherein (i) the point of intersection of each guiding surface and the periphery of one of the two rollers defining said guiding surface is positioned outside of the straight line which extends from the center of the roller to be tangent to the periphery of the other roller from the outside of the wheel and (ii) th

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