Machine element or mechanism – Mechanical movements – Rotary to or from reciprocating or oscillating
Reexamination Certificate
2000-03-28
2002-12-10
Fenstermacher, David (Department: 3682)
Machine element or mechanism
Mechanical movements
Rotary to or from reciprocating or oscillating
C198S750800, C209S314000
Reexamination Certificate
active
06490941
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a step screen for conveying solid particles upwards and securely removing them from wastewater flowing through an aqueduct without any special restrictions in the installation condition, and more particularly to an elliptic motion driving apparatus for a step screen, which enables movable plates to move elliptically so that impurities in wastewater may be drawn and securely carried as they stand on each movable plate even though the step screen is installed at an inclination more than 45° to the ground of the aqueduct.
2. Description of the Related Art
Generally, a step screen is used to convey and eliminate adulterated things in wastewater flowing through a sewage aqueduct such as a sewage disposal plant or industrial wastewater disposal plant. To carry and remove impurities, the step screen has a plurality of lattice plates which are composed of toothed steps configured a set of stairs at a certain angle. The plates are classified into two types; movable and stationary plates, which are arranged in turn. A movable plate is elevated one step per one cycle so as to convey the caught impurities. Thus, the impurities are screened and conveyed without any dissipation or loss of disintegration from their initially filtered state.
FIG. 1
shows a conventional step screen installed with a common inclination of 45° on an aqueduct bottom
10
,
FIGS. 2 and 3
are front and side views of the conventional step screen, respectively.
FIGS. 4 and 5
are a sectional view of a circular motion driving unit
50
and a side view of a driven link
60
for transferring circular motion of the circular motion driving unit
50
to a movable column
45
linked to movable plates
20
.
As shown in the figures, the conventional step screen is commonly installed at 45° on the aqueduct bottom
10
through which wastewater passes. In the step screen, the movable columns
45
linked to both sides of the circular motion driving unit
50
along fixed frames
40
composing both sides of the screen may circularly move to a longitudinal direction. At the same time, the movable plates
20
arranged inside the fixed frames
40
perform circular movements so that impurities
70
(see
FIG. 7
) pushed upward onto the next steps of the stationary plates by movable plates
20
may be successively moved upward along the stationary plates by each circular turn of the movable pates.
In other words, the movable plates
20
perform circular movements so that the inclination of the steps of lattice plates (see
FIG. 6
) has an angle of about 45° to a horizontal level of the aqueduct bottom
10
. For that reason, as an eccentric rotation cam
51
connected through a power transmission shaft
53
to a driving motor
65
at an upper portion of the screen rotates, the circular motion of the circular motion driving motor
50
is transferred to an eccentric shaft
52
. The circular motion of the circular motion driving unit
50
also makes a driven link
60
, axially connected to the eccentric shaft
52
through a link bar
61
, move in a circular motion. At the same time, the corresponding longitudinal movable column
45
is moved circularly so that the movable plates
20
on the whole may perform in a regular circular motion between each pair of stationary plates
30
.
As shown in
FIG. 6
, in the conventional step screen, the downward portion
21
of each toothed step
20
projected at the side view of the movable plates
20
is perpendicular. Thus, when the screen is inclined to a 45° angle to the aqueduct bottom
10
, the movable plates
20
of the conventional step screen may push upward and convey impurities
70
in a stable manner while maintaining horizontally the terrace portion
22
of each toothed step
20
, whose section is triangularly projected at the longitudinal side view of the movable plates
20
, as shown in FIG.
7
. However, if the screen is installed at an angle of more than 45°, the terrace portion
22
of each toothed step
20
inclines downward below the horizontal level. So there still remains a structural difficulty that the screen is not suitable for moving impurities
70
at a steep inclination.
In addition, the conventional step screen in which the movable plates
20
circularly moves at an inclination of 45° is effective only at an installation angle of 45° to the aqueduct bottom, which requires more setup space than a rake classifier (filter) with an installation angle of 75°. Even more, when the installation environment requires an incline of more than 45° to the screen, the construction design should be changed by a large degree.
Furthermore, the conventional screen supports the movable column
45
only at two points, namely top and bottom, in the circular motion of the movable plates
20
. Thus, if there is a large screen requiring a long movable column
45
for a deep aqueduct, the allowable aqueduct depth is limited to 2.7M due to structural limitations. In addition, the method of driving the movable plates
20
in a circular motion also has the problem that the movable plates
20
cannot perform movement proper to push upward the impurities onto the next steps of the stationary when the toothed step is steeply inclined.
SUMMARY OF THE INVENTION
The present invention is designed to overcome the structural problems of the prior art caused by the circular motion of the movable plates which maintain a step angle of about 45°, and an object of the invention is to provide an elliptic motion driving apparatus for a step screen, in which the toothed steps of movable and stationary plates maintain an inclination over 45° even when the screen is installed at a steep incline of more than 45°, so that movable plates having such toothed steps may move elliptically to push upward and convey impurities in wastewater in a stable manner.
In order to accomplish the above object, the present invention provides an elliptic motion driving apparatus for a step screen in which the elliptic motion of an elliptic motion driving unit is transferred to a driven link so as to make steeper movable plates, connected by a movable column, rotate elliptically regularly in a longitudinal direction of the movable column, which includes a driving rotation cam, one end of which is combined to a power transmission shaft rotating in linkage with a worm reduction gear of a driving motor; an eccentric shaft for horizontal motion, axially combined to the other end of the driving rotation cam so that a horizontal eccentric bearing of the eccentric shaft for horizontal motion moves horizontally along a horizontal motion guiding rail as the driving rotation cam rotates; and an eccentric shaft for vertical motion combined to the eccentric shaft for horizontal motion through an eccentric rotation cam so that a vertical eccentric bearing of the eccentric shaft for vertical motion moves vertically along a vertical motion guiding rail as the eccentric shaft for horizontal motion rotates.
REFERENCES:
patent: 5613595 (1997-03-01), Ukada
patent: 5653633 (1997-08-01), Kalverkamp et al.
patent: 5904254 (1999-05-01), Tinsley et al.
patent: 6177020 (2001-01-01), Wiesemann
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