Door damping system

A door damping system includes a base fixed to a wall, a fixing element fixed to the door and a rod connected between the base and the fixing element, the base having a pinion rotatably disposed in the base and the pinion coupled to the rod and a coil spring, a cylinder having a slidable piston rod which has a first end with a rack which is slidably received in the base for an engagement with the pinion and a second end with a piston slidably disposed in the cylinder in which oil is filled, the piston having a first and a second flanges, the first flange having a gap defined between the first flange and an inner periphery of the cylinder, the second flange having a plurality of fifth holes defined therein and a first clearance being defined between the piston and the piston rod, a ring movably disposed between the first and the second flanges so as to seal the gap when the door is returned and oil can only flow through the first clearance so as to slow down the speed of returning of the door.

BACKGROUND OF THE INVENTION 
1. Field of Invention 
The present invention relates to a door damping system and more 
particularly to a door damping system which provides a damping feature 
when closing the door. 
2. Related Prior Art 
A door damping system is designed to prevent the door from slamming back as 
a result of wind or by mischievous action of a user to hurt the following 
person. Such damping is obviously an important feature for a door used in 
the public places such as in a department store or a school. Additionally, 
users want to have a door damping system which provides a feature of 
positioning the door at required angle when closing or opening the door. 
The present invention intends to provide an improved door damping system to 
mitigate and/or obviate the above-mentioned problems. 
SUMMARY OF THE INVENTION 
The present invention provides a door damping system which includes a base 
fixed to a wall, a fixing element fixed to the door and a rod connected 
between the base and the firing element, the base having a pinion 
rotatably disposed in the base and the pinion coupled to the rod and a 
coil spring, a cylinder having a slidable piston rod which has a first end 
with a rack which is slidably received in the base for an engagement with 
the threaded portion of the rotating element and a second end with a 
piston slidably disposed in the cylinder with the piston rod, the cylinder 
having oil filled therein, the piston having a first and a second flanges, 
the first flange having a gap defined between the first flange and an 
inner periphery of the cylinder, the second flange having a plurality of 
fifth holes defined therein and a first clearance being defined between 
the piston and the piston rod, a ring movably disposed between the first 
and the second flanges so as to seal the gap when the door is returned and 
oil can only flow through the first clearance so as to slow down the speed 
of returning of the door. 
It is an object of the present invention to provide a door damping system 
which slows down the speed of returning of the door and provides a smooth 
and steady door-opening action. 
Other objects, advantages, and novel features of the invention will become 
more apparent from the following detailed description when taken in 
conjunction with the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to the drawings and initially to FIGS. 1 through 4, a door 
damping system in accordance with the present invention generally includes 
a base 10, a fixing element 70, a rod 50 connecting between the base 10 
and the fixing element 70 which is fixed to an upper portion of the door 
80 and a cylinder 61. The base 10 is fixed to a wall 81 corresponding to a 
pivotal side of the door 80 and has a first recess 12 defined in an upper 
side thereof, the first recess 12 being defined by a bottom 132 which has 
a first hole 13 centrally defined therein, a second recess 121 defined in 
a bottom side of the base 10 and the second recess 121 coaxially 
communicating with the first hole 13. A side slot 17 is defined in the 
base 10 near an outer side of the base 10 and opposite to the wall 81 and 
extending perpendicular to an axis of the first recess 12. The side slot 
17 extends from a front surface of the base 10, through the base 10 and to 
a rear surface of the base 10 wherein the side slot 17 communicates with 
the first recess 12 via a middle hole 174 defined in the base 10 and 
located between the side slot 17 and the first recess 12. The base 10 has 
a fifth recess 16 laterally defined in the front surface thereof and which 
communicates with the side slot 17, a first slit 152 defined in the bottom 
side of the base 10 and communicating with the second recess 121 and 
opposite to the outer side of the base 10. 
A pinion 20 has a T-shaped configuration and including a head 21 and a 
shank 23, the head 21 having a second slit 25 defined longitudinally 
therein and extending from a bottom of the shank 23, a threaded recess 26 
defined in the shank 23 and extending from the bottom of the shank 23. The 
head 21 is received in the first recess 12 and the shank 23 extends 
downwardly through the first hole 13 of the base 10. A coil spring 30 is 
received in the second recess 121 of the base 10 and has a first end 31 
formed in a center of the coil and a second end, the first end 31 is 
received in the second slit 25 of the shank 23 and the second end received 
in the first slit 152 of the base 10. 
A lower cap 18 is mounted to the bottom side of the base 10 and supports 
the coil spring 30, the lower cap 18 having a second hole 182 defined 
centrally therein and having a third recess 184 defined in a bottom 
thereof for receiving a connecting block 40 therein which has a through 
hole 41 defined longitudinally therein and a side hole 42 defined radially 
from a periphery thereof, the side hole 42 communicating with the through 
hole 41. 
The rod 50 has a first end and a second end, the first end thereof having a 
fourth hole 51 defined radially therethrough, the first end of the rod 50 
being inserted into the side hole 42 of the connecting block 40 and a bolt 
27 being extending through the through hole 41, the fourth hole 51 and 
being engaged with the threaded recess 26 of the shank 23 of the rotating 
element 20, the second end of the rod 50 having a frame 52 formed thereto 
so as to define an elongated space 53 between the rod 50 and the frame 52 
for receiving a stud 72 extending from the fixing element 70 therein. 
The cylinder 61 is filled with oil and has a neck portion 612 extending 
longitudinally therefrom so as to be inserted into the fifth recess 16 of 
the base 10 and is positioned by threading a bolt (not numbered) through a 
hole 162 defined in the upper surface of the base 10 and being engaged 
with a threaded hole 614 defined in the neck portion 612 such that the 
cylinder 61 is securely disposed to the front surface of the base 10. The 
cylinder 61 has a first end and a second end, the first end thereof having 
an end plug 656 to close the first end and the second end thereof having a 
bottom 611. The end plug 656 has a central hole defined therethrough for a 
piston rod 63 being slidably received therein which has a first end and a 
second end, the first end thereof having a rack 64 which is inserted in 
the side slot 17 of the base 10 for an engagement with the pinion 20. The 
second end of the piston rod 63 has a piston 67 disposed thereto, the 
piston 67 having a first clearance 671 defined between the piston rod 63 
and the piston 67 and having a first flange 65 and a second flange 66 
respectively extending radially from an outer periphery thereof and 
defining a first groove 672 between the first and the second flanges 65, 
66. 
Referring further to FIG. 5, the first flange 65 has an outer diameter 
smaller than an inner diameter of the cylinder 61 such that a gap 69 is 
defined between the first flange 65 and the cylinder 61. A ring 68 is 
movably disposed between the first flange 65 and the second flange 66, a 
second clearance 681 is defined between an inner periphery of the ring 68 
and the piston rod 63. The second flange 66 has a plurality of sixth holes 
661 defined therein. The ring 68 is moved to contact against the first 
flange 65 and the second flange 66 depending upon a movement of the piston 
rod 63, when the piston 67 is moved toward the first end of the cylinder 
61 to open the door 80, the ring 68 being moved to contact the second 
flange 66 and the sixth holes 661 being partially covered by the ring 68, 
therefore, oil transferred through the first clearance 671, the gap 69, 
second clearance 681 and the sixth holes 661 gap 69 to push the piston 67 
toward the first end of the cylinder 61 such that the speed to open the 
door 80 is steady and smooth. When closing the door 80, rod 63 is moved 
toward the bottom 611 of the cylinder 61 and the rotating element 20 is 
rotated because of the engagement between the threaded portion 22 and the 
threaded rod 64, the piston 67 is therefore moved toward the bottom 611 of 
the cylinder 61, the ring 68 is pushed by the oil to be moved to contact 
the first flange 65 and to seal the gap 69 such that the oil can only flow 
via the first clearance 671 and this slows the speed of the closing door 
80. 
To have a positioning feature of the door 80 during the opening or the 
closing processes, the base 10 has a fifth hole 14 defined laterally 
therein which is located opposite to the side slot 17 and communicates 
with the first recess 12, the fifth hole 14 has a threaded section (not 
shown) defined in an inner portion thereof so as to receive a ball 142 and 
a spring 144 in the fifth hole 14 and a small bolt 146 threadedly engaged 
with the threaded section to adjust the spring 144. The head 21 of the 
rotating element 20 has at least one fourth recess 24 defined in an outer 
periphery thereof so as to receive the ball 142 therein when the head 21 
of the pinion 20 is rotated to a certain position, that is to say, the 
door 80 can be positioned at a certain angle corresponding to the wall 81. 
Referring now to FIG. 6, the cylinder 61 can be moved to be disposed to the 
rear surface so as to be adapted to a left-handed opening door. 
Accordingly, the door damping system in accordance with the present 
invention provides a feature which slows down the speed of the closing 
door and the door can be positioned when it is opened or closed at a 
certain angle corresponding to the wall 81. 
Although the invention has been explained in relation to its preferred 
embodiment, it is to be understood that many other possible modifications 
and variations can be made without departing from the spirit and scope of 
the invention as hereinafter claimed.