# US 2014/0196995 A1 · Resetting semi-passive stiffness damper and methods of use thereof

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- Number: US 2014/0196995 A1
- Document ID: US20140196995A1
- Status: Published application
- Kind: A1
- Application number: 14/106,185
- Filed: 2013-12-13
- Published: 2014-07-17
- Earliest claimed: 2012-12-14
- Assignees: Ohio University
- Applicants: Ohio University
- Inventors: Kenneth K. Walsh
- Web page: https://patentgrep.com/patent/US20140196995A1

## CPC

- F16F 9/5126: {Piston, or piston-like valve elements (F16F9/504 takes precedence)}
- E04B 1/98: against vibrations or shocks (on foundations E02D31/08); against mechanical destruction, e.g. by air-raids (against incendiary damage only E04B1/94; finishing work therefor E04F; buildings withstanding earthquake or the like, shelters, arrangements of splintercatching walls E04H9/00)
- E04H 9/0215: {involving active or passive dynamic mass damping systems}
- E04H 9/0235: {Anti-seismic devices with hydraulic or pneumatic damping}
- F16F 9/3214: {of pistons (F16F9/0227 and F16F9/36 take precedence; throttling passages in or on piston body F16F9/3405)}
- F16F 9/3292: {Sensor arrangements}
- F16F 9/512: Means responsive to load action, {i.e. static load} on the damper or {dynamic} fluid pressure {changes} in the damper, {e.g. due to changes in velocity (F16F9/504, F16F9/516 take precedence; non-automatic damper adjustment from a distance using servo control, the servo pressure being created by the flow of damping fluid F16F9/465; self-pumping fluid springs in vehicle suspensions B60G17/044)}
- F16F 15/02: Suppression of vibrations of non-rotating, e.g. reciprocating systems; Suppression of vibrations of rotating systems by use of members not moving with the rotating systems ({F16F15/005 takes precedence } ; layered products B32B; suppression of vibration in ships B63; {relieving load on bearings, using magnetic means F16C39/06})
- F16F 2228/001: Specific functional characteristics in numerical form or in the form of equations
- F16F 2228/066: Variable stiffness
- F16F 2228/10: with threshold or dead zone
- F16F: SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- E04B: GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS (border constructions of opening in walls, floors or ceilings E06B1/00; {electromagnetic shielding H05K9/0001})
- E04H: BUILDINGS OR LIKE STRUCTURES FOR PARTICULAR PURPOSES; SWIMMING OR SPLASH BATHS OR POOLS; MASTS; FENCING; TENTS OR CANOPIES, IN GENERAL (foundations E02D)

## Abstract

A resetting semi-passive stiffness damper (RSPSD) for use in damping movement. Embodiments of such a RSPSD include, for example, a pistoned cylinder connected to a grooved rack, and a spring-loaded lever arranged between the rack and a slotted channel above the rack. One end of the lever is allowed to move pivotably and vertically within the channel as the other end moves with the rack. A sensor is provided and communicates with a bypass valve on the cylinder. A change in the direction of movement of the rack forces the lever further into the slotted channel where it eventually triggers the sensor, which then sends a signal to open the bypass valve. As the rack continues to move, the lever eventually reverses direction, and is forced back down the slotted channel by a return spring. Upon leaving the sensing range of the sensor, the valve is signaled to close.

## Claims

### Claim 1

A resetting semi-passive stiffness damper (RSPSD), comprising:
a reciprocatable piston located within a cylinder;
a linearly displaceable grooved rack coupled at one end to the piston;
an actuator coupled between a structure to be damped and an opposite end of the grooved rack;
a triggering assembly, the triggering assembly comprising:
a displaceable, spring-loaded lever arranged between the grooved rack and a slotted channel above the grooved rack, a first end of the lever in contact with the grooved rack and a second end of the lever movably residing in the channel, and
a sensor residing in the channel and located to detect the lever when the second end of the lever reaches a predetermined position within the channel; and
a bypass valve associated with the cylinder and in communication with the sensor of the triggering assembly so as to receive open and close signals therefrom.

### Claim 2 (depends on 1)

The RSPSD of claim 1, wherein vertical travel of the lever in the channel is related to the travel distance of the rack by the formula:
y(t)=√{square root over (L2−[x0−x(t)]2)}−(L−D)
where L is the length of the lever, x0 is the distance between the slotted channel and the contact point of the lever with the rack, x(t) is the distance of movement of the rack and lever end, d is the total vertical travel distance of the lever within the slotted channel, and y(t) is valid for 0<x(t)<2(x0).

### Claim 3 (depends on 2)

The RSPSD of claim 2, wherein the bypass valve is closed while the lever position satisfies the formula y(t)<s, where s is the vertical distance the lever must travel within the slotted channel to be within the sensing range of the sensor.

### Claim 4 (depends on 2)

The RSPSD of claim 2, wherein when the lever reaches a position where s≦y(t)<d, the bypass valve will open, the pressure in the RSPSD will equalize, and the damper force will drop to zero.

### Claim 5 (depends on 4)

The RSPSD of claim 4, wherein the bypass valve will remain open until the lever moves to a position that satisfies the formula y(t)<s.

### Claim 6 (depends on 2)

The RSPSD of claim 2, wherein pressure equalization will take place while 0<x(t)<2(x0) and s≦y(t)<d.

### Claim 7

A resetting semi-passive stiffness damper (RSPSD), comprising:
a reciprocatable piston located within a cylinder;
a linearly displaceable grooved rack coupled at one end to the piston;
an actuator coupled between a structure to be damped and an opposite end of the grooved rack;
a triggering assembly, the triggering assembly comprising:
a displaceable, spring-loaded lever arranged between the grooved rack and a slotted channel above the grooved rack, a first end of the lever in contact with the grooved rack and a second end of the lever movably residing in the channel, and
a sensor residing below the channel and above the rack, the sensor located to detect the lever as the lever passes by the sensor while moving with the rack; and
a bypass valve associated with the cylinder and in communication with the sensor of the triggering assembly so as to receive open and close signals therefrom.

### Claim 8 (depends on 7)

The RSPSD of claim 7, wherein vertical travel of the lever in the channel is related to the travel distance of the rack by the formula:
y(t)=√{square root over (L2−[x0−x(t)]2)}−(L−D)
where L is the length of the lever, x0 is the distance between the slotted channel and the contact point of the lever with the rack, x(t) is the distance of movement of the rack and lever end, d is the total vertical travel distance of the lever within the slotted channel, and y(t) is valid for 0<x(t)<2(x0).

### Claim 9 (depends on 7)

The RSPSD of claim 7, wherein the sensor is oriented such that the sensing direction thereof is substantially perpendicular to the to the direction of movement of the rack.

### Claim 10

A resetting semi-passive stiffness damper (RSPSD), comprising:
a reciprocatable piston located within a cylinder;
a rotatable disc that is directly or indirectly rotatable by linear movement of the piston, a circumferential flange extending from the disc;
an actuator coupled between a structure to be damped and the piston;
a triggering assembly mounted to the disc such that rotation of the disc does not cause a rotation of the triggering assembly, the triggering assembly comprising:
a displaceable, spring-loaded lever arranged between the circumferential flange of the disc and a slotted channel, a first end of the lever in contact with the circumferential flange of the disc and a second end of the lever movably residing in the channel, and
a sensor associated with the channel and located to detect the lever when the lever resides within a sensing range of the sensor; and
a bypass valve associated with the cylinder and in communication with the sensor of the triggering assembly so as to receive open and close signals therefrom;
wherein, reciprocation of the piston will cause a back-and-forth rotation of the disc, and the rotation of the disc will cause the first end of the lever to move with the circumferential flange of the disc and the second end of the lever to reciprocate within the slotted channel.

### Claim 11 (depends on 10)

The RSPSD of claim 10, wherein vertical travel of the lever in the channel is related to the travel distance of the piston by the formula:
y

(
t
)
=
[
L
2
-
[
R
L

sin

(
ϕ
o
-
x
p

(
t
)
R
L
)
]
2
-
(
L
-
d
)
]
-
[
R
L
2
-
[
R
L

sin

(
ϕ
o
-
x
p

(
t
)
R
L
)
]
2
-
R
L
2
-
x
o
2
]
where L is the length of the lever, RL is the radius of the disc, φ0 is the angle formed between the lever and a radial line extending from the first end of the lever, xp(t) is the distance of movement of the piston, d is the total vertical travel distance of the lever within the slotted channel, and x0 is the distance between the slotted channel and the contact point of the lever with the circumferential flange of the disc.

### Claim 12 (depends on 10)

The RSPSD of claim 10, wherein:
the disc is a first of two discs and is rotatably fixed to one end of a rigid shaft; and
a second disc is rotatably fixed to the other end of the rigid shaft, the second disc being of a smaller diameter than the first disc and directly or indirectly rotatable by linear movement of the piston;
wherein, reciprocation of the piston will cause a back-and-forth rotation of the second disc that will, in turn, cause the back-and-forth rotation of the first disc.

### Claim 13 (depends on 12)

The RSPSD of claim 12, wherein vertical travel of the lever in the channel per linear travel distance of the piston is defined by the formula:
y

(
t
)
=
[
L
2
-
[
R
L

sin

(
ϕ
o
-
x
p

(
t
)
R
p
)
]
2
-
(
L
-
d
)
]
-
[
R
L
2
-
[
R
L

sin

(
ϕ
o
-
x
p

(
t
)
R
p
)
]
2
-
R
L
2
-
x
o
2
]
where L is the length of the lever, RL is the radius of the first disc, φ0 is the angle formed between the lever and a radial line of the first disc that extends to the first end of the lever, xp(t) is the distance of movement of the piston, Rp is the radius of the second disc, d is the total vertical travel distance of the lever within the slotted channel, and x0 is the distance between the slotted channel and the contact point of the lever with the circumferential flange of the first disc.

### Claim 14 (depends on 12)

The RSPSD of claim 12, wherein a circumferential displacement and velocity of a point on the first disc relative to a linear displacement and velocity of the piston is magnifiable by increasing the radii ratio of the first disc to the second disc.

### Claim 15

A resetting semi-passive stiffness damper (RSPSD), comprising:
a reciprocatable piston located within a cylinder;
a column;
a rotatable disc rotatably mounted to the column and directly or indirectly rotatable by linear movement of the piston;
an actuator coupled between a structure to be damped and the piston;
a triggering assembly mounted to the column above the disc, the triggering assembly comprising:
a displaceable, spring-loaded lever arranged between a peripheral surface of the disc and a slotted channel associated with the column and residing above the disc, a first end of the lever in contact with the peripheral surface of the disc and a second end of the lever movably residing in the channel, and
a sensor associated with the channel and located to detect the lever when the lever resides within a sensing range of the sensor; and
a bypass valve associated with the cylinder and in communication with the sensor of the triggering assembly so as to receive open and close signals therefrom;
wherein, reciprocation of the piston will cause a back-and-forth rotation of the disc, and the rotation of the disc will cause the first end of the lever to move with the peripheral surface of the disc and the second end of the lever to reciprocate within the slotted channel.

### Claim 16 (depends on 15)

The RSPSD of claim 15, wherein vertical travel of the lever in the channel per linear travel distance of the piston is defined by the formula:
y

(
t
)
=
[
L
2
-
[
R
L

sin

(
ϕ
o
-
x
p

(
t
)
R
L
)
]
2
-
(
L
-
d
)
]
+
[
R
L
2
-
[
R
L

sin

(
ϕ
o
-
x
p

(
t
)
R
L
)
]
2
-
R
L
2
-
x
o
2
]
where L is the length of the lever, RL is the radius of the disc, φ0 is the angle formed between vertical and a radial line extending to the first end of the lever, xp(t) is the distance of movement of the piston, d is the total vertical travel distance of the lever within the slotted channel, and x0 is the distance between the slotted channel and the contact point of the lever with the peripheral surface of the disc.

### Claim 17 (depends on 15)

The RSPSD of claim 15, wherein the peripheral surface of the disc is a circumferential flange that extends from the disc.

### Claim 18 (depends on 15)

The RSPSD of claim 15, wherein:
the disc is a first of two discs and is rotatably fixed to one end of a rigid shaft; and
a second disc is rotatably fixed to the other end of the rigid shaft, the second disc being of a smaller diameter than the first disc and directly or indirectly rotatable by linear movement of the piston;
wherein, reciprocation of the piston will cause a back-and-forth rotation of the second disc that will, in turn, cause the back-and-forth rotation of the first disc.

### Claim 19 (depends on 18)

The RSPSD of claim 18, wherein vertical travel of the lever in the channel per linear travel distance of the piston is defined by the formula:
y

(
t
)
=
[
L
2
-
[
R
L

sin

(
ϕ
o
-
x
p

(
t
)
R
P
)
]
2
-
(
L
-
d
)
]
+
[
R
L
2
-
[
R
L

sin

(
ϕ
o
-
x
p

(
t
)
R
P
)
]
2
-
R
L
2
-
x
o
2
]
where L is the length of the lever, RL is the radius of the first disc, φ0 is the angle formed between vertical and a radial line of the first disc that extends to the first end of the lever, xp(t) is the distance of movement of the piston, Rp is the radius of the second disc, d is the total vertical travel distance of the lever within the slotted channel, and x0 is the distance between the slotted channel and the contact point of the lever with the peripheral surface of the first disc.

### Claim 20 (depends on 18)

The RSPSD of claim 18, wherein a circumferential displacement and velocity of a point on the first disc relative to a linear displacement and velocity of the piston is magnifiable by increasing the radii ratio of the first disc to the second disc.