Note: Descriptions are shown in the official language in which they were submitted.
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BR~KIldC~ FORCE FEEDFsACK DEVICE FOR CALIPER TAIPEI BRAKES
Background of the Invention
Disc caliper brakes are known in the art and have
been used for such applications as braking propeller
shafts, and drill strings on well servicing and
drilling equipment. The applications, particularly in
well servicing and drilling equipment, have not been
completely successful due to the nature ox caliper disc
brakes.
A caliper disc brake is applied by squeezing a
brake pad to a disc which is rotating with the shaft or
equipment, the rotation of which is desired to be con
trolled or stopped. The method of application is to-
tally independent of how the machine or shaft responds
to the brake application. Therefore, the operator has
no "feel" of how the brakes are performing. In other
words, application of the caliper disc brake does not
result in any perceptual feedback to the operator and
thus the operator is unaware of the degree of braking
taking place. This is particularly complicated when
the brake malfunctions, hangs up due to friction, dirt
or the like, or the surface of the brake becomes a-
footed by water, oil, or other surface contaminants.
I
Object of the Invention
The present invention provides the operator ox,
for example, a work over or drilling unit, an actual
- "feel" of the performance of the caliper disc brake.
An object of the present invention therefore is to
provide a braking force feedback signal which is recog-
sizable by the operator and which is directly proper-
tonal to the actual braking force that is occurring.
- An object of the present invention is to mount the
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1 caliper disc brake so that a portion of the reactive
force created by the brake action is transmitted to a --
pressure sensing means, and the pressure sensing means -
in turn imparts a reactive force to the operating lever
for the actuation of the disc brake, which the operator ---
may sense or feel. -
- A further object of the invention is to provide a ---
safe, simple and economic means of accomplishing open-
atop feedback which is essentially failsafe in --
- 10 operation.
These and other objects are obtained in a braking -
force feedback system for caliper disc brakes -
- comprising a means for applying a braking force, a --
control means for controlling the applied braking force
operatively coupled to the means for applying a braking -
force, the control means being operable in response to -
a manual movement, a sensing means for sensing at least ---
a portion of the braking force, and feedback means no- -
sponsive to the sensing means for creating a proper- :
- 20 tonal force to resist the manual movement whereby an --I
operator can sense the amount of braking force. :-
- luff Description of the Drawings
FIG. 1 is an isometric overall assembly view of a --
braking force feedback system according to the present --
invention. --
FIG. 2 is a partial cross section in elevation ox
the force sensing cylinder of the preferred embodiment
- of the present invention. -
FIG. 3 is an elevation view of an operating lever
and lever force cylinder utilized in the present
- invention.
FIG. 4 is a partial cutaway plan view of FIG. 3.
FIG. 5 is a side elevation view of the mounting or
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1 the brake operating valve according to the present
invention.
FIG. 6 is a front elevation of the brake operating
valve according to the present invention.
Description of the Preferred embodiment
The following described embodiment is offered by
way of further describing the invention in terms ox a
presently preferred embodiment.
Referring to FIG. 1, a braking force feedback soys-
them according to the present invention is shown in a
schematic isometric assembly view. A conventional eel-
wiper type disc brake, designated by reference numeral
1, is shown engaging a brake disc 2 which may be also-
elated with any rotating member whose rotation is
desired to be controlled or stopped. In particular,
such rotating member may be, typically, a drill string
or similar rotating shaft wherein the degree ox braking
force developed is of concern to the operation of the
equipment.
The caliper mechanism 3 comprises an opposed pin
lever mechanism which accomplishes equal and opposite
force application on the brake pads 4 in response to
wedging action produced by an operating wedge 5. The
operating wedge 5 is introduced to the caliper mocha-
noisome 3 by means of a pneumatic piston/spring brake act
tutor 6 through the piston rod 7 driven by the Noah-
matte actuator. For purposes of the preferred
embodiment, the pneumatic piston/spring brake actuator
- 30 may be similar to the Commutate spring brake actuator
manufactured by Aero-Quip Corporation ox Jackson,
: Michigan USA. The Commutate actuator provides two-part
braking the first, a service brake which is applied on
positive application of pneumatic pressure, and a sea-
AYE --
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pond emergency brake which is spring applied on loss of
system pressure, as later described. The wedging act
lion transmitted through the caliper mechanism creates
a clamping force on the brake pads 4 which, in turn,
clamp in equal and opposite manner against brake disc
2, thereby producing the desired braking action.
The caliper 1 is shown mounted to a pivoting base
10. Pivoting base 10, in turn, is mounted by means of
pivoting shaft 11 to a fixed base 12. It may be
appreciated by one skilled in the art that, assuming
counterclockwise rotation of the brake disc, braking
force created by the clamping of the brake pads 4 will
result in a braking force directed vertically downward
as shown in FIG. 1. The resulting reaction force on
Thea brake pad would, of course, be vertically upward
and resist the counterclockwise rotation of the brake
disc and hence, through its connection to a rotary
member, the force would resist rotation of that member.
=
The vertically upward braking force on the brake --
pods would tend to rotate the caliper 1 in a clockwise --
direction about pivot shaft 11. In the preferred
embodiment, a force cylinder 15 is provided to resist Jo
the clockwise rotation of the caliper as transmitted -
through pivoting base 10. It may be appreciated by one
squealed in the art that the force applied to the force --
cylinder 15 is therefore directly proportional to the -
braking force generated by the brake pads, and is index
pendant of any forces required to operate the caliper
brake.
Thea construction of the force cylinder 15 is best
seen in FIG. 2. The force cylinder, in general, is a
large diameter, short stroke hydraulic piston which -
converts the mechanical force into a hydraulic pressure ---
sufficient to resist the force. In FIG. 2, the `
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pivoting base 10 is shown connected to an annular pus
ton 20 by means of stud bolts 21. The annular piston
20 bears upon disc plunger 22 which, in turn, bears and
distributes the force load on diaphragm 23.
A hydraulic chamber 25 is formed between the die-
from 23 and a shallow cup shaped cylinder base 26.
The piston 20 is axially guided and retained by a
z-cross section retainer ring 27. The retainer ring 27
also clamps the diaphragm 23 to the cylinder base.
- 10 A convenient number of multiple clamping bolts 29
are provided about the periphery of the cylinder base
to clamp the retainer ring 27 and diaphragm 23 to the
cylinder base. Clamping bolt 29, shown in phantom,
clamps the diaphragm 23 between the retainer ring 27
and the cylinder base. A convenient number of multiple
mounting bolts 30 and nuts 31 are provided about the
periphery of the force cylinder to mount it to the
- fixed base.
It should be understood that the force proportion-
at to the braking force, which is applied to the
pivoting base and thereby to the force cylinder, is
converted into hydraulic pressure sufficient to resist
- the force in hydraulic chamber 25. The hydraulic champ
- bier is filled with hydraulic fluid which is transmitted
through a hydraulic line 35, which is connected to the
f once cylinder 15 by a convenient connection (not
shown) which communicates with the hydraulic chamber.
In the preferred embodiment, the pneumatic piston
actuator 6 forces the wedge 5 to activate the caliper
mechanism 3 when air is supplied through operating air
- line 40. Operating air is received from a convenient
- air supply source, such as an air reservoir 41.
- In the preferred embodiment, air from air riser-
- void 41 is supplied to the pneumatic piston actuator 6
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1 through a series of operating valves and air supply ---
lines. The service brake receives air from reservoir --
41 through line 44 to brake operating valve 45, and -I
when the brake operating valve 45 is opened, air is --
supplied through line 40 to the pneumatic actuator 6. -
The brake operating valve 45 is preferably an on/off -
venting valve, for direct operation by means ox a lever -
actuator 46, such as provided in the preferred --
embodiment. --
The valve actuating lever 46 is shown rotating a- --
bout a pivot 47. The lever 46 is applied by means of -
brake cable 50 in a conventional manner. It should be
understood that air from air reservoir 41 is be sup- ---
- plied to activate the pneumatic piston actuator through --
air supply line 44, brake operating valve 45, and open- -
cling air line 40. Air will be supplied when the valve -
actuating lever 46 is depressed against valve plunger :
48. It should also be understood, at this point, that ---
- valve actuating lever 46 is actuated by brake cable 50. --
In addition to the service brake, a spring opera- -
ted pneumatic released emergency brake is incorporated I-
in the pneumatic piston/spring actuator 6. To accom- ---
polish release of the emergency brake system, air from
reservoir 41 is supplied to a palm operated normally on
delivery vented valve 43 through line 42. Air supplied ---
through palm valve 43 is applied through line 51 to a
normally closed delivery vented pilot operated valve
53. The air supplied through line 51 serves as the
pilot signal to maintain valve 53 in an open position, -I
- 30 whereby air from reservoir 41 is supplied through line --
52 to the spring brake retractor. Emergency release -=
- and activation of the spring brake may be accomplished
- by depressing palm valve 43 which vents the air pros-
sure supplied to pilot valve 53, thereby closing valve --
...
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AYE - -
7 ---
53 and allowing it to vent the spring brake retractor
through line 52, thereby allowing the spring brake to I---
be applied. :
It should also be understood that Should the soys- --
them lose all pressure, the spring brake would also be --
automatically applied as a safety device.
Another feature of the system resides in the --I
mounting of the brake operating valve 45, the valve
actuating lever 46, and the brake cable 50. FIG. 5 -
shows a side elevation of the mounting for the brake --
operating valve. Bracket 60 is secured to the piston ---
rod 7 by means of a slide collar and double nut en- -:-
rangement as shown. Any convenient attachment however --I
- would be adequate as long as the bracket 60 is secured ---
so as to move with the wedge 5. -
Referring to FIG. 6, valve actuating lever 46 is --
shown mounted to the bracket 60 by means of a pivot 47 -
in such a manner as to allow depression of valve plunge -or 48 by the valve actuating lever 46. Cable 50 is ---
mounted by its outer sheath to a bracket on caliper --frame 3. The purpose of this mounting system is that
when the brake lever 55 is applied to a position and ---
held there, the push-pull cable 50 pulls on the lever --
46. This results in the depression of valve plunger 48 -Iand the brake operating valve 45 is opened allowing air --flow to the actuator 6. This increases pressure in the -
actuator service chamber which results in the downward
deployment of the piston rod 7 r the wedge 5, and break- -et 60. Since the cable is mounted to the caliper
frame, the downward movement of the wedge 5 and the --valve 45 releases the force of lever 46 on the valve. -
This action then tends to close the valve 45, and tray-
of of wedge 5 stops and is maintained in this position. ---
- In this situation, the valve 45 is held in its neutral -
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1 position.
If the brake handle 55 is further depressed, a --
further increment of application is achieved. If the -
brake handle 55 is released, the lever 46 releases the --I
- 5 plunger of valve 45 and the air in the actuator 6 servo --
ice chamber is again in proportion to the amount of --
release. -
Another important feature of the system is its a-
ability to achieve a "solid bottom" feel on handle 55. :--
This is achieved by the geometry of the load sensing --
feedback system. Under normal braking conditions with --I
the disc rotating, the friction vector between the pads `
- -
and the disc is essentially vertical as shown in FIG. --I
1. This creates a moment about pivoting shaft 11. The --
moment is counteracted by the force applied by the `
- sensing cell or force cylinder 15. The piston area ray
two between the brake cylinder 65 and the force Cal-
inter 15 is such that the operator can overcome the
maximum moment the system can apply. When the disc no- --
station stops however, it should be appreciated that the
friction vector loses its vertical direction and as- --
sums a direction at approximately right angles to Yen- -
tidal to resist the moment now applied by the force -
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cylinder 15 about pivoting shaft 11. Since the moment --
arm between the vertical friction force and the Herr
zontal friction force about the pivoting shaft 11 is --`
different, a different feel in the handle 55 results ---
when disc rotation stops. In the preferred embodiment, --
the moment arm for the horizontal friction force is
substantially larger (approximately four times), there -
fore stopped disc rotation will result in a substantial
solid bottom feel exhibited in the handle 55.
- The combination of the braking force feedback de- :-
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vice and position responsive operation of brake opera-
:- ,
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g .-.
1 tying valve 45 results in an operator controlled feed- -
back system never before possible with caliper type ---
disc brakes. -
Referring now to FIGS. 3 and 4, a brake handle 55
is shown mounted on a bell crank 56 for rotation -
therewith about an axis perpendicular to the longitude- ----
net axis of the handle. The bell crank 56 is pivotal -
mounted on a mounting plate 57 which is in turn mounted --
to the brake handle case 58. There are two projecting
levers in addition to the brake handle 55 forming bell -
crank Thea first, a brake actuating lever 59, and ---
the second, a reaction lever 60. Brake actuating lever
59 retracts brake cable 50 through adjustable rod 61. -
In the preferred embodiment, the brake cable is a
conventional sliding armored cable, sometimes referred ---
to as a choke cable, and operates in a conventional
manner in that when cable rod 61 is displaced towards ---
the right, as shown in FIG. 3, the flexible center cay -
bye will transmit the movement to valve actuation lever `
46, shown in FIG. 1. This motion displaces the valve --
actuation lever 46 and thereby the valve plunger 48 to
operate the brake operating valve. It may thus be seen
that pushing brake handle 55 down results in applique-
lion of the disc brake.
The outside cable of the brake cable 50 is attach- --
Ed to a mounting bracket 62 in a conventional manner -:
for such cables. The second lever on the bell crank is --
reaction lever 60, which is connected to an adjustable --
reaction rod 63. The reaction rod in turn displaces a -
small bore hydraulic piston which reacts to the hydra-
fig pressure and hydraulic fluid flow produced in the --
force cylinder 15 in response to the braking reaction:-:
force. `-
For purposes of the preferred embodiment, it has
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1 been found extremely convenient to utilize a convent
tonal automotive or truck type master cylinder for
this purpose. Therefore, shown mounted on mounting
plate 57 is a typical heavy duty brake master cylinder
65. The use of a conventional brake master cylinder
has been found convenient because of its reservoir cay
paucity and suitable construction, although its prince-
pal function is reversed in the present application, as
will now be explained.
In a normal master cylinder function, displacement
of the adjustable reaction rod 63 to the left would no-
suit in hydraulic pressure and fluid flow exiting ho-
draulic line connection 66. This hydraulic fluid
would activate the brakes of a vehicle to cause the Ye-
hide to stop. In the present application, however,
the function is reversed in that hydraulic fluid is
pressurized in the force cylinder 15 and allowed to
flow through hydraulic line 35 into the hydraulic line
connection 66 which, in turn, forces the small diameter
piston to be displaced to the right. Adjustable react
lion rod 63 is also thereby displaced to the right.
The movement of the reaction rod transmitted through
bell crank 56, results in an upward movement of the
brake handle 55.
In summary, as the operator depresses the brake
handle 55, the control valve 48 will supply air to the
pneumatic piston actuator 6 and the brake will be
applied. In response to the application of the brake,
a resulting force will be applied in proportion to the
amount of braking reaction force applied to force Cal-
inter 15. Force cylinder 15, in turn, will produce ho-
draulic fluid pressure and flow which will be applied
to the brake master cylinder 65. Movement of the small
bore piston in the brake master cylinder results in a
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1 force resisting the downward movement of the brake ken- --
die in proportion to the amount of braking. A Unsolid ---
bottom feel is achieved when the rotation is stopped -
completely.
The proportional resistance or feedback produced --
by this system assists the operator in determining pro- --
wisely the amount of braking force occurring and, in
......
fact, the amount of braking is proportional to the ---
force applied to the handle. The amount of reaction,
and therefore the amount of braking for a given force ---
in the brake handle, may be controlled by relocation ox
the pivot shaft 11 relative to the effective lever arm --
between the brake pad and the pivot point, and the peeve
ox point and the point of application ox the force on
the force cylinder. In addition, it may also be en
footed by choice of appropriate relative cylinder sizes -
between the force cylinder and the brake master Solon- --
don and/or, alternatively, the length of the reaction -
lever 60 relative to the length of the brake handle 55.
waving described my invention in terms of a pro- ---
furred embodiment, numerous modifications or substitu-
lions of equipment may be made by one skilled in the --
art. Therefore, I do not wish to be limited in the
scope of my invention except as claimed.
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