192 clutches and power-stop control – Transmission and brake – Torque-responsive brake
Reexamination Certificate
2001-03-09
2003-12-02
Schwartz, Christopher P. (Department: 3683)
192 clutches and power-stop control
Transmission and brake
Torque-responsive brake
C192S075000, C188S083000
Reexamination Certificate
active
06655520
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to brake drives (reverse brakes) which can be employed in many engineering sectors, for example as adjusting and fixing devices in machines, medical instruments and equipment, sports and household devices, control mechanisms, for chairs and other items of furniture, in vehicles, aeroplanes, car seats etc. These brake drives can be actuated by both a hand wheel
6
and by a control lever (
6
a
in
FIG. 5
) or by electrical, pneumatic, hydraulic or any other switching or control elements which are not shown.
The object of the invention is to create brake drives which can be designed in a simple and cost-effective manner owing to their construction and optimal brake pressure distribution, and can also be designed in plastics material, zinc injection moulding or aluminium injection moulding, i.e. from less rigid material (parts
1
to
6
a
) and can be adjusted and fixed by both a hand wheel (
6
) and by a control lever (
6
a
in
FIG. 5
) or by electric, pneumatic, hydraulic, magnetic or any other switching or control elements (not shown) from the primary or drive side “by entraining the drive side, for example shaft
3
” in both directions, in other words against a blocking or braking force, with the smallest amount of slippage between primary rotational movement (adjustment or actuation) and secondary reverse locking or movement, for example at a drive or driven shaft
3
. A forward or reverse movement, each rotational movement of the drive and driven shafts can be severely braked or completely blocked and released again as quickly as desired and at any time depending on the design and adjustment. The disadvantages or weaknesses of brake drives and overrunning-type brakes according to the current state of the art are avoided by the subject of the invention.
Up until now, brake drives had inter alia multi-threaded cylindrical helical springs as braking element, which springs gradually expand along a stationary drum cylinder from one spring winding to the next owing to circular pressure (for example anticlockwise) on one of the two spring ends in a stationary drum cylinder until all windings are gradually jammed against the stationary drum and block further rotation in the same direction. Owing to a circular tensile force at the other end of the same brake spring (understandably only with slippage with respect to the preceding circular force of pressure at the other spring end), the individual spring windings can gradually be spooled onto a smaller cylindrical external diameter of the spring and jamming or blocking against rotation of the spring and therefore of a potential drive shaft are gradually cancelled only with an undesirable slippage path.
This dead rotational slippage between releasing, rotating and blocking in previous reverse brakes constitutes a big disadvantage compared with the present “Brake drive” invention.
A further disadvantage of these multiple springs is that only a very thin, circular, external line of the individual helical spring windings, in other words a very small face, is supported on the housing inner cylinder, as a result of which, a high rigidity material such as steel or the like must be used as a spring and also for the brake drum (as a large specific force has to be exerted by the mini-friction face of the spring onto the cylindrical friction face).
A further significant disadvantage is that “a large amount” of unused space and unused cylindrical friction face of the housing, in other words unused brake drum face between the thin actual spring friction faces, is wasted between the very thin, helical friction faces of each individual helical spring winding supported tangentially on the brake cylinder.
The hitherto conventional overrunning roller-type or overrunning ball-type brakes require a similar waste of space and unnecessarily require an extremely high level of material rigidity (and are therefore generally made of steel and with expensive, and the highest levels of precision), which brake types all operate only with point application in terms of material even when the largest braking or blocking force is desired.
Shoe brakes have the disadvantage inter alia that their cylindrical friction faces are constantly rigid in diameter and in the curvature with the housing internal cylinder curvature do not achieve a really saturated specific force of pressure applied uniformly to the entire brake periphery or cannot guarantee this over a prolonged period of time. For this reason, nearly all shoe brakes must comprise an additional compressible material (the brake linings) between the shoe brake face and the drum inner cylinder brake face which also has to be replaced with prolonged use.
SUMMARY OF THE INVENTION
Advantageous embodiments of the present “Brake drive” invention are provided in the patent claims and sub-claims and the drawings and, in brief, provide the following advantages:
1. Both “active” brake cylinder faces
5
are many times larger because they rest on one another “with their entire faces” without unused intermediate spaces and therefore can be used 100%.
2. As a result, the specific surface pressure (per mm
2
) is so small that even plastics material, aluminium, zinc or other injection moulded materials or less rigid materials and more favourable production methods can be used for the active elements.
3. The expanding ring
2
has no no-load operation (slippage) between blocking and releasing because (like a helical spring) it does not have to wind or unwind over a plurality of spring windings when it receives a circular push at a brake cylinder end of the expanding ring to radially enlarge the diameter or the brake force and inversely, receives circular tensile force at the other pitch circle end of the brake cylinder once to reduce the expanding ring diameter and therefore to lift the brake in order to be able to adjust the brake drive.
4. The entire one-piece expanding ring (see
FIG. 1
) can also be designed as a double ring as in FIG.
3
and with and without additional expansion springs (
9
,
9
′,
9
″, see
FIG. 2
) and can also be of multi-layered laminated design and despite this retains all the advantages of the new brake drive.
5. The expanding ring
2
which, with its larger external cylinder diameter, was squeezed upon installation into the smaller internal cylinder of the brake drum
1
, has (in contrast to rigid shoe brakes) the active snap force (expansion force) at all points of its friction cylinder periphery, in addition to the normal application force, to convert itself from a smaller radius into a larger radius by means of its inherent tendency and its stored force.
Owing to the previously mentioned advantages alone, the brake drives according to the present invention rarely have any undesired slippage between control and blocking or braking any more, and this is in both primary and secondary terms, in other words at the input and at the output side.
6. Further advantages are given by an additional increase in the brake force of the brake drive inter alia by, for example:
a) keyway-shaped inner and outer faces between expanding ring and housing (transverse to the cylinder face, see
FIG. 4
on the brake faces
5
) as a result of which an additional snap and braking effect or blockage is produced by the tapered rings in the opposing keyways at the entire periphery, as is the case with a V-belt.
b) Owing to symmetrical or asymmetrical micro or normal waviness of one or both friction faces, in longitudinal direction or direction of rotation of the circular brake faces (see
FIG. 3
, circular pictures a and b), a complete standstill against a rotation is achieved between drum
1
and expanding ring
2
with the slightest expansion, and running is again achieved with slight compression of the expanding ring.
c) Owing to such a symmetrical or asymmetrical micro- or macro-waviness of one or both friction surfaces, or micro- or macro-waviness extending in another way, an ideal state can be achieved for many purposes, for example, in such a way that the b
Haldiman, Esq. Robert C.
Kang, Esq. Grant D.
Nguyen Xuan Lan
Schwartz Christopher P.
Shukra-Geratebau A.G.
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