Note: Descriptions are shown in the official language in which they were submitted.
213~8~ :
COMPENSATION
This invention relates to elevator systems, and
more particularly to a compensation arrangement for such
systems.
5In high-rise buildings, elevators need to be
provided with compensating ropes, belts or chains to offset
the unbalance moment generated when the car is moving. If
this were not done, motors of a considerably larger size
would have to be used. This phenomenon would become worse
with increasing height. If the height in the shaft is
increased sufficiently without such compensation, a situa-
tion occurs in which friction is insufficient. In these,
the compensation rope is fastened via a fixed wheel to the
bottom of the elevator shaft.
15There are two different types of rope compensa-
tion. In the first type, a rope, belt or chain is used,
often lined with rubber or plastic and having additional
masses attached to them. These ropes, belts or chains are
mounted as loops below and between the elevator car and
counterweight, and they are preferably attached to a lower
part of the car or counterweightO The application range of
this rope compensation is limited to relatively low speeds
because of the danger of rope swing. At the culmination
point of the loop, the speed of the rope, belt or chain is
the same as that of the elevator. This speed is referred to
as the loop circulation speed. If the speed of the elevator
is changed during acceleration or deceleration, the speed of
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the loop also changes -- and the rope starts to swing. The
larger the speed range, the greater i5 the danger that the
swinging will result in the rope, belt or chain being caught
on a piece of shaft equipment.
In the other type of compensation, additional
masses used are generally a rope or ropes hanging in the
form of loops below and between the car and counterweight.
Additionally, these loops are tightened by means of a ten-
sioning device. In this other type, swing is prevented by
using a guided tension weight. An example of technology
known for solving this problem is disclosed in U.S. Patent
No. 3,653,467. Drawbacks of this technology include high
cost and complex structure.
The solution offered by the invention eliminates
these drawbacks by rendering the expensive tension weight
unnecessary, and halving the prior art loop speed. This is
achieved by suspending the compensating ropes so that they
run from the underside of the elevator car to fixing points
in the wall of the elevator shaft, and similarly from the
underside of the counterweight to fixing points in the shaft
wall. Thus, the compensating ropes are suspended in the
same way as the car cable, i.e. the cable that carries call
button signalling and the electricity supply to the elevator
car. Both compensation loops are attached to the shaft wall
at a point at or above the midpoint of the path of the ele~
vator car or counterweight. When the car moves downwardly,
both the car cable loop and the car compensation loop move
'.,.'"' ~
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downwardly, and the loop circulation speed is only half the
travelling speed of the car. Simultaneously the counter-
weight and its compensation loop are moving upwardly. The
circulation speed of the counterweight compensation loop is
half the travelling speed of the counterweight. With the
compensating rope and the car cable are suspended in the
same fashion, it is possible to combine their functions.
This can be done, for instance, by adding steel balls to the
armature of the car cable, as in Whisperflex* compensation
chain.
The invention provides considerable advantages.
Firstly, the loop circulation speed is only half the car
speed, which means that swing is reduced significantly.
This effect is known in car cables, which need no guiding
even at high speed. Secondly, an expensive tensioning
device for swing damping is no longer needed. Thirdly, the
cost of the compensation as a whole is about the same as for
the present chain/belt compensation. Fourthly, compensation
can now be implemented by means of the car cable, part or
all of which is used as a compensation loop. Fifthly, in
very high buildings no stopper for the prevention of coun-
terweight bounce is needed if a solution using the subject
invention and that in Finnish Patent No. FI 82823 is used,
because the speed of the counterweight is lower and there-
fore the counterweight bounce smaller.
* Trade-mark
213~818
The invention is a compensation arrangement for an
elevator system having a car, a counterweight, suspension
cable means for suspending the car and counterweight, a
traction sheave around which the cable means passes and
whose motion is transmitted via the cable means to the car
and counterweight, at least one diverting pulley around
which the cable means also passes, and a car cable suspended
by one end from the car. The compensating arrangement com~
prises a car compensation loop for the car, and a counter-
weight compensation loop for the counterweight. The carcompensation loop is suspended by one end from the car and
by the other end from a wall of the elevator shaft. The
counterweight compensation loop is suspended by one end from
the counterweight and by the other end from a wall of the
elevator shaft. The circulation speed of the car compensa-
tion loop is half the travelliny speed of the car, and the
circulation speed of the counterweight compensation loop is
half the travelling speed of the counterweight. The car
loop and the compensation loop are attached to the wall of
the elevator shaft at a point located at or above the
midpoint of the path of the car and counterweight. The car
cable may be used either partly or entirely as the car
compensation loop.
The invention will next be more fully described by
means of two preferred embodiments, utilizing the accompany~
ing drawings, in which:
,' ',,
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Fig. 1 is a schematic illustration of an elevator
system with a f irst embodirnent of the compensation
arrangement of the subject invention, the elevator car and
counterweight of the system being positioned midway in an
elevator shaft;
Fig. 2 is a schematic illustration of the elevator
system of Fig. 1, but illustrating the car and counterweight
positioned near the top of the shaft;
Fig. 3 is a schematic illustration of the elevator
system of Fig. 1, but illustrating the car and counterweight
positioned near the bottom of the shaft;
Fig. 4 is a schematic illustration of an elevator
system with a second embodiment of the compensation
arrangement of the subject invention, the car cable and car
compensation loop being combined in this embodiment;
Fig. 5 is a schematic illustration of an elevator
system with a third embodiment of the compensation
arrangement of the subject invention, the counterweight
being suspended in an alternate way in this embodiment.
As illustrated in Fig. 1, an elevator system 1 has
an elevator car 2 and a counterweight 3 suspended in a ratio
1:1 by an elevator rope 11 extending over a traction sheave
5 and a diverting pulley 6. Rotational motion of traction
sheave 5 is transmitted via rope 11 to the elevator car 2
and the counterweight 3~ A car cable 4 extends from the car
2 to a f ixing point 8 in a shaft wall of the elevator system
1. A compensation loop 7a extends from the car 2 to a
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fixing point 9 in a shaft wall. Similarly, the compensation
loop 7b extends from the counterweight 3 to a fixing point
10 in a shaft wall. The compensation loops 7a and 7b are
attached to the shaft wall at a point located at or above ~ ~-
the midpoint of the path of the elevator car 2 and counter~
weight 3. The fixing point 8 of the car cable 4 is at the ;;;
same height as the fixing point of the compensation loops. ~ ~
The circulation spaed of the compensation loop 7b for the ~ "~t
counterweight 3 is half the travelling speed of counter~
weight 3, and the circulation speed of the compensation loop
7a for the elevator car 2 is half the travelling speed of ~
car 2. ;;
Consider next the situation where the elevator car
2 and the counterweight 3 are both located midway in the
15 shaft. In this case, the mass of the elevator car 2 has `
been increased by an amount corresponding to the balancing
percentage of the counterweight, so the elevator car should
be in equilibrium with the counterweight 3. The brake of
the machinery can now be released without the elevator car
2 and counterweight 3 getting in motion. This is only
possible if the rope forces on the side of the elevator car
2 and on the side of the counterweight 3 are equal. In this
position, the suspension ropes ll on the side of elevator ~ `
car 2 and on the side of the counterweight 3 are about the ~ `
same length, which is half the travel height H. The mass/
length of the hoisting rope is equal to Ml. Below the
alevator car 2 hangs compensation loop 7a. The loop length
,~
~, .
hanging from the ele~ator car ~' is at this point half the
total loop length, i.e. about % o~ the travel height H. The
mass/length of the car cable 4 is M2, and the mass/length of
compensation loop 7a is M3. The counterweight 3 contains:
(the mass o~ the elevator car 2) ~ (balancing percentage)*
(nominal load) + (so-called cable setoff). Below the coun-
terweight 3 hangs the counterweight compensation loop 7b, in
which the portion hanging from the counterweight 3 equals ~
of the travel height H. The mass/length of this compensa-
tion loop is also M3. The bare weight of the elevator car
2 is P, the nominal load is Q, the counterweight balancing
percentage is T, and X is an extra mass which is added to
the counterweight 3 to achieve balance midway in the shaft.
The balancing formula is as follows:
P + (Q*T) + (~H*Ml) + (%H*(M2+M3)) =
P + (Q*T) + X + (~H*M1) + (%H*M3) (1)
Consequently, X = %H*M2 (2)
From equation (2), the extra mass X of the counterweight 3
is obtained. With this extra mass X, balance is achieved.
Fig. 2 presents a situation where the car is near
the top of the shaft, and the counterweight is near the
bottom. The balancing equation is now:
P + (Q*T) + (~H*(M2+M3)) =
_~ P + (Q*T) + X + (H*M1) (3)
When equation (2) is added to equation (3), one obtains:
P`+ (Q*T) + (~H*(M2+M3)) =
P + (Q*T) + (~H*M1) + (H*M1) (4)
::: . . , , - ~
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- ` .
Consequently, M3 = 2M1 - ~M2 (5)
Fig. 3 presents a situation where the elevator car
is near the bottom of the shaft, and the counterweight is
near the top.
The balanciny equation is now:
P + (Q*T) ~ (H*M1) = P + (Q*T) + X + (~H*M3), and
combining this with equation (2) results in:
P + (Q*T) + (H*M1) =
P + (~*T) + (~H*M2) + (~H*M3), from which:
M3 = 2Ml - ~M2, i.e. the same as equation (5).
By using an extra mass X = ~H*M2 and compensating
mass M3 = 2M1 - ~M2, a situation is achieved where the
elevator is in equilibrium regardless of the position of the
elevator car 2 and the counterweight 3.
Fig. 4 presents an alternative solution in which
the car cable 4 can be used for compensation, either in part
or entirely. If the car cable 4 is used for full
compensation, we obtain a solution as presented in Fig. 4.
In this example, the elevator car 2 is located midway in the
shaft. The extra mass X is zero, equation (2) yields M2 =
0, and equation (5) yields M3 = 2M1.
Fig. 5 presents a solution which can be used in
the invention of Finnish Patent No. FI 82823. In this
solution, the counterweight 3 is twice as heavy as in the
above-mentioned Figs. 1-4, and the path travelled and the
speéd of the counterweight 3 are half those of the car 2.
Fig. 5 shows the elevator car 2 in its extreme positions.
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..
The result in this case is also a fully-compensated solu-
tion. The mass/length of the compensation loop 7b for the
counterweight 3 is larger than the mass/length of the
compensation loop 7a for the elevator car 2. As explained
in connection with with Figs. 1-4, appropriate balancing
equations can be solved to provide different solutions for
the elevator car 2 and the counterweight 3. The equations
depend on the location of the path of the counterweight 3,
which may vary from case to case.
It should be obvious to a person skilled in the
art that different embodiments of the invention are not
restricted to the examples described above, but that such
embodiments my be varied within the scope of the claims
presented below.
. . . . . . . . . . ~ . .
