Elevator – industrial lift truck – or stationary lift for vehicle – Having specific means contacting or on load support for... – Includes movable contact component on support for engaging...
Reexamination Certificate
2002-08-02
2004-06-22
Lillis, Eileen D. (Department: 3652)
Elevator, industrial lift truck, or stationary lift for vehicle
Having specific means contacting or on load support for...
Includes movable contact component on support for engaging...
C187S287000, C187S305000, C188S187000
Reexamination Certificate
active
06752246
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
This application claims benefit of priority to Japanese Application number JP 2001-236746 filed Aug. 3, 2001, the entire content of which is incorporated by reference herein.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a speed governor that detects excessive traveling speed of an elevator cage or counterweight and to an elevator employing this speed governor.
2. Description of the Related Art
Article 129 No. 9(7) of Regulations made under regulation of the Japanese Building Standards Law specifies that, as a safety device in an elevator, there must be provided a device to automatically restrain descent of the cage if the speed of the descending cage exceeds a prescribed value.
FIG. 1
is a view showing diagrammatically the mechanism of a typical elevator provided with an emergency stop device. Elevator cage
101
is raised and lowered within an ascent/descent path (shaft) by means of a winding machine (hoist)(not shown) from which it is suspended by a main rope
102
, its ascent/descent being guided by a guide rail
103
provided in the ascent/descent path. An emergency stop device
104
is mounted on cage
101
. If the speed of elevator cage
101
exceeds the rated speed due to breakage of main rope
102
or abnormal increase of the speed of rotation of the winding machine, emergency stop device
104
mechanically stops cage
101
by gripping guide rail
103
.
That is, when excessive speed of the elevator is detected by speed governor
105
provided in the mechanism chamber, a rope clamping element
106
incorporated in a speed governor
105
is actuated, causing speed governor rope
107
that passes over the sheave of speed governor
105
to be gripped. When speed governor rope
107
is gripped, emergency stop device
104
is actuated by means of a safety link
108
mounted on cage
101
.
FIG. 2
shows a typical speed governor employed in a high-speed elevator. This speed governor is a type of centrifugal speed governor. When sheave
108
mounted on speed governor rope
107
is rotated, this rotation is transmitted by means of a rotary shaft
113
directed in the vertical direction, by means of gear wheel
112
. First links
110
A constituting part of speed governor linkage mechanism
110
are mounted on a rotary shaft
113
and rotary weights (flyweights)
109
are mounted at the tips of the link arms of first links
110
A. When sheave
108
is rotated, the link arms on which rotary weights
109
are mounted are opened by centrifugal force C acting on rotary weights
109
, thereby raising or lowering a shaft sliding sleeve mounted on rotary shaft
113
. A support shaft of a second link
110
B constituting another part of speed governor linkage mechanism
110
is mounted on the shaft sliding sleeve. Second link
110
B is moved with displacement of the shaft sliding sleeve in the vertical direction and when the amount of displacement of the shaft sliding sleeve exceeds a prescribed value, a hook (not clearly shown in the drawing) provided at the end of the second link
110
B is released from rope clamping element
106
. Rope clamping element
106
thereby grips speed governor rope
107
, causing the movement of speed governor rope
107
to be arrested. When this happens, emergency stop device
104
is actuated by means of a safety link
108
mounted on cage
101
(see FIG.
1
).
However, typically, in order to achieve stable operation and to prevent unwanted operation, the speed governor is adjusted such that the first and second links
110
A and
110
B i.e. speed governor linkage mechanism
110
are not operated until the rated operating speed of the elevator cage has been slightly exceeded. With this object, a speed adjustment spring
111
is provided on first link
110
A; this speed adjustment spring ill generates a balancing force opposing centrifugal force C that acts on the rotary weights
109
at the rated speed of travel of elevator cage
101
. Also, speed adjustment spring
111
is adjusted so as to generate a spring force such as to restrict the movement of speed governor linkage mechanism
110
such that second link
100
B actuates rope clamping element
106
just when the speed of cage
101
exceeds the rated value.
The speed governor shown in
FIG. 2
is called an “upright type” speed governor, since the rotary shaft
113
of rotary weights
109
is directed vertically upwards. In contrast, there are also available “horizontal type” centrifugal speed governors, in which the rotary shaft of the rotary weights is directed horizontally. An example of such is shown in FIG.
3
. The construction of the speed governor shown in
FIG. 3
can be understood by reference to the construction of the speed governor shown in
FIG. 5
, which is described in detail later, in the section “Detailed description of the preferred embodiments”. The speed governor shown in
FIG. 3
is described with the object of a comparative explanation of the technical effect with the speed governor according to the present invention in the section “Detailed description of the preferred embodiments” later; it is not the case that the entire construction of the speed governor shown in
FIG. 3
is publicly known.
In the upright type centrifugal speed governor shown in
FIG. 2
, in order to convert the rotation of sheave
108
about a horizontal axis into rotation about a vertical axis it is necessary to provide a gear wheel
112
. This has the drawback that the mechanism becomes complicated and the number of components are increased. On the other hand, since the mass of rotary weights
109
and/or link mechanism
110
A acts as a balancing force opposing the centrifugal force C acting on centrifugal weights
109
, there is the advantage that operation of the speed governor can be restrained by these masses.
In contrast, in the case of the horizontal type of centrifugal speed governor shown in
FIG. 3
, since the rotary shaft of rotary weights
19
and the rotary shaft of the sheave can be shared, a mechanism such as a gear wheel is unnecessary. The number of components can therefore be decreased compared with the upright type. Also, since the rotary shaft of sheave
11
rotates the rotary weights directly, there is the advantage that the speed governor operates linearly in respect of changes of speed of movement of the elevator i.e. the advantage that precision of the speed governor is increased. However, since the pair of rotary weights
19
and the links
16
associated therewith are arranged in a condition with their weights balanced about rotary shaft
13
, the mass of rotary weights
19
and/or link
16
and the like does not act as a balancing force opposing centrifugal force C. There is therefore the disadvantage that movement of the speed governor linkage mechanism must be restrained i.e. controlled solely by means of the spring force generated by speed adjustment spring
26
.
The magnitude of the centrifugal force C acting on the rotary weights is expressed in the form:
C=mr&ohgr;
2
=mv
2
/r
where C is the centrifugal force, m is the mass of the rotary weights, r is the radius of rotation of the rotary weights, &ohgr; is the angular velocity of the rotary weights and v is the elevator speed.
As can be seen from this equation (expression), the centrifugal force C is proportional to the square of the rotational speed. In recent years, very high-speed elevators of rated speed surpassing 600 m/min have appeared. In the speed governors of such high-speed elevators, as shown in
FIG. 4
, not only the magnitude of the centrifugal force C itself acting on the rotary weights but also the range of the centrifugal force C (i.e. the difference of the centrifugal force at the rated speed and the centrifugal force under excess speed conditions under which the emergency stop device would be expected to be actuated) is much greater than in a conventional elevator. Consequently, a speed governor is required having a function of being able to control in a reliable fashion actuation of the speed governor linkage mech
Kobayashi Hidehiko
Takai Kazuhiko
Lillis Eileen D.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Toshiba Elevator Kabushiki Kaisha
Tran Thuy V.
LandOfFree
Speed governor and elevator employing the speed governor does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Speed governor and elevator employing the speed governor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Speed governor and elevator employing the speed governor will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3305328