Patent Application
20200002129
The present disclosure is generally directed to a slack detection device for use in elevator systems. More particularly, the present disclosure is directed to a counterweight slack detection switch for detecting slack in a tension member connected to a counterweight.
Elevators for vertically transporting people and goods are an integral part of modern residential and commercial buildings. A typical elevator system includes an elevator car raised and lowered by a hoist system. The hoist system typically includes one or more tension members connecting the elevator car to a counterweight. The tension members are routed over drive and idler sheaves. The elevator car is raised or lowered due to frictional traction between the tension members and the rotating drive sheaves. A variety of tension member types, including wire rope, V-belts, flat belts, and chains, may be used, with the sheave assemblies having corresponding running surfaces to transmit tractive force between the tension members and the sheave assemblies.
If for any reason the counterweight becomes immovable during operation of the elevator, slack may propagate in the one or more tension members as the drive sheaves continue to rotate against the tension members. Depending on the coefficient of friction of the tension members, propagation of slack eventually causes the tension members to slip on the drive sheaves such that the elevator car ceases to move any further. Many elevator regulatory codes require that the tension members have a sufficiently low coefficient of friction so that only a small amount of slack is permitted to propagate in the tension members before the tension members begin to slip on the drive sheaves. Limiting the amount of slack in the tension members prevents excessive, even catastrophic, slippage of the elevator car once the slack overcomes the frictional traction of the tension members against the drive sheaves. Thus, limiting the coefficient of friction of the tension members partially self-regulates the elevator against unacceptable levels of car slippage.
Some modern types of tension members, such as composite belts, have inherently high coefficients of friction that permit unsafe levels of slack to propagate in the tension members. In order for such tension members to be safely utilized, alternative means of preventing slack propagation in the tension members is needed.
In view of the foregoing, there exists a need for devices for stopping operation of an elevator system to prevent unsafe levels of slack from propagating in tension members due to, for example, the counterweight not moving.
Embodiments of the present disclosure are directed to a counterweight slack detection switch including a body, a first belt guide mounted to the body and configured to engage a first side of a tension member, a second belt guide mounted to the body and configured to engage the first side of the tension member, a lever arm having a first end and a second end, the first end pivotally mounted to the body, a deflectable member biasing the lever arm relative to the body, a third belt guide mounted to the second end of the lever arm and configured to bias the tension member from a tension position to a slack position, and a switch mounted to the body and configured to contact the tension member when the tension member is in at least one of the tension position and the slack position.
In some embodiments, the third belt guide is configured to engage the first side of the tension member.
In some embodiments, the third belt guide is configured to engage a second side of the tension member opposite the first side of the tension member.
In some embodiments, counterweight slack detection switch further includes a clamp for securing the counterweight slack detection switch to the tension member.
In some embodiments, at least one of the first belt guide and the second belt guide includes a clamp for securing the counterweight slack detection switch to the tension member.
In some embodiments, the switch includes one of a momentary switch and a latching switch.
In some embodiments, the deflectable member includes one of a torsion spring, a compression spring, a leaf spring, and a tension spring.
In some embodiments, the lever arm includes a tab for engaging a portion of the deflectable member.
Other embodiments of the present disclosure are directed to an elevator system including an end termination, a tension member extending from the end termination, the tension member having a first side and second side opposite the first side, and a counterweight slack detection switch. The counterweight slack detection switch includes a body, a first belt guide mounted to the body and configured to engage the first side of the tension member, a second belt guide mounted to the body and configured to engage the first side of the tension member, a lever arm having a first end and a second end, the first end pivotally mounted to the body, a deflectable member biasing the lever arm relative to the body, a third belt guide mounted to the second end of the lever and configured to bias the tension member from a tension position to a slack position, and a switch mounted to the body and configured to contact the tension member when the tension member is in at least one of the tension position and the slack position.
In some embodiments, the third belt guide of the counterweight slack detection switch is configured to engage the first side of the tension member.
In some embodiments, the third belt guide of the counterweight slack detection switch is configured to engage the second side of the tension member opposite the first side of the tension member.
These and other features and characteristics of a counterweight slack detection switch, as well as elevator systems including the same, will become more apparent upon consideration of the following description and the appended claims with reference to the accompanying drawings, all of which form a part of this specification, wherein like reference numerals designate corresponding parts in the various figures. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the disclosure. As used in the specification and claims, the singular forms of “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise.
For purposes of the description hereinafter, the terms “upper”, “lower”, “right”, “left”, “vertical”, “horizontal”, “top”, “bottom”, “lateral”, “longitudinal”, and derivatives thereof shall relate to the disclosed apparatus as it is oriented in the figures. However, it is to be understood that the apparatus of the present disclosure may assume alternative variations and step sequences, except where expressly specified to the contrary. It is also to be understood that the specific systems and processes illustrated in the attached drawings and described in the following specification are simply exemplary examples of the apparatus disclosed herein. Hence, specific dimensions and other physical characteristics related to the examples disclosed herein are not to be considered as limiting.
As used herein, the terms “sheave” and “pulley” are used interchangeably to describe a wheel for tractive connection to a tension member of any type. It is to be understood that a “pulley” is encompassed by the recitation of a “sheave”, and vice versa, unless explicitly stated to the contrary.
As used herein, the terms “substantially” or “approximately”, when used to relate a first numerical value or condition to a second numerical value or condition, means that the first numerical value or condition is within 10 units or within 10% of the second numerical value or condition, as the context dictates and unless explicitly indicated to the contrary. For example, the term “substantially parallel to” means within plus or minus 10° of parallel. Similarly, the term “substantially perpendicular to” means within plus or minus 10° of perpendicular. Similarly, the term “substantially equal in volume” means within 10% of being equal in volume. “Substantially the same” means within normal manufacturing tolerances.
As used herein, the terms “transverse”, “transverse to”, and “transversely to” a given direction mean not parallel to that given direction. Thus, the terms “transverse”, “transverse to”, and “transversely to” a given direction encompass directions perpendicular to, substantially perpendicular to, and otherwise not parallel to the given direction.
As used herein, the term “diameter” means any straight line segment passing through a center point of a circle, sphere, ellipse, ellipsoid, or other rounded two- or three-dimensional object from one point on the periphery of said object to another point on the periphery of said object. Non-circular and non-spherical objects may have several such diameters of differing length, including a major diameter being the longest straight line segment meeting the aforementioned criteria, and a minor diameter being the shortest straight line segment meeting the aforementioned criteria.
As used herein, the term “associated with”, when used in reference to multiple features or structures, means that the multiple features or structures are in contact with, touching, directly connected to, indirectly connected to, adhered to, or integrally formed with one another.
As used herein, the term “configured” or “configuration” refers to structural size and/or shape.
Referring to the drawings in which like reference numerals refer to like parts throughout the several views thereof, the present disclosure is generally directed to a counterweight slack detection switch for use on a tension member of an elevator system. It is to be understood, however, that the slack detection switch described herein may be used in many different applications in which tension members are utilized in traction with sheaves. The present disclosure is also directed to an elevator system utilizing the counterweight slack detection switch.
Referring now to
A deflectable member 150 biases the lever arm 140 such that the third belt guide 130 is drawn toward a plane tangent to the first belt guide 110 and the second belt guide 120. The deflectable member 150 is configured such that the force applied to the tension member 2000 by the third belt guide 130 causes deflection of the tension member 2000 when the tension member 2000 is in a state of reduced tension.
The components of the slack detection switch 1000 shown in
Each of the first, second, and third belt guides 110, 120, 130 may include a roller 111, 121, 131 which is freely rotatable to facilitate vertical positioning of the slack detection switch 1000 along the tension member 2000, and to prevent frictional shearing between the tension member 2000 and the first, second, and/or third belt guides 110, 120, 130 during deflection of the third belt guide 130. Each roller 111, 121, 131 may include a lip 112, 122, 132 on one or both ends to prevent lateral movement of the tension member 2000 relative to the slack detection switch 1000. In embodiments in which the tension member 2000 is a v-belt, cable, or wire rope, each of the rollers 111, 121, 131 may include a groove corresponding to the profile of the tension member 2000. In other embodiments, each of the first, second, and third belt guides 110, 120, 130 may be fixed, i.e., not rotatable relative to the body 101.
The lever arm 140 has a first end 141 pivotally attached to the body 101 via a pin 142 or other suitable fastening member. A second end 143 of the lever arm 140 provides a mounting location for the third belt guide 130. The lever arm 140 may include a tab 144 for engaging a portion of the deflectable member 150.
The deflectable member 150 may be a torsion spring, as shown in the drawings, or may be a tension spring, a compression spring, a leaf spring, an elastomer, a bladder, a hydraulic cylinder, a pneumatic cylinder, and/or a shock absorber. The deflectable member 150, when mounted to the body 101 and the lever arm 140, produces a force sufficient to bias the lever arm 140 when the tension member 2000 is in a state of reduced tension, such as when the counterweight is not moving as intended.
The clamp 160 may include a fixed portion 161 attached to or integral with the body 101, a moveable portion 162, and a fastener 163 for securing the moveable portion 162 to the fixed portion 161 with the tension member 2000 arranged between the moveable portion 162 and the fixed portion 161. Surfaces of the fixed portion 161 and/or the moveable portion 162 which engage the tension member 2000 may include surface features or a coating to prevent slipping of the tension member 2000 relative to the clamp 160.
The switch 170 includes a terminal connector 172 for communicating with a controller (not shown) of the elevator system. The switch 170 may be a momentary switch or a latching switch. The switch 170 may be either normally open or normally closed, depending on the programming of the controller. In the embodiment shown in the accompanying drawings, the switch 170 is arranged to engage the first side 2001 of the tension member 2000, such that deflection of the lever arm 140 biases the tension member 2000 toward the switch 170. If the contact 171 of the switch 170 is depressed due to deflection of the lever arm 140, the switch 170 communicates a fault state to the drive controller. In other embodiments, the switch 170 may be arranged to engage the second side 2002 of the tension member 2000 such that deflection of the lever arm 140 biases the tension member 2000 away from the switch 170. In such embodiments, the tension member 2000 depresses the contact 171 of the switch 170 when the tension member 2000 is under a normal load, i.e., when the counterweight is moving as intended. If the tension member 2000 releases from the contact 171 of the switch 170 due to deflection of the lever arm 140, the switch 170 communicates a fault state to the drive controller.
Referring now to
The controller (not shown) of the elevator system is configured to operate the elevator car and counterweight based at least partially on input received from the switch 170. In particular, the slack detection switch 1000 communicates to the controller whether the tension member 2000 is in the tension position or the slack position. Under normal operation of the elevator system, the tension member 2000 is in the tension position, as shown and described with reference to
In contrast, if the slack detection switch 1000 detects that the tension member 2000 is in the slack position, as shown and described with reference to
While several examples of a counterweight slack detection switch are shown in the accompanying figures and described in detail hereinabove, other examples will be apparent to and readily made by those skilled in the art without departing from the scope and spirit of the present disclosure. For example, it is to be understood that aspects of the various embodiments described hereinabove may be combined with aspects of other embodiments while still falling within the scope of the present disclosure. Accordingly, the foregoing description is intended to be illustrative rather than restrictive. The devices of the present disclosure described hereinabove are defined by the appended claims, and all changes to the disclosed devices that fall within the meaning and range of equivalency of the claims are to be embraced within their scope.
This application is a non-provisional application claiming priority to U.S. Provisional Patent Application No. 62/690,687, which was filed Jun. 27, 2018, the entire contents of which are hereby incorporated by reference herein.
| Number | Date | Country | |
|---|---|---|---|
| 62690687 | Jun 2018 | US |
