Elevator braking device

An elevator assembly (20) includes braking devices (30) for controlling movement of an elevator car (22). A braking device (30) includes an electrical actuator (62) for controlling relative movement between a carriage (42) and a base (40) that is mountable on the elevator car (22). Relative movement between the carriage (42) and the base (40) results in at least one braking member (46) following a surface (60) on the base (40) for movement between a released position and a braking position.

BACKGROUND

This invention generally relates to elevators. More particularly, this invention relates to braking devices for elevators.

Elevator systems typically include safety braking devices to protect against overspeed conditions. Conventionally, safety governors include a governor wheel located near the top of a hoistway, a governor rope and a tension pulley in a hoistway pit. The governor rope is connected to a mechanical linkage that is supported on the elevator car. In the event of an overspeed condition, the governor wheel stops rotating. This prevents further movement of the governor rope. Any further movement of the elevator car causes the linkage to be pulled upon by the stationary governor rope. Movement of the linkage activates safety braking devices in a known manner.

While such arrangements have proven useful, they are not without limitations. One drawback associated with conventional arrangements is that the governor rope is typically provided on one side of an elevator car such that a linkage is utilized to activate safety braking devices on both sides of the car.

Recent developments in elevator systems make it desirable to introduce new approaches. For example, conventional safety governor arrangements take up space in the hoistway because there must be a certain amount of space allocated to the governor wheel and the tension pulley, for example. The use of machine roomless elevators includes the desire to reduce hoistway dimensions as much as possible. This requires reducing the volume occupied by the various components in the hoistway as much as possible. At the same time, the safety functions provided by an overspeed governor should be maintained.

One improvement in this area is disclosed in U.S. Pat. No. 6,161,653, which discloses a ropeless governor mechanism for an elevator car that relies upon electrically-based activation of the safety device.

This invention provides another arrangement for preventing undesired movement of an elevator car.

SUMMARY

An embodiment addresses an assembly for controlling movement of an elevator car. The assembly includes, among other possible things, a base, a carriage, at least one brake member, and an electric actuator. The base is mountable for movement with the elevator car. The carriage is supported by the base and is moveable relative to the base. The at least one brake member is coupled with the carriage and is moveable along a surface on the base between a released position and a braking position. The electric actuator is configured to selectively cause a relative movement between the base and the carriage to cause the at least one brake member to move between the released position and, the braking position.

Another embodiment addresses a method of controlling movement of an elevator car. This method includes, among other possible steps: stopping the elevator car in a desired position using a brake associated with an elevator machine; and applying a supplementary brake member supported on the elevator car, using an electrical actuator, to prevent undesired movement of the elevator car from the desired position.

DETAILED DESCRIPTION

Efforts have been made throughout the drawings to use the same or similar reference numerals for the same or similar components.

Disclosed exemplary embodiments are useful for controlling movement of an elevator car. An electrical actuator is controlled to apply a braking force to prevent undesired movement of an elevator car. The disclosed embodiments are useful in a variety of situations including when there is an elevator overspeed condition, when a stopped elevator car is at a desired position and when there is an unexpected movement of an elevator car.

FIG. 1schematically illustrates selected portions of an embodiment of an assembly20including an elevator car22and guide rails24positioned within a hoistway, for example, in a known manner. A plurality of guide roller devices26facilitate movement of the elevator car22along the guide rails24in a known manner.

Braking devices30are supported for movement with the elevator car22for selectively engaging a blade portion of the guide rails24to prevent undesired movement of the elevator car22in a variety of situations. A controller32determines when a condition exists in which it is desired to control an electrical actuator to apply the braking devices30. A link schematically shown at34between the controller32and, each of the braking devices30allows the controller32to selectively control application of a braking force by the braking devices30. The link34in one embodiment includes a hard-wired connection between the controller32and a corresponding portion of the braking devices30. In another embodiment, the link34includes wireless signal transmission.

FIG. 2schematically illustrates an embodiment of an arrangement in which the braking device30includes a base40that is mountable on an appropriate portion of the elevator car22such as a car frame member. The base40remains stationary relative to the elevator car22and moves vertically with the elevator car22. A carriage42is supported on, and moveable relative to, the base40.

At least one link44couples at least one brake member46to the carriage42. In this embodiment, there are two links44and two brake members46. In the illustrated embodiment, the brake members46comprise rollers that are situated for engaging a blade portion48on the guide rail24. Wedge-style brake members are used in another embodiment.

The illustrated base40includes a plurality of locators50that are received within receivers52on the carriage42. In the illustrated embodiment, the locators50comprise posts and the receivers comprise slots. A biasing member54biases the carriage42into a position in which the locators50are received against one end of the corresponding receivers52. In the drawing, the bias of the biasing member54urges the carriage42in a downward direction. In the illustrated embodiment, the basing member54comprises a spring that reacts against a surface56that remains fixed relative to the base40and against a reaction surface58on the carriage42to urge them away from each other.

The illustrated, base40includes at least one surface60that controls a position of the braking members46relative to the blade portion48of the guide rail24. In the position ofFIG. 2, the braking members46are able to contact the blade portion48and roll along that portion during elevator car movement. The bias of the biasing member54maintains the carriage42in a position to keep the brake members46in a released position where they do not apply a braking force to the blade portion48of the guide rail24.

Under selected conditions, it is desirable to apply a braking force using the braking members46. The controller32is programmed to determine when there is such a condition. If so, the controller32activates an electric actuator62for applying a braking force using the braking members46. In this embodiment, the electric actuator62comprises two coils64that receive electrical power through the link34, which in this embodiment includes a hardwired connection to a source of power. A post66is normally biased toward the blade portion48by a spring68. When the coils64are energized, the posts66are retracted in a direction away from the blade portion48as schematically shown by the arrows inFIG. 2. In this position, stop members70, which comprise brake linings in one embodiment, arc held away from contact with the blade portion48.

In the event that the controller32determines it is desirable to control movement of the elevator car22using the braking devices30, the controller32controls activation of the coils64to allow the springs68to urge the stop members70into engagement with the blade portion48of the guide rail24. This condition is shown in.FIG. 3, for example. By de-energizing the coils64in one embodiment, the stop members70are urged into engagement with the brake portion48. Any movement of the elevator car22in this condition, as schematically shown by the arrow72, results in relative movement between the base40and the carriage42. The elevator car22and base40move relative to the guide rail24. The stop members70prevent the carriage42from moving relative to the guide rail24. This relative movement overcomes the bias of the biasing member54and results in. the brake members46following the contour of the surface60on the base40such that the brake members46move into a braking position as shown inFIG. 3. In this embodiment, the brake members46become wedged between the base40and the blade portion48of the guide rail24. This results in applying a braking force that prevents further movement of the elevator car22.

Once the controller32determines that it is no longer desired to apply a braking force using the braking devices30, the controller32appropriately controls the electrical actuator62(e.g., re-energizes the coils64) and the brake members46are returned to a released position by application of the biasing force of the biasing member54.

The embodiment ofFIGS. 2 and 3is useful for controlling movement of an elevator car in one direction. For controlling movement in more than one direction, another device like that shown inFIGS. 2 and 3could be installed in a reversed orientation.

FIG. 4shows another embodiment of a braking device30that is useful for controlling movement of an elevator car in more than one direction. In. this embodiment, the locators50associated with the base40are at least partially received within receivers52on the carriage42. Biasing members54in this embodiment bias the carriage42into a position in which the locators50are near a center of a range of movement relative to the corresponding receivers52.

The embodiment ofFIG. 4shows the stop members70retracted away from the blade portion48by operation of the electrical actuator62. The brake members46are shown in a released position. In the event that a braking force from the device30ofFIG. 4is desired, the electrical actuator62releases the rods66and stop members70to engage the blade portion48. If the elevator car22then moves in either direction (e.g., up or down in the drawing), the brake members46follow the contour of the surface60on the base40into a braking position. Subsequently releasing the stop member70from the blade portion48by energizing the coils64, for example, will result in the biasing members54urging the brake members46into the released position shown inFIG. 4so that further movement of the elevator car22is possible as desired.

The illustrated braking device embodiments are useful for controlling movement of an elevator car and applying a braking force to prevent an overspeed condition, unexpected or undesired movement of an elevator car in a manner that provides the functions of an elevator safety governor device. The controller32obtains information from known devices or techniques for determining when such a condition exists. Given this description, those skilled in the art will realize how to configure or program a controller for that purpose according to their particular needs.

The illustrated embodiments are also useful for another type of control of elevator car movement. When an elevator car is stopped in a desired position at a landing, the controller32controls the electrical actuator62to apply the stop members70to the blade portion48. In the event that the load on the elevator car changes significantly such that there would be so-called rope stretch or a perceived bouncing of the elevator car relative to the landing, the braking device embodiments operate to prevent such movement of the elevator car relative to the landing outside of a desired range. The contour of the surfaces60and the sizes of the components selected for the braking devices30may set an acceptable range of movement of the elevator car when it is otherwise stopped using a brake associated with the elevator machine as known. Accordingly, the braking device embodiments provide additional elevator car movement control compared to previous governor arrangements.

With traditional governor arrangements, the governor rope would have to move at a high speed to trigger the centrifugal action of the governor wheel to result in activation of the associated safeties. The relatively slight movement of an elevator car at a landing during loading or unloading, for example, is not sufficient enough to trigger activation of traditional governor wheels or safeties. The illustrated embodiments, however, can be controlled in a manner that facilitates preventing such movement of an elevator car under such circumstances.

In one embodiment, the controller32is programmed with a variety of conditions for selectively controlling the electrical actuator62for controlling the application of a braking force using the braking devices30. Given this description, those skilled in the art will realize how to configure or program a controller and what type of software, hardware, firmware or combination of these will best meet the needs of their particular situation.

One advantage of the disclosed embodiments is that the application of a braking force can be synchronized on both sides of an elevator car for simultaneously applying a braking force to each of the guide rails24. This provides better elevator performance and reduces the likelihood for any damage or deformation to elevator system components. Moreover, the arrangement does not require a mechanical linkage between the braking devices30. This eliminates components from an elevator system that provides cost advantages and introduces economies into the elevator installation process. Additionally, the elimination of mechanical linkages for attempting to synchronize safeties reduces the dimensions of components required within the hoistway to allow for further reducing the space occupied by an elevator system.

Another advantage to the disclosed embodiments is that the stop members70need not apply a large force against the blade portion48to achieve activation of the braking device30. In one embodiment, only approximately two percent of the braking force used to stop an elevator car is applied when the springs68urge the stop members70against the blade portion48. This provides the advantage of allowing for lower cost components to be used and reduces the likelihood of any deformation or damage to the surfaces on the blade portion48. This enhances the useful life of the guide rails24and facilitates improved elevator system operation.

Additionally, the low power required by the disclosed embodiments allows for battery powered operation of the electrical actuator62, which can be useful in situations in which a normal power source becomes unavailable (e.g., a power failure).

Further advantages of the described embodiments include: (a) eliminating the need to adjust, both in the factory and in the hoistway, the parts associated with conventional mechanical applications; (b) enabling electronic monitoring of the assemblies, which may occur remotely via a wired or wireless connection to the assemblies; (c) reducing costs associated with manufacturing and installing the number parts used in conventional mechanical applications; (d) reducing the likelihood of car movement while the doors are open; (e) reducing the overall weight of the car; (f) increasing hoistway efficiency; and (g) providing assemblies that are configured to interface with Programmable Electronic components and Systems for Safety Related Applications on Lifts (“PESSRAL”).

The preceding discussion is intended to be merely illustrative and should not be construed as limiting the appended claims to any particular embodiment or group of embodiments. Thus, while specific exemplary embodiments have been described, it should also be appreciated that numerous modifications and changes may be made without departing from the broader and intended scope of the invention as set forth in the claims that follow. The specification and drawings are accordingly to be regarded in an illustrative manner and are not intended to limit the scope of the appended claims. In light of the foregoing disclosure of the present invention, one versed in the art would appreciate that there may be other embodiments and modifications within the scope of the present invention. Accordingly, all modifications attainable by one versed in the art from the present disclosure within the scope of the present invention are to be included as further embodiments of the present invention. The scope of the present invention is to be defined as set forth in the following claims