Patent Description:
Each of the known types of elevator systems has features that present challenges for some implementations. For example, although roped elevator systems are useful in taller buildings, in ultra-high rise installations the ropes or belts are so long that they introduces appreciable mass and expense. The added mass of long ropes requires more power and that results in added power consumption cost. Sag due to stretch and bounce of the elevator car are other issues associated with longer ropes or belts. Additionally, longer ropes or belts and taller buildings are more susceptible to sway and drift, each of which requires additional equipment or modification to the elevator system.

<CIT> describes a self-propelled elevator car according to the preamble of the independent claims, comprising friction wheels attached to the elevator car by respective guide arms, the friction wheels being pressed against a running surface of a hoistway by a compression spring attached to guide arms to hold the elevator car within the hoistway. <CIT> describes an elevator car with a frictional drive system comprising two frictional engagement means for frictional engagement with two respective sides of a track located above the elevator car. <CIT> describes a drive frame for a self-propelled elevator car which comprises drive wheels that are held against running surfaces in an elevator hoistway by biasing springs.

According to an aspect of the present invention there is provided an elevator according to claim <NUM>.

In an example embodiment of the elevator of the previous paragraph, the vertical structure includes a traction surface that the at least one rotatable drive member engages, the at least one drive member rotates while engaging the traction surface, and the biasing force is normal to the traction surface.

In an example embodiment having at least one feature of the elevator of any of the previous paragraphs, the actuator increases the biasing force for urging the at least one rotatable drive member in a direction to engage the vertical surface or structure based on an increase in the load of the elevator car and decreases the biasing force for urging the at least one rotatable drive member in the direction to engage the vertical surface or structure based on a decrease in the load in the elevator car.

An example embodiment having at least one feature of the elevator of any of the previous paragraphs includes a feedback sensor that provides an indication of the biasing force between the at least one rotatable drive member and the vertical structure. The controller uses the indication from the feedback sensor to selectively adjust the biasing force applied by the actuator.

In an example embodiment having at least one feature of the elevator of any of the previous paragraphs, the at least one rotatable drive member comprises a plurality of rotatable drive members, the biasing mechanism comprises a plurality of beams supported for movement in a first direction to urge the at least one rotatable drive member into engagement with the vertical structure, the at beams move at least partially in a first direction based upon a force in a second, different direction, and the load of the elevator car is in the second direction.

In an example embodiment having at least one feature of the elevator of any of the previous paragraphs, the plurality of beams that are supported for pivotal movement relative to each other to change the biasing force.

In an example embodiment having at least one feature of the elevator of any of the previous paragraphs, the biasing mechanism includes an actuator that causes movement of the beams based on a change in the load of the elevator car and the actuator is one of electrical, electromagnetic, hydraulic or pneumatic.

In an example embodiment having at least one feature of the elevator of any of the previous paragraphs, the at least one rotatable drive member comprises a plurality of rotatable drive members, the rotatable drive members are supported by flexible mounts, and the biasing mechanism includes at least one actuator that changes a condition of the flexible mounts to change the biasing force.

In an example embodiment having at least one feature of the elevator of any of the previous paragraphs, the actuator imposes a force on the flexible mounts to change the condition.

In an example embodiment having at least one feature of the elevator of any of the previous paragraphs, the actuator causes deflection of the flexible mounts to change the biasing force.

In an example embodiment having at least one feature of the elevator of any of the previous paragraphs, the biasing mechanism includes deflectors that are moveable by the actuator to deflect the flexible mounts in a manner that changes the biasing force.

In an example embodiment having at least one feature of the elevator of any of the previous paragraphs, the biasing mechanism includes a chamber configured to contain a fluid, the biasing force is based on an amount of fluid in the chamber or a pressure of the fluid in the chamber, the biasing mechanism includes a plunger that is moveable relative to the chamber based on a change in the load of the elevator car, and movement of the plunger changes the biasing force.

In an example embodiment having at least one feature of the elevator of any of the previous paragraphs, the biasing mechanism includes a vacuum chamber that establishes an at least partial vacuum to apply the biasing force.

In an example embodiment having at least one feature of the elevator of any of the previous paragraphs, the vacuum chamber includes a flexible seal that is received against a surface of the vertical structure, the flexible seal is moveable in a vertical direction along the surface as the elevator car moves, and vacuum pressure of the vacuum chamber urges the at least one rotatable drive member into engagement with the vertical structure.

A method of controlling movement of an elevator car is provided according to claim <NUM>.

In an example embodiment of the method of the previous paragraph, the condition comprises a status of the elevator car.

In an example embodiment having at least one feature of the method of either of the previous paragraphs, the status includes an active status in which the elevator car is providing elevator service or an inactive status in which the elevator car is parked in a designated position.

An example embodiment having at least one feature of the method of any of the previous paragraphs includes releasing the biasing force when the inactive status includes the elevator car parked in the designated position and vertically supported independent of the at least one rotatable drive member engaging the vertical structure.

According to the present disclosure there is provided an elevator including an elevator car frame. A drive mechanism is situated near only one side of the elevator car frame. The drive mechanism includes at least one rotatable drive member that is configured to engage a vertical surface near the one side of the elevator car frame, selectively cause movement of the elevator car frame as the rotatable drive member rotates along the vertical surface, and selectively prevent movement of the elevator car frame when the drive member does not rotate relative to the vertical surface. A biasing mechanism urges the rotatable drive member in a direction to engage the vertical surface. At least one stabilizer is situated near the one side of the elevator car frame and is configured to prevent the elevator car frame from tipping away from the vertical surface.

In an embodiment of the elevator of the previous paragraph, the at least one rotatable drive member comprises a wheel and a motor supported at least partially within the wheel.

In an embodiment having one or more features of the elevator of any of the previous paragraphs, the at least one rotatable drive member comprises a second wheel.

In an embodiment having one or more features of the elevator of any of the previous paragraphs, the second wheel includes a motor supported at least partially within the second wheel.

In an embodiment having one or more features of the elevator of any of the previous paragraphs, the biasing mechanism comprises at least one beam supported for movement in a first direction to urge the at least one rotatable drive member in the direction to engage the vertical surface and the at least one beam moves in the first direction based upon a force in a second, different direction.

In an embodiment having one or more features of the elevator of any of the previous paragraphs, the first direction is horizontal and the second direction is vertical.

In an embodiment having one or more features of the elevator of any of the previous paragraphs, the force is based on a load on the elevator car frame.

In an embodiment having one or more features of the elevator of any of the previous paragraphs, the at least one rotatable drive member comprises two drive wheels situated to engage oppositely facing vertical surfaces, the at least one beam comprise two beams, each of the two beams has a first end and a second end, the beams are respectively associated with one of the drive wheels, the beams are supported for pivotal movement relative to the elevator car frame in response to the force, the first ends of the beams move toward each other in response to an increase in the force, and the second ends of the beams move away from each other in response to the increase in the force.

In an embodiment having one or more features of the elevator of any of the previous paragraphs, the biasing mechanism includes an actuator portion that moves in the second direction in response to a change in the force, the actuator portion moves in response to the increase in the force to cause movement of the first ends of the beams toward each other, and the actuator portion moves in response to a decrease in the force to allow movement of the first ends of the beams away from each other.

In an embodiment having one or more features of the elevator of any of the previous paragraphs, the actuator portion moves along the second direction.

In an embodiment having one or more features of the elevator of any of the previous paragraphs, the actuator portion includes an angled surface that has a first profile along a portion of the angled surface and a second profile along a second portion of the angled surface, the first profile includes a first angle that is steeper than a second angle of the second portion, and the second portion of the angled surface causes movement of the first ends of the beams in response to the force being above a preselected threshold.

In an embodiment having one or more features of the elevator of any of the previous paragraphs, the second profile includes a curved surface.

In an embodiment having one or more features of the elevator of any of the previous paragraphs and comprising a vertical support member that includes the vertical surface, the vertical support member includes at least one reaction surface that is transverse to the vertical surface; and the stabilizer is received against the at least one reaction surface.

In an embodiment having one or more features of the elevator of any of the previous paragraphs, the vertical support comprises an I-beam having a web and a flange at each end of the web, the web defines the vertical surface, and at least one of the flanges defines the at least one reaction surface.

In an embodiment having one or more features of the elevator of any of the previous paragraphs, the stabilizer comprises at least one roller that is received against the at least one reaction surface on the at least one of the flanges.

An embodiment having one or more features of the elevator of any of the previous paragraphs includes a cabin supported on the elevator car frame, a sensor that provides an output indicating a load in the elevator car, and a processor that determines the load in the elevator car based on the output of the sensor. The biasing mechanism comprises an actuator that is controlled by the processor to change a force for urging the at least one rotatable drive member in the direction to engage the vertical surface based on a change in the load in the elevator car.

In an embodiment having one or more features of the elevator of any of the previous paragraphs, the actuator increases the force for urging the at least one rotatable drive member in the direction to engage the vertical surface based on an increase in the load in the elevator car and decreases the force for urging the at least one rotatable drive member in the direction to engage the vertical surface based on a decrease in the load in the elevator car.

Disclosed example embodiments include controlling a force associated with establishing traction for a drive member that climbs a vertical structure to move an elevator car. The force control is based on a condition of the elevator car, wherein the condition comprises the load of the elevator car and may further comprise if the elevator car is currently providing service. The force control system may apply different forces and be active under only selected conditions. The disclosed embodiments prolong the useful life of the drive mechanism components. In some embodiments, a sensor that detects the force can be used as a safety device.

<FIG> schematically illustrates selected portions of an elevator system <NUM>. An elevator car <NUM> includes a frame that supports a cab <NUM> and a drive mechanism <NUM>. An elevator controller <NUM>, which includes a computing device such as a microprocessor, controls various aspects of the operation of the drive mechanism <NUM>. For example, the controller <NUM> controls the drive mechanism <NUM> to move or park the elevator car <NUM> as needed to provide elevator service to passengers.

The drive mechanism <NUM> includes at least one rotatable drive member <NUM> that is configured to engage a vertical structure. The rotatable drive member <NUM> selectively causes vertical movement of the elevator car <NUM> as the rotatable drive member <NUM> rotates and moves along the vertical structure. The rotatable drive member <NUM> maintains a desired vertical position of the elevator car <NUM> when the rotatable drive member <NUM> engages the vertical structure remains stationary and does not rotate.

As can be seen in <FIG>, for example, the illustrated example embodiment includes two rotatable drive members <NUM>. In the illustrated example embodiment, the drive mechanism <NUM> and the rotatable drive members <NUM> are situated near the bottom of the elevator car <NUM>. This arrangement takes advantage of the structural rigidity at the lower portion of the elevator car frame.

The vertical structure in the example embodiment of <FIG> includes a structural member <NUM> in the form of an I-beam that includes a web <NUM> and flanges <NUM>. The web <NUM> defines a vertical surface that the rotatable drive members <NUM> engage. In the illustrated example embodiment, the rotatable drive members <NUM> engage opposite sides of the web <NUM>. The rotatable drive members <NUM> engage the web <NUM> with sufficient force to achieve traction for controlling vertical movement and position of the elevator car <NUM>.

In the illustrated example embodiment, the structural member <NUM> is secured by mounting brackets <NUM> to one side of a hoistway <NUM>. Other embodiments include a structural member that is made as part of the hoistway <NUM> or a corresponding portion of the building in which the elevator system <NUM> is installed. There are a variety of ways of providing a vertical structure including a traction surface <NUM> that can be engaged by one or more rotatable drive members <NUM> for purposes of propelling and supporting the elevator car.

In the example of <FIG>, the drive members <NUM> are situated on only one side of the elevator car <NUM>. This results in a cantilevered arrangement of the elevator car <NUM>. A stabilizer <NUM> is provided near the one side of the elevator car <NUM> to prevent the elevator car <NUM> from tipping away from the structural member <NUM>. In this example, the stabilizer <NUM> includes at least one roller that engages a surface on at least one of the flanges <NUM> of the I-beam structural member <NUM>. In some embodiments, the stabilizer <NUM> includes rollers configured like guide rollers on known elevator systems.

<FIG> and <FIG> illustrate another configuration of an elevator system <NUM> in which the elevator car <NUM> is not cantilevered. In this example, the drive mechanism <NUM> includes rotatable drive members <NUM> on both sides of the elevator car <NUM>. The example of <FIG> includes drive members <NUM> near the top and bottom of the elevator car <NUM>. Other embodiments include drive members <NUM> only near the top or only near the bottom of the elevator car <NUM>.

<FIG> illustrates an example rotatable drive member <NUM>. A wheel or tire <NUM> provides the engagement surface for engaging the vertical surface <NUM> to achieve sufficient traction for controlling movement of the elevator car <NUM>. A motor <NUM> in this example embodiment is situated within the rotatable drive member <NUM>, which provides a compact arrangement of components that is capable of achieving the necessary torque to cause desired movement and stable positioning of the elevator car <NUM> based on engagement with the vertical surface <NUM>.

As shown schematically in <FIG> and <FIG>, a biasing mechanism <NUM> is associated with the drive mechanism <NUM>. The biasing mechanism <NUM> applies a biasing force FN that is normal or perpendicular to the vertical surface <NUM> engaged by each drive member <NUM> in the illustrated embodiments to urge the rotatable drive members <NUM> into engagement with the example vertical surfaces <NUM>.

The biasing mechanism <NUM> applies the biasing force depending on a condition of the elevator car <NUM>. The biasing force depends on or is in response to a load of the elevator car <NUM>. The biasing force changes based on changes in the load of the elevator car <NUM>. In some embodiments, the biasing mechanism <NUM> has a default condition that applies a maximum biasing force available from the biasing mechanism <NUM>. The biasing mechanism <NUM> reduces the biasing force in such embodiments by an amount that is based on the load of the elevator car <NUM>. The default condition in such embodiments ensures sufficient traction to hold the elevator car <NUM> in a stable position during a power failure, for example.

The biasing mechanism <NUM> in other embodiments has a default condition that applies a relatively low biasing force when the elevator car <NUM> is empty. The biasing mechanism in such embodiments increases the biasing force from that of the default condition based on changes in the load of the elevator car <NUM>.

In some embodiments, when the elevator car <NUM> is parked and supported vertically, such as by a buffer beneath the elevator car <NUM>, the biasing mechanism <NUM> releases any normal force. This allows for reducing any unnecessary load on the drive members <NUM> and associated components. When the drive members <NUM> include rubber tires, for example, releasing the biasing force entirely avoids developing flat spots on the tires.

The example configurations shown in <FIG> and <FIG> include a sensor <NUM> that is configured to detect the load of the elevator car <NUM>. The sensor <NUM> provides an indication of the load to the controller <NUM> and the controller <NUM> may use that indication to control the biasing mechanism <NUM> to change the biasing force depending on the current load. Some arrangements include an active biasing mechanism that is controlled by the controller <NUM> while others are passive and respond to a change in the load of the elevator car <NUM> without requiring action by the controller <NUM>.

One example type of passive biasing mechanism <NUM> that is useful with a cantilevered elevator car <NUM> is schematically shown in <FIG>. This example biasing mechanism <NUM> includes beams <NUM> that are associated with drive member supports <NUM>. In this example, the drive member supports <NUM> and the beams <NUM> are situated for pivotal movement relative to the elevator car <NUM> about pivots <NUM>. In this example, first ends of the beams <NUM> are situated near the drive member supports <NUM> while second ends of the beams <NUM> are distal from the rotatable drive members <NUM>.

At least one actuator <NUM> selectively changes a distance D between the second ends of the beams <NUM> to change the engagement force FN with which the rotatable drive members <NUM> engage the vertical surfaces of the web <NUM> of the I-beam structural member <NUM>. The actuator <NUM> changes the distance D in response to a change in the load in the elevator cab <NUM>. The load in the cab <NUM> imposes a downward force FL. The actuator <NUM> urges the distal ends of the beams <NUM> away from each other to urge the rotatable drive members <NUM> in a direction to engage the vertical surfaces on the web <NUM> of the I-beam structural member <NUM>. In the illustrated example embodiment, the movement of the beams <NUM> is in a first direction, which is horizontal, and the force FL associated with the load in the elevator cab <NUM> is in a second direction, which is vertical. In the illustrated example embodiment, the first direction is perpendicular to the second direction.

The actuator <NUM> facilitates changing the amount of engagement force or normal force FN to accommodate differences in load in the elevator car <NUM>. Such an arrangement facilitates maintaining adequate traction between the drive mechanism <NUM> and the structural member <NUM> without maintaining forces or conditions that would tend to introduce additional wear on the components of the drive mechanism <NUM> or the structural member <NUM>, for example.

<FIG> illustrates an example arrangement of an actuator <NUM> useful in the arrangement shown in <FIG>. In this example, a wedge-shaped actuator portion <NUM> moves in response to the force FL caused by the load in the elevator cab <NUM>. Downward movement (according to the drawing) of the wedge-shaped actuator portion <NUM> causes sideways and outward movement (according to the drawing) of intermediate members <NUM> against the bias of springs <NUM>. As the intermediate members <NUM> move outward, they urge the nearby second ends of the beams <NUM> to spread apart, increasing the distance D shown in <FIG>.

In this example embodiment, the wedge-shaped actuator portion <NUM> engages a ramped surface <NUM> on the intermediate members <NUM>. The outer surface of the actuator portion <NUM> and the ramped surfaces <NUM> are coated with a low friction material in some embodiments. The wedge-shaped actuator portion <NUM> includes an angled surface that has a first profile <NUM> along a portion of the angled surface and a second profile <NUM> along another portion of the angled surface. The first profile <NUM> includes a steeper angle than an angle of the second profile <NUM>. Additionally, the second profile <NUM> includes a curvature. The second profile <NUM> reduces the frictional load associated with engaging the angled surfaces <NUM> as the force FL increases. The second profile <NUM> compensates for an increase in the co-efficient of friction by reducing the effect of the normal force at the interface of the second profile <NUM> and the angled surfaces <NUM> under higher loads in the elevator cab <NUM>.

As can be appreciated from <FIG> and <FIG>, as the force FL increases, the actuator <NUM> increases the distance D, which results in the rotatable drive members <NUM> moving toward the vertical surfaces on the web <NUM> of the I-beam structural member <NUM>. In other words, the actuator <NUM> increases the engagement force FN between the rotatable drive members <NUM> and the vertical surfaces <NUM> based upon an increase in the load in the elevator cab <NUM>. An increased engagement force provides the appropriate amount of traction for achieving desired movement of the elevator car <NUM> and for parking the cab <NUM> at a desired landing.

As shown in <FIG>, a counterbalancing mechanism <NUM> provides a bias for urging the beams <NUM> back toward a default position corresponding to a minimum amount of normal force FN applied by the rotatable drive members <NUM> to the vertical surfaces <NUM>. The minimum normal force FN is useful for conditions such as an empty elevator cab <NUM>. As the load in the elevator cab <NUM> decreases, a spring <NUM> (<FIG>) urges the wedge-shaped actuator portion <NUM> in an upward direction (according to the drawing). Under those conditions, the counterbalancing mechanism <NUM> urges the first ends of the beams <NUM> apart and decreases the distance D between the second ends of the beams <NUM>.

<FIG> schematically illustrates a biasing mechanism <NUM> that is configured for use on an elevator car <NUM> that is not cantilevered. In this example, the actuator <NUM> can be passive and operate similar to that shown in <FIG>. The beams <NUM> in this example include multiple segments and a second pivot <NUM> so that the ends of the beams <NUM> situated closer to the center of the elevator car <NUM> are moveable relative to each other. Changing the distance between those ends of the beams <NUM> changes the normal or engagement force of the drive members <NUM> against the vertical surfaces <NUM>.

While not illustrated in <FIG>, such embodiments may include a counterbalancing mechanism <NUM> between the pivot locations <NUM> and the vertical structures <NUM> to return the biasing force to a force corresponding to an empty cab <NUM> whenever there is no additional load on the elevator car <NUM>. As the load of the elevator car <NUM> increases, the actuators <NUM> urge the inner ends of the beams <NUM> further apart and, therefore, increase the biasing force urging the drive members <NUM> against the surfaces <NUM>. If counterbalancing mechanisms <NUM> are included, they impose an opposite force urging the outer ends of the beams <NUM> apart into a position that maintains a minimum acceptable engagement force urging the drive members <NUM> into engagement with the surfaces <NUM>. The counterbalancing mechanism <NUM> will not overcome a base clamping or biasing force that urges the drive members <NUM> into engagement with the surfaces <NUM> sufficient to support the load of an empty cab for preventing undesired or unexpected descent of the elevator car <NUM>.

Some embodiments include active control over the biasing mechanism <NUM> and the biasing force based on the load of the elevator car <NUM>.

<FIG> schematically illustrates an example embodiment in which the sensor <NUM> provides an output indicating the load of the elevator car <NUM> to the controller <NUM>. The actuator <NUM> in <FIG>, such as an electric linear actuator, is active in response to commands from the controller <NUM> and changes a position of the rotatable drive members <NUM> relative to the structural members <NUM> as schematically shown by the arrows <NUM> to alter the engagement force based on changes in the load as indicated by the sensor <NUM>. The controller <NUM> controls the actuator <NUM> to achieve a desired engagement force corresponding to the current load in the elevator car <NUM>.

A feedback sensor <NUM> provides an indication of the force applied by the biasing mechanism <NUM>. The controller <NUM> in this example uses the indication from the feedback sensor <NUM> to adjust the biasing force if needed. One way in which the feedback sensor <NUM> is useful is to provide an indication of the biasing force at each drive member <NUM> so that the controller <NUM> can adjust the biasing force at each drive member <NUM> individually to ensure a desired distribution of the traction forces among the drive members <NUM>.

Only one set of drive members <NUM> and a single actuator is shown in <FIG> for discussion purposes but all drive members <NUM> that use traction and engagement with a corresponding surface <NUM> has an associated actuator <NUM> that applies the biasing force based on the load of the elevator car <NUM>.

<FIG> shows an example configuration of an electromechanical actuator <NUM> that is included in some embodiments. The actuator <NUM> in this example includes an actuator motor <NUM> that causes rotation of a spur gear <NUM>. Rack gears <NUM> move linearly in a direction dictated by the direction of rotation of the spur gear <NUM>. The rack gears <NUM> and guide beams <NUM> are connected with connecting structural members <NUM> that are configured to be connected with the drive member supports <NUM> to alter the biasing force urging the drive members <NUM> into engagement with the surfaces <NUM>. As the spur gear <NUM> rotates, the rack gears <NUM> move in opposite directions so the drive member supports <NUM> move as represented by the arrows <NUM>.

Other embodiments include an electromechanical actuator <NUM> that has a ball screw configuration or a self-locking worm gear. Some such actuators <NUM> have a feature that avoids back-driving so the actuator is capable of maintaining the positions of the components to apply a selected biasing force without requiring a constant supply of electrical energy.

<FIG> schematically shows a biasing mechanism <NUM> that includes active actuators <NUM> for altering the biasing force urging the drive members <NUM> toward the surfaces <NUM>. In this example embodiment, the beams <NUM> are moved toward each other by the actuators <NUM> to increase the biasing force or away from each other to decrease the biasing force. The controller <NUM> (not shown in <FIG>) controls the actuators <NUM> depending on the load of the elevator car. The actuators <NUM> in <FIG> operate on electric power in some embodiments, hydraulic pressure in some embodiments, pneumatic pressure in some embodiments, electromagnetic attraction in some embodiments or based on an electric field in some embodiments.

<FIG> shows another configuration of a biasing mechanism <NUM> that changes the biasing force based on changes in the load of the elevator car <NUM>. In this example, beams <NUM> and <NUM> support the drive members <NUM>. The beams <NUM> and <NUM> are in a scissors configuration and can move relative to each other and the elevator car <NUM> by pivoting about a pivot <NUM>. Actuators <NUM> cause relative movement of the beams <NUM> and <NUM> to change the biasing force urging the drive members <NUM> toward the surfaces <NUM>. The actuators <NUM> in some such embodiments utilize or operate on electric power and include solenoids, rack and pinion gears, ball screws, or electric linear actuators. Other embodiments include actuators <NUM> that are hydraulic and operate based on pressurized fluid or pneumatic and operate based on pressurized gas. As the actuators <NUM> expand in the illustrated arrangement, the beams <NUM> and <NUM> move in a direction that reduces the biasing force. The actuators <NUM> contract to increase the biasing force.

<FIG> shows another biasing mechanism configuration. In this example embodiment, beams <NUM> and <NUM> move relative to each other about a pivot <NUM> based on operation of the actuator <NUM>. The scissors-type configuration of the beams <NUM> and <NUM> provides the ability to adjust the biasing force imposed on the drive members <NUM> by expanding or contracting the actuator <NUM>. In such embodiments, the actuator may be electric, electromagnetic, electromechanical, hydraulic or pneumatic.

In <FIG>, the drive members <NUM> near the top of the elevator car <NUM> are not affected by the actuator <NUM> or the biasing mechanism <NUM>. Those drive members <NUM> near the top of the elevator car <NUM> are spring biased into engagement with the surfaces <NUM> using a biasing force that is based on the spring constant of springs <NUM>. In some embodiments, wheels are provided near the top of the elevator car <NUM> that are idler wheels that follow along the vertical structure <NUM> without providing torque to move the elevator car <NUM>.

<FIG> shows another configuration of a biasing mechanism <NUM>. This example embodiment includes flexible mounts <NUM> that support the drive members <NUM>. The mounts <NUM> may be springs or include springs with additional structural members. The flexible mounts <NUM> provide some resiliency while always maintaining at least a minimum required biasing force urging the drive members <NUM> into engagement with the surfaces <NUM>. The actuators <NUM> in <FIG>, which may be electric, electromagnetic, electromechanical, hydraulic or pneumatic, alter the biasing force by imposing a force on the spring-based mounts <NUM>.

The biasing mechanism <NUM> in <FIG> includes flexible mounts <NUM>. In some such embodiments, the mounts <NUM> comprise springs. The actuators <NUM> in the illustrated example are connected with deflectors <NUM> that move along a track <NUM> on the elevator car <NUM>. The actuators <NUM> cause movement of the deflectors to alter the biasing force imposed by the resilient mounts <NUM>. As in previously discussed embodiments, the actuators may be electric, electromagnetic, electromechanical, hydraulic or pneumatic.

In <FIG>, actuators <NUM> are arranged to expand or contract to change the biasing force urging the drive members <NUM> into engagement with the surfaces <NUM> as the load of the elevator car <NUM> changes. The drive members <NUM> near the top of the elevator car <NUM> in this example may be urged with a different biasing force than that applied to the drive members <NUM> near the bottom of the elevator car <NUM>. Additionally, either of the actuators <NUM> in such an embodiment may be used to apply a biasing force that is strong enough to serve as a safety braking force while at least the corresponding drive members <NUM> are prevented from rotating.

The arrangement shown in <FIG> includes an actuator <NUM> near the top of the elevator car <NUM> like those shown in <FIG>. This embodiment also includes a passive, hydraulic biasing mechanism <NUM> near the bottom of the elevator car <NUM>. As the load of the elevator car <NUM> changes, a plunger <NUM> moves vertically to change the amount of hydraulic fluid in a chamber <NUM>. The hydraulic fluid acts against pistons <NUM> that move in a direction to change the biasing force on the drive members <NUM>.

The example embodiment of <FIG> includes a back-up actuator <NUM> that can be controlled independently of the plunger <NUM> to alter the pressure within the chamber <NUM> if needed to achieve a desired biasing force. The actuator <NUM> near the top of the elevator car <NUM> in this example may be used to apply a biasing force to achieve traction for moving the elevator car <NUM> or may be used exclusively to apply a biasing force that is sufficient to use the associated drive members as brake members for a safety brake application.

<FIG> includes pneumatic actuators <NUM> that utilize air pressure. In this example, vacuum portions <NUM> each include a seal <NUM> received against the surface <NUM>. The seals <NUM> are flexible and able to slide along the surface <NUM> while maintaining a sufficient seal for the vacuum portions <NUM> to establish a vacuum. The vacuum effect draws a base <NUM> toward the surface <NUM> and, therefore, urges the drive members <NUM>, which are supported by the base <NUM>, toward the surface to achieve a desired biasing force. The bases <NUM> are resiliently supported on the elevator car <NUM> as shown at <NUM> so the base <NUM> can be moved relative to the surfaces <NUM> based on changes in the vacuum pressure of the vacuum portions <NUM>.

The example shown in <FIG> also includes a compressed air chamber <NUM> associated with each side of the elevator car <NUM>. In some implementations, the compressed air chamber <NUM> is used to release a portion of the vacuum of the vacuum portions <NUM> for lessening the biasing force by introducing additional air into the vacuum portions <NUM> in response to a decrease in the load of the elevator car <NUM>.

Although not illustrated in <FIG>, the controller <NUM> controls the actuators <NUM> to alter the biasing force based on a change in the load of the elevator car <NUM>.

The illustrated example embodiments include various features that can be advantageous. For example, in a cantilevered arrangement, situating the drive mechanism <NUM> on only one side of the elevator car <NUM> leaves more room in the hoistway <NUM> to accommodate a larger sized elevator cab <NUM> or a variety of car configurations. Additionally, it is possible to position a door <NUM> (<FIG>) of the elevator car on any of the three remaining sides of the elevator cab <NUM> other than the one that the drive mechanism <NUM> is situated near. In addition to utilizing hoistway space more efficiently, less material is required with a drive mechanism near only one side of the elevator car frame. Reducing the required amount of materials reduces the costs of an elevator system.

Other features of example embodiments include reduced installation time, which is due for example to the requirement for only one structural member on only one side of the elevator car. Additionally, the structural member may be more strategically placed where load rated attachment points are more easily or more effectively accommodated inside the hoistway.

Another feature of the illustrated example embodiments is the ability to change the biasing force based on the condition or state of the elevator car. Changing the biasing force responsive to the load of the elevator car <NUM> allows for avoiding unnecessary wear on the drive members <NUM> and the surfaces <NUM> while consistently providing a sufficient biasing force under different conditions, such as those mentioned above.

Another feature of example embodiments is that it becomes more straightforward to incorporate more than one elevator car in a single hoistway. Multiple cars can use the same structural member without complicated arrangements to avoid interference between the operative components of the drive mechanisms for each car. Some embodiments include the ability to transfer elevator cars among different hoistways. The United States Patent Application Publications <CIT> and <CIT> each show ways of transferring elevator cars among hoistways and having more than one car in a hoistway.

Claim 1:
An elevator, comprising:
an elevator car (<NUM>);
a drive mechanism (<NUM>) connected with the elevator car (<NUM>), the drive mechanism (<NUM>) moving with the elevator car (<NUM>) in a vertical direction, the drive mechanism (<NUM>) including at least one rotatable drive member (<NUM>) that is configured to
engage a vertical structure near the elevator car (<NUM>),
climb along the vertical structure to selectively cause movement of the elevator car (<NUM>), and
selectively prevent movement of the elevator car (<NUM>) when the at least one rotatable drive member (<NUM>) remains in a selected position relative to the vertical structure;
a biasing mechanism (<NUM>) that urges the at least one rotatable drive member (<NUM>) in a direction to engage the vertical structure, the biasing mechanism (<NUM>) applying a biasing force based upon a condition of the elevator car (<NUM>), the biasing force changing based upon a change in the condition;
wherein the biasing mechanism (<NUM>) comprises an actuator (<NUM>) that applies the biasing force, and the actuator (<NUM>) varies the biasing force based on the change in the condition; characterized in that:
the condition comprises a load of the elevator car (<NUM>);
the elevator comprises a sensor (<NUM>) that provides an output indicating the load of the elevator car (<NUM>), and a controller (<NUM>) that determines the load in the elevator car (<NUM>) based on the output of the sensor (<NUM>); and
the actuator (<NUM>) is controlled by the controller (<NUM>) to change the biasing force for urging the at least one rotatable drive member (<NUM>) to engage the vertical structure based on the change in the load in the elevator car (<NUM>).