HK1189868B - Elevator governor having two tripping mechanisms on separate sheaves - Google Patents

Description

Elevator governor having two tripping mechanisms on separate sheaves

Technical Field

Elevator systems include a variety of devices for providing control over movement of an elevator car. Elevator governors for preventing overspeed conditions are well known. Most elevator governors include a release mechanism located near the top of the hoistway. A governor rope extends along the length of the hoistway, wrapping around a governor sheave associated with a release mechanism and an idler sheave associated with a tensioning weight near an opposite end of the hoistway. The elevator car is connected with the ropes such that the ropes move when the elevator car moves. The speed of rotation of the governor sheave activates the release mechanism if the elevator car is moving at a speed higher than the desired speed.

Background

Speed governors in elevator systems serve two purposes. One use of elevator governors is for actuating or dropping a machine brake and interrupting power to a machine motor in the event of an overspeed condition. Another use is for activating elevator safety devices, which engage the guide rails, e.g. in case of a further overspeed condition. It is known that the response of the governor to each overspeed condition is not independent and it is difficult to achieve a specific control of the speed at which the governor performs both functions. Furthermore, relying on a single governor tripping mechanism for both functions presents additional challenges in meeting the specifications of a low speed elevator.

Disclosure of Invention

An exemplary elevator system includes an elevator car. A first governor sheave is supported on the elevator car for movement with the elevator car. A first governor sheave is supported for rotational movement relative to the elevator car in response to movement of the elevator car. A first governor tripping mechanism is supported on the first governor sheave. A first governor tripping mechanism provides an indication to perform a first governor function for controlling elevator car speed in response to the elevator car moving at a speed above a first threshold speed. A second governor sheave is supported on the elevator car for movement with the elevator car and for rotational movement relative to the elevator car in response to movement of the elevator car. A second governor tripping mechanism is supported on the second governor sheave. A second governor tripping mechanism provides an indication to perform a different second governor function for controlling movement of the elevator car in response to the elevator car moving at a speed above a second threshold speed.

An exemplary method of controlling movement of an elevator car, comprising: an indication from a first governor tripping mechanism is provided to perform a first governor function for controlling elevator car speed in response to an elevator car moving at a speed above a first threshold speed. A first governor tripping mechanism is supported on a first governor sheave that is supported on the elevator car. The second release mechanism is supported by a second governor sheave that is also supported by the elevator car. An indication from the second governor tripping mechanism is provided to perform a different second governor function for controlling movement of the elevator car in response to the elevator car moving at a speed above a second threshold speed.

The individual governor tripping mechanism of each governor sheave supported on its own provides specific control of the tripping mechanism reaction at the desired, corresponding threshold speed. Separate release mechanisms on their own governor sheaves also provide more flexibility and a more reliable arrangement to perform both functions than using a single release mechanism.

The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description. The drawings that accompany the detailed description can be briefly described as follows.

Drawings

Figure 1 schematically illustrates selected portions of an exemplary elevator system designed according to an embodiment of this invention.

Figure 2 diagrammatically illustrates an example governor arrangement designed according to an embodiment of this invention.

Fig. 3 is a side view of the arrangement shown in fig. 2.

Detailed Description

Fig. 1 schematically illustrates selected portions of an elevator system 20. An elevator car 22 is supported for movement along guide rails 24 in a known manner. The elevator machine 26 includes a motor and brake for controlling movement of the elevator car 22 in a generally known manner.

A governor assembly 30 is provided for preventing an overspeed condition in which the elevator car 22 is moving at a speed above a desired speed. Governor assembly 30 includes a first governor sheave 32 supported on elevator car 22 for movement with elevator car 22 as elevator car 22 moves along guide rails 24. As the car 22 moves along the guide rails 24, the first governor sheave 32 rotates relative to the elevator car 22. A second governor sheave 34 is also supported on the elevator car 22 and is rotatable relative to the elevator car 22. The governor rope 36 has an end that remains near an end of a hoistway in which, for example, the elevator car 22 is located. In one example, the upper end is fixed and the lower end is attached to a hanging mass to maintain a desired tension on governor rope 36. In some examples, the hanging mass is positioned to allow limited, guided vertical movement. The governor rope 36 at least partially wraps around the respective governor sheave 32 and 34 such that the respective sheaves rotate as the elevator car 22 moves relative to the governor rope 36.

Fig. 2 illustrates an example arrangement of governor assembly 30. A first governor tripping mechanism 40 is supported on the first governor sheave 32. As the elevator car 22 moves, the plurality of centrifugal elements 42 rotate with the first governor sheave 32. The centrifugal element 42 is maintained in the unactuated position by the biasing member 44. When the rotational speed of the first governor sheave 32 exceeds a selected first threshold rotational speed, centrifugal forces exerted on the element 42 overcome the force of the biasing member 44 and the element 42 moves at least partially in a radially outward direction relative to the rotational axis 45 of the first governor sheave 32. When the centrifugal elements 42 move outwardly, they interact with an actuator mechanism (not shown) which operates in a known manner to perform a first governor function. In one example, the first governor function is to cause actuation (e.g., dropping) of the machine brake 26 to slow movement of the elevator car 22 and interrupt power to the machine motor. In another example, the first governor function is to control the speed of movement of the elevator car 22 in an upward or downward direction.

In this example, the biasing member 44 includes a magnet that cooperates with the magnetic portion 46 to maintain the centrifugal element 42 in a first, non-triggered position (shown, for example, in fig. 2) relative to the first governor sheave 32 whenever the first governor sheave 32 is rotating at a speed below a first threshold rotational speed. When the speed of elevator car 22 exceeds a first threshold speed, the corresponding rotational speed of first governor sheave 32 and the centrifugal force on element 42 overcome the magnetic attraction between magnet 44 and magnetic portion 46 such that centrifugal element 42 moves outward to provide an indication to perform the first governor function.

Although the illustrated example includes a magnetic biasing member, other embodiments include a different biasing member, such as a spring.

The second governor sheave 34 supports a second governor tripping mechanism 50 that includes a centrifugal member 52. A biasing member 54, in this example a magnet, biases the centrifugal element 52 into a retracted position (shown in fig. 2) as the governor sheave 34 rotates about an axis of rotation 55. When the speed of the elevator car 22 exceeds a selected second threshold speed, the corresponding rotational speed of the second governor sheave 34 and the centrifugal force on the element 52 overcome the biasing force of the biasing member 54, and the centrifugal element 52 moves in a radially outward direction relative to the axis 55. Under such conditions, the second governor tripping mechanism 50 provides an indication to perform the second governor function. In one example, the second governor function is to activate an auxiliary brake, such as an elevator safety 60 (shown generally in fig. 1) provided to the elevator car 22. In this example, the elevator safety device 60 engages the guide rails 24 to cause the elevator car 22 to stop in a known manner. Another example second governor function is to control movement of the elevator car in a direction opposite to that associated with the first governor function.

In the illustrative example, the biasing member 54 includes a magnet that cooperates with the magnetic portion 56 to maintain the centrifugal element 52 in the first position relative to the second governor sheave 34 at a speed below the second threshold speed.

The illustrated governor assembly 30 includes separate governor sheaves 32 and 34 and separate governor tripping mechanisms 40 and 50 to provide separate independent control of two distinct governor functions. This independent control of the individual functions increases the accuracy with which the individual functions are performed. The independent mechanism also provides greater flexibility to address multiple situations.

For example, a first threshold speed at which the machine brake is dropped (and power to the machine motor is interrupted) and a higher second threshold speed at which an auxiliary brake, such as the elevator safety device 60, is engaged can be independently controlled. The first threshold speed and the second threshold speed may be selected to meet the needs of a particular situation. The individual governor sheaves 32 and 34 and corresponding individual tripping mechanisms provide precise control over the activation provided by each tripping mechanism to individually address different overspeed conditions associated with two different threshold speeds. This arrangement is advantageous over governor assemblies that rely on a single release mechanism to provide actuation of the machine brake and auxiliary brake, for example, at different threshold speeds.

In one example, each release mechanism is dedicated to controlling elevator speed in a particular direction. The first governor sheave 32 and its first release mechanism 40 are used to control the upward movement of the elevator car 22. In this example, the second release mechanism 50 is used to control the speed of downward movement of the elevator car 22. Having two independently actuated release mechanisms provides the ability to select different threshold speeds for respective directions.

The example of fig. 2 includes a governor rope 36 that at least partially wraps around each governor sheave 32 and 34. In this example, the angle of wrap around each governor sheave is at least 240 ° to provide a secure engagement between the governor rope 36 and each governor sheave 32 and 34, respectively. In this example, the first governor sheave 32 rotates in one direction and the second governor sheave 34 rotates in the opposite direction.

The release mechanisms 40 and 50 may comprise the same components. In some examples, the force applied by the second biasing member 54 is greater than the force applied by the first biasing member 44 such that the second release mechanism 50 provides an indication to activate the auxiliary brake to activate the machine brake 26 (and interrupt power to the motor) at a higher speed than the first release mechanism 40 provides an indication. In one example, a stronger magnet is used for the biasing member 54 of the second release mechanism 50 than for the biasing member 44 of the first release mechanism 40. In another example, the centrifugal element 52 of the second release mechanism 50 is configured differently than the centrifugal element 42 of the first release mechanism 40. For example, different weights may be used to alter the speed at which the release mechanism provides its respective indication. The different weights allow all the centrifugal elements and magnets to be identical and to have different release speeds. Those skilled in the art who have the benefit of this description will recognize how to configure two release mechanisms to achieve two separate threshold speeds each providing an indication for performing a corresponding governor function.

One feature of the illustrated example is that governor sheaves 32 and 34 rotate about separate axes 45 and 55, respectively. That arrangement, combined with the profile of release mechanisms 40 and 50, allows for the implementation of a relatively narrow governor assembly 30 having a width w as shown in fig. 3. Known governor assembly 30 is mounted to elevator car 22 and is expected to fit within the small space constraints of a typical hoistway. The illustrated example allows for positioning governor assembly 30 to elevator car 22 such that it easily fits between one side of elevator car 22 and the hoistway wall adjacent that side.

The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from the essence of this invention. The scope of legal protection given to this invention can only be determined by studying the following claims.

Claims (20)

1. An elevator system comprising:

an elevator car;

a first governor sheave supported on the elevator car for movement with the elevator car and for rotational movement relative to the elevator car in response to movement of the elevator car;

a first governor tripping mechanism supported on the first governor sheave that provides an indication to perform a first governor function to control movement of the elevator car in response to the elevator car moving at a speed above a first threshold speed;

a second governor sheave supported on the elevator car for movement with the elevator car and for rotational movement relative to the elevator car in response to movement of the elevator car;

a second governor tripping mechanism supported on the second governor sheave that provides an indication to perform a second governor function to control movement of the elevator car in response to the elevator car moving at a speed above a second threshold speed.

2. The elevator system of claim 1, wherein the first governor tripping mechanism includes a first centrifugal element, the second governor tripping mechanism includes a second centrifugal element, the first centrifugal element being biased into a first position relative to the first governor sheave and the second centrifugal element being biased into a first position relative to the second governor sheave, the first centrifugal element moving outward toward a second position in response to movement of the elevator car approaching the first threshold speed, the second centrifugal element moving outward toward a second position in response to movement of the elevator car approaching the second threshold speed.

3. The elevator system of claim 2, wherein the first centrifugal element of the first governor tripping mechanism is configured to move out of the first position at a first sheave rotational speed corresponding to the first threshold speed, and the second centrifugal element of the second governor tripping mechanism is configured to move out of the first position at a second, higher sheave rotational speed corresponding to the second threshold speed.

4. The elevator system of claim 3, wherein the first centrifugal element and the second centrifugal element each have a counterweight secured thereto, and wherein the counterweight of the first governor tripping mechanism is different than the counterweight of the second governor tripping mechanism.

5. The elevator system of claim 3, wherein a biasing member biasing the first centrifugal element of the first governor tripping mechanism exerts a lower biasing force than a biasing member of the second governor tripping mechanism.

6. The elevator system of claim 5, wherein the biasing member of each of the first governor tripping mechanism and the second governor tripping mechanism includes a magnet, and a magnetic force of the magnet of the first governor tripping mechanism is less than a magnetic force of the magnet of the second governor tripping mechanism.

7. The elevator system of claim 1, comprising a governor rope that remains substantially fixed relative to the elevator car, each of the first and second governor sheaves engaging the governor rope and rotating relative to the governor rope as the elevator car moves.

8. Elevator system according to claim 7,

the governor rope at least partially wrapping around each of the first governor sheave and the second governor sheave,

the first governor sheave rotates in a first direction, an

The second governor sheave rotates in an opposite second direction.

9. The elevator system of claim 1, wherein the first governor function includes activating a machine brake for reducing a speed of the elevator car and the second governor function includes activating an auxiliary brake for stopping the elevator car.

10. The elevator system of claim 1, wherein the first governor function includes controlling a speed of movement of the elevator car in a first direction and the second governor function includes controlling a speed of movement of the elevator car in an opposite second direction.

11. A method for controlling movement of an elevator car having first and second governor sheaves supported on the elevator car for movement with the elevator car and for rotational movement relative to the elevator car in response to movement of the elevator car and first and second governor tripping mechanisms each supported on one of the first and second governor sheaves, the method characterized by comprising the steps of:

providing an indication from the first governor tripping mechanism to perform a first governor function for controlling a speed of the elevator car in response to the elevator car moving at a speed above a first threshold speed; and

providing an indication from the second governor tripping mechanism to perform a second governor function for controlling a speed of the elevator car in response to the elevator car moving at a speed above a second threshold speed.

12. The method of claim 11, wherein the first governor tripping mechanism comprises a first centrifugal element and the second governor tripping mechanism comprises a second centrifugal element, the first centrifugal element being biased into a first position relative to the first governor sheave and the second centrifugal element being biased into a first position relative to the second governor sheave, the first centrifugal element moving outward toward a second position in response to movement of the elevator car approaching the first threshold speed, the second centrifugal element moving outward toward a second position in response to movement of the elevator car approaching the second threshold speed.

13. The method of claim 12, wherein the first centrifugal element of the first governor tripping mechanism is configured to move out of the first position at a first sheave rotational speed corresponding to the first threshold speed, and the second centrifugal element of the second governor tripping mechanism is configured to move out of the first position at a second, higher sheave rotational speed corresponding to the second threshold speed.

14. The method of claim 13, wherein each of the first and second centrifugal elements includes at least one weight and the weight of the first governor tripping mechanism is different than the weight of the second governor tripping mechanism.

15. The method of claim 13, wherein a biasing member that biases the first centrifugal element of the first governor tripping mechanism exerts a lower biasing force than a biasing member of the second governor tripping mechanism.

16. The method of claim 15, wherein the biasing member of each of the first and second governor tripping mechanisms includes a magnet, and the magnetic force of the magnet of the first governor tripping mechanism is less than the magnetic force of the magnet of the second governor tripping mechanism.

17. The method of claim 11, comprising:

providing a governor rope that remains substantially fixed relative to the elevator car; and

engaging the governor rope with the first and second governor sheaves such that the first and second governor sheaves rotate relative to the governor rope as the elevator car moves.

18. The method of claim 17, comprising:

rotating the first governor sheave in a first direction, an

Rotating the second governor sheave in an opposite second direction.

19. The method of claim 11, wherein the first governor function includes activating a machine brake for reducing a speed of the elevator car and the second governor function includes activating an auxiliary brake for stopping the elevator car.

20. The method of claim 11, wherein the first governor function comprises controlling a speed of movement of an elevator car in a first direction and the second governor function comprises controlling a speed of movement of an elevator car in a second, opposite direction.