HK1208896B - Brake - Google Patents

Description

Brake

Technical Field

The present invention relates to brakes and more particularly to control mechanisms for brakes to be used as safety devices.

Background

In elevator hoisting machines, for example, a machinery brake mechanically engaged with a rotating part of the hoisting machine is commonly used as a braking device. Structurally, the mechanical brake may be, for example, a shoe brake (shoe brake), a drum brake (drum brake), or a disc brake (disk brake).

Mechanical brakes typically comprise a spring that pushes a brake member provided with a brake pad against a braking surface of the rotating part to brake the movement of the rotating part of the hoisting machine. The mechanical brake also generally comprises an electromagnet with which a braking member provided with a magnetic core is pulled against the thrust of a spring to a release position of the brake, remote from the braking surface. The machinery brake is dropped by disconnecting the current supply of the electromagnet of the machinery brake, in which case the attraction force of the electromagnet ceases and a spring in the brake pushes the brake member provided with the brake pad from an initial position of the disengaging (drop out) movement to a braking position against the braking surface of the rotating part.

During operation, a current is connected to the electromagnet, in which case the detent is in the released position and the elevator car can move up and down in the elevator hoistway.

As the current of the electromagnet decreases, the thrust exerted by the spring eventually exceeds the attraction force of the electromagnet, and the braking member is displaced to the braking position. Due to the imbalance of forces, the brake pads hit the braking surfaces of the rotating parts of the machine. When the brake is open, the electromagnet exerts a force on the brake again in the direction opposite to the thrust of the spring. When the force exerted by the electromagnet on the brake increases to be greater than the spring force, the air gap between the base of the brake and the brake closes and the armature component strikes against the base.

Disclosure of Invention

The collision of the components of the brake against each other when the brake is activated or opened is likely to cause disturbing noise. The noise problem can be remedied by adding, for example, a separate damper to the air gap between the base and the brake that prevents direct contact between the opposing surfaces of the base and the brake when the brake is open. The damper may be made of an elastic material such as rubber or polyurethane; the damper can also be implemented with a separate spring, such as a coil spring or a disc spring, dimensioned for this purpose.

There are drawbacks associated with the use of dampers for the brakes described above. In particular, dampers made of rubber or polyurethane have a short service life and are strongly dependent on the operating temperature. To prevent heating, the field winding of the electromagnet of the brake often has to be oversized.

The damper may be arranged in the air gap between the base and the brake, in which case the reluctance of the magnetic circuit of the brake increases and the current demand of the electromagnet increases simultaneously. On the other hand, increasing attention is being given to the energy consumption of elevators, so that it should also be possible to reduce the energy consumption of the electromagnet of the brake.

It is therefore an object of the invention to disclose an improved construction of a brake, which is particularly suitable for use as a mechanical safety device in an elevator. The object of the invention is to solve the problem of noise, in particular of brakes. It is an object of the invention to reduce the energy consumption of the brake. It is an object of the invention to solve the problems associated with heating of the brake. One object of the invention is to disclose a brake with which the braking force can be adjusted and varied more precisely than in the prior art. One object of the invention is to disclose a brake in the control mechanism of which the necessary power generation is achieved with smaller component parts than in the prior art.

To achieve these objects, the invention discloses a brake, an elevator system, a method of controlling a brake, and a method for controlling a brake of an elevator in an operational abnormality of the elevator. Some inventive embodiments, as well as inventive combinations of various embodiments, are also presented in the descriptive section and drawings of the present application.

The brake according to the present invention comprises: a base; a brake movably supported on the base, the brake configured to move between a braking position and a release position; a spring, by which the braking member can be dropped from an initial position of the disengagement movement to a braking position; a movable supporting member for limiting an initial position of the disengaging movement of the stopper; and also a controllable actuator mechanically connected to the aforementioned support member and configured to displace the initial position of the disengagement movement of the braking member with respect to the braking position. The aforementioned spring may also consist of several springs, for example several disc springs connected to each other. The braking position means that the braking member arranged in this position is pressed against the component to be braked, braking its movement and/or preventing activation of the component to be braked. Accordingly, the brake member in the released position is arranged not to brake the aforementioned component to be braked and/or not to prevent activation of the component to be braked. The initial position of the disengaging movement means the position of the brake member at the beginning of the disengaging movement before the disengaging movement of the brake takes place.

According to the present invention, by displacing the brake member at/from the initial position of the disengaging movement from/to the releasing position to the braking position in a controlled manner utilizing the predetermined movement profile achieved by the actuator, with this profile, the collision of the surfaces of the brake against each other and the disturbing noise generated by this collision are prevented, so that the braking function can be activated silently. Also, the brake can be silently released by displacing the brake member at/from the initial position of the disengaging movement from the braking position to the releasing position in a controlled manner utilizing the predetermined movement profile achieved by the actuator.

At the same time, safe operation of the brake is ensured with a disengaging device which, when the triggering part is immediately controlled upon detection of an operational anomaly/possible danger, drops the brake to be displaced from the initial position of the disengaging movement to the braking position. As a result, the brake of the elevator according to the invention can be controlled silently with the actuator during normal operation of the elevator and can be dropped when an operational anomaly of the elevator is detected, in which case the braking member is displaced to the braking position and the braking is started as soon as possible when the braking member hits the braking surface due to the effect of the spring force. The disturbing noise generated by the release of the braking member in an operational abnormality of the elevator can be accepted because it is more important than the noise nuisance in this case to provide the safety of the elevator and to provide the braking activation as quickly and reliably as possible. For the reasons of safety and reliable operation described above, the brake according to the invention is also suitable for use as a mechanical safety device of an elevator.

A second aspect of the invention relates to an elevator system to which a brake according to the invention is fitted.

The invention also relates to a method for controlling a brake according to the invention. In the method the operating mode of the elevator is determined and the brake is also controlled during normal operation of the elevator by displacing the initial position of the disengaging movement of the brake member with the actuator.

It is also possible to adjust the deceleration during an emergency stop of the elevator with the brake according to the invention by changing the braking force with the actuator. As a result, the present invention enables the following solution: wherein a movement curve, more preferably a speed curve, is formed, according to which the movement of the elevator car can be stopped safely in connection with an emergency stop of the elevator and also the elevator car is stopped by changing the movement of the elevator car towards the aforementioned movement curve by adjusting the braking force with the actuator. This solution enables the movement of the elevator car to be stopped in a controlled manner and at a sufficiently low deceleration, in which case dangerously large deceleration forces in connection with an emergency stop are not exerted on the passengers in the elevator car. In a preferred embodiment of the invention the aforesaid movement curve is formed such that the speed of the elevator car is decelerated to zero starting from the starting point of the deceleration when the elevator car reaches the floor at which it is about to stop. In this case the elevator passengers can quickly transfer to the stopping floor and they can also quickly leave the elevator regardless of the operationally abnormal situation of the elevator. If an operation abnormality of a type that prevents continuation of the run for safety or other reasons occurs during the run using the elevator, it is necessary to perform an emergency stop of the elevator. This type of operational anomaly may be, for example, a power interruption or an opening of an entrance to an elevator hoistway of an elevator hoistway.

The brake according to the invention is preferably the machinery brake of the hoisting machine of the elevator or a car brake that moves together with the elevator car and engages in a fork-like manner with and brakes against a braking surface on the guide rail of the elevator car and/or counterweight.

The brake according to the invention can also be used as a mechanical brake for the drive machinery of an escalator or a moving walkway. In addition, the fork-type car brake according to the invention can be applied as a brake for escalators or moving walkways by configuring the brake fork to be in clamping attachment with the path of movement of the escalator/moving walkway.

The foregoing summary, as well as the additional features and additional advantages of the invention presented below, will be better understood with the aid of the following description of some embodiments, which does not limit the scope of application of the invention.

Drawings

Fig. 1a to 1c present a shoe brake according to an embodiment of the invention of the hoisting machine of an elevator.

Fig. 2 presents a brake according to an embodiment of the invention of the hoisting machine of an elevator.

Fig. 3 illustrates a control method according to an embodiment of the invention of the brake of an elevator.

Detailed Description

Fig. 1a to 1c present a shoe brake of the hoisting machine of an elevator in different operating conditions such that:

figure 1a presents a situation in which the brake is activated in connection with normal operation of the elevator to brake the hoisting machine of the elevator,

fig. 1b presents a situation in which the brake is released in connection with normal operation of the elevator, and

fig. 1c presents a situation in which the brake is dropped as a result of an operational anomaly of the elevator and a disengaging movement of the brake has occurred.

It is also possible to fit the brake control mechanism according to fig. 1a to 1c to a disc brake instead of a brake pad brake, for example such that one of the braking elements on the opposite side of the brake disc is configured to be controlled with the control mechanism according to fig. 1a to 1 c.

The hoisting machine of an elevator means a drive arrangement with which the elevator car is driven in the elevator shaft in the up-down direction on the basis of elevator calls given by the elevator passengers. As is generally known in the art, the driving force required for driving the elevator car is transmitted via a rope or belt transmission between the elevator car and the rotating traction sheave of the hoisting machine.

The shoe brake of fig. 1a to 1c comprises a base 1 attached to the frame of the hoisting machine. In addition, the brake comprises a brake shoe 2 which is movably supported on the base. The brake comprises a spring 5 which generates a thrust between the base 1 and the brake shoe 2, which thrust presses a brake pad comprised in the brake shoe 2 into contact with the braking surface 16. The brake further comprises an articulated counter-force element (counter-force element)9 against the thrust of the spring 5, which element engages with the brake shoe 2 via the lever arm 3. The electromagnet 8, which receives its power supply from the power source 21, is fitted in connection with the counter-force element 9. The electromagnet 8 attached to the base 1 exerts an attractive force on the hinge of the counter-force element 9, which force prevents bending of the counter-force element 9.

The brake is controlled by the electric motor 11 during normal operation of the elevator. The rotational shaft 14 of the electric motor 11 is connected to an eccentric adjustment member 15, which is connected via a bearing to a support 20, which is further connected with an articulated joint to the lever arm 3 and via the lever arm 3 to the brake shoe 2, such that when the rotational shaft 14 is rotated by means of the electric motor 11, the brake shoe 2 is moved between a release position according to fig. 1b and a braking position according to fig. 1 a. The brake is activated by displacing the brake shoe 2 from the release position according to fig. 1b to the braking position according to fig. 1a, in which the brake pad on the brake shoe presses against the braking surface 16 of the rotating part of the hoisting machine to brake the movement of the traction sheave/the movement of the elevator car of the hoisting machine. Correspondingly, the brake is opened by displacing the brake shoe 2 from the braking position according to fig. 1a to the release position according to fig. 1 b. The electric motor is controlled such that: in the course of the movement of brake shoe 2, the speed of brake shoe 2 just before the collision with the braking surface is so small that no noise from the collision is generated that could disturb the elevator passengers or other users of the building. A requirement for controlling the brake with the electric motor is to prevent bending of the counter-force element 9. The electric motor may be a dc motor or an ac motor. In some embodiments, the electric motor 11 is a brushless dc motor comprising a rotor with magnetized permanent magnets, and the motor 11 is controlled with a frequency converter implementing a predetermined movement profile for the brake shoe 2. In some embodiments, the ac motor 11 may be directly connected to the network supplying the ac power with suitable switches, such as with relays or contactors, and the brake shoe 2 is moved by the ac motor 11 by connecting the phase of the ac motor 11 to the phase of the ac network by controlling the aforementioned switches.

In an operational abnormality of the elevator, the brake is dropped by disconnecting the current supply to the electromagnet 8 with the switch 13 functioning as a trigger member. When the current supply is switched off, the counter-force element 9 bends and the force action of the counter-force element 9 against the thrust force of the spring 5 stops, in which case the brake shoe 2 is displaced at the greatest possible speed due to the spring force from the initial position of the disengaging movement limited by the eccentric adjusting part 15, the support 20, the lever arm 3 and the counter-force element 9 to the position according to fig. 1c pressing against the brake surface 16 to brake the movement of the hoisting machine. As a result, when dropping the brake, starting from the initial position of the disengaging movement according to fig. 1a or 1b always ends in the situation according to fig. 1 c. It should be noted that also in fig. 1a, the brake shoe is in a braking position engaging against the braking surface 16 of the hoisting machine; the situation according to fig. 1c differs from the situation of fig. 1a, however, in that, unlike the situation in fig. 1a in which the brake is not dropped and the brake shoe 2 is therefore still in the initial position of the disengagement movement, in the situation of fig. 1c the brake is dropped and in this case the brake can no longer be opened again with the electric motor 11. It is possible to control the brake with the electric motor 11 only when the brake shoes are in an initial position of disengagement movement. As a result, opening the dropped brake again with the electric motor 11 requires switching the eccentric adjusting member 15 to the position according to fig. 1a and connecting the current to the electromagnet 8. The current supplied to the electromagnet 8 is connected in the situation of fig. 1a, because in this case the counter force element 9 has straightened out so that the hinge joint of the counter force element 9 is located in the vicinity of the electromagnet 8 and the current requirement of the electromagnet is smaller. When the current of the electromagnet 8 is connected, the capacity of the counter-force element 9 to resist the spring force is restored and the brake shoe is displaced to the initial position of the disengagement movement. For the reasons mentioned above, the situation in fig. 1c is therefore also a failsafe, so that a malfunction of the electric motor or of the control device of the electric motor cannot lead to an incorrect opening of the brake.

When the operation of the elevator is abnormal, the brake is dropped, and at this time, the safety of the elevator requires the rapid start of the brake by the spring force. An operational anomaly of this type can be e.g. an emergency stop of an elevator, a stop of an elevator with a servo drive, a stop of an elevator with a rescue drive, a stop of an elevator due to a power interruption and also in connection with a precise leveling of the elevator car. An operational anomaly is normally detected because of the opening of the safety switch in the safety circuit of the elevator.

The transmission of the electric motor 11 may be chosen such that the shaft of the electric motor rotates a number of turns when the eccentric adjusting member 15 rotates 180 degrees to open or close the brake. In this case, the torque demand of the electric motor is small and the size of the electric motor 11 can be reduced. The required attraction force of the electromagnet 8 for preventing bending of the counter-force element 9 is small, for which reason the electromagnet 8 can also be made small in its dimensions. This is e.g. useful in those elevator systems where two machinery brakes according to the embodiment of fig. 1 a-1 c are fitted to the same hoisting machine for increased safety.

During standstill of the elevator, the energy consumption of the brake can be reduced by dropping the brake by disconnecting the current supply of the electromagnet 8 after the brake has first been activated with the electric motor 11. In this case, the brake is opened again by switching the eccentric adjusting member 15 into the position according to fig. 1a and supplying current to the electromagnet 8, thereby switching to the initial position of the disengaging movement. After this, the situation is switched from the situation of fig. 1a to the situation of fig. 1b by opening the brake with the electric motor 11.

Fig. 2 presents schematically a brake according to an embodiment of the invention of the hoisting machine of an elevator. The brake according to the operating principle of fig. 2 can be e.g. a drum brake, a shoe brake, a disc brake or a car brake of an elevator car engaging with guide rails in a fork-like manner to brake the movement of the elevator car. The brake comprises a frame part 1 attached to the frame of the hoisting machine. In addition, the brake comprises a brake element 2 supported in a movable manner on the frame part 1, and a spring 5 which in the state supported on the frame part 1 pushes a brake pad attached to the brake element 2 against a braking surface 16 of a rotating part of the hoisting machine. The braking member 2 comprises a magnetic core and the frame part 1 comprises an electromagnet 10, to which current is supplied to generate an attractive force between the frame part 1 and the braking member 2.

In order that it would be possible to control the brake during normal operation of the elevator, the braking member 2 must be pulled towards the frame part 1 by supplying current to the electromagnet 10 of the brake. The detent 2 is pressed against the screw 3 by the attractive force of the electromagnet. After this, during normal operation of the elevator, the brake is controlled with the motor 11, with the combination of the solenoid 11 and the lever arm, or with other such actuators 11 that effect a rotational movement for rotating the screw 3. The rotational movement moves the screw 3, displacing the detent 2 to the release position by means of the screw 3 when the screw is moved away from the detent surface 16 and to the detent position when the screw is moved towards the detent surface 16, at which point the detent 2 is finally pressed against the detent surface 16. Therefore, the brake can be moved at a low speed by the control of the actuator 11, which reduces noise generated by the operation of the brake.

At an abnormal operation of the elevator, the brake is dropped by disconnecting the current supply of the electromagnet 10 with the switch 13, as presented in fig. 2. When the current supply is switched off, the action of the electromagnet 10 against the spring force ceases and the spring 5 pushes the braking member 2 from the initial position of disengagement movement, limited by the screw 3, to the braking position against the braking surface 16. After this, the brake cannot be opened with the actuator 11 until the disengaged condition is reset by supplying current to the electromagnet 10 again.

The energy consumption of the brake can be reduced during standstill of the elevator by de-energizing the brake by switching off the current supply to the electromagnet 10 after the brake has first been activated with the actuator 11. In this case, the next time when the brake is opened, the disengagement condition must first be reset by supplying current to the electromagnet 10, which can then open the brake by control with the actuator 11.

Fig. 3 presents a control method of the brake according to the embodiment of fig. 1 or fig. 2, for example. Time t marked in FIG. 3₁At this point, a power interruption occurs, in which case the safety system of the elevator performs an emergency stop. The elevator control unit calculates a speed reference for the elevator car from the starting moment of deceleration, on the basis of which the movement of the elevator can be decelerated with a sufficiently low deceleration so that the elevator car finally stops at the floor immediately before stopping in the driving direction; time of rest t₂Also marked in figure 3. Sufficiently low deceleration preferably means having no more than about 3m/s²A deceleration of the value of (a); however, the deceleration may also be somewhat larger than this (about 6 m/s) if the elevator car may otherwise be in danger of colliding with the end of the elevator shaft or with an object in the elevator shaft²Or smaller).

The elevator control unit compares the measured speed of the elevator car (e.g. the measured speed of the traction sheave of the hoisting machine) with a speed reference and controls the actuator 11 on the basis of the comparison. The measured speed of the elevator car can be adjusted towards the speed reference by controlling the brake with the actuator 11 so that the deceleration of the elevator car is increased by pressing the brake shoe/brake 2 in the initial position of the disengaging movement against the moving surface 16 more strongly than before with the actuator 11, in which case the speed of the elevator car decreases faster than before as the friction increases; accordingly, the deceleration of the elevator car is reduced by relieving the brake shoe/brake 2 with the actuator 11 of the force with which it is pressed against the braking surface 16. In this way, by changing the deceleration of the elevator car, the speed of the elevator car is adjusted towards the speed reference, so that the elevator car stops at the stopping floor according to the speed reference and passengers can leave the elevator car.

If the measured speed of the elevator car exceeds the value permitted by the speed reference, the elevator control unit switches the brake off by means of the switch 13, in which case the action of the counter-force element 9/electromagnet 10 against the spring force ceases, the brake shoe/brake 2 is pressed against the braking surface 16 by the spring force and the elevator car stops as quickly as possible.

In some embodiments a separate electronic monitoring unit for the opening of the brake is fitted into the elevator system, which monitors the emergency stop performed by the elevator control unit and following the speed reference and, if the speed of the elevator car in such a situation exceeds the value allowed by the speed reference, opens the brake by opening the switch 13.

The elevator control unit/electronic monitoring unit receives its operating power, e.g. from a battery, during a power interruption.

It is obvious to the person skilled in the art that different embodiments of the invention are not limited to the examples described above, but that they may be varied within the scope of the claims presented below.

It will be apparent to those skilled in the art that instead of a rotatable screw 3 for moving the brake, a linearly moving support member 3 may be used.

It is obvious to the person skilled in the art that the initial position of the disengagement movement, which can be modified in a controlled manner, can also be achieved, for example, by adjusting the shape or length of the detent of the base such that the distance of the detent from the detent position in the initial position of the disengagement movement changes. In this case the detent/base may for example be two parts such that the parts are successively in the direction of the disengaging movement and the distance between them can be changed with a suitable adjusting part.

Claims (12)

1. A brake, comprising:

a base (1);

a brake (2) movably supported on the base, the brake configured to move between a braking position and a release position;

a spring (5) with the spring force of which the braking element (2) can be lowered from an initial position of the disengagement movement into the braking position;

characterized in that it comprises a movable support member (3, 20) for limiting said initial position of said disengagement movement of said braking member (2);

the brake comprises a controllable actuator (11) mechanically connected to the aforementioned support member (3) and configured to displace the braking member in the initial position of the disengagement movement with respect to the braking position;

wherein the actuator (11) is an electric motor, the frame of which is attached to the base (1) of the brake, and wherein the rotating shaft (14) of the electric motor is connected to an eccentric adjustment means (15) which is connected to a support member (3) with a hinged engagement, such that the support member (3) moves when the rotating shaft (14) of the electric motor rotates.

2. Brake according to claim 1, characterized in that the actuator (11) is configured to displace the brake member (2) in the initial position of the disengagement movement from the release position to the braking position by displacing the brake member (2) in the initial position of the disengagement movement.

3. The brake of claim 2, characterized in that the actuator (11) is configured to displace the brake member (2) in the initial position of the disengagement movement from the braking position to the release position by displacing the brake member (2) in the initial position of the disengagement movement.

4. A brake according to any one of claims 1-3, characterized in that the brake comprises a counter-force element (9, 10) acting against the spring force for holding the brake in the initial position of the disengagement movement.

5. Brake according to claim 4, characterized in that the brake comprises a triggering part (8, 13) connected to the force generating mechanism of the counter-force element (9, 10);

and in that the triggering means (8, 13) are configured to drop the braking member (2) from the initial position of the disengaging movement to the braking position by reducing the force effect of the counter-force element (9, 10).

6. Brake according to claim 5, characterized in that the brake is used in an elevator and that the triggering part (8, 13) is configured to drop the braking member (2) in connection with an operation abnormality of the elevator.

7. Elevator system, characterized in that the elevator system comprises a brake according to any of claims 1-6 for braking the movement of an elevator car.

8. Elevator system according to claim 7, characterized in that the brake of the elevator system is configured to be controlled with an actuator (11) during normal operation of the elevator.

9. A method for controlling a brake according to any one of claims 1-6, in which method:

-determining the operating mode of the elevator

It is characterized in that the preparation method is characterized in that,

-controlling the brake during normal operation of the elevator by displacing the braking member (2) in the initial position of the disengagement movement with the actuator (11).

10. The method of claim 9, wherein:

-dropping the braking member (2) from the initial position of the disengagement movement to a braking position when an operational anomaly of the elevator is detected.

11. Method for controlling the brake of an elevator according to any of claims 1-6 in an operational anomaly of the elevator, characterized in that:

-adjusting the braking force with the actuator.

12. The method of claim 11, wherein:

-forming a motion curve according to which the movement of the elevator car can be stopped safely in connection with an emergency stop of the elevator,

-stopping the elevator car by changing the movement of the elevator car towards the aforementioned motion curve by adjusting the braking force with the actuator.