Claims:We claim: -

1. A safety apparatus (100) for a braking system (10) of an elevator, said braking system (10) comprises
? an electro-magnetic brake (20) with a plunger (30), said plunger (30) is movable between a braking position and a release position;
? a set of braking arms (40) press-against a drive axle (50) of said elevator for applying brake, in said braking position;
? said braking arms (40) move away from said drive axle (50) of said elevator for releasing brake, in said release position;
? a set of brake springs (60) for driving said braking arms (40) to press against said drive axle (50) to apply the brake, when power supply to said electro-magnetic brake (20) is stopped; characterized in that,
? a hydraulic unit (70) for controlling the movement of said plunger (30) to regulate the braking.
2. The safety apparatus (100) as claimed in claim 1, wherein said hydraulic unit (70) has a valve (80) which is controlled to regulate the discharge of oil in a hydraulic cylinder (90) coupled to said plunger (30).
3. The safety apparatus (100) as claimed in claim 2, wherein said valve (80) is controlled to regulate the movement of said plunger (30) such that brake is applied in a selective manner.
4. The safety apparatus (100) as claimed in claim 3, wherein the movement of said plunger (30) controlled such that brake is applied in a controlled manner and the braking arms (40) do not forcedly press against the drive axle (50) abruptly.
5. The safety apparatus (100) as claimed in claim 3, wherein said valve (80) is controlled to regulate the movement of said plunger (30) when power supply to said electro-magnetic brake (20) is stopped such that brake is applied in a controlled manner.
6. The safety apparatus (100) as claimed in claim 1, wherein said valve (80) is opened selectively based on an input from a relay (95) when power supply to said electro-magnetic brake (20) is stopped.
7. A retrofit type safety device for an elevator, comprises a hydraulic unit (70) with a valve (80) to regulate supply of oil to a hydraulic cylinder (90).
8. The retrofit type safety device as claimed in claim 7, wherein said hydraulic cylinder (90) is couplable to a plunger (30) of an electro-magnetic brake (20) of said elevator for actuating said plunger (30).
9. The retrofit type safety device as claimed in claim 7, said valve (80) is couplable to a relay (95), and said valve (80) is selectively controllable based on power OFF condition.
, Description:Complete Specification:
The following specification describes and ascertains the nature of this invention and the manner in which it is to be performed:
Field of the invention:
[0001] The present invention relates to a safety apparatus for a braking system of an elevator. More specifically, it relates to a retrofit type safety device for an elevator.
Background of the invention:
[0002] Elevators in multi-story buildings come with lot of interesting and sophisticated features. However, in a small and mid-sized building, there is a limitation to have sophisticated systems. There is still a challenge to stop the elevator car or cage in a safe floor without any physical discomfort or jerk, when the mains power supply goes off.
[0003] JP10095580A2 discloses an emergency operation device for an elevator. If there is a power failure, an external power source is connected to the external power source connector and then the electromagnetic brake is released by the electromagnetic brake releasing switch to move down a car to the nearest floor by its self-weight.
Brief description of the invention:

[0004] This invention relates to a safety apparatus for a braking system of an elevator. The braking system comprises an electro-magnetic/electric brake with a plunger. The plunger is movable between a braking position and a release position. A set of braking arms press-against a drive axle of the elevator for applying brake in the braking position. The braking arms move away from the drive axle of the elevator for releasing brake in the release position. A set of brake springs are provided for driving the braking arms to press against the drive axle to apply the brake, when power supply to the electro-magnetic brake is stopped. A hydraulic unit controls the movement of the plunger to regulate the braking. The hydraulic unit has a valve which is controlled to regulate the discharge of oil in a hydraulic cylinder coupled to the plunger. The valve is controlled to regulate the movement of the plunger such that brake is applied in a selective manner. The movement of the plunger is controlled such that brake is applied in a controlled manner, and the braking arms do not forcedly press against the drive axle abruptly. The valve is controlled to regulate the movement of the plunger when power supply to the electro-magnetic brake is stopped such that brake is applied in a controlled manner. The valve is opened selectively based on an input from a relay when power supply to the electro-magnetic brake is stopped.
[0005] The invention also relates to a retrofit type safety device for an elevator. The retrofit type safety device comprises a hydraulic unit comprising a valve to regulate supply of oil to a hydraulic cylinder. The hydraulic cylinder is couplable to a plunger of an electro-magnetic brake of the elevator for actuating the plunger. The valve is couplable to a relay, and selectively controllable based on power OFF condition
Brief description of the accompanying drawings:
[0006] An embodiment of the disclosure is described with reference to the following accompanying drawing,
[0007] Fig. 1 illustrates a schematic block diagram of a safety apparatus for a braking system of an elevator, according to an embodiment of the present invention; and
[0008] Fig. 2 shows a schematic block diagram of a hydraulic unit implemented in a safety apparatus for a braking system of an elevator, according to an embodiment of the present invention.
[0009] Detailed description of the embodiments:
[0010] Fig. 1 shows a schematic block diagram of a safety apparatus 100 for a braking system of an elevator. The braking system 10 comprises an electro-magnetic brake 20 or electric brake with a plunger 30. The plunger 30 is movable between a braking position and a release position. A set of braking arms 40 are coupled to the plunger 30 and actuated by the plunger 30. In the braking position of the plunger 30, the braking arms 40 press-against a drive-axle 50 of the elevator to restrict the movement of the drive-axle 50 and thereby stop the movement of an elevator cage or car. Similarly, the release position of the plunger 30, the set of braking arms 40 move away from the drive axle 50 for releasing the brake.
[0011] In an embodiment of the invention, the plunger 30 is moved vertically up and down between the release position and the braking position. By electromagnetic force, the plunger 30 is moved upwards to the release position, in which the braking arms 40 move away from the drive axle 50, thereby permitting the movement of the elevator cage or car. Similarly, the plunger 30 is moved downwards to the braking position, in which the braking arms 40 press-against the drive-axle 50 of the elevator.
[0012] When power supply to the electro-magnetic brake 20 is stopped, the braking arms 40 are driven by a set of brake springs 60 to press against the drive-axle 50 to apply the brake. When the power supply is stopped, the plunger 30 goes up towards the release position, because of the absence of the electro-magnetic force. However, in order to ensure safety to the passengers, a set of brake springs 60 are provided in the braking system 20.
[0013] By default, the braking arms 40 are pressed against the drive-axle 50 by the force of the brake springs 60. When the elevator needs to be moved, the plunger 30 is moved to the release position by the electromagnetic force, against the force of the brake springs 60. As a result, the elevator cage/car is movable to different floors. When the power supply is stopped, there is no electro-magnetic force, hence the plunger 30 is not moved to braking position. However, the braking arms 40 are driven by the brake springs 60 suddenly to apply brake to the drive-axle 50, which may cause jerks or unintentional oscillations. The safety apparatus 100 of the present invention comprises a hydraulic unit 70 for controlling the movement of the plunger 30 to regulating the braking. The hydraulic unit 70 avoids such jerks and abrupt movements while braking, especially during power off conditions.
[0014] Fig. 2 shows a schematic block diagram of a hydraulic unit of a safety apparatus for a braking system of an elevator, according to an embodiment of the present invention. The safety apparatus 100 of the present invention comprises a hydraulic unit 70 for controlling the movement of the plunger 30 to regulating the braking. The hydraulic unit 70 has a valve 80 which is controlled to regulate discharge of oil in a hydraulic cylinder 90 which is coupled to the plunger 30. The valve 80 is controlled to regulate the movement of the plunger 30 such that the brake is applied in a selective manner. The valve 80 is controlled to regulate the movement of the plunger 30 such that brake is applied in a controlled manner so that the braking arms 40 do not forcedly press against the drive-axle 50 in an abrupt manner by the action of the braking arms 60.
[0015] When power supply to the electro-magnetic brake 20 is stopped, the valve 80 is opened based on an input from a relay 95 which is connected to the mains power supply, to regulate the movement of the plunger 30. By controlling the valve 80, oil is discharged selectively to the hydraulic cylinder 90 which assists the plunger 30 to act against the force of the brake springs 60 selectively. As a result, braking is applied smoothly by the brake springs 60 in the event of power failure using the hydraulic unit 70. Both safety as well as comfort are achieved by the present invention.
[0016] Instead of allowing the braking arms 30 to forcedly and abruptly dash against the drive-axle 50, the valve 80 is controlled to control the brake application by the brake springs 60. Therefore, jerky stop of the elevator cage/car is avoided.
[0017] The present invention also discloses a retrofit type safety device can be used in the existing elevators having electromagnetic or electric brakes. The retrofit type safety device has a hydraulic unit 70 with a valve 80. The valve 80 is operated to regulate the discharge of the oil to a hydraulic cylinder 90 which is couplable to a plunger 30 of an electromagnetic or electric brake 20 of the elevator.
[0018] The valve 80 is selectively controlled based on the power OFF condition in order to regulate the braking. The valve 80 is coupled to a relay 95. Based on the input from the relay 95, the valve 80 regulates the discharge of oil to the hydraulic cylinder 90 when the power supply to the electro-magnetic brake 20 is stopped. As a result, braking is applied smoothly without any harm or discomfort to the users. Both safety as well as comfort are ensured to the elevator users even when power is cut off. As the safety device is retrofit type, existing elevators can be upgraded with higher safety and comfort features at less cost.
[0019] Embodiments explained in the description above are only illustrative and do not limit the scope of this invention. Many such embodiments and other modifications and changes in the embodiment explained in the description are envisaged. The scope of the invention is only limited by the scope of the claims.