HK1057032B - Holding brake for an elevator - Google Patents

Description

Holding brake for elevator

Technical Field

The invention relates to an elevator holding brake.

Background

The function of the holding brake of an elevator is to keep the elevator car immobile at a floor and to stop it when needed, e.g. in case of a power failure of some kind. The braking action is therefore based on the use of a mechanical pressing device, such as a spring, which holds the brake in place when it is not subjected to any external force. The operation of the elevator brake must be as fast, accurate and noiseless as possible in view of the elevator passengers. The air gap between the brake pad holding the brake and the braking surface of the traction sheave or a separate brake wheel must therefore be as small as possible. Thus, the braking action is fast and the impact energy of the brake shoes is small, while the braking noise is minimal.

The braking force of the holding brake, i.e. the pressing force of the spring used therein, must be large in order to enable an optimum operation of the brake. The impact of the brake shoes against the braking surface generally tends to produce some noise or vibration. Also, when the mechanical spring is compressed when the brake is released, some noise may be generated due to the impact between the brake main body and the movable frame. There are good reasons for continuing efforts in developing various solutions for attenuating the types of impulsive noise described above.

FI patent application 982788 proposes the concept of damping the noise generated by the operation of the holding brake by using a separate damping device made of some elastic material, which is placed between the moving parts and the brake body.

Disclosure of Invention

The invention aims to realize a novel holding brake. A particular object is to specify an arrangement in which a hydraulic brake release device is used to dampen the braking action and the noise generated by it. The holding brake of the present invention includes a hydraulic circuit that resists movement of the movable frame.

To achieve the above object, the present invention provides an elevator holding brake comprising

A brake main body, a brake device and a brake device,

a movable frame movably supported on the brake main body,

a brake pad attached to the movable frame,

a pressing member designed to move the movable frame away from the braking body and to press the braking pad attached to the movable frame against a braking surface,

an electromagnet as a first brake release means mounted on the brake main body to attract the movable frame toward the brake main body, and,

a hydraulic circuit to resist movement of the movable frame, the hydraulic circuit including a hydraulic actuator connected to the movable frame, and the actuator being designed to be operated by a second brake release device connected to the hydraulic circuit to release the brakes. The advantage of the present invention, in contrast to the previous solutions, is the low manufacturing cost due to its combination of a brake release device and a damper in the same physical device. Another advantage is that the structure of the braking device can be implemented in various ways. A further advantage is that the same device can be used to achieve damping in both the release and abutment directions. The motion of the movable frame during braking is small, whereas the device of the invention produces an accurate braking motion without delay. The device of the invention also makes it possible to avoid various types of movement disturbances caused by play. One of the advantages is also the fact that the brake release device and the brake damper share the same fluid source. The structure of the invention is preferably achieved by integrating parts of the hydraulic circuit in the piston. On the other hand, the components of the hydraulic circuit, when placed separately from the brake body, will be relatively easily accessible for maintenance and service. Another advantage of the present invention is that it employs a grooved channel in conjunction with the hydraulic circuit to eliminate leaks and seal wear. The tank circuit is preferably designed so that it shares the same liquid line leading to a release pump with the hydraulic circuit, thereby eliminating the need for a separate pipe to connect the tank circuit to the release pump.

Drawings

In the following, the invention will be described in detail with reference to the attached drawings, which show an elevator holding brake according to the invention.

Fig. 1 presents an overall view of a traction sheave elevator;

FIG. 2 illustrates a partially cut-away elevator holding brake with a brake release cylinder, a damping hydraulic circuit, and a tank circuit integrated therewith;

figure 3 shows a slightly different embodiment of the device in figure 2, with parts of the hydraulic circuit made in the piston.

Detailed Description

Fig. 1 presents a traction sheave 51 provided with a motor and transmitting force via ropes 53 to an elevator car 54 and a counterweight 55. Two holding brakes 52 are placed against the braking surface of the traction sheave. This figure embodies the placement and operation of the holding detent.

The holding brake 52 shown in fig. 2 comprises a brake body 1 on which a movable frame 2 is movably mounted. A brake pad 3, which abuts the braking surface 4 of the traction sheave 51, is attached to the outer surface of the movable frame. The brake body houses an electromagnet 5 which exerts an attractive force between the brake body 1 and the movable frame 2. A lifting member, such as a lifting shaft 6, is fixed to the movable frame 2. A pressing device, such as a mechanical spring 11 consisting of, for example, disc springs, is placed between the braking body 1 and the movable frame 2 to push the movable frame 2 away from the braking body 1 and press the brake pad 3 against the braking surface 4. A brake release device is provided in combination with the holding brake 52, which device comprises a piston 7 attached to the lifting shaft 6 and adapted to generate hydraulic pressure to force liquid from a brake release cylinder 12 into conduits k1 and k2 comprised in a separate hydraulic circuit that resists movement of the movable frame 2. Conduits k1 and k2 communicate with throttle (choker) V1 and V2, which dampen the flow and thus dampen the impulsive noise generated by the braking action. The hydraulic circuit comprises a mechanical release device 8, which is operated to cause brake fluid to flow from a fluid reservoir 9 of the release device via a release pump 10 into the spaces above and below the piston 7, which spaces are defined in part by unequal areas a1 and a2 above and below the piston. A tank circuit 13 is connected to the hydraulic circuit to prevent leakage of fluid from the brake release cylinder 12 and to prevent wear of the sealing gaskets.

By using a damping hydraulic circuit, it is possible to combine a brake release and a damper in the same device. When the brake is released mechanically, for example during a power failure, without the electromagnet 5 functioning, hydraulic pressure is transmitted from the reservoir 9 of the release device 8 via the conduits k1 and k2 into the space on each side of the piston 7. The brake is released when the brake is pushed upward as the piston 7 is pushed by the pressure generated due to the difference between the upper and lower side areas of the piston 7. When the brake is released using the brake release device, the pressure above the piston 7 tends to increase with the movement of the piston, as the pressure equalisation in the system is delayed by the sealing gasket between the upper and lower sides of the piston and the throttle V1. The sealing of the spaces above and below the piston 7 to the tank circuit 13 may leak significantly. In this case, a suitable amount of liquid is forced to pass through the sealing gasket (gasket) around the upper part of the piston into the channel 13, as a result of which the pressure is equalized and the release delay is considerably shortened.

When the braking is released by means of the electromagnet 5, the latter attracts the mobile frame 2 and the braking body 1 towards each other, as a result of which the braking pad 3 starts to move upwards, while at the same time the upper side of the piston 7 pushes some liquid into the duct k1, where the liquid flow is damped by the throttle V1 and the impact noise due to the mobile frame 2 and the braking body 1 colliding with each other is thus dampened, while the kinetic energy is converted into thermal energy. Liquid from the upper side of the piston 7 passes to the lower side of the piston 7, but since the area a2 on the lower side is larger than the area a1 on the upper side, an appropriate amount of liquid from the reservoir 9 of the discharge pump 10 flows in to compensate for the shortage. When the brake is released, fluid from the release pump 10 flows through the throttle valve V2. When the brake is closed, the action of the electromagnet 5 is terminated and the mechanical spring 11 of the brake pushes the movable frame 2 and the brake pad 3 attached to it downwards towards the braking surface 4. At the same time the piston 7 forces a suitable liquid from below into the conduit k2, from where it flows via the throttle V1 to the upper side of the piston 7, damping the impact noise generated by the brake pad 3 hitting the traction sheave 51. After this, the liquid flows back via the throttle V2 into the container 9 of the releasing device 8 due to the difference between the areas a1 and a2 on the upper and lower sides of the piston. The liquid leaking past the sealing gasket on the lower part of the piston 7 flows into the tank circuit 13 so that it will not damage the underlying braking system or cause wear on the other sealing gaskets.

Figure 3 illustrates the apparatus of the present invention shown in figure 2, using a slightly different embodiment. Fig. 3 differs from fig. 2 only in that the fluid communication between the two spaces which are partly defined by the upper and lower sides a1 and a2 of the piston has been achieved by drilling a conduit k1 in the piston 7, in which conduit the throttle V1, which reduces the impact noise, is placed. The device according to fig. 3 also has no tank circuit. Thus, the damping hydraulic circuit of the present invention may be integrated with the piston 7 in the brake release cylinder 12, such as by drilling a hole in the piston 7. As a result, fluid circulating between the upper and lower sides of the piston 7 will flow through this drilled hole. If the orifice is small enough it will constitute a good throttle restricting the flow. A separate choke may also be placed in the drilled hole. Alternatively, a fluid flow path may be provided at the side of the piston.

The invention can be implemented in connection with a brake in many ways without departing from the inventive idea. For example, the conduit k1 connecting the two spaces partially defined by the areas a1 and a2 and the throttle V1 may be made inside the piston 7, and the pressure equalization conduit together with the throttle V1 and V2 may be directly connected to one of the two spaces partially defined by the areas a1 and a 2. The throttle valves for restricting the flow may also be placed in a separate device next to the side of the brake release cylinder 12.

Claims (9)

1. An elevator holding brake (52) comprising

A braking body (1),

a movable frame (2) movably supported on the brake body,

a brake pad (3) attached to the mobile frame,

a pressing member (11) designed to move the mobile frame away from the braking body and to press the braking pad attached to the mobile frame against a braking surface (4),

an electromagnet (5) as a first brake release means mounted on the brake main body to attract the movable frame toward the brake main body, and,

a hydraulic circuit to resist the movement of the mobile frame (2), characterized in that it comprises a hydraulic actuator connected to the mobile frame (2), and in that said actuator is designed to be operated by means of a second brake release device (8) connected to said hydraulic circuit to release the brakes.

2. Holding brake (52) according to claim 1, characterized in that the actuator is a brake release cylinder (12) in which a piston (7) for pushing the movable frame (2) is housed, said piston having unequal areas (a1, a2) on its upper and lower sides contacting the liquid in the brake release cylinder (12).

3. Holding brake (52) according to claim 2, characterized in that it comprises a fluid passage between said upper and lower sides, and a throttle valve (V1) is placed in said passage.

4. Holding brake (52) as defined in claim 2, characterized in that the hydraulic circuit comprises a liquid container (9) and that a throttle (V2) is arranged between the liquid container (9) and the piston (7).

5. Holding brake (52) as defined in any one of the preceding claims, characterized in that the second brake release means (8) is provided with a reservoir (9) from which liquid can flow to different sides of the piston (7) by means of a release pump (10).

6. Holding brake (52) as defined in any one of claims 1-4, characterized in that the hydraulic circuit is a separate device connected to the holding brake (52).

7. Holding brake according to any of claims 1-4, characterized in that at least part of the hydraulic circuit has been machined into the piston (7).

8. Holding brake according to any of claims 1-4, characterized in that it comprises a tank circuit (13) integrated with the hydraulic circuit to eliminate leaks and wear of sealing gaskets.

9. Holding brake according to claim 1, characterized in that the actuator is designed to be operated by the second brake release means (8) for releasing the brake during a power failure.