What happens when the elevator reaches the station level and passengers are streaming in and out of the open-door car, which suddenly moves up or down? As a matter of fact, this has happened all over the country and caused serious casualties. A few days ago the area that the author is in unit area area a passenger elevator that USES for many years also had similar situation. The industry calls the movement of an elevator car (running or sliding car) while the door is open for accidental movement. So what are the reasons that cause the car to move unexpectedly? How do you prevent it? Combined with some problems found in elevator inspection, the author makes some analysis and puts forward some Suggestions for elevator colleagues to refer to.

The reason why the car moved unexpectedly

1.1 electrical reasons

Starting, acceleration, operation of the lift, slow down, stop, open the door, and the elevator all instructions, signals are accomplished by electrical control devices, or programmable logic circuit and computer controller, once part of the system or application problems, the maloperation of the elevator are likely.

(1) the electric interlock device of car door and floor door is invalid. If the door or floor door electric interlock device fails, the car may move unexpectedly. Especially the car door, the door layer electrical interlocking device failure at the same time, the lift station after flat layer to open the door, then as long as there is called within or outside the elevator signal, the elevator will immediately start to call the layer, this is the car accident move one of the most serious accident, often caused by shear, extrusion, falling and other serious consequences.

(2) the control circuit fails. If a link failure in the control circuit, such as brake contactor in the circuit relay contact fusion unreleased, brake coil without losing electricity, the elevator after a flat layer to open the door, the car is in a state of "free float", to the capsules and capsules for heavy heavier on one side of the mobile, and speed will be faster and faster, people in and out of the danger occurs.

(3) other electrical faults. Electromagnetic interference outside the elevator, the elevator itself line defects may cause the car to move accidentally.

1.2 reasons for brakes

Brake is one of the most important safety device in the elevator, car accident that occurred from the mobile accident statistics that the old brake on the brake, especially the old elevator defects is the main cause of the accident. The following factors lead to a situation where the brake torque is not sufficient to stop the elevator car.

(1) improper adjustment. Improper adjustment of brake torque spring, top bolt, electric iron core stroke, brake shoe and brake wheel clearance.

(2) defect of brake components. The brake wheel is out of circle, the surface has furrow mark, the intertile wear is serious, the rivet is exposed, the intertile deformation and the brake wheel do not stick, the component is aging, the action card is blocked and so on.

(3) there is grease on brake shoe of brake wheel. I often in the process of inspection found oil, brake wheel and brake piece is a worm gear traction engine shaft Kong Duan oil seal leak, the elevator at high speed when the oil is flung to the brake wheel drum and the brake shoe friction between the surface; The second is that the brake arm pin shaft USES excessive lubricating oil, and the third is that the maintenance staff accidentally drops oil on the brake wheel.

1.3 reasons for the tractor

The traction elevator runs up and down by the friction between the drag wheel rope groove and the steel wire rope. It can be seen from the formula of traction condition that the defect of the tractor wheel and rope will directly affect the traction ability of the elevator. The tractor is the driving device of the elevator, and the defects of the tractor components will directly affect the normal operation of the elevator.

(1) traction wheel defect. Drag wheel rope groove wear serious, even groove deformation, there is oil on the wheel groove.

(2) defects of traction rope. Wrong type selection of traction wire rope, serious wear of wire rope, smaller diameter, oil stain on wire rope.

(3) cantilever towed wheel shaft is broken. Traction wheel shaft fracture moment, no matter what kind of state, the elevator in the capsules will sink (an avenue of the jurisdiction of the writer's institution elevator has happened 2 times, mainly manufacturing quality problem, now all change).

(4) worm wheel defect. The worm gear of traction machine and the flange of connecting worm gear sleeve are broken.

1.4 human reasons

The personnel of the elevator operation and maintenance department illegally use and operate the elevator, resulting in the accident movement of the car.

(1) the switch of electric interlock device of car door and floor door is shortened by human. Elevator installation and maintenance personnel for debugging and some troubleshooting convenience, will the car door, door interlock switch is short, forget to remove the short connection, the elevator back to normal operation after the consequences of opens up the car.

(2) overloading. Some old freight elevator no overload device. Some overload device failure after failing to repair the elevator, the elevator overload operation, forming a slide after capsules smooth layer to open the door, or traction rope slipping in the tractive sheave groove.

(3) the equilibrium coefficient is too small. Because the elevator installation personnel debugging inaccuracy or elevator users in elevator after put into use to decorate capsules, lead to the balance coefficient is too small, in carrying the rated load and overload device failure cases, capsules down runtime is easy to form the "down" phenomenon, and occurs as the flat layer to open the door of the elevator car.

(4) improper rescue operation. After the elevator closes the person, asks for help personnel to cooperate badly. When the floor door and car door have been opened, other people entering the machine room will loosen the brake and drive the car, causing accidents such as cutting and squeezing.

2. Prevention of accidental movement of car

2.1 elevator service unit

The elevator service unit is the first responsible person for elevator safety. In addition to formulating various rules and regulations and equipping full-time elevator management and operation personnel, the following work should be done.

(1) don't let the elevator run with illness. When the elevator use unit finds that there is a problem or hidden danger, it should deal with it in time. The problems raised by the inspection unit and the maintenance unit should be rectified in time. The problems that should be replaced or repaired should not be used as a compromise. To sign the maintenance agreement with the elevator maintenance unit in time to ensure that the elevator is not out of warranty.

(2) do not overload the elevator. Some old and old cargo elevators without overloading devices should be operated by licensees to strictly control the load.

(3) do not increase the weight of the car at will. After the installation and acceptance of the elevator, the balance coefficient of the elevator has been adjusted and determined. Users should not add marble floors, wooden handrails, wall panels and mirrors to the car at will. Even if want to decorate car, one does not overdecorate, two should inform inspection unit, maintain a unit to re-measure balance coefficient.

(4) do not open the floor door or car door at will. Elevator floor door key should be kept by special person, do not open at will. When rescuing a person, it is necessary to make sure that the personnel in the machine room do not release the brake winding car, so as to open the floor door and release the person. When loosening the brake winding car, the personnel in the machine room also need to make sure that no one opens the floor door and car door. In addition, the author suggests that the use of the unit does not hold the key to the floor door, the release of rescue work in the best professional maintenance personnel under the cooperation.

2.2 elevator maintenance unit

The normal operation of an elevator has a lot to do with the elevator maintenance unit and maintenance personnel. Because of elevator professional knowledge of elevator users don't understand, but once a year check the elevator inspection departments regularly inspection, so the elevator maintenance personnel's quality and maintenance quality will determine the elevators can run normally.

(1) strengthen the sense of responsibility. Maintenance personnel should be familiar with the maintenance of elevator performance, parameters, principle, according to the relevant regulations of the state, regularly inspection on the elevator, maintenance, adjustment, for the maintenance of the elevator status must accomplish know fairly well.

(2) develop good professional habits. The elevator installation and maintenance personnel should have certain professional qualities, and avoid short connection of floor doors, door interlocking devices and all kinds of safety switches, and timely deal with the detected equipment defects.

(3) key inspection of key parts. During maintenance, the inspection of brake, traction rope and overload device should be strengthened to remove oil stains on brake wheel and traction wire rope, so as to ensure the effectiveness of overload device.

(4) strengthen communication with users. In the maintenance found in the elevator problems to inform users timely, and take effective protection measures. In case of any major problem or potential accident, it shall inform the user in writing and report to the local special equipment safety supervision and inspection department.

2.3 elevator inspection unit

The elevator inspection unit is the authoritative institution of elevator safety technical inspection, and the inspection personnel should use the regular inspection once a year to carry out a comprehensive "physical examination" of the elevator, strictly check, and check the quality.

(1) inspection shall be conducted strictly in accordance with the regulations. No matter how busy the inspection work is, no matter how many elevators the elevator users have, the inspection personnel should be on the platform to check, never spot check.

(2) on-site validation. The interlock device, braking performance, traction capacity and overload device of elevator lock should be tested on site to ensure its effectiveness.

(3) supervise and urge the rectification. For old and old elevators without overloading devices and using old brakes with long service time, it is necessary to urge the use unit to repair and reform. It is necessary to replace the traction wheel and the steel wire rope whose wear exceeds the standard until it meets the current national standards and inspection requirements.

2.4 passenger

Car accidents are often caused by elevator attendants, so passengers should pay attention to the following aspects when using the elevator.

(1) do not take an elevator without the elevator inspection mark. There are safety risks in the elevator without inspection or unqualified inspection.

(2) try to pass in and out of the car as quickly as possible, so as not to be stuck in the floor door or door

(3) don't rush into the car when there are too many people.

(4) in case of accidental movement of the car, at the initial stage of movement, the action must be quick, either immediately return or immediately rush out.

2.5 add protection device for accidental movement of car

In addition to the preventive measures taken by the above people, add a set of protective devices on the elevator to prevent accidental movement. In the A3 amendment of European standard en81-1:1998, the relevant contents and requirements of accidental movement protection of the car have been put forward and officially implemented in Europe on January 1, 2012, for which the author proposes the following Suggestions.

(1) China should connect with European standards as soon as possible and add safety protection devices to the elevators.

(2) the protective device shall be composed of a monitoring (monitoring) system, a control system and an execution (stopping) system.

(3) it is suggested that the research, design and manufacturing unit of this device should design the stop making device into safety pliers, rope clamps and other components according to the reasons for the unexpected movement of the car. If the braking device is a brake, it will not work once the traction capacity drops, the tractor parts are damaged, and the brake itself defects cause the car to move unexpectedly.

3 conclusion

The author analyzes the reasons for the unexpected movement of the car and the corresponding preventive measures. It is not hard to see that most of them can be controlled and prevented, especially those man-made factors can be completely avoided. As long as everyone does a good job in all aspects, the car accident will be reduced or even avoided.