Double-effect emergency braking apparatus for elevator cars

Abstract

 The invention relates to a double-effect emergency braking apparatus for elevator cars having friction wedges (110) and friction shoes (120) configured to be applied on first and second surfaces (210, 220) of a rail (200) of the elevator. The friction wedges (110) are located in a prismatic cam (111) which is actuated so that the rail (200) is gripped by the friction wedges (110) and the friction shoes (120) so as to reach a friction between the friction wedge (110) and the friction shoes (120) with the rail (200) and thus brake the elevator when the actuation device (140) is activated.

Description

Field of the Invention

[0001] The invention relates to bidirectional safety gears for elevator cars.

Background of the Invention

[0002] There are several embodiments known in the state of the art for obtaining an emergency brake in an elevator car. Two lever mechanisms are used to obtain a double-effect braking device, as an up-direction and down-direction safety gear, obtaining an up-direction safety gear by reversing the down-direction safety gear and placing it on the upper part of the elevator car. A solution of this type entails a substantial increase in the cost of the device since both the lever mechanism and the braking system are doubled.

[0003] The invention described in document EP 1283189B1 shows a safety braking device for elevator cars. The device comprises a support element to be fixed to the car and at least one brake block acting on a rail. The brake block is fixed on a base plate which moves perpendicularly to the rail relative to the support element. A lever pivots about a shaft positioned in the base plate opposite to the brake block and is moved from a release position into a braking position in which the rail is clamped between the free end of the lever and the brake block.

Description of the Invention

[0004] The present invention proposes an apparatus solving the aforementioned drawbacks present in the state of the art.

[0005] According to a first aspect, the invention describes a double-effect emergency braking apparatus for elevator cars having:

support means configured to be coupled to a car;

first friction means configured to be applied in a substantially perpendicular first direction on a first surface of a rail of the elevator;

second friction means configured to be applied in a substantially perpendicular second direction on a second surface of a rail of the elevator opposite to the first surface;

compression means comprising:

a first end opposite to the second surface comprising the second friction means;

a second end opposite to the first end fixed to the support means;

said apparatus being characterized in that it comprises:

a substantially prismatic cam having:

a first base for resting on the support means;

a second base opposite to the first base;

a plurality of first side faces forming a convex first portion comprising:

a front face opposite to the first surface;

two faces contiguous to the front face forming an acute angle with the rail of the elevator and provided with the first friction means;

a plurality of second side faces forming a second portion opposite to the first portion, said second portion comprising a housing configured to allow the cam to rotate about a first shaft:

traversing said housing,

said first shaft being perpendicular to the first base,

said first shaft being fixed to the support means;

movement and stress transmission means to allow a movement of the support means in a third direction substantially perpendicular to a direction defined by the rail of the elevator;

actuation means configured to be actuated by an excess speed detection mechanism of the elevator comprising:

connection means to connect the actuation means with the cam by means of a hinge allowing a rotation between the cam and the actuation means about a second shaft parallel to the first shaft, the connection means being located in the second base at a distance from the first shaft so as to cause a rotation of the cam about the first shaft when the actuation means are activated;

where:

the support means are configured to be moved according to the third direction so that:

the first friction means are moved along the first direction until they are applied to the first surface of the rail;

the second friction means are moved along the second direction until they are applied to the second surface of the rail;

the rail is gripped by the first friction means and the second friction means so as to reach a friction between the first friction means, the second friction means and the rail and thus brake the elevator when the actuation means are actuated;

the first direction, the second direction and the third direction are parallel.

[0006] In the apparatus of the invention:

• The first friction means can be regulated so as to allow braking elevators with different masses.
• The second friction means are configured to provide a total friction coefficient necessary for braking the elevator.
• The first friction means and the second friction means can comprise a contact face with the rail provided with a plurality of grooves.
• The compression means can comprise a plurality of washers that are stacked to form a spring and provide a run and force necessary for braking the elevator.
• The movement and stress transmission means can comprise four screws placed in a rear position of the support means.
• The shaft of the cam can comprise a self-lubricated bushing to facilitate a rotation of the cam and to provide a low friction coefficient for facilitating dewedging.

Brief Description of the Drawings

[0007] A series of drawings which aid in better understanding the invention and expressly related to an embodiment of said invention which is set forth as a non-limiting example thereof will very briefly be described below.

Figure 1 is a perspective view showing the apparatus of the invention and a portion of an elevator rail.

Figure 2 is a view of the rear part of the apparatus of the invention showing the guiding and stress transmission formed by four screws.

Description of a Preferred Embodiment of the Invention

[0008] A preferred embodiment of the invention is described below with the aid of the figures.

[0009] The invention relates to a braking apparatus as a down-direction safety gear and as rising overspeed, carrying out both functions in a single apparatus. The force elastic device is provided by spring washers 121 forming a pressure spring assembly. The braking and horizontal translation forces, as well as the clearances of operation at rest, are absorbed by four movement screws 130 sliding on slit boreholes made on the stringers of the stirrup.

[0010] The safety gear assembly comprises two grips according to figures 1 and 2 acting on the two side rails 200 of the elevator pressing the wedges 110 and the shoes 120 on the rails 200, which by friction or pulling the material of the rails 200 provide a braking force causing the stop of the elevator with a defined deceleration.

[0011] The most important parts or components of the apparatus are:

• support means or support 100: element carrying all the components of the apparatus. All the braking and compression stresses of the spring washers 121 fall on the support 100.
• cam 111: acts on the rail 200. It causes the cam effect and achieves the movement of the support means 100 necessary to absorb the clearances of its rest position on the rails to achieve the flattening of the spring washers 121, obtaining the necessary pressure force on the rail 200 to cause the braking friction.
• first friction means or wedge 110: it provides the apparatus with the propping and friction necessary to achieve the displacements of the support means 100 causing the pressure forces on the rails 200. The first friction means or wedge 110 can be regulated so as to obtain different intervals of forces to brake different vehicle or car masses. The wedge 110 together with the shoe 120 provide the necessary friction with the material of the rails 200 for braking with a certain deceleration.
• second friction means or shoe 120: provides the apparatus with the necessary total friction coefficient for braking due to the grooves 1210 it has in the face of contact with the rail. This part is suspended and slides on the shafts carrying the spring washers 121 in the compression run of the latter.
• rotation means or bolt of the cam 111: supports the propping and compression forces of the spring washers 121. It has incorporated a self-lubricated bushing facilitating the rotation of the cam 111 subjected to high pressure. Its self-lubrication provides a low friction coefficient facilitating dewedging.
• guiding means or bolt of the rail: components carrying the spring washers 121, allowing the sliding in its compression movement. It allows suspending and fixing the shoe 120.
• compression means or spring washers 121: parts arranged in a certain position to form a spring and provide the run and force necessary for braking the vehicle or car.
• movement and stress transmission means 130: they are four screws placed in the rear part of the support 100 allowing the transverse movement of the grip assembly for the absorption of clearances and regulations. The braking stress of the vehicle braking stresses are transmitted on these screws.
• actuation means or actuation screw 140: this screw connects the cam 111 with the stirrup level assembly, i.e., with a part of the excess speed detection mechanism. The actuation movement of the cam 111 is achieved by means of this actuation means or screw 140.

[0012] The operation of the apparatus of the invention is described below:

[0013] The cams 111 are actuated in unison in an emergency situation by means of the actuation screw 140 of each cam 111 connected to the lever assembly carrying he stirrup of the elevator. In this situation, the safety gear, an assembly of the two grips, behaves in the manner described below; the operation in a down-direction safety gear mode will be explained since the rising speed braking actuation mode is the same, simply reversing the direction of the movement.

[0014] The action of the emergency speed limiter for surpassing the considered speed causes the cams 111 to remain in a fixed position, motivated by the propping of the cable of the limiter acting on the levers of the stirrup. The grips continue moving in a vertical direction. The shaft of the cam 111 moves in the vertical direction, this movement causing the rotation of the cam 111, said cam 111 being propped by means of the wedge 110 on the rail 200; this causes a movement of the support 100 in a direction horizontal and transverse to the rail 200, until the clearances existing between the shoe 120, the wedge 110 and the rail 200 are absorbed. At this time, the spring washers 121 are compressed providing at each side of the rail by an action-reaction effect the force needed to press the wedge 110 and the shoe 120 against the rail 200, driving into the grooves that both of them have. The friction necessary to brake and reach wedging is obtained by pulling out the material from the grooves 1210 on the friction surface of the rails 200.

[0015] The dewedging operation of the down-direction safety gear is carried out in the opposite direction to wedging. The elevator installation machine pulls the stirrup, dragging the grip which, although it is pressed by the shoe 120 and the wedge 110, causes a cam effect in the opposite direction favorable for dewedging; in this way the braking apparatus is managed to be moved to its rest position.

Claims

1. A double-effect emergency braking apparatus for elevator cars having:

support means (100) configured to be coupled to a car;

first friction means (110) configured to be applied in a substantially perpendicular first direction on a first surface (210) of a rail (200) of the elevator;

second friction means (120) configured to be applied in a substantially perpendicular second direction on a second surface (220) of a rail (200) of the elevator opposite to first surface (210);

compression means (121) comprising:

a first end opposite to the second surface (220) comprising the second friction means (120);

a second end opposite to the first end fixed to the support means (100);

said apparatus characterized in that it comprises:

a substantially prismatic cam (111) having:

a first base for resting on the support means (100);

a second base opposite to the first base;

a plurality of first side faces forming a convex first portion comprising:

a front face opposite to the first surface (210);

two faces contiguous to the front face forming an acute angle with the rail (200) of the elevator provided with the first friction means (110);

a plurality of second side faces forming a second portion opposite to the first portion, said second portion comprising a housing configured to allow the cam to rotate about a first shaft:

traversing said housing,

said first shaft being perpendicular to the first base,

said first shaft being fixed to the support means (100);

movement and stress transmission means (130) to allow a movement of the support means (100) in a third direction substantially perpendicular to a direction defined by the rail of the elevator;
actuation means (140) configured to be actuated by an excess speed detection mechanism of the elevator comprising:

connection means to connect the actuation means (140) with the cam (111) by means of a hinge allowing a rotation between the cam (111) and the actuation means (140) about a second shaft parallel to the first shaft, the connection means being located in the second base at a distance from the first shaft so as to cause a rotation of the cam about a first shaft when the actuation means (140) are activated;

wherein:

the support means (100) are configured to be moved according to the third direction so that:

the first friction means (110) are moved along the first direction until they are applied to the first surface (210) of the rail (200);

the second friction means (120) are moved along the second direction until they are applied to the second surface (220) of the rail (200);

the rail (200) is gripped by the first friction means (110) and the second friction means (120) so as to reach a friction between the first friction means (110), the second friction means (120) and the rail (200) and thus brake the elevator when the actuation means (140) are activated;

the first direction, the second direction and the third direction are parallel.

2. The apparatus according to claim 1, characterized in that the first friction means (110) are adjustable to allow braking elevators with different masses.

3. The apparatus according to any of claims 1-2, characterized in that the second friction means (120) are configured to provide a total friction coefficient necessary for braking the elevator.

4. The apparatus according to any of claims 1-3, characterized in that the first friction means (110) and the second friction means (120) comprise a face of contact with the rail (200) provided with a plurality of grooves (1210).

5. The apparatus according to any of claims 1-4, characterized in that the compression means (121) comprise a plurality of washers that are stacked to form a spring and provide a run and force necessary for braking the elevator.

6. The apparatus according to any of claims 1-5, characterized in that the movement and stress transmission means (130) comprise four screws placed in a rear position of the support means (100), said screws being configured to slide on slit boreholes made in stringers of a stirrup of the car.

7. The apparatus according to any of claims 1-6, characterized in that the shaft of the cam comprises a self-lubricated bushing to facilitate a rotation of the cam (111) and to provide a low friction coefficient for facilitating dewedging.

Drawing