Safety gear

Abstract: A safety gear designed to be mounted on an elevator car (1) moving along guide rails (7), comprising a frame (4), an area of wedge housings (3d,6d) formed in the frame, and wedges (3,6) placed in the wedge housings on each side of the guide rail (7), said wedges gripping the guide rail when the safety gear is activated, the wedges being so placed relative to each other that the wider end of one wedge (3) points upwards while the wider end of the other wedge (6) points downwards. To allow safety gear action in both upward and downward directions, the safety gear is provided with an activating means (10) connected to and moving both wedges, and an overspeed governor or equivalent for controlling the activating means.

Description: The present invention relates to a safety gear designed to be mounted on an elevator car moving along guide rails, said safety gear comprising a frame, an area of wedge housings formed in the frame, and wedges placed in the wedge housings on each side of the guide rail, said wedges gripping the guide rail when the safety gear is activated, the wedges being so placed relative to each other that the wider end of one wedge points upwards while the wider end of the other wedge points downwards. In certain countries, the regulations concerning elevators have been revised to prevent accidents where an elevator car crashes against the ceiling of the hoistway after an overspeed upward drive; a passenger is injured by the doorway structures of an elevator car which has moved off from a floor with the doors open. The new regulations also provide more freedom of design of the safety equipment as they accept even non-mechanical solutions. The device of the invention is used to stop the motion of an elevator car unit when necessary. To stop an elevator car unit, both the elevator car unit and the counterweight can be provided with safety gears as defined e.g. in FI publication print 74686, and it is also possible to provide the overspeed governor with an electrically operated low speed trigger to guarantee safety in the doorway area. However, this is an expensive solution. Besides, it occupies a large space in the hoistway since the counterweight, too, has to be provided with a safety gear. It is also possible to use known safety gears and rope arresters mounted in the machine room. However, this solution is expensive and difficult to implement in different rope systems. GB-2-2 190 356 discloses a safety gear having an action wedge and a counter wedge and a wedge housing for both wedges which are placed symmetrically, but upward down on both sides of a guide rail. After activation of the action wedge by means of an activating means the action wedge grips the guide rail and leads to a lateral movement of the wedge housing thereby effecting the gripping action of the counter wedge. This known safety gear only works in case of a downward movement of the elevator car. DE-U-87 14 860.9 discloses a catch device consisting of a single wedge which has two guide surfaces which are inclined symmetrically to a horizontal axis. The wedge is activated in the upward or downward direction according to the working direction of the catch device corresponding to the movement of the elevator car. By activating the wedge according to the upward or downward direction one of the guide surfaces comes into contact with a guiding surface thereby being pressed against the guide rail of the elevator car. However, the breaking force of this safety gear is not as high as the braking force comprising two wedges which act on opposite sides of a guide rail. FR-A-728 326 discloses a catch device comprising an action wedge and a counter wedge, the action wedge being activated in case of an exceeding upward or downward movement. The counter wedge is connected to the action wedge by means of a pivotable lever, so that in case of the activation of the action wedge even the counter wedge is activated so as to grip the guide rail on the opposite side of the guide rail. However, by means of the pivotable lever no exact simultaneous operation of both action wedge and counter wedge can be obtained and the interaction of action wedge and counter wedge is affected by friction losses caused by the pivoting lever and by a backlash between the pivoting arrangement and the two wedges. The object of the present invention is to eliminate the drawbacks referred to above. The safety gear of the invention is characterized by the features of the independent claims 1 and 2, respectively. The preferred embodiments of the invention are presented in the corresponding subclaims. The safety gear of the invention meets the new safety prescriptions using a single standard device. The solution is cheaper than other solutions because it contains fewer components and because the two halves of the safety gear consist of identical parts. In the following, the invention is described in detail by the aid of examples by referring to the attached drawings, in which Fig. 1 presents one embodiment of the safety gear of the invention as seen in the plane of the guide rail. Figs. 2a and 2b present another embodiment of the safety gear of the invention as seen from above and from one side in the plane of the guide rail. Figs. 3a - 3c present a third embodiment of the safety gear of the invention. The safety gear has a frame 4 which is attached to the elevator car unit 1 by means of spring-loaded bolts 2 in such manner that the frame 4 can move laterally against the spring force along the bolts 2. The frame is provided with wedge housings 3d and 6d housing wedges 3 and 6 on each side of the guide rail 7. The wedges move against guide surfaces 3b and 6b provided in the frame 4, said surfaces being at an oblique angle relative to the guide rail. The upper edge of guide surface 3b is farther away from the guide rail than its lower edge and, correspondingly, the lower edge of guide surface 6b is farther away from the guide rail than its upper edge. One wedge 3 moves along guide surface 3b and the other wedge 6 moves along guide surface 6b. To reduce the friction, bearing means 5 are provided between the wedge and the guide surface. The wedges are provided with pilots 4a and 4b. In Fig. 1, the safety gear comprises actuating rods 3a and 6a attached to the upper end of wedge 3 and to the lower end of wedge 6, and a pressure spring 3c placed around the actuating rod between the upper end of wedge 3 and the upper end of wedge housing 3d. Similarly, a pressure spring 6c is provided between the lower end of wedge 6 and the lower end of wedge housing 6d. The lower end of wedge housing 3d is provided with an adjusting screw 3e and the upper end of wedge housing 6d with another adjusting screw 6e. Thus, the wedges act in opposite directions. The safety gear works as follows. When the elevator car unit is moving downwards at an overspeed, or when it has moved too far downwards with the doors open, actuating rod 6a is pushed upwards. Wedge 6 slides against the guide rail 7, the whole safety gear moves right along the guide bolts 2 and wedge 3 touches the guide rail 7. Wedge 3 rises, thereby increasingly compressing spring 3c, until wedge 6 touches adjusting screw 6e. In this situation, an almost constant pressure prevails across spring 3c. In reality, some vibration occurs due to variations in the friction, but essentially the pressure remains constant. When wedge 6 touches the adjusting screw, the braking force is at a maximum and, due to the constant pressure of spring 3c, acts in a constant direction until the elevator car stops. Wedge 3 rises compressing spring 3c until wedge 6 touches the adjusting screw 6e. The small angle of the spring 3c relative to the guide rail 7 allows large normal forces to be generated relative to the guide rail. "Normal force" means a pressure acting in a direction perpendicular to the guide rail. The angle enables sufficient gripping forces to be achieved with a low spring pressure and therefore with a small spring. For upward movement, the safety gear acts in a corresponding manner. When actuating rod 3a is pushed downwards, wedge 3 moves against the guide rail 7, the whole safety gear moves left and wedge 6 touches the guide rail. Wedge 6 moves downwards compressing spring 6c until wedge 3 touches adjusting screw 3e. Since the braking is initiated during downward travel by wedge 6 and during upward travel by wedge 3, it is possible to set different braking forces for the safety gear gripping action during upward and downward car travel. The necessary information regarding the need for safety gear action can be obtained e.g. from a separate tachometer monitoring the car movement. The wedges can be moved e.g. using electromagnets. In the solution illustrated by Figs. 2a and 2b, safety gear action in both downward and upward directions is initiated by an overspeed governor which triggers the safety gear when its speed of rotation exceeds the allowed limit, regardless of direction. When the elevator movement in the upward direction is accelerated and reaches the preset gripping speed, the overspeed governor is locked and the activating lever 10 connected to it via the rope attachment 9 of rope 8 is turned in an anti-clockwise direction. Pin 4b of the activating lever hits the lower edge of the elongated slot 3f laid in the direction of movement of wedge 3, and wedge 3 moves downward along guide surface 3b, compressing spring 11. Pin 4a moves freely in the slot 6f of wedge 6 and both pins move freely in the slots 12a and 12b of the safety gear housing. Wedge 3 slides against the guide rail, the safety gear housing 4 moves left and wedge 6, too, touches the guide rail. Wedge 6 moves downwards compressing spring 6c until wedge 3 touches the adjusting screw 3e. During downward travel, the activating lever 10, connected to a synchroning tube 13, turns in a clockwise direction and the safety gear operates in a corresponding manner. The solution illustrated by Figs. 3a - 3c is fully analogous to that in Fig 2a and 2b, with the difference that the slots 3f' and 6f' are placed in the activating lever 10 in a transverse direction relative to the lever. In this case, the wedges are provided with pins 4a' and 4b'. It is obvious to a person skilled in the art that different embodiments of the invention are not restricted to the examples described above, but that they may instead be varied within the scope of the following claims.

Claims: Safety gear designed to be mounted on an elevator car (1) moving along guide rails (7), said safety gear comprising a frame (4), an area of wedge housings (3d,6d) formed in the frame, and wedges (3,6) placed in the wedge housings on each side of the guide rail (7), said wedges gripping the guide rail when the safety gear is activated by an activating means (10) in case of overspeed or other emergency braking situations, the wedges being so placed relative to each other that the wider end of one wedge (3) points upwards while the end of the other wedge (6) points downwards, and said activating means (10) being connected to at least one wedge serving to move said wedge in its housing to allow gripping action in both upward and downward directions, characterized in that the activating means (10) is connected to both wedges (3,6) that the activating means (10) is actuated in different directions dependent on upward or downward travel of the elevator car, and that according to the actuating direction of the activating means (10) different wedges (3,6) are activated. Safety gear designed to be mounted on an elevator car (1) moving along guide rails (7), said safety gear comprising a frame (4), an area of wedge housings (3d,6d) formed in the frame, and wedges (3,6) placed in the wedge housings on each side of the guide rail (7), said wedges gripping the guide rail when the safety gear is activated by an activating means (3a,6a) in case of overspeed or other emergency braking situations, the wedges being so placed relative to each other that the wider end of one wedge (3) points upwards while the end of the other wedge (6) points downwards, and said activating means (3a,6a) being connected to at least one wedge serving to move said wedge in its housing to allow gripping action in both upward and downward directions, characterized in that each wedge (3,6) being provided with its own activating means (3a,6a), that dependent on upward or downward travel of the elevator car different activating means (3a,6a) are activated, so that different wedges (3,6) are activated according to the travel direction of the elevator car. Safety gear according to claim 2, characterized in that a power device such as a pressure spring (3c, 6c) is provided between the wider end of each wedge and the wedge housing. Safety gear according to claim 2 or 3, characterized in that the activating means is an actuating rod (3a,6a) connected to the wider end of the wedge (3,6). Safety gear according to claim 2, 3 or 4, characterized in that the activating means is moved by means of an electromagnet or equivalent. Safety gear according to claim 1, characterized in that the wedge is provided with a slot (3f,6f) laid essentially in the direction of the wedge motion and accommodating a projection (4a,4b) attached to an activating lever (10) or equivalent which moves the wedge and is actuated by an overspeed governor. Safety gear according to claim 1, characterized in that each wedge is provided with a projection (4a',4b'), said projections being accommodated in essentially transverse slots (3f',6f') provided in an activating lever (10) or equivalent actuated by an overspeed governor. Safety gear according to any one of the preceding claims, characterized in that each wedge housing is provided with an adjusting screw (3e,6e) permitting ajustment of the stopping position of the wedge during safety gear action. Safety gear according to any one of the preceding claims, characterized in that the safety gear has a symmetrical construction relative to the guide rail (7), but with one half of the safety gear turned upside down relative to the other half.

Inventors: KORHONEN HELGE, KORHONEN, HELGE
Applicants: KONE ELEVATOR GMBH
Application year: 1990
Main classification: B66B5
IPC codes: B66B5