Speed limiter

Abstract

The invention discloses a speed limiter which comprises a pawl, a ratchet wheel, a pull rod, an elastic piece, a rope wheel, a brake shoe and a mounting base. When the speed governor is triggered, the pawl is clamped into the ratchet wheel, the ratchet wheel rotates to drive the pull rod to compress the elastic piece, the elastic piece applies pressure to the mounting base, and the mounting base drives the brake shoe to press a speed governor steel wire rope. The elastic piece is a constant force mechanism; and when the compression amount of the constant force mechanism is within a preset range, the pressure applied to the mounting seat by the constant force mechanism is kept at a preset constant value. The overlarge positive pressure can be prevented from being applied to the steel wire rope of the speed governor after the speed governor is triggered.

Description

Technical Field

[0001] This invention relates to the field of elevator technology, and more specifically to a speed limiter. Background Technology

[0002] The elevator safety clamp is one of the key devices in the elevator safety protection system. It is usually fixed on the elevator car. When the elevator descends at excessive speed and triggers the speed governor, the speed governor wire rope pulls the safety clamp wedge through the safety clamp lifting mechanism, so that the safety clamp clamps the elevator guide rail to achieve car braking.

[0003] Currently, the speed limiter is triggered via a ratchet and pawl mechanism. The ratchet drives a lever to compress a spring, providing the positive pressure required to exert friction on the speed limiter's wire rope. The greater the compression, the greater the positive pressure, and thus the greater the friction. If the positive pressure is too high, the speed limiter components will experience excessive force and impact. In severe cases, the speed limiter's pulley, ratchet and pawl, frame, and central shaft may deform and be damaged, affecting the normal operation of the safety components. Summary of the Invention

[0004] The technical problem to be solved by this invention is how to avoid applying excessive positive pressure to the speed limiter wire rope after the speed limiter is triggered.

[0005] To solve the above-mentioned technical problems, the present invention provides a speed limiter, including a pawl, a ratchet, a lever, an elastic element, a pulley, brake shoes, and a mounting base. When the speed limiter is triggered, the pawl engages with the ratchet, the ratchet rotates and drives the lever to compress the elastic element, the elastic element applies pressure to the mounting base, and the mounting base drives the brake shoes to press against the speed limiter's wire rope. The elastic element is a constant force mechanism. When the compression amount of the constant force mechanism is within a preset range, the pressure applied by the constant force mechanism to the mounting base remains at a preset constant value.

[0006] Preferably, the constant force mechanism consists of a positive stiffness mechanism and a negative stiffness mechanism; when the compression of the constant force mechanism is within a preset range, the total stiffness of the constant force mechanism is approximately zero.

[0007] Preferably, when the compression amount of the constant force mechanism is less than the preset deformation range, the pressure applied by the constant force mechanism to the mounting base increases as the compression amount increases.

[0008] Preferably, when the compression of the constant force mechanism is greater than the preset deformation range, the pressure applied by the constant force mechanism to the mounting base increases with the increase of the compression.

[0009] This invention also provides a speed limiter, including a pawl, a ratchet, a lever, an elastic element, a pulley, brake shoes, and a mounting base. When the speed limiter is triggered, the pawl engages with the ratchet, the ratchet rotates to drive the lever to compress the elastic element, the elastic element applies pressure to the mounting base, and the mounting base drives the brake shoes to press against the speed limiter's wire rope. The pawl includes a movable end, a fixed end, and a constant force mechanism. The fixed end is rotatably connected to the pulley, and the movable end is connected to the fixed end through the constant force mechanism. When the pawl engages with the ratchet, and the compression amount of the constant force mechanism is within a preset range, the pressure applied by the constant force mechanism to the movable end remains at a preset constant value.

[0010] Preferably, the constant force mechanism is a bellows constant force mechanism.

[0011] Preferably, when the compression amount of the bellows constant force mechanism is less than the preset deformation range, the pressure applied by the bellows constant force mechanism to the movable end increases with the increase of the compression amount.

[0012] Preferably, when the compression of the bellows constant force mechanism is greater than the preset deformation range, the pressure applied by the bellows constant force mechanism to the movable end increases with the increase of the compression.

[0013] This invention can avoid applying excessive positive pressure to the speed limiter wire rope after the speed limiter is triggered. Attached Figure Description

[0014] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments: Figure 1 This is a schematic diagram of a speed limiter structure in the prior art; Figure 2 This is a schematic diagram of the speed limiter structure in Example 1; Figure 3 This is a schematic diagram of a constant force mechanism structure according to Example 1; Figure 4 This is a schematic diagram of another constant force mechanism structure in Example 1; Figure 5 The force-displacement curve of the constant force mechanism in Example 1; Figure 6 This is a partial schematic diagram of the speed limiter in Example 2; Figure 7 This is a schematic diagram of the bellows constant force mechanism in Example 2; Figure 8 The force-displacement curve is shown for the bellows constant force mechanism in Example 2. Detailed Implementation

[0015] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can fully understand other advantages and technical effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through different specific embodiments, and the details in this specification can also be applied based on different viewpoints, with various modifications or changes made without departing from the overall design concept of the invention. It should be noted that, unless otherwise specified, the following embodiments and features can be combined with each other. The following exemplary embodiments of the present invention can be implemented in many different forms and should not be construed as being limited to the specific embodiments set forth herein. It should be understood that these embodiments are provided to make the disclosure of the present invention thorough and complete, and to fully convey the technical solutions of these exemplary embodiments to those skilled in the art.

[0016] The structure of a speed limiter in the prior art is as follows: Figure 1 As shown, the speed governor includes a pawl 5, a ratchet 2, a lever 7, a spring 11, a pulley 1, brake shoes 8, a base 4, and a central shaft 3. The pulley 1 and ratchet 2 are mounted on the base 4 via the central shaft 3. The pawl 5 is mounted on the pulley 1. The ratchet 2 is connected to the lever 7 via a fixing pin 6. The brake shoes 8 are connected to the mounting base 10 via a connecting rod 9. The lever 7 passes through the mounting base 10 and is connected to the spring 11. The speed governor's wire rope 12 is wound around the pulley 1. When the speed limiter is triggered, the pawl 5 is activated by the overspeed lever and engages in the ratchet 2. The ratchet 2 rotates, causing the lever 7 to compress the spring. The spring 11 applies pressure to the mounting base 10, which in turn causes the brake shoe 8 to press against the speed limiter wire rope 12. The friction between the speed limiter wire rope 12 and the pulley 1 increases. The more the ratchet 2 compresses the lever 7, the greater the positive pressure of the brake shoe 8 on the speed limiter wire rope 12, and the greater the friction between the speed limiter wire rope 12 and the pulley 1. Example 1

[0017] like Figure 2 As shown, the speed limiter provided in this embodiment, compared with the speed limiter of the prior art described above, uses a flexible constant force mechanism 400 to replace the existing one. Figure 1 Spring 11 in the middle. When the compression of the constant force mechanism 400 is within a preset range, the pressure applied by the constant force mechanism to the mounting base remains at a preset constant value.

[0018] The constant force mechanism in this embodiment can be composed of mechanisms with different stiffnesses. The structure of a three-dimensional constant force mechanism 400 is as follows: Figure 3 As shown, it includes a positive stiffness mechanism 401 and a negative stiffness mechanism 402. The combination of the two can achieve the following design: Figure 5 The force-displacement curves are shown. The positive stiffness mechanism 401 is a standard compression spring, and the negative stiffness mechanism 402 is a three-dimensional compliant mechanism. The structure of another three-dimensional constant force mechanism 400 is shown below. Figure 4 As shown, both the positive stiffness mechanism 407 and the negative stiffness mechanism 408 are three-dimensional compliant mechanisms.

[0019] By replacing the original spring 11 with a constant force mechanism 400, the pull rod 7 can be directly passed through the center of the constant force mechanism 400, and then tightened and adjusted with a pressure block 403 and a nut 404.

[0020] The force-displacement curve of the constant force mechanism 400 in this embodiment is as follows: Figure 5 As shown, the vertical axis represents the pressure on the constant force mechanism, the horizontal axis represents the deformation of the constant force mechanism after being subjected to force, kp is the stiffness of the positive stiffness mechanism, kn is the stiffness of the negative stiffness mechanism, and kc is the total stiffness of the constant force mechanism.

[0021] exist Figure 5 The curve includes a fast response zone (a), a constant force zone (b), and an over-limit zone (c). In the fast response zone (a), as the compression increases, the constant force mechanism can quickly reach the design force value by applying pressure to the mounting base; within the constant force zone (b), the compression is within a preset range (e.g., ...). Figure 5 In the d1 to d2 interval, the total stiffness of the constant force mechanism is approximately zero, which keeps the pressure applied by the constant force mechanism to the mounting base constant and maintains the preset constant value; when the constant force mechanism reaches the over-limit zone (c), the stiffness is positive, and as the compression increases, the pressure applied by the constant force mechanism to the mounting base continues to increase.

[0022] When the speed limiter is in the untriggered state, the pawl 5 and ratchet 2 are not in contact, the constant force mechanism 400 is in the initial installation state, there is a gap between the brake shoe 8 and the speed limiter wire rope 12, and the speed limiter wire rope 12 is in the normal tension state.

[0023] When the speed governor is triggered, and ratchet 5 and pawl 2 begin to engage, the constant force mechanism 400 is initially in the rapid response zone (a). As the compression increases rapidly, reaching the design force value, ratchet 5 drives the lever 7 to compress the constant force mechanism 400, deforming it to reach the stable zone (b). As the car continues to descend, the speed governor wire rope 12 drives the pulley 1 to continue rotating, and the pawl 2 further pushes the ratchet 5 and lever 7. Although the distance between the nut 404 and the mounting seat 10 continues to decrease, meaning the compression of the constant force mechanism 400 continues to increase, the pressure exerted by the constant force mechanism on the mounting seat does not increase. Therefore, the brake shoe pressure and the friction of the speed governor wire rope do not increase, and the speed governor wire rope slips under the car's movement. When the compression of the constant force mechanism exceeds the design value and reaches the over-limit zone, the pressure exerted by the constant force mechanism on the mounting seat further increases with the compression, and the brake shoe pressure and the friction of the speed governor wire rope increase accordingly to prevent insufficient lifting force. (Please explain why the increased friction does not damage the speed governor components.) Compared with the prior art, the speed limiter in this embodiment provides a stable friction force of the speed limiter wire rope within a certain range of motion. When the ratchet action of the speed limiter increases, the constant force mechanism compensates for the compression of the spring by deformation, so that the pressure applied by the constant force mechanism to the mounting base remains unchanged, so that the friction force of the speed limiter wire rope will not be too large and damage the parts, thus ensuring the safety of the components. Example 2

[0024] This embodiment provides a speed limiter, the structure of which differs from existing technologies; other structures are as described in existing technologies. Figure 1 The structure. Figure 6 The structure of the rope pulley 1 in this embodiment is shown. The pawl includes a movable end 902, a fixed end 901, and a constant force mechanism 800. The fixed end 901 is rotatably connected to the rope pulley 1, and the movable end 902 is connected to the fixed end 901 through the constant force mechanism 800. When the pawl engages with the ratchet 5, and the compression of the constant force mechanism 800 is within a preset range, the pressure applied by the constant force mechanism 800 to the movable end 902 remains at a preset constant value.

[0025] like Figure 7 As shown, the constant force mechanism 800 in this embodiment is a bellows constant force mechanism, comprising a metal bellows 801, an end plate 802, and a connector 803. The force-displacement curve of the bellows constant force mechanism is shown below. Figure 8 As shown, the right side represents the stretching region, which includes a rapid response zone (a) and an elastic zone (b); the left side represents the compression region, which includes a rapid response zone (a), a constant force zone (b), and an over-limit zone (c). Within the preset compression range of the constant force zone (b) (e.g....), Figure 8 (The interval from δy to δu on the left side of the vertical axis) The pressure applied by the constant force mechanism 800 to the movable end 902 remains at a preset constant value.

[0026] After the pawl fixed end 901 is installed on the rope pulley 1, it is linked with the overspeed swing block 20 for adjustment to ensure the trigger speed and other indicators of the speed limiter. The pawl fixed end 901 and the pawl movable end 902 are connected by a constant force mechanism 800, which can be easily disassembled and replaced.

[0027] When the speed limiter is in the untriggered state, the pawl and ratchet 2 are not in contact, the bellows constant force mechanism 800 is in the initial installation state, there is a gap between the brake shoe and the speed limiter wire rope, and the speed limiter wire rope is in the normal tension state.

[0028] When the ratchet and pawl begin to engage, the constant force mechanism is initially in the rapid response zone (a). As the compression increases rapidly, the pressure applied by the constant force mechanism 800 to the movable end 902 reaches the design force value. At this time, the ratchet drives the lever to compress the spring to a stable value. When the car continues to descend, the speed limiter wire rope drives the pulley to continue rotating. Although the fixed end 901 of the pawl continues to move together, the distance between the fixed end 901 of the pawl and the movable end 902 of the pawl is compensated by the deformation of the connecting constant force mechanism. The movable end 902 of the pawl maintains stable force and contact with the ratchet, and will not further push the ratchet and the lever to move. The spring compression will not increase, the brake shoe positive pressure and the friction of the speed limiter wire rope will not increase, and the speed limiter wire rope slips under the action of the car. When the compression of the constant force mechanism exceeds the design value and reaches the over-limit zone, the pressure applied by the constant force mechanism to the movable end 902 increases with the increase of the compression. The movable end of the pawl further pushes the ratchet and the lever to move, which increases the spring compression. The brake shoe positive pressure and the friction of the speed limiter wire rope increase accordingly to prevent insufficient lifting force.

[0029] Compared with the prior art, the speed limiter in this embodiment provides a stable friction force on the speed limiter wire rope within a certain range of motion. When the compression of the speed limiter spring increases, the constant force mechanism drives the pawl displacement through the compensating pulley and keeps the pawl trigger force constant, so that the ratchet rotation, i.e., the spring compression, does not become too large. Thus, the friction force on the speed limiter wire rope will not be too large, which may damage the parts and ensure the safety of the components. The constant force mechanism divides the pawl into a fixed end, a constant force mechanism, and a movable end. When the movable end is damaged by repeated actions, it is easy to disassemble and replace. It can be used without adjustment, which is convenient for maintenance.

[0030] The present invention has been described in detail above through specific embodiments and examples, but these are not intended to limit the invention. Many modifications and improvements can be made by those skilled in the art without departing from the principles of the invention, and these should also be considered within the scope of protection of the present invention.

Claims

1. A speed limiter, comprising a pawl, a ratchet, a lever, an elastic element, a pulley, brake shoes, and a mounting base; when the speed limiter is triggered, the pawl engages with the ratchet, the ratchet rotates to drive the lever to compress the elastic element, the elastic element applies pressure to the mounting base, and the mounting base drives the brake shoes to press against the speed limiter wire rope; characterized in that, The elastic element is a constant force mechanism; when the compression of the constant force mechanism is within a preset range, the pressure applied by the constant force mechanism to the mounting base remains at a preset constant value.

2. The speed limiter according to claim 1, characterized in that, The constant force mechanism consists of a positive stiffness mechanism and a negative stiffness mechanism; when the compression of the constant force mechanism is within a preset range, the total stiffness of the constant force mechanism is approximately zero.

3. The safety clamp constant force lifting mechanism according to claim 2, characterized in that, When the compression amount of the constant force mechanism is less than the preset deformation range, the pressure applied by the constant force mechanism to the mounting base increases as the compression amount increases.

4. The safety clamp constant force lifting mechanism according to claim 2, characterized in that, When the compression of the constant force mechanism is greater than the preset deformation range, the pressure applied by the constant force mechanism to the mounting base increases with the increase of the compression.

5. A speed limiter, comprising a pawl, a ratchet, a lever, an elastic element, a pulley, brake shoes, and a mounting base; when the speed limiter is triggered, the pawl engages with the ratchet, the ratchet rotates to drive the lever to compress the elastic element, the elastic element applies pressure to the mounting base, and the mounting base drives the brake shoes to press against the speed limiter wire rope; characterized in that, The pawl includes a movable end, a fixed end, and a constant force mechanism; the fixed end is rotatably connected to the pulley, and the movable end is connected to the fixed end through the constant force mechanism; when the pawl engages with the pulley and the compression of the constant force mechanism is within a preset range, the pressure applied by the constant force mechanism to the movable end remains at a preset constant value.

6. The speed limiter according to claim 5, characterized in that, The constant force mechanism is a bellows constant force mechanism.

7. The safety clamp constant force lifting mechanism according to claim 6, characterized in that, When the compression amount of the bellows constant force mechanism is less than the preset deformation range, the pressure applied by the bellows constant force mechanism to the movable end increases with the increase of the compression amount.

8. The safety clamp constant force lifting mechanism according to claim 6, characterized in that, When the compression of the bellows constant force mechanism is greater than the preset deformation range, the pressure applied by the bellows constant force mechanism to the movable end increases with the increase of the compression.

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