JP2007331365A - Blackboard lifting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve such problems that in a conventional blackboard-lifting device, there is no suitable method for balancing the weight of a blackboard to a large extent except enlargement of the displacement amount of a spring because the spring is directly used for such balancing and thus, the spring is overstretched and cannot endure a load exceeding the acceptable stress of a spring material, and further a brake wire is entangled with other portions because a hand brake is used for fixing the board at an optional height. <P>SOLUTION: The displacement of the spring to the vertical stroke is made smaller than ever by utilizing a lever through the employment of a small-sized highly tensional spring and a big weight adjustment can be realized by a small controlling by changing the arm of torque. In addition, braking troubles can be minimized by utilizing a link, a friction bar or the like without using the braking wire in the brake. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to the rationalization and convenience of a blackboard lifting device equipped in a school or the like.

  The conventional blackboard lifting device uses a spring directly to balance the weight of the blackboard in the manual type, and the balance adjustment with respect to the fluctuation of the tensile force due to the displacement of the spring is a crescent disk as shown in FIG. The chain is wrapped around a chain or the like, but the diameter and length of the spring are limited in order to reduce the installation space of the apparatus. It is impossible to adjust the weight balance significantly only by the displacement of the spring within the allowable stress range of the spring material.

  However, the weight of the blackboard varies greatly depending on the size, and even the same size often varies depending on the type of blackboard (wood, magnetic banding, metal cover, etc.). Therefore, adjustment beyond a certain range requires only replacing the spring, and work on site requires a considerable amount of work, such as once removing the blackboard or disassembling some devices.

  In addition, the band brake is used as the brake to stabilize the position when the vertical movement of the blackboard is stopped, and the brake and the operating handle are connected by a brake wire, which causes trouble by touching the other parts of the chain. There are many things and the life span is short.

  In the device using power, all the problems of the previous four steps are solved, but the cost is high and it is not so desirable at the site.

Problems to be solved by the invention

  When the blackboard is moved up and down manually, the weight balance is maintained regardless of the position of the blackboard so that the weight balance can be easily adjusted even if the weight of the blackboard is significantly different or the spring tension is deteriorated. Moreover, a stable mechanism and a brake function with very few troubles are provided so that there is no wobbling at that position.

Means to solve the problem

  In order to solve these problems, the present invention is provided with a weight balance adjusting mechanism and a stabilizing mechanism, and in order to reduce the weight of the entire apparatus, the spring is made smaller by increasing the tensile force, and is used as an amplifying mechanism to secure the vertical movement stroke of the blackboard. Applied.

The invention's effect

  The present invention makes it easy to adjust the balance of the blackboard installed in classrooms, etc., and the weight of the blackboard varies greatly. The weight of the blackboard is renewed and the spring tension is attenuated by long-term use. This can be done without changing the balance spring. Therefore, it is not necessary to remove the blackboard or disassemble the device for each of these measures.

  In addition, since the device is lightened by downsizing the spring and applying the lever, it is easy to transport when installed on the upper floor of a school or the like, and the installation work at the site is streamlined, resulting in a great economic effect.

BEST MODE FOR CARRYING OUT THE INVENTION

  An embodiment of the present invention will be described with reference to FIGS. In FIG. 1, 1 is a device frame having a weight balance adjusting mechanism composed of 4 to 12, 2 is a blackboard frame for mounting a blackboard, 3 is a top and bottom blackboard frame 2, and the blackboard is smoothly vertical It is a guide spindle for moving.

  FIG. 1 shows a state in which the blackboard is positioned at the uppermost position. When the blackboard is lowered with the operation handle 13, the lever 6 roll 7 as shown in FIG. 2 passes through the wire 16 fixed to the lower blackboard frame. And the planetary sheave 9 falls down along the arc a with the pin 8 as a fulcrum.

At this time, the roll 7 falls with the lever 6 while being pulled in the opposite direction by the displaced spring 5. The roll 7 is lowered along the lever 6 and the spring is displaced to increase the tension, while the distance between the roll 7 and the pin 8 (torque arm) is shortened to maintain the torque balance.
The blackboard frame stops when the upper blackboard frame hits the buffer spring 14. 4 is a spring metal fitting.

10 and 11 are torque adjusting mechanisms for dealing with variations in the weight of the blackboard, and the push-up bar 11 moves up and down the point d shown in FIG. 2 by twisting a bolt attached to the lower part thereof. The position of b is also moved up and down, the spring tensions P _{1 to} P _n and the torque arms l _{1 to} l _n at the pin 8 are both increased and decreased, and the torque, which is the product of P and l, slightly raises and lowers the point d. It can cope with a large variation in load W depending on the blackboard. The point d moves up and down but does not swing back and forth and left and right.

  In addition, the bolts for raising and lowering the push-up bar 11 are attached to the lower part of the apparatus frame 1, so that the blackboard can be adjusted at any time with the blackboard raised to the uppermost position. Even if there is, can respond immediately.

  Reference numeral 12 denotes a guide sheave for converting the direction of force vertically, 15 denotes a pin for fixing a wire, 16 denotes a wire, and 17 denotes a metal fitting for fixing the blackboard frame 2 and the blackboard 24 shown in FIG.

  FIG. 3 is a brake mechanism for preventing the blackboard frame from wobbling at any height when moving up and down, and FIG. 4 is an enlarged arrow view of the AA cross section shown in FIG.

  A brake mechanism is demonstrated based on FIG.3 and FIG.4. When the blackboard frame 2 is lowered, the connecting rod 18 of the brake mechanism having a fulcrum at the extreme end of the apparatus frame 1 is tilted with the fulcrum pin 19 as a fulcrum, and accordingly the friction bar 20 is fixed to the lower blackboard frame. Slide in the box-shaped bar holder 21.

  As shown in FIG. 4, the friction bar 20 is tightened to the friction plate 22 pulled by the brake spring 23. If the friction bar does not move, the blackboard frame will not move. Therefore, the brake is applied.

  When the operation handle 13 is lifted by using the powder receiver of the blackboard when moving up and down the blackboard, the friction plate 22 becomes vertical and the brake is released. Reference numeral 24 in FIG. 4 is a virtual diagram of the blackboard shown for explanation, although it is not directly related to the present invention.

FIG. 2 is for explaining the weight balance of the blackboard dynamically. When the blackboard load is expressed by W, the forces W _{1 to} W _n applied to the planetary sheave 9 and the vertical stroke S of the blackboard frame, the planetary sheave 9 and the guide sheave 12 are shown. The relationship with the interval E is

And the torque due to the blackboard load at pin 8 is

It is. On the other hand, the force applied to the roll 7 and the lever 6 depending on the tension of the spring changes from P _{1 to} P _n according to the displacement of the spring. The torque generated on the pin 8 due to the tension of the spring is

  The arcs a, b and c are formed so that the torque at the pin 8 due to the tension of the spring corresponds to the torque at the pin 8 due to the blackboard load.

  Further, the vertical stroke S of the blackboard frame 2 is amplified about twice as much as the moving amount of the planetary sheave 9.

  Front view of device representing all of the invention   Drawings that dynamically explain the main movements of the device   Drawing explaining the brake part and its movement   Brake cross section details arrow view   Main mechanism diagram of devices used in the past

Claims (3)

  A blackboard lifting / lowering device that simplifies and lightens the mechanism by amplifying the displacement of the weight balance spring using a lever and reducing the displacement of the spring with respect to the vertical stroke of the blackboard.   By providing a torque adjustment mechanism to keep the distance (torque arm) between the lever fulcrum and the action point in "Claim 1" within a certain range, the tension due to the spring displacement and the arm length A blackboard lifting device that can greatly change the torque obtained as a product of a small amount of adjustment.   The brake to hold the blackboard at an arbitrary height and stabilize it at that position is connected by a connecting rod between the frame of the device and the frame on which the blackboard is mounted, and the friction bar that slides up and down the blackboard is sandwiched between the bar holder and the friction plate A blackboard lifting and lowering device having a mechanism that operates based on the frictional force.

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