JP2006055494A - Equal repulsion spring mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce force to be required for a sitting or standing motion by pushing up a seat with the use of fixed force in a standing-up assisting chair. <P>SOLUTION: In an equal repulsion spring mechanism, one end of a primary spring 4 is connected to an upper frame to be vertically moved and the other end is connected to a fixed lower frame 3. One end of a secondary spring 5 is fixed to a fixing supporter 8 so as to be rotatable and the other end of the secondary spring 5 is connected to a main mobile body 6, which is movable in one direction, so as to be rotatable. One end of a main link 9 is connected to a connection point with the primary spring 4 in the upper frame 2, so as to be rotatable. Fixed repulsion is added to the upper frame with respect to the displacement of the upper frame 2 due to a load. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is a chair for assisting standing up, a wheelchair, a Japanese-style chair, a Western-style chair, a car chair, a lift for taking elderly people into a bath, a lift for unloading to a place with a step such as a car, and the like when carrying heavy objects. The present invention relates to an equal repulsion spring mechanism that is installed in a lift to be used and assists these operations.

  Here, an auxiliary chair that assists the sitting or standing operation will be described. Auxiliary chairs have been proposed that raise and lower the chair so that people with weak legs can easily sit on the chair or stand up from the chair. As means for raising and lowering the seat, there are methods using a spring, an electric gear, an air bag and the like.

  As a method using a spring, a method is known in which the seating of a chair is supported by a spring having a wide range of expansion and contraction, and the operation of standing up by the reaction force of the spring is assisted. When a person is sitting on a chair, a large reaction force works because the spring that supports the seating is compressed. In the process of standing up, the compressed spring returns to its original state, and the reaction force of the spring supports the human buttocks.

  The electric gear system is a method in which the seating of the chair is moved up and down with the electric gear, and a sufficient auxiliary force can be obtained for the sitting or standing operation. Further, in order to move the electric gear, electric power is required, and a charger is mounted or an external power source is used.

The air bag system is a method of helping a person stand up from a chair by attaching an air bag under a seat and inflating it with an air pump. By adjusting the amount of air, it is possible to obtain auxiliary force as required. This device requires an air pump, an electric power for moving the air pump, and the like outside the air bag. Moreover, in order to move a heavy load from a low position to a high position, a relatively large apparatus using an electric gear or hydraulic pressure is used.
JP 60-40049

  For people who have weak leg muscles, when using a normal chair, they will bend and stretch their legs, and they need to be muscular. Sometimes it is necessary to borrow the power of others. In order to easily perform the operation of sitting on a chair from a standing state or the operation of standing from a sitting state on a chair, it is particularly desirable to support the buttocks of the body with a certain external force.

  In the method of reinforcing the seat spring of the chair and assisting the start-up by the reaction force, the compressed spring returns to its original state and the reaction force of the spring rapidly decreases in the process of rising. Therefore, there is a problem that a necessary and sufficient reaction force cannot be applied before standing up.

  Also, when a flexible spring is used, when sitting on a chair, the seat connected to the spring vibrates and the body swings up and down or left and right. This vibration makes the sitting person's body unstable, and makes a person feel particularly uneasy, especially for a person with weak feet. Thus, when a person sits on a chair or stands up, it is necessary to use a seating structure that supports the buttocks with a sufficient reaction force and does not cause unstable vibration.

  The electric gear system that raises and lowers the seating of the chair and makes it easy to stand up is heavy in the device and applicable chairs are limited. Further, it is expensive because a gear mechanism, a motor, a control device and the like are necessary. Furthermore, in order to move the electric gear, electric power is necessary, and securing the power source becomes a problem. The air bag system has a problem that the seating system tends to be unstable, and power for moving the air pump is necessary, and noise is generated when air is supplied and discharged.

  The chair auxiliary mechanism desirably lifts the buttocks with a stable and constant force when a person stands up from the chair. In addition, when sitting, it is necessary to be able to sit down comfortably with a certain amount of force, and the vibration that gives an uneasy feeling is minimized. In addition, since a chair with an auxiliary mechanism is easy to carry and requires a structure that does not cause a sense of incongruity, it must be easily attached under the seat, and must be small, light, safe and inexpensive. Also, a mechanism that does not use other power sources such as electricity is desirable.

  Further, although an apparatus for moving a heavy load from a low position to a high position uses an electric gear or hydraulic pressure, the equipment is relatively large, and therefore the equipment is heavy and expensive. In addition, there is a problem that a power source such as electric power must be supplied from the outside, and a simple and economical apparatus is desired.

  The present invention is composed of a primary spring, a secondary spring, an upper frame and a lower frame positioned in parallel vertically, a main movable body, and a main link. The primary spring is connected to an upper frame whose one end is movable up and down. One end of the secondary spring is connected to the fixed frame with one end fixed, and the other end of the secondary spring is connected to the main movable body movable in one direction. The one end of the main link is connected to the main movable body in a rotatable state, and the other end of the main link is connected to the connection point with the primary spring of the upper frame in a rotatable state. On the other hand, an equal repulsion spring mechanism is characterized in that a constant repulsive force is applied to the upper frame.

  In the present invention, one end of the secondary spring is fixed in a state where it can rotate on a fixed support installed in the lower frame, and the other end of the secondary spring is connected in a state where it can rotate in a main movable body movable in one direction, One end of the main link is connected to the main movable body in a rotatable state, the repulsive force of the compressed secondary spring is transmitted to the main link, and a negative spring characteristic in one direction is formed at the other end of the main link. This is an equal repulsion spring mechanism.

  The present invention optimizes the set repulsive force, the maximum and minimum heights of the primary spring, the fixed strut height, the bottom length, the rotational margin length, the load application position, the spring constant of the primary spring and the secondary spring. Thus, the equal repulsion spring mechanism is characterized in that a repulsive force substantially equal to the displacement is generated at the load point.

  In the present invention, the main movable body is installed in the lower frame, the auxiliary movable body movable in one direction is installed in the upper frame, one end of the main link is connected to the main movable body in a rotatable state, and the other of the main links is connected. One end is connected to the upper frame in a rotatable state, one end of the auxiliary link is connected to the auxiliary movable body in a rotatable state, the other end is connected to the lower frame in a rotatable state, and the intersection of the main link and the auxiliary link is The equal repulsion spring mechanism is characterized in that both links are fixed in a rotatable state, and the upper frame is configured to move parallel to the lower frame.

  The primary spring and the secondary spring of the present invention are an equal repulsion spring mechanism comprising a helical spring, a torsion coil spring, a leaf spring, a bamboo shoot spring, a torsion bar, an air spring and the like.

When the equal repulsion spring mechanism based on this invention is applied to a standing auxiliary chair, there exist the following effects.
When a person with weak legs sits on a normal chair or stands up from a chair, the leg is burdened, and it is necessary to borrow power from the outside as an auxiliary. Especially when you get up from a chair, you need a lot of power.

  When the equal repulsion spring mechanism of the present invention is installed at the lower part of the seating of the chair, the person's buttocks are pushed up with a constant force through the seating of the chair to assist the operation of the person standing up. Therefore, the operation of sitting on the chair or the operation of standing up can be facilitated. Also, this mechanism apparently has a spring constant of almost zero, and does not feel vibration when sitting. When the seating vibrates, the body becomes unstable and anxiety is felt, but without these problems, it is possible to sit safely.

  In order to stand up easily from a chair, a repulsive force or a pattern of repulsive force suitable for each person is required. For example, the required repulsive force differs depending on the degree of weakness of the foot, the body weight, etc., but the repulsive spring mechanism of the present invention has a feature that the repulsive force can be freely selected. In addition, the pattern of repulsive force can be changed in the process of standing up.

  Since the equal repulsion spring mechanism based on this invention can be made into a flat structure, it can be installed in the seating of a chair without a problem. Moreover, the weight is light and the chair can be moved easily. In addition, this equal repulsion spring mechanism is composed only of a mechanical mechanism, does not require other power such as electric power, and is economically inexpensive.

  Furthermore, the iso-repulsion spring mechanism can be applied to a device for moving a heavy load from a low position to a high position. When the equal repulsion spring mechanism of the present invention is applied to these devices, the load can be moved while being always supported by a constant force. Therefore, it is possible to easily carry heavy loads alone.

  FIG. 1 is a view showing the principle of an equal repulsion spring mechanism according to the present invention. The horizontal axis in FIG. 1 indicates the displacement of the spring, and the vertical axis indicates the repulsive force at that time. A positive spring having a positive spring constant has a proportional increase in spring repulsion as the spring stretches. Conversely, if a mechanism of a negative characteristic spring having the same absolute value of the spring constant and a negative inclination is made and the two are combined in parallel, the repulsive force is the sum of the two. By this principle, the combined repulsive force is always constant with respect to the displacement, and the characteristic of equal repulsion can be obtained.

  On the other hand, in order to improve the vibration transfer characteristics of a one-degree-of-freedom mass-damped-spring system subject to displacement excitation, it is generally known that a method of reducing the spring constant of the system and bringing it close to zero is effective. Yes. Here, the spring constant is the slope of the straight line in the load-one-displacement curve, but the fact that the spring constant is zero means that the slope of the straight line is zero.

  As shown in FIG. 1, in the case of the iso-repulsive spring mechanism, the slope of the straight line is zero, in other words, the fluctuation of the repulsive force is zero with respect to the displacement. For this reason, the vibration is minimized when an equal repulsion spring mechanism is employed. On the contrary, in order to make the spring constant zero, it is only necessary to create a mechanism for generating an equal repulsive force at any displacement.

  FIG. 2 is an example of a mechanism relating to negative spring characteristics according to the present invention. This negative spring characteristic according to the present invention is constituted by the normal secondary spring 5 having a positive spring constant, the main movable body 6, the main link 9, and the auxiliary B movable body 11. The amount of movement in the vertical direction of point A on the auxiliary B movable body 11 is defined as displacement, and the direction of displacement is positive in the downward direction.

  In an initial state, that is, in a state where there is no displacement, at one point B on the main movable body 6, one end of the secondary spring 5 is connected to one end of the main link 9 in a state that allows rotational movement. The other end of the secondary spring 5 is connected and fixed in a state in which only rotation is allowed at the point C.

  However, the main movable body 6 is restricted in vertical movement, and can move only in the horizontal direction. Further, the auxiliary B movable body 11 is configured such that the movement in the horizontal direction is restricted and the movement is allowed only in the vertical direction.

  FIG. 3 is an example of force balance in the negative spring characteristic according to the present invention. In the initial state, the secondary spring 5 is compressed and attached between B and C. As shown in FIG. 3, a secondary spring repulsive force 20 of the secondary spring is generated at point B on the main movable body 6.

  The main movable body 6 can move only in the horizontal direction. Therefore, the secondary spring repulsive force 20 becomes a force 21 that pushes up the main link 9 connected to the main movable body 6. Since the auxiliary B movable body 11 can move only in the vertical direction, an upward lifting force 22 is generated at the point A connected to the main link 9.

  Here, when the point A is moved downward, the length of the main link 9 does not change, so the point B on the main movable body 6 moves to the left. That is, the secondary spring 5 is compressed around the point C as it rotates, and the secondary spring repulsive force 20 increases. As the secondary spring is compressed, the force 22 that lifts upward at point A generally decreases.

  That is, the tendency of a negative spring characteristic is shown. At this time, since the angle formed by the secondary spring 5 and the main link 9 changes, the magnitude of the force 22 that lifts upward at point A changes under these influences.

  FIG. 4 is a diagram showing a balance of forces when a secondary spring having a negative spring characteristic according to the present invention is vertical. When the point A moves further downward, the secondary spring 5 becomes vertical. At this time, the force 21 for pushing up the main link 9 by the secondary spring 5 becomes zero, and the lifting force 22 at the point A1 on the auxiliary B movable body 11 also becomes zero.

  FIG. 5 shows another example of the mechanism relating to the negative spring characteristic according to the present invention. The negative spring characteristic shown in FIG. 5 is also constituted by the normal secondary spring 5 having a positive spring constant, the main movable body 6, the main link 9, and the auxiliary B movable body 11. The amount of vertical movement of point A on the auxiliary B movable body 11 is defined as displacement.

  One end of the secondary spring 5 is connected to the one end of the main link 9 at a point B on the main movable body 6 in a state where rotational movement is allowed, and the other end of the secondary spring 5 is fixed C It is connected in a state where only rotation is allowed at the point. However, the main movable body 6 is restricted in vertical movement and can move only in the horizontal direction. Further, the movement of the point A is restricted in the horizontal direction, and only the vertical movement is allowed.

  FIG. 6 shows another example of force balance in the negative spring characteristic according to the present invention. In the initial state, the secondary spring 5 is attached vertically between B and C in a compressed state. When the point A moves downward, the point A1 and the point B1 on the main movable body 6 are connected by the link 9, so the main movable body 6 moves to the left.

  At this time, the compressed secondary spring 5 extends while rotating about the C point. At the same time, the main link 9 is pulled by the main link pulling force 24 by the secondary spring repulsive force 20 of the secondary spring. At the point A1 of the auxiliary B movable body 11 moved downward, the main link pulling force 24 generates a pulling force 24 vertically downward.

  At the same time, since the angle formed by the secondary spring 5 and the main link 9 also changes, the magnitude of the pull-down force 24 at the point A1 changes under these influences. At this time, the compressed secondary spring extends and the repulsive force of the secondary spring decreases, but the pulling-down force 24 at the point A1 increases. That is, the tendency of a negative spring characteristic is shown.

  FIG. 7 is a basic configuration diagram of an embodied equal repulsion spring mechanism according to the present invention. FIG. 7 employs the negative spring characteristic shown in FIG. FIG. 8 is a configuration diagram in the case where the iso-repulsive spring mechanism according to the present invention is applied to a chair. The apparatus comprises an upper frame 2 and a lower frame 3, a primary spring 4 and a secondary spring 5, a main movable body 6 and an auxiliary A movable body 7, a main link 9 and an auxiliary link 10. When the equal repulsion spring mechanism 1 is installed in the chair 30, it is accommodated in the equal repulsion spring mechanism storage portion 31 below the seat 32 and the seat 32 is installed on the upper frame 2 of the equal repulsion spring mechanism 1. Become.

  The primary spring 4 is connected to the upper frame 2 whose one end is movable up and down, and is connected to the lower frame 3 whose other end is fixed. On the other hand, one end of the secondary spring 5 is fixed to the fixed support column 8 in a rotatable state, and the other end of the secondary spring 5 is connected to the main movable body 6 movable in one direction. One end of the main link 9 is connected to the main movable body 6 in a rotatable state, and the other end of the main link 9 is connected to a connection point with the primary spring 4 in the upper frame 2 in a rotatable state. A certain repulsive force is applied to the upper frame against the displacement of the upper frame 2 due to the load.

  When a person sits on the seat 32, the upper frame 2 is pushed down. Therefore, the primary spring 4 attached between the upper frame 2 and the lower frame 3 is compressed. The secondary spring 5 is also compressed as described in the negative spring characteristics. At this time, since the primary spring 4 is compressed, the repulsive force that lifts the upper frame 2 upward increases. The compression force of the secondary spring 5 lifts the upper frame 2 upward via the main movable body 6 and the main link 9, and this repulsive force becomes smaller.

  The equal repulsion spring mechanism 1 is configured such that the sum of these repulsive forces is constant. That is, the upper frame 2 is pushed up with this constant repulsive force, and the seat 32 installed on the upper frame 2 is pushed up with a constant force. An auxiliary A movable body 7 that can move left and right is attached to the upper frame 2, and the auxiliary A movable body 7 is attached to one end of an auxiliary link 10 in a state where it can rotate.

  The other end of the auxiliary link 10 is fixed to the lower frame 3. The auxiliary link 10 and the main link 9 intersect, and the intersection is fixed in a state where each link can rotate. Therefore, the upper frame 2 can be moved in the vertical direction while keeping the level. As the primary spring and the secondary spring, a helical spring, a torsion coil spring, a leaf spring, a bamboo shoot spring, a torsion bar, an air spring, or the like can be used.

  When standing up from the chair 30, the equal repulsion spring mechanism 1 moves in the reverse direction when sitting, and at this time, the seat 32 attached to the upper frame 2 pushes up the human buttocks with a constant force. Become. That is, when a person with weak legs uses the chair 30, the most force is required immediately before bending or sitting, or immediately before standing, but at this time, the seating 32 pushes up the buttocks to help sitting or standing. Will be. In addition, since the spring constant of the iso-repulsive spring mechanism 1 is almost zero, no unstable vibration occurs when sitting.

FIG. 9 is a diagram showing a balance of forces in the basic configuration of the equal repulsion spring mechanism according to the present invention. When an external load W (x) acts on an arbitrary point ξ of the upper frame 2, the repulsive force F (x) and the repulsive force W ₁ (x) at the load point are expressed by the following equations. The repulsive force F (x) is the sum of the effectiveness F ₁ (x) of the primary spring and the effectiveness F ₂ (x) due to the repulsive force of the secondary spring. The effect F ₂ (x) is an effect of a vertical component in which the repulsive force of the secondary spring acts on the connection point between the main link 9 on the upper frame 2 and the primary spring 4 via the main link 9. However, to the weight of the upper frame 2 Mg, a length initial upper frame 2 is moved to the vertical lower x, respectively the spring constant of the primary spring 4 and the secondary spring 5 k ₁ and k _2.

なお、ｘ＝０での上部フレーム高さを最大高さｈ_max、ｘ＝ｘ_maxでの上部フレーム高さを最小高さｈ_minとした。また、ｘ＝ｘ_maxでのｂ_２（ｘ）を回転余裕長さλとした。理想的な等反発力特性とは、変位過程のおける反発力が一定での変動が無い特性である。しかし、理想的な特性を実際に得ることは困難であり、ある程度の変動が生じる。上記した力の釣り合いのバランス式から、反発力Ｆ（ｘ）を求めることができる。図１０は本発明に基づく、変位ｘの変化に対する反発力の変化を示す図である。

The upper frame height at x = 0 is the maximum height h _max , and the upper frame height at x = x _max is the minimum height h _min . Further, b ₂ (x) at x = x _max was _defined as a rotation allowance length λ. The ideal iso-repulsive force characteristic is a characteristic in which the repulsive force in the displacement process is constant and does not fluctuate. However, it is difficult to actually obtain ideal characteristics, and some fluctuations occur. The repulsive force F (x) can be obtained from the balance formula of the balance of forces described above. FIG. 10 is a diagram showing a change in repulsive force with respect to a change in displacement x based on the present invention.

  Therefore, in order to evaluate the iso-repulsive force characteristics, the difference between the repulsive force F (x) and the set repulsive force was obtained, and the average fluctuation rate δ was defined as follows.

ここで、平均変動率δとは、ある設定反発力Ｆ_０に対して、メカニズムの変位過程における、任意の位置での実際の反発力Ｆ（ｘ）とＦ_０との差の絶対値を、全変位において平均しＦ_０で割った値、すなわち、実際に得られる反発力分布と、Ｆ_０とのずれの度合いを表す値である。

Here, the average fluctuation rate δ is the absolute value of the difference between the actual repulsive force F (x) and F ₀ at an arbitrary position in the mechanism displacement process with respect to a certain set repulsive force F ₀ . A value obtained by averaging all displacements and dividing by F ₀ , that is, a value representing a degree of deviation between the repulsive force distribution actually obtained and F ₀ .

Therefore, it can be said that the smaller the δ is, the closer the repulsive force becomes to be constant and the better the repulsive force characteristic of the model. Here, ΔF is the difference between the set repulsive force F ₀ and the actually obtained repulsive force F (x), and N is the number of divisions for the total displacement.

  As shown by the balance equation of force balance, the factors governing the iso-repulsive force characteristics are governed by the factors that constitute the iso-repulsive spring mechanism, and the shape of the repulsive force distribution can be changed by changing these factors. Change. Therefore, calculation by a computer program was used as a method for obtaining the optimum repulsive force distribution of the equal repulsion spring mechanism. As an optimization method, for each design condition, each parameter is changed independently, the repulsive force distribution is calculated, and the average variation rate δ is the smallest among the changed parameter combinations. The one was selected.

FIG. 11 is a diagram showing an example of the optimum shape of the equal reaction force spring generating mechanism based on the present invention. According to the configuration of the equal repulsion spring mechanism in FIG. 9, the set repulsive force F ₀ is set to 300 N, and each factor is changed and optimized. At this time, the average fluctuation rate is a low value of 1.5%.

  When a practical machine is planned by applying the equal repulsion spring mechanism according to the present invention, each factor is restricted by the product structure. In the device design, the degree of freedom of each factor is required for these constraints. In addition, since the effect of equal repulsion can be obtained sufficiently if the average fluctuation rate is 5% or less, the range of each factor was obtained under these conditions.

FIG. 12 is a diagram showing an example of the range of each factor when the average fluctuation rate is 5% or less based on the present invention. At this time, the set repulsive force F _0, stroke h _max −h _min , base length b, primary spring constant k ₁ and secondary spring constant k ₂ are fixed, maximum height h _max , fixed strut height a, rotation This is a result of changing the margin length λ. The range of the maximum height h _max is determined by the maximum value and the minimum value at which the average fluctuation rate is 5% or less, with the fixed column height a and the rotation margin length λ set to the optimum values shown in FIG.

  The range between the maximum value and the minimum value of each factor having an average fluctuation rate of 5% or less is sufficiently wide. When planning a device incorporating an iso-repulsive spring mechanism, each factor has a sufficient margin and can be designed with a degree of freedom. Also, when applied to an auxiliary chair, there are individual differences in height, weight, body sensation, etc., but it is possible to design a chair corresponding to these.

  FIG. 13 is a diagram showing an example of a change in the repulsive force with respect to the displacement when the maximum height is changed according to the present invention. FIG. 14 is a diagram showing an example of a change in the repulsive force with respect to the displacement when the height of the fixed column is changed according to the present invention. FIG. 15 is a diagram showing an example of a change in the repulsive force with respect to the displacement when the rotation allowance length is changed based on the present invention.

  In FIGS. 13, 14, and 15, changes in the repulsive force when the respective factors take the maximum value, the optimum value, and the minimum value are represented by A, B, and C, respectively. These results also show that the repulsive force is almost constant with respect to the displacement.

FIG. 1 is a view showing the principle of an equal repulsion spring mechanism based on the present invention. FIG. 2 is a diagram illustrating an example of a mechanism related to negative spring characteristics according to the present invention. FIG. 3 is a diagram for explaining an example of force balance in the negative spring characteristic based on the present invention. FIG. 4 is a diagram showing a balance of forces when a secondary spring having a negative spring characteristic is vertical according to the present invention. FIG. 5 is a diagram illustrating another example of a mechanism relating to negative spring characteristics according to the present invention. FIG. 6 is a diagram for explaining another example of force balance in the negative spring characteristic based on the present invention. FIG. 7 is a basic configuration diagram of an embodied equal repulsion spring mechanism according to the present invention. FIG. 8 is a configuration diagram in the case where the iso-repulsive spring mechanism according to the present invention is applied to a chair. FIG. 9 is a diagram showing a balance of forces in the basic configuration of the equal repulsion spring mechanism based on the present invention. FIG. 10 is a diagram showing a change in repulsive force with respect to a change in displacement x based on the present invention. FIG. 11 is a diagram showing an example of the optimum shape of the equal repulsion spring mechanism based on the present invention. FIG. 12 is a diagram showing an example of the range of each factor when the average fluctuation rate is 5% or less based on the present invention. FIG. 13 is a diagram showing an example of a change in the repulsive force with respect to the displacement when the maximum height is changed according to the present invention. FIG. 14 is a diagram showing an example of a change in the repulsive force with respect to the displacement when the height of the fixed column is changed according to the present invention. FIG. 15 is a diagram showing an example of a change in the repulsive force with respect to the displacement when the rotation allowance length is changed based on the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Equal repulsion spring mechanism 2 Upper frame 3 Lower frame 4 Primary spring 5 Secondary spring 6 Main movable body 7 Auxiliary A movable body 8 Fixed support | pillar 9 Main link 10 Auxiliary link 11 Auxiliary B movable body 20 Secondary spring repulsive force 21 Main link Push-up force 22 Lift-up force 23 Main link pulling force 24 Pull-down force 30 Chair 31 Recoil spring mechanism storage part 32 Seating 33 Backrest 34 Leg

Claims (5)

  It consists of a primary spring, a secondary spring, an upper frame and a lower frame that are positioned in parallel vertically, a main movable body, and a main link. One end of the primary spring is connected to the upper frame that moves up and down, and the other end is fixed. The other end of the secondary spring is connected to the main movable body movable in one direction, and is connected to the main link. One end of the main link is connected to the main movable body in a rotatable state, and the other end of the main link is connected to a connection point with the primary spring of the upper frame in a rotatable state. On the other hand, an equal repulsion spring mechanism that applies a constant repulsive force to the upper frame.   One end of the secondary spring is fixed in a state where it can rotate on a fixed support installed in the lower frame, and the other end of the secondary spring is connected in a state where it can rotate in a main movable body movable in one direction. One end of the main link is connected to the main movable body in a rotatable state, and the repulsive force of the compressed secondary spring is transmitted to the main link, and a negative spring characteristic in one direction is formed at the other end of the main link. The equal repulsion spring mechanism according to claim 1.   By optimizing the set repulsive force, the maximum and minimum height of the primary spring, the fixed strut height, the base length, the margin of rotation, the load application position, and the spring constant of the primary spring and secondary spring, 2. The equal repulsion spring mechanism according to claim 1, wherein a repulsive force substantially equal to the displacement is generated at the point.   The main movable body is installed on the lower frame, an auxiliary movable body movable in one direction is installed on the upper frame, one end of the main link is connected to the main movable body in a rotatable state, and the main link The other end of the auxiliary link is connected to the upper frame in a rotatable state, the other end of the auxiliary link is connected to the auxiliary movable body in a rotatable state, and the other end is connected to the lower frame in a rotatable state. 2. The equal repulsion spring according to claim 1, wherein an intersection of the auxiliary link and the auxiliary link is fixed in a state where both the links can rotate, and the upper frame is configured to be movable in parallel to the lower frame. mechanism.   4. The equal repulsion according to claim 1, wherein the primary spring and the secondary spring include a helical spring, a torsion coil spring, a leaf spring, a bamboo shoot spring, a torsion bar, an air spring, and the like. Spring mechanism.

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