JP2004116644A - Nonlinear spring mechanism using linear spring - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide "a nonlinear spring mechanism using a linear spring" to minimize the amount of change in a load to the deflection of a coil spring for pressing a brush for extending the life of, for example, a brush type compact DC motor. <P>SOLUTION: The coil spring having linear spring characteristics is placed in a coil spring accommodation box, and the inner surface width of the coil spring accommodation box is set slightly larger than the outside dimension of the coil spring so that the coil spring can travel freely. The inner surface width at right angle to the inner surface width is fully larger than the outer diameter dimension of the coil spring, and is approximately 1.5-2 times larger than the coil spring outer diameter dimensions. The length of the coil spring accommodation box differs depending on the purpose of use, but is set to approximately the free length of the coil spring in this case. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a coil spring, which is a mechanical component used in various electric and electronic devices such as electric tools, household electric appliances, and office equipment, and various mechanical devices.
[0002]
[Prior art]
[Non-patent document 1]
Spring Technology Research Society edition "Spring" Maruzen Co., Ltd., issued on December 20, 1982.
[0003]
Many coil springs are used in various electric / electronic devices and mechanical devices, but generally, coil springs having linear spring characteristics are often used. However, in order to optimize the performance of the device, non-linear spring characteristics may be required in some applications.
For example, in a small DC motor widely used in electrical and electronic equipment, etc., the relationship between the brush pressure and the brush abrasion degree is as shown in FIG. It is said that as the size increases, mechanical wear increases.
However, in practice, since a coil spring having a linear spring characteristic is used, the range of the brush pressure is in the mechanical wear range at the beginning of the motor operation, and the brush wear gradually progresses so that the brush is operated in the optimum range. become. Further, as the brush wear progresses, the brush pressure is reduced, so that spark rectification is performed, and the brush enters the range of electrical wear. As this proceeds, the brush will be completely worn, eventually leading to the life of the small DC motor.
Therefore, the brush pressure is in the optimum range shown in FIG. 9 from the beginning of the drive of the small DC motor to the time when the effective length of the brush is worn, and it is desirable that the amount of change in the brush pressure be as small as possible. .
[0004]
Considering the conditions for brush wear as described above, the ideal spring characteristic for reducing brush wear is shown in FIG. That is, the coil spring is designed so that the range from O to A is small so as not to be used, so that it may be linear. However, the load in the range from A to B actually used is D to E, and the amount of change in the load is as small as possible. It is desirable that there be few. Further, when the deflection becomes large, the wires of the coil spring come into contact with each other, so that the load rapidly increases and the range becomes from B to C, but it is desirable that this range is not used as much as possible.
[0005]
Conventionally, coil springs having non-linear spring characteristics include unequal-pitch coil springs, conical coil springs, continuous coil springs, barrel coil springs, etc., but none of these are general-purpose springs. An ideal spring characteristic for a small DC motor as shown in FIG. 10 has not been obtained.
[0006]
Non-Patent Document 1 describes a method for obtaining a nonlinear spring characteristic. The outline is as follows.
As a method for obtaining nonlinear spring characteristics, there is a “combination spring by a series method”. This method is a method of combining coil springs having different spring constants (K1, K2, K3) in series as shown in FIG. At this time, the total spring constant K is given by the following equation, and the relationship between the deflection and the load is as shown in FIG.
1 / K = 1 / K1 + 1 / K2 + 1 / K3 +...
In the present invention, focusing on a method of obtaining the non-linear spring characteristic, an attempt is made to obtain a "non-linear spring mechanism" using "one coil spring having a linear spring characteristic".
[0007]
[Problems to be solved by the invention]
In the present invention, for example, in order to prolong the life of a brush type small DC motor, a “non-linear spring mechanism using a linear spring” is such that the amount of change in load with respect to the deflection of the coil spring for brush pressing becomes as small as possible. The challenge is to provide
[0008]
[Means for Solving the Problems]
A coil spring having linear spring characteristics is placed in a coil spring storage box, and the inner surface width B2 of the coil spring storage box is made slightly larger than the outer dimensions of the coil spring so that the coil spring can move freely.
The inner surface width B1 in the direction perpendicular to the inner surface width B2 is sufficiently larger than the outer diameter of the coil spring, and is about 1.5 to 2 times the outer diameter of the coil spring.
Although the length of the coil spring storage box varies depending on the purpose of use, in this example, the length is set to the free length of the coil spring.
By storing the coil spring in this coil spring storage box, closing one of the storage open portions as a coil spring receiving portion, and pressing the coil spring from the other open portion with a spring pressing tool, a "non-linear spring mechanism using a linear spring" is obtained. Is constituted.
[0009]
【Example】
An embodiment in which a "non-linear spring mechanism" is constructed using "one coil spring having linear spring characteristics" will be described below.
As shown in FIG. 1, a coil spring 1 having a linear characteristic is put in a coil spring storage box 2 so that a load can be applied by a spring pressing tool 3. The inner surface width B1 of the coil spring storage box 2 is sufficiently wider than the outer diameter S1 of the coil spring 1 and is about 1.5 to 2 times the outer diameter of the coil spring. The inner surface width B2 is slightly larger than the outer diameter S1 of the coil spring, and is configured so that the coil spring 1 can move in the coil spring storage box 2.
FIG. 2 shows a state where the coil spring 1 is stored in the coil spring storage box 2 and a load F1 is applied by the spring press 3. An arrow Y at this time is shown in FIG. The coil spring 1 is spaced apart from the side plates 6 and 7, while being substantially in contact with the side plates 8 and 9, while receiving the wire end of the coil spring 1 on the receiving plate 10 and fixed.
When the load F1 is applied by the spring pressing tool 3 in this state, the relationship between the deflection and the load shows a linear characteristic. Assuming that the total spring constant at this time is ka, the spring characteristics are in the range from a to b in FIG.
[0010]
Next, when the load is increased to F2, as shown in FIG. 4, the coil spring is compressed and deformed into a "C" shape. Therefore, the center line of the coil spring is also nonlinearly deformed. It comes into contact with the side plate 6 of the coil spring storage box 2 at the point P1. In such a state, since the deflection of each turn of the coil spring 1 is different, the spring constant is not uniform. Therefore, the spring constants k1 and k2 are assumed to be divided into a plurality of sections having substantially the same deflection. I do. Therefore, the total spring constant kb at this time can be equivalently expressed by the following equation.
1 / kb = 2 / k1 + 1 / k2
Accordingly, the spring characteristic at this time is in the range from b to c in FIG.
[0011]
When the load is further increased to F3, the coil spring 1 is compressed and deformed into an "S-shape" as shown in FIG. Assuming that the spring constants divided into a plurality of sections at this time are k3, k4, and k5, the total spring constant kc can be equivalently expressed by the following equation.
1 / kc = 2 / k3 + 2 / k4 + 1 / k5
Accordingly, the spring characteristic at this time is in the range from c to d in FIG.
[0012]
When the load is further increased to F4, the coil spring 1 is compressed as shown in FIG. 6 and the "S-shape" is further compressed and deformed. Assuming the spring constants k6, k7, and k8 in the same manner as described above, the total spring constant kd at this time can be equivalently expressed by the following equation.
1 / kd = 2 / k6 + 2 / k7 + 1 / k8
Accordingly, the spring characteristic at this time is in the range from d to e in FIG.
When further compressed from this state, the element wires of the spring come into close contact with each other, and the deflection in the range from e to f in FIG. 7 reaches the limit.
[0013]
As described above, the linear coil spring 1 is placed in the coil spring storage box 2, and the inner surface width B1 is sufficiently larger than the outer diameter S1 of the coil spring 1, and the inner surface width B2 is slightly wider than the outer diameter S1 of the coil spring. The coil spring 1 is configured to be movable in the coil spring storage box 2, and a “non-linear spring mechanism” is formed by applying a load with a spring pressing tool 3 using “one coil spring having linear spring characteristics”. Can be configured.
As the load is applied to the coil spring 1, the coil spring is strongly pressed against the side plates 6, 7, 8, 9 in the four directions of the coil spring storage box 2, so that a friction loss occurs. Therefore, the curve H in FIG. 8 is obtained due to the change in the spring constant and the decrease in the load. However, since the research and analysis on the “non-linear spring mechanism” has not been obtained, the details are omitted here.
[0014]
If the approximately constant load characteristic in the range of b to e among the non-linear spring characteristics shown in FIG. 7 obtained by the present invention is used for a brush pressing coil spring of a brush type small DC motor, an ideal brush pressing characteristic is obtained. Can do things.
FIG. 8 shows an embodiment in which the "non-linear spring mechanism" using the "one coil spring having a linear spring characteristic" according to the present invention is applied to a brush pressing coil spring of a brush type small DC motor. Is an actually measured value indicating the relationship.
The curve H shows the same tendency as the curve G in FIG. 7 and has a non-linear spring characteristic. The actual use range of the deflection is a range from the point p to the point q in FIG. 8, and the range from the point p to the point r is a substantially constant load range where the amount of change in the load is small. The recommended load value of the brush type DC motor falls within the range of the horizontal line L and the horizontal line M, and satisfies the recommended load value.
As described above, as a result of applying the "nonlinear spring mechanism" according to the present invention to a brush type small DC motor, the usefulness of the present invention was verified.
[0015]
As a result of applying the "non-linear spring mechanism" according to the present invention to a coil spring for pressing a brush of a brush type small DC motor, the spring characteristic becomes non-linear, and a substantially constant load characteristic range with a small load change amount can be obtained. Was. As a result, the operating range for spark rectification was eliminated, and a long-life brush-type DC motor was obtained, demonstrating the usefulness of the "non-linear spring mechanism".
[Brief description of the drawings]
FIG. 1 is a configuration of a nonlinear spring mechanism. FIG. 2 is a nonlinear spring mechanism-1.
FIG. 3 is a Y view of FIG. 2; FIG. 4 is a non-linear spring mechanism-2;
FIG. 5 shows a non-linear spring mechanism-3.
FIG. 6 shows a non-linear spring mechanism-4.
FIG. 7: Non-linear spring characteristics FIG. 8: Actual measurement values showing the relationship between deflection and load FIG. 9: Relationship between brush pressure and brush wear degree FIG. 10: Relationship graph between deflection and load showing ideal spring characteristics FIG. 11 is a diagram showing a combination spring according to a series method. FIG. 12 is a graph showing a relationship between deflection and load showing non-linear spring characteristics.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Coil spring 2 Coil spring storage box 3 Spring pressing tool 6, 7, 8, 9 Side plate 10 Receiving plates a, b, c, d, e, f Position symbols p, q, r of spring characteristics Deflection point symbols ka, kb , Kc, kd Total spring constants k1, k2, k3, k4, k5, k6, k7, k8 Spring constants B1, B2 Inner surface widths F1, F2, F3, F4 Loads A, B, C Deflection point symbols D, E Load points Symbol G, H Curve symbol K Total spring constant K1, K2, K3 Spring constant L, M Horizontal line symbol O Graphic origin symbol S1 Outer diameter Y of coil spring Y View symbol

Claims (2)

In a coil spring mechanism including a coil spring storage box including four side plates and a single receiving plate, a coil spring having linear spring characteristics, and a spring pressing tool,
One inner surface width of the coil spring storage box is slightly larger than the outer dimensions of the coil spring so that the coil spring can move freely, and the other inner surface width in a direction perpendicular to the inner surface width is larger than the outer diameter of the coil spring. Make the coil spring storage box approximately 1.5 to 2 times as large as the outer diameter of the coil spring, make the length of the coil spring storage box equal to or less than the free length of the coil spring, and press the coil spring with a spring press. The spring mechanism is characterized in that the center line in the pressing direction of the coil spring is non-linearly deformed to obtain a non-linear spring characteristic. 2. The spring mechanism according to claim 1, wherein the ratio between the width of one inner surface of the coil spring storage box and the width of the other inner surface in a direction perpendicular to the inner surface of the coil spring storage box is arbitrarily changed.

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