Spring device

Abstract

To provide a spring device capable of preventing failure due to overload with a simple structure.SOLUTION: A spring device comprises: a case 3 with a shaft body 2 inside; and a spiral spring 4 in which a terminal 5a of an inside end part 5 is engaged with the shaft body 2 and a terminal 6a of an outside end part 6 is in a free state, and which is arranged between the shaft body 2 and the case 3. The outside end part 6 of the spiral spring 4 is wound so as to be in contact with the entire surface of the inner surface of the case, with a length of at least one revolution of the circumference of the inner surface of the case 3.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a spring device that utilizes the winding and tightening force of a spiral spring. [Background technology]

[0002] A spring device that utilizes the spring force of a spiral spring has been developed as a device for winding up long objects such as seat belts. Fig. 6 shows the spring device disclosed in Patent Document 1, and Fig. 7 shows the spring device disclosed in Patent Document 2.

[0003] 6, a spiral spring 100 is disposed between a case 110 and a shaft 120, and a tightening force is applied to the spiral spring 100. An inner end 130 of the spiral spring 100 is engaged with a shaft 120 having an outer diameter larger than the inner diameter of the coiled spring in a free state, and an outer end 140 of the spiral spring 100 is engaged with the case 110. In this device, when a seat belt 150 is pulled out in the direction of the arrow, the shaft 120 rotates, and the spiral of the spiral spring 100 unwinds in the unwinding direction, and a restoring force in the tightening direction is generated in the shaft 120.

[0004] 7 is a device in which a spiral spring performs a tension reduction function, with a spiral spring 200 acting as a reduction spring being disposed between a case 210 having ratchet teeth and a shaft body 220, and the whole being housed within a cover 250. An inner end 230 of the spiral spring 200 is engaged with the shaft body 220, and an outer end 240 is engaged with the case 210. In addition, in order to provide a one-way function, a ratchet lever 270 that engages with the ratchet teeth of the case 210 is provided within the cover 250. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2007-92981 A [Patent Document 2] JP 2012-126237 A Summary of the Invention [Problem to be solved by the invention]

[0006] In conventional spring devices, when rotation beyond the range of use is applied, there is a problem that the spiral spring breaks or the parts are damaged. Also, in order to transmit rotational force in only one direction, it is necessary to use a structure equipped with a ratchet mechanism as in Patent Document 2, which causes a problem that the structure becomes complicated.

[0007] To provide a spring device which will not break down even if rotation beyond the range of use is applied, and which is capable of transmitting a rotational force in one direction even when a ratchet function is not required. [Means for solving the problem]

[0008] The spring device of the present invention comprises a case with an axle therein, and a spiral spring arranged between the axle and the case, with the end of its inner end engaged with the axle and the end of its outer end being free, and the outer end of the spiral spring is wound so as to contact the entire surface of the inner surface of the case, with a length of at least one circumference of the inner surface of the case.

[0009] In the present invention, the outer end portion is wound so as to overlap at least twice, and the outermost peripheral portion is in contact with the entire inner surface of the case. Effect of the Invention

[0010] According to the present invention, when a rotational force acts in the same direction as the winding direction of the spiral spring, the outer end is pulled toward the shaft body and the spiral spring slips relative to the case, providing a one-way clutch function. Also, when an excessive torque acts in the opposite direction to the winding direction of the spiral spring, the outer terminal slips, providing a torque limiter function against overload. This makes it possible to prevent breakdowns due to overload with a simple structure. [Brief description of the drawings]

[0011] [Figure 1] 1 is a cross-sectional view showing the basic structure and operation of the present invention. [Diagram 2] 1(A) to 1(C) are perspective views showing a method of machining the outer end of a spiral spring. [Diagram 3] FIG. 11 is a cross-sectional view illustrating a one-way function. [Figure 4] FIG. 4 is a cross-sectional view illustrating a torque limiter function. [Diagram 5] 2 is a graph illustrating the function of the present invention. [Figure 6] FIG. 1 is a cross-sectional view showing a spring device of Patent Document 1. [Figure 7] FIG. 2 is a cross-sectional view showing the spring device of Patent Document 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] An embodiment of the present invention will be described with reference to Figures 1 to 5. As shown in Figure 1, a spring device 1 of this embodiment includes a case 3 with a shaft body 2 therein, and a spiral spring 4.

[0013] Case 3 is a case member used in a seat belt device or the like, and has shaft 2 provided therein. A long object such as a belt (not shown) is connected to case 3, and case 3 rotates when the long object is pulled. Case 3 and shaft 2 are mutually rotatable.

[0014] Spiral spring 4 is wound in a spiral shape and disposed between case 3 and shaft 2. As shown in Fig. 1(A), inner end 5 of spiral spring 4 is in a state where plate material is tightly wound, and end 5a of inner end 5 is inserted into shaft 2 and locked.

[0015] The spiral spring 4 is wound so that the plate material is rougher toward the outside, and its outer end 6 is in contact with the entire inner surface of the case 3. The contact of the outer end 6 with the inner surface of the case 3 generates a frictional force between the case 3 and the outer end 6. The end 6a of the outer end 6 is free and not locked to the case 3, and when the fixed state is released, the outer end 6 slips relative to the case 3.

[0016] The outer end 6 is wound with a length of at least one revolution relative to the circumferential length of the inner surface of the case 3. As a result, when the outer end 6 is housed inside the case 3, the outer end 6 is pressed against the inner surface of the case 3, and this pressing force 7 (see FIG. 1(B)) increases the frictional force and adheres closely to the case 3. In other words, the case 3 and the outer end 6 of the spiral spring 4 are fixed in place by the tightening force of the outer end 6 against the inner surface of the case 3. Furthermore, when the fixation is released, the spiral spring 4 can rotate in both forward and reverse directions, making it possible to change the starting point of torque generation of the spiral spring 4.

[0017] In the spiral spring 4 of this embodiment, the outer end 6 is wound with a length equivalent to two revolutions around the inner surface of the case 3, so that the outer end 6 is wound so as to overlap in two folds. The overlap of the outer end 6 may be one fold or may be three or more folds.

[0018] Fig. 2 shows a mode for winding the outer end 6 of the spiral spring 4. Fig. 2(A) shows a mode in which the plate material of the outer end 6 extends in the same direction as the winding direction of the inner end 4, and is wound in the same direction as the inner end 4. Fig. 2(B) shows a mode in which the plate material of the outer end 6 extends in the opposite direction to the winding direction of the inner end 4, and in this state is wound in the winding direction of the inner end 4. Fig. 2(C) shows a mode in which the plate material of the outer end 6 extends linearly, and in this state is wound in the same direction as the winding direction of the inner end 4.

[0019] The operation of the spring device 1 of this embodiment will be described with reference to Figures 3 and 4. As shown in Figure 3, when a rotational force acts on the case 3 in the same direction as the winding direction of the spiral spring 4 (X direction) while the shaft body 2 is fixed, a force Y is generated that draws the outer end 6 toward the shaft body 2. As a result, the force fixing the outer end 6 weakens, and the spiral spring 4 slips in the direction of the arrow Z relative to the case 3. This results in a spring device with a one-way clutch function that transmits rotational force in only one direction. This eliminates the need for a ratchet mechanism such as a ratchet lever or ratchet teeth for transmitting rotational force in one direction, allowing for a simple structure. This makes it possible to suppress the generation of judder noise when the ratchet mechanism comes off and slips. Furthermore, when designing a mechanism that does not operate normally but reduces the load torque at any time, such as a seat belt tension reduction mechanism, the rotation capacity of the reduction spring can be set beyond the range of conventional spring designs.

[0020] As shown in Figure 4, when a rotational force acts on the case 3 in the direction opposite to the winding direction of the spiral spring 4 (direction M) while the shaft 2 is fixed, and this force is an overload torque that is greater than the frictional force between the outer end 6 and the case 3, the outer end 6 slips relative to the case 3 in the winding direction of the spiral spring 4 (direction N). This provides a spring device with a torque limiter function that cuts off torque transmission when an overload is applied. As a result, no large torque is applied, and damage to parts can be prevented.

[0021] 5 is a graph qualitatively showing the operation of the spring device of this embodiment, where the dashed line shows the one-way clutch function of the spring device 1 of this embodiment, the dashed line shows the torque limiter function of the spring device 1 of this embodiment, and the solid line shows a conventional spring device. [Explanation of symbols]

[0022] 1 Spring device 2-axis body 3 Cases 4. Spiral Spring 5 Inner end 5a End of inner end 6 Outer edge 6a End of outer edge 100 200 Spiral spring 110 210 Case 120 220 Shaft 130 230 Inner end 140 240 Outer end 150 Seatbelt 270 Ratchet Lever

Claims

1. a case having an axle therein; and a spiral spring disposed between the axle and the case, the end of the inner end being engaged with the axle and the end of the outer end being in a free state; A spring device characterized in that an outer end of the spiral spring is wound so as to contact the entire surface of the inner surface of the case with a length of at least one circumference of the inner surface of the case.

2. 2. The spring device according to claim 1, wherein the outer end portion is wound so as to overlap at least twice, and the outermost periphery of the outer end portion is in contact with the entire inner surface of the case.

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