JP2018100732A - Pulley structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inhibit resonance of a torsion coil spring in a torsion direction and thereby prevent damage of the torsion coil spring.SOLUTION: A pulley structure 1 includes: an outer rotating body 2 around which a belt B is wound; an inner rotating body 3 which is provided at the radial inner side of the outer rotating body 2 and can rotate relative to the outer rotating body 2; and a spring 4 disposed between the outer rotating body 2 and the inner rotating body 3. The spring 4 has: a rear end side area 43 which contacts with the outer rotating body 2 in a state where the outer rotating body 2 and the inner rotating body 3 do not rotate; a front end side area 44 which contacts with the inner rotating body 3; and a middle area 45 which is located between the rear end side area 43 and the front end side area 44 and does not contact with the outer rotating body 2 and the inner rotating body 3. The outer rotating body 2 has a contact surface 22 which contacts with an outer peripheral surface 41 of the middle area 45 of the spring 4 in conjunction with diameter expansion of the spring 4 to restrict diameter expanding deformation of the spring 4. A radial size X1 of a gap between the outer peripheral surface 41 of the middle area 45 of the torsion coil spring 4 and the contact surface 22 of the outer rotating body 2 changes in a rotation axis direction.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a pulley structure including a torsion coil spring.

  The drive shaft of an auxiliary machine having a large moment of inertia, such as an alternator driven by the power of an engine such as an automobile, is described in Patent Document 1, for example, for the purpose of absorbing fluctuations in the rotational speed of the crankshaft of the engine. A pulley structure is connected.

  FIG. 10 is a cross-sectional view showing a pulley structure 201 having the same configuration as the pulley structure shown in FIG. As shown in FIG. 10A, the pulley structure 201 includes an outer rotating body 202 around which a belt B for transmitting the power of the crankshaft is wound, and an inner side of the outer rotating body 202. An inner rotating body 203 that can rotate relative to 202, and a torsion coil spring 204 (hereinafter simply referred to as a spring 204) disposed between the outer rotating body 202 and the inner rotating body 203. Further, the spring 204 has a rear end side region 241 where the outer peripheral surface is in contact with the outer rotator 202 and the inner peripheral surface is in contact with the inner rotator 203 when the outer rotator 202 and the inner rotator 203 are not rotating. And a middle region 243 that is located between the rear end region 241 and the front end region 242 and that is not in contact with either the outer rotator 202 or the inner rotator 203. Then, when the power of the crankshaft is transmitted to the outer rotator 202 via the belt B, the outer rotator 202 rotates relative to the inner rotator 203 and the spring 204 is twisted. When the spring 204 is twisted in the direction of expanding the diameter (in the direction of increasing diameter), the rear end side region 241 of the spring 204 rotates together with the outer rotator 202, and the front end side region 242 of the spring 204 presses the inner rotator 203. Rotate. As a result, torque is transmitted between the outer rotator 202 and the inner rotator 203. On the contrary, when the spring 204 is twisted in the direction of reducing the diameter (the direction of diameter reduction), the outer peripheral surface of the rear end side region 241 of the spring 204 is separated from the outer rotator 202, and the outer rotator 202 and the inner rotator 203 Torque is not transmitted between the two. Thus, torque is transmitted or interrupted between the outer rotator 202 and the inner rotator 203 via the spring 204.

  Here, when the twist angle in the diameter expansion direction of the spring 204 becomes excessively large, the middle region 243 may be deformed to expand beyond the limit, and the spring 204 may be damaged. As a configuration for solving this problem, the outer rotator 202 has an annular surface 221 that contacts the outer peripheral surface 244 of the middle region 243 of the spring 204 in the radial direction. In the above configuration, when the torsion angle of the spring 204 reaches a predetermined value or more, the outer peripheral surface 244 of the middle region 243 of the expanded spring 204 comes into contact with the annular surface 221 of the outer rotating body 202, and the torsion of the spring 204 beyond that. Deformation (expansion deformation) is restricted. This prevents damage to the spring 204 due to excessive diameter expansion deformation.

JP 2014-114947 A

  In Patent Document 1, the size Z of the gap between each winding of the middle region 243 of the spring 204 and the annular surface 221 of the outer rotator 202 is determined in a state where the outer rotator 202 and the inner rotator 203 are not rotating. It is constant in the rotation axis direction of the outer rotating body. For this reason, the entire middle region 243 is separated from the annular surface 221 until the outer peripheral surface 244 contacts the annular surface 221 of the outer rotating body 202 after the middle region 243 of the spring 204 starts to expand in diameter. As the diameter of the middle region 243 increases, as shown in FIG. 10B, the entire outer peripheral surface 244 of the middle region 243 and the annular surface 221 come into contact almost simultaneously at the same time. That is, the effective number of turns of the spring 204 (the number of turns in a deformable range excluding the portion where the deformation is constrained from the total length of the spring) is substantially constant from when the middle region 243 starts to expand until the expansion is restricted. become. Since the effective number of turns is inversely proportional to the spring constant (torsion torque / torsion angle) of the spring 204, the spring constant is also constant in the range of the torsion angle of the spring 204 where the effective number of turns is constant. In other words, the natural frequency in the torsional direction of the spring 204 becomes substantially constant from the start of diameter expansion of the middle region 243 to the diameter expansion restriction by the annular surface 221.

  By the way, in the engine accessory drive system, when the rotational speed of the crankshaft of the engine periodically varies, if the frequency of the variation is close to the natural frequency, the spring 204 is in the radial direction over a wide range of torsion angles. It tends to resonate. In particular, if the spring 204 resonates in a state where the spring 204 is in contact with the annular surface 221, the diameter expansion deformation or its maximization is excessively repeated, and the spring 204 may be easily damaged.

  An object of the present invention is to prevent the torsion coil spring from being damaged by suppressing resonance in the torsion coil spring.

  A pulley structure according to a first aspect of the present invention is provided with a cylindrical outer rotating body that is wound around a belt and rotated by a torque applied via the belt, and provided on the radially inner side of the outer rotating body. An inner rotating body that can rotate relative to the rotating body around the same rotation axis as the outer rotating body, and a torsion coil spring disposed between the outer rotating body and the inner rotating body, The torsion coil spring includes a first region that contacts one of the outer rotator and the inner rotator in a state where the outer rotator and the inner rotator are not rotating, the outer rotator, and the inner rotator. A second region that contacts the other of the rotator, and a middle region that is located between the first region and the second region and that does not contact either the outer rotator or the inner rotator. And the outer rotating body moves along with the diameter expansion of the torsion coil spring. A state in which the outer rotating body and the inner rotating body are not rotating, having a contact surface that regulates the diameter expansion deformation of the torsion coil spring by contacting the outer peripheral surface of the middle region of the torsion coil spring In the above, the size in the radial direction of the gap between the outer peripheral surface of the middle region of the torsion coil spring and the contact surface of the outer rotating body changes in the rotation axis direction of the outer rotating body. It is what.

  According to the present invention, in the state where the outer rotator and the inner rotator are not rotating, the radial size of the gap between the outer peripheral surface of the middle region of the torsion coil spring and the contact surface of the outer rotator is small. It changes in the axial direction of the rotation axis of the outer rotator. For this reason, when the torsion coil spring is twisted and expanded in diameter by relative rotation between the outer rotating body and the inner rotating body, the outer peripheral surface of the middle region and the contact surface are sequentially brought into contact with each other from the portion where the gap is small. Go. As the twist angle of the torsion coil spring in the diameter expansion direction increases, the contact portion (that is, the portion in which the diameter expansion deformation is restricted) increases, so the contact between the outer peripheral surface and the contact surface starts and The effective number of turns of the torsion coil spring decreases until the entire region comes into contact with the contact surface. In inverse proportion to this, the spring constant of the torsion coil spring increases. In other words, the natural frequency in the torsional direction of the torsion coil spring changes with the change in the torsional angle in the range of torsional angles from when the contact starts until the diameter expansion deformation is maximized.

  In the range of torsion angles as described above, the rotational speed of the outer rotating body fluctuates, and even if the frequency coincides with the natural frequency of the torsion coil spring at a certain torsion angle, if the torsion angle changes, the torsion angle changes. Since the natural frequency of the coil spring also changes, the state in which the frequency of external rotation fluctuations matches the natural frequency of the torsion coil spring does not continue. Therefore, resonance of the torsion coil spring can be suppressed. In this way, by suppressing the resonance in the torsional direction, it is possible to prevent the torsion coil spring from undergoing excessive expansion and expansion of the diameter of the torsion coil spring. Therefore, resonance in the torsional direction of the torsion coil spring can be suppressed, and damage to the torsion coil spring can be prevented.

  The pulley structure according to a second aspect of the present invention is the pulley structure according to the first aspect, wherein the gap increases from one to the other in the direction of the rotation axis when the outer rotating body and the inner rotating body are not rotating. It is characterized by.

  According to the present invention, as the diameter of the middle region of the torsion coil spring increases, the outer peripheral surface of the middle region and the contact surface of the outer rotator sequentially come into contact with each other from one side in the rotational axis direction (the side with the smaller gap). To go. For this reason, the effective number of turns of the torsion coil spring can be gradually changed according to the torsion angle as compared with the case where the other gap in the direction of the rotation axis, the middle portion, and the like have a small gap. Therefore, the spring constant (that is, the torsion torque characteristic of the torsion coil spring) can be gradually changed according to the torsion angle, and a sudden change can be suppressed.

  A pulley structure according to a third aspect of the present invention is the pulley structure according to the first or second aspect, wherein the gap continuously changes in the direction of the rotation axis when the outer rotating body and the inner rotating body are not rotating. It is characterized by doing.

  According to the present invention, as the middle region of the torsion coil spring increases in diameter, the area of the contact portion between the outer peripheral surface of the middle region and the contact surface of the outer rotator gradually increases continuously. The effective number of turns changes slowly. Therefore, the spring constant of the torsion coil spring can be changed gently.

  The pulley structure according to a fourth aspect of the present invention is the pulley structure according to any one of the first to third aspects, wherein the torsion angle in the diameter expansion direction of the torsion coil spring is the maximum at which the expansion deformation of the entire torsion coil spring is restricted. The torsion coil spring and the outer rotating body are formed so that a part of the outer peripheral surface of the middle region contacts the contact surface when the torsion angle becomes 10% or more. It is what.

  According to the present invention, the outer peripheral surface of the middle region and the contact surface start to come into contact with each other when the torsion angle in the diameter expansion direction of the torsion coil spring is relatively small. As a result, the natural frequency of the torsion coil spring can be changed over a wide range of torsion angles, and it is possible to further prevent the torsion coil spring from undergoing diameter expansion deformation and excessive repetition thereof.

  In the pulley structure according to a fifth aspect of the present invention, in any one of the first to fourth aspects, the contact surface is a tapered surface whose diameter increases from one to the other in the rotation axis direction. It is a feature.

  According to the present invention, since the contact surface of the outer rotator becomes a simple tapered surface, an increase in manufacturing cost of the outer rotator can be suppressed.

  The pulley structure according to a sixth aspect of the present invention is the pulley structure according to any one of the first to fourth aspects, wherein the contact surface has a pitch in the rotation axis direction of the winding of the torsion coil spring in the rotation axis direction. It is a spiral surface equal to.

  According to the present invention, when the diameter of the middle region is increased, the area of the contact portion between the outer peripheral surface of the middle region and the contact surface of the outer rotator is likely to increase. Therefore, since the stress generated in the contact portion is easily dispersed, wear of the torsion coil spring and the outer rotating body can be suppressed.

It is a front view of the belt transmission mechanism containing a pulley structure. It is sectional drawing of the pulley structure which concerns on 1st Embodiment of this invention. FIG. 3 is a sectional view taken along line III-III in FIG. 2. It is IV-IV sectional drawing of FIG. It is explanatory drawing which shows the diameter expansion of the middle area | region of a torsion coil spring. It is a graph which shows the relationship between the twist angle of a torsion coil spring, and a twist torque. It is sectional drawing of the pulley structure which concerns on 2nd Embodiment of this invention. It is explanatory drawing which shows the diameter expansion of the middle area | region of a torsion coil spring. It is sectional drawing of the pulley structure which concerns on a modification. It is sectional drawing which shows the conventional pulley structure.

<First Embodiment>
Next, a first embodiment of the present invention will be described with reference to FIGS.

(Schematic configuration of belt transmission mechanism)
First, an example of a belt transmission mechanism using a pulley structure 1 described later will be described with reference to FIG. FIG. 1 is a front view of the belt transmission mechanism 101. The belt transmission mechanism 101 includes, for example, a pulley 102 connected to a crankshaft of an engine such as an automobile, a pulley structure 1 connected to a drive shaft of an alternator that is an auxiliary machine, and driving of other auxiliary machines such as a water pump. A pulley 103 connected to the shaft and a belt B wound between these pulleys are provided. Each pulley is rotatably supported. When the engine is driven, the rotational power of the crankshaft is transmitted from the pulley 102 to the pulley structure 1 and the pulley 103 via the belt B.

(Configuration of pulley structure)
Next, the structure of the pulley structure 1 is demonstrated using FIGS. FIG. 2 is a cross-sectional view of the pulley structure 1 according to the first embodiment. 3 is a cross-sectional view taken along the line III-III in FIG. 4 is a cross-sectional view taken along the line IV-IV in FIG. The left-right direction in FIG. 2 is the front-rear direction (the “rotation axis direction” in the present invention), the left side on the paper is the front (the “other” in the present invention), and the right side on the paper is the rear (the “one” in the present invention) And The direction in which the pulley structure 1 rotates is the circumferential direction. Moreover, let the radial direction of the outer rotary body 2 mentioned later be a radial direction.

  The pulley structure 1 is for transmitting the power of the crankshaft of the engine to an auxiliary machine such as an alternator. As shown in FIG. 2, the pulley structure 1 is provided with an outer rotating body 2 around which the belt B is wound, and an inner rotating body 3 provided inside the outer rotating body 2 and connected to the drive shaft S of the alternator. And a torsion coil spring 4 (hereinafter simply referred to as “spring 4”) disposed between the outer rotator 2 and the inner rotator 3.

  First, the outer rotating body 2 will be described. The outer rotating body 2 is a substantially cylindrical member. As shown in FIG. 2, the belt B is wound around the outer peripheral surface of the outer rotator 2. The outer rotator 2 is configured to rotate about the rotation axis R when torque is applied via the belt B. A pressure contact surface 21 is formed on the inner periphery of the rear end portion of the outer rotating body 2 to contact an outer peripheral surface 41 of the rear end portion of the spring 4 described later. A contact surface 22 is formed in front of the pressure contact surface 21. Details of the contact surface 22 will be described later.

  Next, the inner rotor 3 will be described. The inner rotator 3 is a substantially cylindrical member, and is provided on the radially inner side of the outer rotator 2. As shown in FIG. 2, the inner rotator 3 is configured to be rotatable relative to the outer rotator 2 around the same rotation axis R as the outer rotator 2. The front end of the inner rotator 3 is covered with an end cap 5 attached to the front end of the outer rotator 2.

  The inner rotating body 3 includes a tube main body 31, an outer tube portion 32 disposed on the radially outer side of the front end portion of the tube main body 31, a connection portion 33 that connects the tube main body 31 and the outer tube portion 32, and the like. The cylinder body 31 is connected to the drive shaft S of the alternator. The outer diameter of the front end portion of the tube main body 31 is larger than the outer diameter of other portions in the front-rear direction. The outer peripheral surface of the inner rotating body 3 in this portion is referred to as a contact surface 35. The contact surface 35 is in contact with the inner peripheral surface 42 of the front end portion of the spring 4 described later.

  The outer cylinder part 32 is a cylindrical part arranged on the radially outer side of the front end part of the cylinder main body 31. The outer cylinder part 32 extends rearward to such an extent that it does not interfere with the outer rotating body 2. The inner diameter of the outer cylindrical portion 32 is larger than the diameter of the pressure contact surface 21 of the outer rotating body 2. The connection portion 33 is an annular portion that is formed on the radially outer side of the front end portion of the cylinder body 31 and connects the cylinder body 31 and the outer cylinder portion 32.

  At the front end portion of the inner rotator 3, a facing surface 36 is formed between the tube main body 31 and the outer tube portion 32 (see FIG. 3). The facing surface 36 faces a front end surface 49 of the spring 4 described later in the circumferential direction. Moreover, the protrusion 37 which protrudes in the radial inside of the outer cylinder part 32 is formed in the internal peripheral surface of the outer cylinder part 32 (refer FIG. 3). The protrusion 37 is formed in the vicinity of a position 90 ° away from the facing surface 36 in the circumferential direction.

  A rolling bearing 6 is interposed between the inner peripheral surface of the rear end portion of the outer rotator 2 and the outer peripheral surface of the rear end portion of the cylindrical main body 31 of the inner rotator 3. Further, a slide bearing 7 is interposed between the inner peripheral surface of the front end portion of the outer rotator 2 and the outer peripheral surface of the outer cylinder portion 32 of the inner rotator 3. By the rolling bearing 6 and the sliding bearing 7, the outer rotating body 2 and the inner rotating body 3 can be rotated relative to each other. An annular thrust plate 8 is disposed in front of the rolling bearing 6. The thrust plate 8 is fixed to the inner rotating body 3 and rotates integrally with the inner rotating body 3.

  A space 9 is formed between the outer rotator 2 and the inner rotator 3. More specifically, the space 9 includes the inner peripheral surface of the outer rotating body 2 and the inner peripheral surface of the outer cylindrical portion 32 of the inner rotating body 3, the outer peripheral surface of the cylindrical main body 31, the rear surface of the connecting portion 33, and the thrust. The front surface of the plate 8 is formed. The spring 4 is accommodated in this space 9.

  Next, the spring 4 will be described. The spring 4 is a torsion coil spring formed by spirally winding a spring wire. The spring 4 is left-handed (counterclockwise from the front end toward the rear end). As shown in FIG. 2, the number of turns of the spring 4 is, for example, 7 turns, but is not limited thereto. The spring 4 has a substantially constant diameter over the entire length in a state where the outer rotating body 2 and the inner rotating body 3 are not rotating (that is, a state where an external force that twists the spring 4 is not applied to the spring 4). is there. The spring 4 is housed in the space 9 while being slightly compressed in the axial direction by being sandwiched between the rear surface of the connecting portion 33 of the inner rotator 3 and the front surface of the thrust plate 8. In addition, the compression ratio with respect to the natural length of the spring 4 is, for example, about 20%.

  The spring 4 has an outer peripheral surface 41 and an inner peripheral surface 42, and the cross-sectional shape of the spring line is, for example, a trapezoid as shown in FIG. The outer peripheral surface 41 and the inner peripheral surface 42 are substantially parallel to the rotation axis R of the outer rotator 2. Further, the spring 4 has a rear end side region 43 (main book) in which the outer peripheral surface 41 is in contact with the pressure contact surface 21 of the outer rotator 2 at the rear end in a state where the outer rotator 2 and the inner rotator 3 are not rotating. “First region” of the invention, a front end side region 44 in which the inner peripheral surface 42 contacts the contact surface 35 of the inner rotor 3 (“second region” of the present invention), and a rear end side region at the front end portion. 43 and a front end side region 44, and has a middle region 45 that does not contact either the outer rotator 2 or the inner rotator 3.

  The rear end side region 43 is a region of one or more rounds (360 ° or more around the rotation axis) from the rear end of the spring 4. In a state where the outer rotator 2 and the inner rotator 3 are not rotating, the rear end side region 43 is accommodated in the space 9 in a state where the diameter is slightly reduced. The outer peripheral surface 41 of the rear end side region 43 is pressed against the pressure contact surface 21 by the self-elastic restoring force in the diameter expansion direction of the spring 4 (see FIGS. 2 and 4).

  The front end side region 44 is a region of one or more rounds (360 ° or more around the rotation axis) from the front end of the spring 4. The front end side region 44 is accommodated in the space 9 in a state where the diameter is slightly expanded in a state where the outer rotating body 2 and the inner rotating body 3 are not rotating. The inner peripheral surface 42 of the front end side region 44 is pressed against the contact surface 35 (see FIGS. 2 and 3). Moreover, the front end side area | region 44 consists of three parts. That is, as shown in FIG. 3, the front end side region 44 includes a first portion 46 on the front end side (the same direction as the arrow in FIG. 3) of the spring 4 with respect to the protrusion 37 of the inner rotator 3 in the circumferential direction. 2 has a second portion 47 facing the projection 37 and a third portion 48 on the rear end side (in the same direction as the arrow in FIG. 3) with respect to the second portion 47. In FIG. 3, a portion of the spring 4 sandwiched between two-dot chain lines is a second portion 47. In addition, a front end surface 49 is formed at the front end portion of the first portion 46 so as to face the facing surface 36 of the inner rotator 3 in the circumferential direction.

  As shown in FIG. 2, the middle region 45 is a region between the rear end side region 43 and the front end side region 44. In a state where the outer rotator 2 and the inner rotator 3 are not rotating, the middle region 45 is not in contact with either the outer rotator 2 or the inner rotator 3. Further, the outer peripheral surface 41 of the middle region 45 faces the contact surface 22 of the outer rotator 2 in the radial direction. Details will be described later.

(Details of contact surface of outer rotating body)
Next, details of the contact surface 22 of the outer rotator 2 will be described.

  As shown in FIG. 2, the contact surface 22 is a tapered surface formed in a tapered shape in front of the pressure contact surface 21 in the inner peripheral surface of the outer rotator 2. The diameter of the contact surface 22 is larger than the diameter of the pressure contact surface 21 and continuously increases from the rear to the front. The contact surface 22 faces the outer peripheral surface 41 of the middle region 45 in the radial direction.

  When the outer rotator 2 and the inner rotator 3 are not rotating, the radial size of the gap between the outer peripheral surface 41 of the middle region 45 of the spring 4 and the contact surface 22 of the outer rotator 2 is X1. . As described above, the diameter of the contact surface 22 is continuously increased from the rear to the front, and the diameter of the spring 4 in a state where the outer rotating body 2 and the inner rotating body 3 are not rotating. Is substantially constant over the entire length. For this reason, the size X1 of the gap is the smallest at the rear end of the middle region 45 and continuously increases from the rear to the front. That is, the gap size X1 continuously changes in the front-rear direction.

(Operation of pulley structure)
Next, operation | movement of the pulley structure 1 is demonstrated using FIGS. FIG. 5 is an explanatory view showing the diameter expansion of the middle region 45 of the spring 4. First, the case where the rotation speed of the outer rotator 2 is higher than the rotation speed of the inner rotator 3 (that is, the case where the outer rotator 2 accelerates) will be described. In addition, let the arrow direction of FIG.3 and FIG.4 be a positive direction.

  First, the outer rotator 2 starts to rotate relative to the inner rotator 3 in the positive direction. Here, since the outer peripheral surface 41 of the rear end side region 43 of the spring 4 is pressed against the pressure contact surface 21 of the outer rotating body 2 (see FIG. 4), the spring rotates with the relative rotation of the outer rotating body 2. 4, the rear end side region 43 moves in the positive direction together with the pressure contact surface 21, and rotates relative to the inner rotating body 3 in the positive direction. As a result, the spring 4 undergoes torsional deformation (hereinafter simply referred to as diameter expansion deformation) in the diameter expansion direction. The pressure contact force of the rear end side region 43 of the spring 4 against the pressure contact surface 21 increases as the torsion angle in the diameter expansion direction of the spring 4 increases.

  When the torsion angle in the diameter expansion direction of the spring 4 is 0 ° or more and less than a predetermined angle θ1 (for example, 3 °), the largest torsional stress is generated in the second portion 47 of the front end region 44 of the spring 4. Thus, the second portion 47 is most easily deformed by expanding its diameter. For this reason, when the torsion angle in the diameter expansion direction of the spring 4 is increased, the inner peripheral surface 42 of the second portion 47 is first separated from the contact surface 35 by the diameter expansion deformation. When the second portion 47 is separated from the contact surface 35, or at the same time or when the torsion angle in the diameter increasing direction of the spring 4 is further increased, the outer peripheral surface of the second portion 47 abuts against the protrusion 37, and the second portion 47 The 47 diameter expansion deformation is regulated. At this time, the first portion 46 and the third portion 48 are still in contact with the contact surface 35.

  At the same time when the second portion 47 abuts against the protrusion 37 or when the torsion angle in the diameter increasing direction of the spring 4 is further increased, the pressure contact force of the third portion 48 against the contact surface 35 becomes substantially zero. At this time, the torsion angle in the diameter increasing direction of the spring 4 is the aforementioned θ1. When the twist angle exceeds θ1, the third portion 48 moves away from the contact surface 35 due to the diameter expansion deformation.

  When the twist angle in the diameter expansion direction of the spring 4 is equal to or greater than θ1, the diameter expansion deformation of the front end side region 44 of the spring 4 is restricted by the projection 37, and the front end side region 44 is slid with respect to the arc 37, that is, the projection 37. The shape is easy to move. For this reason, when the torsional angle is further increased and the torsional torque acting on the spring 4 is increased, the front end side region 44 is brought into contact with the pressing force of the second portion 47 against the protrusion 37 and the pressing force of the first portion 46 against the contact surface 35. On the contrary, it slides in the circumferential direction with respect to the protrusion 37 and the contact surface 35. Then, when the front end surface 49 of the spring 4 abuts against the opposing surface 36 and presses the opposing surface 36, torque is reliably transmitted between the outer rotator 2 and the inner rotator 3. At this time, since the third portion 48 of the front end side region 44 is separated from the contact surface 35, compared to when the twist angle is less than θ1 (when the third portion 48 is pressed against the contact surface 35). The effective number of turns of the spring 4 (the number of turns in a deformable range excluding the fixed portion from the entire length of the spring 4) increases.

  Next, the diameter expansion deformation of the middle region 45 when the twist angle in the diameter expansion direction of the spring 4 is equal to or greater than θ1 will be described with reference to FIG. First, in the state before the middle region 45 of the spring 4 undergoes diameter expansion deformation, the size in the radial direction of the gap between the outer peripheral surface 41 of the middle region 45 and the contact surface 22 of the outer rotor 2 is X1 as described above. (See FIG. 5A). As the torsion angle increases, the middle region 45 of the spring 4 increases in diameter, and the gap becomes smaller. However, when the twist angle is less than a predetermined angle θ2 (for example, 5 °), the outer peripheral surface 41 of the middle region 45 and the contact surface 22 are not yet in contact with each other. For this reason, the effective number of turns of the spring 4 does not change when the twist angle is in the range of θ1 to θ2.

  When the torsional angle in the diameter expansion direction of the spring 4 exceeds θ2, the rear end having the smallest clearance with the contact surface 22 in the outer peripheral surface 41 of the middle region 45 of the spring 4 as shown in FIG. A portion (that is, a portion closest to the rear end side region 43) contacts the contact surface 22. That is, when the twist angle exceeds θ2, a part of the middle region 45 is started to be restricted in diameter expansion by the contact surface 22. As the torsion angle is further increased, the portion of the middle region 45 of the spring 4 where the expansion deformation is not restricted continues further expansion. Then, the outer peripheral surface 41 of the middle region 45 is in contact with the contact surface 22 gradually and sequentially from the portion close to the rear end side region 43 (see FIGS. 5B to 5D). Further expansion deformation of the contacted portion is restricted. For this reason, as the torsional angle increases, the effective number of turns of the spring 4 gradually decreases continuously.

  When the torsion angle in the diameter increasing direction of the spring 4 reaches a predetermined angle θ3 (for example, 45 °), the outer peripheral surface 41 of the entire middle region 45 of the spring 4 is brought into contact with the contact surface as shown in FIG. 22 abuts. At this time, the front end side region 44 of the spring 4 is also in contact with the outer cylindrical portion 32 of the inner rotating body 3. As a result, further expansion of the diameter of the spring 4 is restricted, the torsion angle of the spring 4 does not become larger than θ3, and the outer rotating body 2 and the inner rotating body 3 rotate integrally. Thus, the lock mechanism works in the pulley structure 1 to prevent the spring 4 from being damaged due to excessive diameter expansion deformation.

  Next, the relationship between the torsion angle of the spring 4 and the torsion torque acting on the spring 4 in the range of the torsion angle as described above (0 ° to θ3) will be described with reference to the graph of FIG. First, when the torsion angle in the diameter expansion direction of the spring 4 is in the range of 0 ° to θ1, the third portion 48 of the front end side region 44 of the spring 4 is in contact with the contact surface 35, and the effective number of turns of the spring 4 does not change. Therefore, the spring constant (torsion torque / torsion angle) inversely proportional to the effective number of turns is constant in the above range. That is, in the range where the torsion angle is 0 ° to θ1, the torsion torque is proportional to the torsion angle, and the graph is linear.

  When the torsion angle in the diameter expansion direction of the spring 4 is θ1 to θ2, the third portion 48 of the front end side region 44 of the spring 4 is separated from the contact surface 35, so that the spring is smaller than the case where the torsion angle is less than θ1. The effective number of turns of 4 increases, and the spring constant of the spring 4 decreases. Even when the twist angle is in the range of θ1 to θ2, the effective number of turns does not change as described above, and the spring constant is constant.

  When the torsion angle in the diameter expansion direction of the spring 4 is θ2 to θ3, the contact portion of the outer peripheral surface 41 of the middle region 45 of the spring 4 with respect to the contact surface 22 of the outer rotor 2 gradually increases as the torsion angle increases. Will increase continuously. For this reason, as the torsion angle increases, the effective number of turns of the spring 4 gradually decreases continuously, and in inverse proportion to this, the spring constant of the spring 4 gradually increases. Here, as described above, the value of the torsion angle θ2 at which the outer peripheral surface 41 of the middle region 45 of the spring 4 starts to contact the contact surface 22 is, for example, 5 °. Moreover, the value of the maximum torsion angle (that is, θ3) at which the expansion expansion of the entire spring 4 is restricted is 45 °, for example. That is, when the torsion angle in the diameter expansion direction of the spring 4 becomes approximately 10% or more of the maximum torsion angle, a part of the outer peripheral surface 41 of the middle region 45 abuts on the abutment surface 22 and the spring constant changes. Begin to.

  Compared to the case where the spring constant is constant even when the twist angle is in the range of θ2 to θ3 as in the prior art (see the broken line in the graph of FIG. 6, this characteristic is obtained in the pulley structure 201 described above). Thus, the spring 4 of the pulley structure 1 is not easily deformed by expanding its diameter. For example, even when a torsion torque T that maximizes the diameter expansion deformation of the spring 204 of the conventional pulley structure 201 (that is, the torsion angle in the diameter expansion direction becomes θ3) acts on the spring 4, the spring The torsion angle in the diameter expansion direction of 4 remains at θ4 smaller than θ3, and the diameter expansion deformation is not maximized.

  Next, the case where the rotation speed of the outer rotator 2 is lower than the rotation speed of the inner rotator 3 (that is, the case where the outer rotator 2 decelerates) will be described. In this case, the outer rotating body 2 rotates relative to the inner rotating body 3 in the reverse direction (the direction opposite to the arrow direction in FIGS. 2 and 3). With the relative rotation of the outer rotating body 2, the rear end side region 43 of the spring 4 moves together with the pressure contact surface 21 and rotates relative to the inner rotating body 3. As a result, the spring 4 is torsionally deformed in the diameter reducing direction (hereinafter simply referred to as diameter reducing deformation).

  When the torsion angle in the diameter reduction direction of the spring 4 is less than a predetermined angle θ5 (see FIG. 6, for example, θ5 = 10 °), the press contact force with respect to the press contact surface 21 of the rear end side region 43 is when the torsion angle is zero. However, the rear end region 43 is in pressure contact with the pressure contact surface 21. Further, the pressure contact force of the front end side region 44 against the contact surface 35 is slightly increased as compared with the case where the twist angle is zero. When the torsion angle in the diameter reducing direction of the spring 4 is equal to or larger than θ5, the pressure contact force of the rear end side region 43 with respect to the pressure contact surface 21 is substantially zero, and the rear end side region 43 is Slide in the direction. Therefore, torque is not transmitted between the outer rotator 2 and the inner rotator 3. In this way, the spring 4 transmits or blocks torque in one direction. The rear end portion of the spring 4 in the front-rear direction is in contact with the front surface of the thrust plate 8 that rotates integrally with the inner rotor 3, so that the spring 4 is further reduced in diameter and the rear end region 43 is pressed. When separated from the surface 21, the spring 4 moves integrally with the inner rotator 3 and is not in contact with the outer rotator 2. As described above, when the diameter of the spring 4 is reduced, wear of both of the spring 4 and the outer rotating body 2 due to abrasion is suppressed.

  As described above, when the outer region 2 accelerates and the middle region 45 of the spring 4 increases in diameter, the outer peripheral surface 41 and the contact surface 22 of the middle region 45 sequentially come into contact with each other from the portion where the gap is small. I will do it. Since the contact portion increases as the torsion angle in the diameter expansion direction of the spring 4 increases, the entire middle region 45 contacts the contact surface 22 after the contact between the outer peripheral surface 41 of the middle region 45 and the contact surface 22 begins. In the meantime, the effective number of turns of the spring 4 decreases, and the spring constant increases inversely proportionally. In other words, the natural frequency in the torsional direction of the spring 4 changes in accordance with the change in the torsional angle in the range of the torsional angle from when the contact starts until the diameter expansion deformation is maximized. In the range of the torsional angle, the rotational speed of the outer rotating body 2 varies due to, for example, fluctuations in the rotational speed of the crankshaft, and even if the frequency coincides with the natural frequency of the spring 4 at a certain torsional angle, If the torsional angle changes, the natural frequency of the spring 4 also changes. Therefore, the state in which the frequency of the rotational fluctuation of the outer rotating body 2 matches the natural frequency of the spring 4 does not continue. Therefore, resonance of the spring 4 is suppressed. By suppressing the resonance in the torsional direction in this way, it is possible to prevent the spring 4 from undergoing excessive expansion and maximal deformation. Therefore, the resonance of the spring 4 in the torsional direction can be suppressed and the spring 4 can be prevented from being damaged. Moreover, since it can suppress that the contact with the outer peripheral surface 41 of the spring 4 and the contact surface 22 is repeated excessively, wear of a member can be suppressed.

  Moreover, the said clearance gap becomes large as it goes to the front from the back in the state which the outer rotating body 2 and the inner rotating body 3 are not rotating. For this reason, according to the diameter expansion deformation of the middle region 45 of the spring 4, the outer peripheral surface 41 and the contact surface 22 of the middle region 45 sequentially contact from the side where the gap is small, that is, from the side closer to the rear end side region 43. To go. For this reason, it is possible to reliably change the effective number of turns of the spring 4 gradually according to the twist angle. Therefore, the spring constant of the spring 4 can be gradually changed according to the twist angle, and a sudden change can be suppressed.

  In addition, the size of the gap continuously changes in the front-rear direction while the outer rotating body 2 and the inner rotating body 3 are not rotating. For this reason, as the middle region 45 of the spring 4 expands and deforms, the area of the contact portion between the outer peripheral surface 41 and the contact surface 22 of the middle region 45 gradually increases continuously, and the effective number of turns of the spring 4 gradually decreases. To change. Therefore, the spring constant of the spring 4 can be changed gently.

  Further, when the torsion angle in the diameter expansion direction of the spring 4 becomes 10% or more of the maximum torsion angle at which the expansion expansion of the entire spring 4 is restricted, a part of the outer peripheral surface 41 of the middle region 45 comes into contact. Abuts against the surface 22. That is, the outer peripheral surface 41 of the middle region 45 and the contact surface 22 start to come into contact from a stage where the twist angle is relatively small. Thereby, the natural frequency of the spring 4 can be changed over a wide range of torsion angles, and it is possible to further prevent the spring 4 from undergoing diameter expansion deformation and excessive repetition of its maximization.

  Moreover, since the contact surface 22 of the outer rotator 2 is a simple tapered surface, an increase in the manufacturing cost of the outer rotator 2 can be suppressed.

  In addition, since the spring constant of the spring 4 of the pulley structure 1 is likely to be larger than that of the conventional pulley structure 201 in which the spring constant is constant in the range of the torsion angle at which the middle region 45 expands and deforms, the spring 4 Difficult to expand and deform. Therefore, for example, even if the capacity of the alternator connected to the pulley structure 1 is large (that is, even if the moment of inertia of the alternator is large and the torque necessary to rotate the drive shaft of the alternator is large), the spring 4 The twist angle in the diameter expansion direction is difficult to maximize as compared with the conventional pulley structure 201. That is, in the pulley structure 1, not only when connected to an alternator having a small capacity, but also when connected to an alternator having a relatively large capacity, the diameter expansion deformation and maximization of the spring 4 are excessively repeated. Since it is difficult to be broken, the spring 4 is not easily damaged. Therefore, for example, even if it is necessary to change the capacity of the alternator for each vehicle type, it becomes easy to use the same pulley structure 1 regardless of the capacity of the alternator. Can be reduced.

Second Embodiment
Next, a second embodiment of the present invention will be described with reference to FIGS. However, about the thing which has the structure similar to 1st Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted suitably.

  FIG. 7 is a cross-sectional view of the pulley structure 1a according to the second embodiment. In the pulley structure 1a, the shape of the outer rotator 2a is different from the shape of the outer rotator 2 of the first embodiment. Other configurations are the same as those in the first embodiment.

  A pressure contact surface 21a is formed on the inner periphery of the rear end portion of the outer rotating body 2a, and a contact surface 22a is formed in front of the pressure contact surface 21a. The shape of the pressure contact surface 21a is the same as that of the pressure contact surface 21 of the first embodiment.

  The contact surface 22a is a spiral surface formed in a spiral shape throughout. The pitch in the front-rear direction of this spiral is substantially equal to the pitch of the windings of the spring 4. The spiral surface is substantially parallel to the rotation axis R. The size in the radial direction of the gap between the contact surface 22a and the outer peripheral surface 41 of the middle region 45 in a state where the outer rotator 2 and the inner rotator 3 are not rotating is defined as X2. X2 is continuously increased from the rear to the front, similarly to the gap size X1 of the first embodiment.

  Also in the pulley structure 1a as described above, when the twist angle in the diameter expansion direction of the spring 4 is θ2 to θ3, the outer surface 41 and the abutting surface of the middle region 45 increase as the diameter of the middle region 45 of the spring 4 increases. 22a sequentially contacts from the side close to the rear end side region 43. In the second embodiment, as compared with the first embodiment (see FIG. 5), as shown in FIG. 8, the area of the contact portion between the outer peripheral surface 41 of the middle region 45 and the contact surface 22a increases. Therefore, since the stress generated in the contact portion is easily dispersed, wear of the spring 4 and the outer rotating body 2 can be suppressed.

  Next, a modified example in which the above embodiment is modified will be described. However, components having the same configurations as those of the above-described embodiments are denoted by the same reference numerals and description thereof is omitted as appropriate.

(1) The configuration of the outer rotator 2 and the like is not limited to that described above. For example, in the embodiments described above, the contact surface 22 or the like is formed in a tapered shape or a spiral shape, but may be a stepped shape or the like. In the embodiments described above, the diameter of the contact surface 22 and the like is increased from the rear toward the front, but is not limited thereto. For example, as shown to Fig.9 (a), in the outer rotary body 2b of the pulley structure 1b, the diameter of the contact surface 22b may become large as it goes to the back from the front. Furthermore, the diameter of the contact surface 22 or the like does not necessarily increase as it goes from one to the other in the front-rear direction. For example, as shown in FIG. 9B, in the outer rotating body 2c of the pulley structure 1c, the diameter of the contact surface 22c is small on both the rear end side region 43 side and the front end side region 44 side of the spring 4, In the region between them, the diameter of the contact surface 22c may be large. Even in this case, the outer peripheral surface 41 and the contact surface 22c of the middle region 45 sequentially come into contact with a portion having a small gap as the diameter of the spring 4 increases. Accordingly, the spring constant of the spring 4 is likely to change during the diameter expansion of the middle region 45, that is, the natural frequency is likely to change, so that resonance in the torsional direction of the spring 4 can be suppressed.

(2) In the embodiments described above, the spring 4 has a substantially constant diameter over the entire length in a state where the outer rotating body 2 and the inner rotating body 3 are not rotating, but is not limited thereto. . For example, a conical shape or a barrel shape may be used, and the gap between the outer peripheral surface of the middle region 45 and the contact surface 22 or the like changes in the front-rear direction when the outer rotating body 2 and the inner rotating body 3 are not rotating. It only has to be configured to do so.

(3) The cross-sectional shape of the spring 4 may not be trapezoidal as shown in FIG. For example, it may have various shapes such as a circle.

(4) In the above-described embodiments, the spring 4 has the front end side region in which the outer peripheral surface of the rear end side region 43 is pressed against the outer rotary body in a state where the outer rotary body 2 and the inner rotary body 3 are not rotating. Although the inner peripheral surface of 44 is pressed against the inner rotating body, the present invention is not limited to this. For example, in a state where the outer rotator 2 and the inner rotator 3 are not rotating, the inner peripheral surface of the rear end side region 43 of the spring 4 is pressed against the outer rotator, and the outer peripheral surface of the front end region 44 is the inner rotator. (See FIG. 5 etc. in Patent Document 1 (Japanese Patent Laid-Open No. 2014-114947) mentioned above). Alternatively, the outer peripheral surface of the rear end side region 43 may be pressed against the inner rotator, and the inner peripheral surface of the front end side region 44 may be pressed against the outer rotator. That is, any configuration may be used as long as torque can be transmitted between the outer rotating body and the inner rotating body via the spring 4.

DESCRIPTION OF SYMBOLS 1, 1a Pulley structure 2, 2a Outer rotating body 3 Inner rotating body 4 Torsion coil spring 22, 22a Contact surface 41 Outer surface 43 Rear end side region (first region)
44 Front end region (second region)
45 Middle area B Belt R Rotating shaft

Claims (6)

A cylindrical outer rotating body around which a belt is wound and rotated by a torque applied through the belt;
An inner rotator which is provided on the inner side in the radial direction of the outer rotator and is rotatable relative to the outer rotator about the same rotation axis as the outer rotator;
A torsion coil spring disposed between the outer rotating body and the inner rotating body,
The torsion coil spring includes a first region that contacts one of the outer rotator and the inner rotator in a state where the outer rotator and the inner rotator are not rotating, the outer rotator, and the inner rotator. A second region that contacts the other of the rotator, and a middle region that is located between the first region and the second region and that does not contact either the outer rotator or the inner rotator. And
The outer rotating body has an abutment surface that regulates deformation of the torsion coil spring by expanding in contact with the outer peripheral surface of the middle region of the torsion coil spring as the diameter of the torsion coil spring increases.
In the state where the outer rotating body and the inner rotating body are not rotating, the radial size of the gap between the outer peripheral surface of the middle region of the torsion coil spring and the contact surface of the outer rotating body is small. The pulley structure changes in the direction of the rotation axis of the outer rotating body.   2. The state in which the radial size of the gap increases from one to the other in the rotation axis direction in a state where the outer rotating body and the inner rotating body are not rotating. The pulley structure described.   3. The size of the gap in the radial direction continuously changes in the direction of the rotation axis when the outer rotating body and the inner rotating body are not rotating. Pulley structure.   When the torsion angle in the diameter increasing direction of the torsion coil spring becomes 10% or more of the maximum torsion angle at which diameter expansion deformation of the entire torsion coil spring is restricted, a part of the outer peripheral surface of the middle region is The pulley structure according to any one of claims 1 to 3, wherein the torsion coil spring and the outer rotating body are formed so as to be in contact with the contact surface.   The pulley structure according to any one of claims 1 to 4, wherein the contact surface is a tapered surface having a diameter that increases from one to the other in the rotation axis direction.   The pulley according to any one of claims 1 to 4, wherein the contact surface is a spiral surface having a pitch in the rotation axis direction equal to a pitch in the rotation axis direction of the winding of the torsion coil spring. Structure.

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