JP2011214708A - Torsional damper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a torsional damper improving a vibration damping function in a high rotation area.SOLUTION: This torsional damper includes a hub 1 attached to a rotating shaft, a bearing 2 concentrically mounted on the hub 1, a plurality of circumferential mass bodies 3 arranged to be brought into contact with the inner peripheral surface of the bearing 2, and an elastic body 4 connecting the mass bodies 3 to the hub 1 so that the mass bodies are moved in the radial direction and the circumferential direction. The mass bodies 3 and elastic body 4 compose a spring-mass system resonating in a torsional vibration direction within a predetermined vibration frequency range, and exhibit a dynamic vibration absorbing effect. The mass bodies 3 cause friction damping with respect to input vibration by sliding on the inner peripheral surface of the bearing 2 due to vibration displacement in a torsional direction. The contact loads of the mass bodies 3 with respect to the inner peripheral surface of the bearing 2 increase due to an increase in rotational speed. Therefore, the friction damping increases in a higher rotation area.

Description

  The present invention relates to a torsional damper that absorbs torsional vibration generated in a rotating shaft such as a crankshaft of an automobile engine.

  A torsional damper is attached to the crankshaft of an engine such as an automobile in order to prevent occurrence of problems due to an increase in amplitude of torsional vibration (vibration in the rotational direction) that occurs with rotation.

  As shown in FIG. 4, this type of torsional damper 100 is arranged concentrically on the outer peripheral side of a rim 101b and a hub 101 having an inner diameter boss 101a attached to a shaft end of a crankshaft (not shown). And an elastic body 103 made of a rubber material or a synthetic resin material having rubber-like elasticity that elastically connects the hub 101 and the annular mass body 102.

  A predetermined torsional direction natural frequency is set in the spring-mass system (sub vibration system) including the elastic body 103 and the mass body 102. That is, in the torsional damper 100, the spring-mass system composed of the elastic body 103 and the mass body 102 is resonated by being vibrated in the torsional direction in a predetermined vibration frequency range where the torsional amplitude of the crankshaft is maximum. The torque due to the vibration displacement is generated in the opposite direction to the torque due to the input vibration, thereby exhibiting a dynamic vibration absorption effect (see, for example, Patent Document 1 below).

JP 2003-56645 A

  However, in the conventional torsional damper 100, the vibration damping action that consumes the vibration energy as heat depends only on the internal friction caused by the deformation of the elastic body 103. Therefore, there is a problem that it is difficult to efficiently reduce the torsional vibration in which the torsion angle (amplitude in the circumferential direction) increases in a high rotation range.

  The present invention has been made in view of the above points, and a technical problem thereof is to provide a torsional damper having an improved vibration damping function in a high rotation range.

  As means for effectively solving the above technical problem, a torsional damper according to the invention of claim 1 includes a hub attached to a rotary shaft, a bearing concentrically mounted on the hub, A plurality of mass bodies in the circumferential direction disposed so as to be in contact with the inner peripheral surface, and an elastic body that couples the mass bodies to the hub so as to be movable in the radial direction and the circumferential direction.

  In the above configuration, each mass body and the elastic body that is connected to the hub so as to be movable in the circumferential direction constitute a spring-mass system that resonates in the torsional vibration direction in a predetermined vibration frequency range, and has a dynamic vibration absorption effect. To demonstrate. Further, each mass body slides with the inner peripheral surface of the bearing in accordance with the vibration displacement in the torsional direction, thereby generating frictional damping against input vibration, and each mass body is movable in the radial direction by the elastic body. Since they are connected, the contact load of each mass body with respect to the inner peripheral surface of the bearing increases as the rotational speed increases, and therefore the frictional damping increases as the rotational speed increases.

  The torsional damper according to a second aspect of the present invention is the torsional damper according to the first aspect, wherein there is a gap between the opposing surfaces of each mass body and the bearing in a non-rotating state, and due to centrifugal force at a predetermined rotational speed or higher. Each said mass body is closely_contact | adhered to the internal peripheral surface of the said bearing.

  A torsional damper according to a third aspect of the present invention is the torsional damper according to the first aspect, wherein the corners at both ends in the circumferential direction of the opposing surface of each mass body with respect to the bearing are chamfered.

  In the torsional damper according to the first aspect of the present invention, the contact load of the mass body with respect to the inner peripheral surface of the bearing changes due to the centrifugal force, so that the frictional damping caused by the sliding between the bearing and the mass body changes with the rotational speed. In addition, it is possible to improve the damping property against vibration in which the torsion angle increases in a high rotation range.

  According to the torsional damper according to the invention of claim 2, in addition to the effect of claim 1, the resonance amplitude of the spring-mass system composed of each mass body and the elastic body is not impaired at less than a predetermined number of revolutions. A dynamic vibration absorption effect can be obtained.

  According to the torsional damper of the invention of claim 3, in addition to the effect of claim 1, wear and damage due to sliding of the mass body and the bearing can be suppressed.

1 is a cross-sectional perspective view showing a preferred embodiment of a torsional damper according to the present invention by cutting along a plane passing through an axis. It is the figure which looked at the torsional damper of FIG. 1 from the front side. It is a diagram which shows the change of the twist angle of the crankshaft by the rotation speed of an engine by comparing with the case where the conventional torsional damper is used, and the case where the torsional damper of the present invention is used. It is a cross-sectional perspective view which cuts and shows an example of the conventional torsional damper by the plane which passes along an axial center.

  Hereinafter, preferred embodiments of a torsional damper according to the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional perspective view showing this embodiment cut along a plane passing through an axis, and FIG. 2 is a view of the torsional damper of FIG. 1 as viewed from the front side. In the following description, “front” means the left side in FIG. 1 and the front side of the vehicle, and “back” means the right side in FIG.

  The torsional damper of this embodiment includes a metal hub 1 fixed to a crankshaft of an engine (not shown), a dry bearing 2 concentrically mounted on the hub 1, and an inner periphery of the dry bearing 2. A plurality of circumferential mass bodies 3 arranged so as to be in contact with the surface, and an elastic body 4 that connects each mass body 3 to the hub 1 so as to be movable in the radial direction and the circumferential direction. The dry bearing 2 corresponds to the bearing described in claim 1.

  Specifically, the hub 1 is made of a cast metal such as iron or aluminum, and has a boss 11 formed with a shaft hole 11a and a key groove 11b that are fixed to the shaft end of the crankshaft. From the front end portion of the disk portion 12 extending in the outer diameter direction, the inner peripheral cylinder portion 13 extending from the position closer to the inner diameter to the front side, and the outer diameter end portion of the disk portion 12 And an outer peripheral cylindrical portion 14 extending to the front side. A poly V groove 14a is formed on the outer peripheral surface of the outer peripheral cylindrical portion 14, and an endless belt (not shown) for transmitting power to the auxiliary machine is wound around the outer peripheral surface.

  The dry bearing 2 is a sliding bearing made of a material having self-lubricating properties such as PTFE (tetrafluoroethylene) and carbon, and is used in a dry state without any liquid lubrication by a lubricating oil, and is formed in a cylindrical shape. The hub 1 is held in an inserted state on the inner peripheral surface of the outer peripheral cylindrical portion 14.

  The mass body 3 is made of a metal such as an iron-based material, and is formed into an arcuate curved shape obtained by cutting the ring at three locations in the circumferential direction (at intervals of 120 °) by post-processing. A cylindrical surface having a radius of curvature equivalent to the inner peripheral surface of the dry bearing 2 is formed. Each mass body 3 is arranged on the inner peripheral side of the dry bearing 2 with both ends in the circumferential direction facing each other through the slits S. Moreover, chamfering 3b of R surface is given to the circumferential direction both ends of the outer peripheral surface 3a of each mass body 3 facing the dry bearing 2.

  The elastic body 4 is made of, for example, a rubber-like elastic material (rubber or a synthetic resin material having rubber-like elasticity) having excellent heat resistance, cold resistance, and mechanical strength. Between the outer peripheral surface of the metal sleeve 5 press-fitted to the outer peripheral surface and the inner peripheral surface of each mass body 3 facing the radial sleeve, the vulcanization is integrally performed.

  The resonance frequency in the torsional direction of the spring-mass system comprising the elastic body 4 and the mass body 3 is determined by the crankshaft torsion angle depending on the circumferential shear spring constant of the elastic body 4 and the circumferential inertia mass of the mass body 3. It is tuned to the maximum predetermined frequency range, in other words, the torsional direction resonance frequency of the crankshaft.

  Further, as described above, the mass body 3 is not formed in an annular shape but is divided in the circumferential direction. Therefore, when it receives a centrifugal force due to rotation, it is displaced in the outer diameter direction against the tensile elasticity of the elastic body 4. be able to. For this reason, in the non-rotating state, the mass body 3 is held in a state in which a minute gap is formed between the inner peripheral surface of the dry bearing 2 by the restraining force of the elastic body 4, but at a predetermined rotational speed or higher, The outer peripheral surface 3 a is in close contact with the inner peripheral surface of the dry bearing 2.

  In addition, the elastic body 4 has a groove 4a formed from the outer peripheral side in a portion between the mass bodies 3, and the groove 4a constitutes an independent spring for each mass body 3.

  In the torsional damper having the above-described configuration, the dry bearing 2 is inserted and attached to the inner periphery of the outer peripheral cylindrical portion 14 of the hub 1, and the integrally formed product of the mass body 3, the elastic body 4, and the sleeve 5 is placed inside the hub 1. The sleeve 5 is assembled by being inserted into the annular space between the peripheral cylinder part 13 and the outer peripheral cylinder part 14 and press-fitted to the outer peripheral surface of the inner peripheral cylinder part 13 of the hub 1.

  At this time, since the outer peripheral surface 3a of the mass body 3 is a clearance fit with respect to the inner peripheral surface of the dry bearing 2, in the process of press-fitting the sleeve 5 to the outer peripheral surface of the inner peripheral cylindrical portion 13 of the hub 1, Friction resistance does not occur between the outer peripheral surface 3a of the body 3 and the inner peripheral surface of the dry bearing 2, so that the assembling work can be easily performed.

  The torsional damper is fixed to the shaft end of the crankshaft by a bolt and a key (not shown) in the shaft hole 11a of the boss portion 11 of the hub 1, and is rotated together with the crankshaft by driving the engine. When the crankshaft rotates, the torsional vibration frequency input via the hub 1 is in the vicinity of the band where the crankshaft amplitude is maximized. The spring-mass system configured by the mass body 3 and the elastic body 4 is used. However, since each mass body 3 has the same shape and the same size and the same mass, the mass bodies 3 vibrate in a translational manner as if they are continuous with each other. In addition, a dynamic vibration absorption effect is exhibited by the torque generated by the resonance being generated in the opposite direction to the torque of the input vibration. On the other hand, when the sleeve 5 fitted to the outer peripheral surface of the inner peripheral cylindrical portion 13 of the hub 1 and each mass body 3 are relatively displaced in the torsional direction due to such input vibration and resonance, the elastic body 4 is repeatedly sheared between them. Due to the deformation, an internal friction is generated, that is, a vibration damping action that consumes vibration energy as heat is generated. For this reason, the peak of the torsional vibration of the crankshaft can be effectively reduced.

  Here, centrifugal force due to rotation acts on the mass body 3, but since the centrifugal force is small when the crankshaft rotates at a low speed, a minute gap is formed between the elastic body 4 and the inner peripheral surface of the dry bearing 2. Is kept in a state that exists. Therefore, the resonance amplitude of the spring-mass system composed of each mass body 3 and the elastic body 4 is not impaired, and a good dynamic vibration absorption effect can be obtained.

  As the number of rotations of the crankshaft increases, the centrifugal force acting on the mass body 3 increases accordingly, so that each of the resistance against the elasticity of the elastic body 4 that restrains the mass body 3. The mass body 3 is displaced in the outer diameter direction, and the outer peripheral surface 3a of each mass body 3 is brought into close contact with the inner peripheral surface of the dry bearing 2 in due course. For this reason, the mass body 3 slides with the inner peripheral surface of the dry bearing 2 in accordance with the vibration displacement of the mass body 3 in the torsional vibration direction, and a friction damping action is generated that consumes vibration energy as frictional heat. Moreover, since the contact load between the outer peripheral surface 3a of each mass body 3 and the inner peripheral surface of the dry bearing 2 increases with a further increase in the rotational speed (an increase in centrifugal force), the above-described friction damping action also increases. .

  Therefore, FIG. 3 shows the change in the twist angle of the crankshaft according to the engine speed as compared with the case of using the conventional torsional damper and the case of using the torsional damper of the present invention. When the rotational speed is higher than the rotational speed range, the torsional damper according to the present invention applies a damping effect due to the close sliding of the dry bearing 2 and the mass body 3 in addition to the damping action due to the internal friction caused by the shear deformation of the elastic body 4. Therefore, the twist angle of the crankshaft can be greatly reduced as compared with the conventional torsional damper that depends only on the damping force of the elastic body.

  In addition, since the chamfering 3b of the R surface is provided at both ends in the circumferential direction of the outer circumferential surface 3a of each mass body 3, the mass body 3 is "galled" during the sliding process with the inner circumferential surface of the dry bearing 2. Therefore, vibration displacement in the torsional direction of each mass body 3 is not hindered, and wear and damage to the inner peripheral surface of the dry bearing 2 can be suppressed.

  In the above-described embodiment, there is a gap between the outer peripheral surface 3a of each mass body 3 and the inner peripheral surface of the dry bearing 2 in the non-rotating state, and the outer peripheral surface 3a of each mass body 3 at a predetermined rotational speed or more. However, the outer peripheral surface 3a of each mass body 3 and the inner peripheral surface of the dry bearing 2 may be in close contact with each other in the initial state.

  Further, the mass body 3 is not limited to the three-divided shape as shown in the figure, and may be divided into four or more, and can be manufactured by molding in addition to cutting the ring by post-processing.

DESCRIPTION OF SYMBOLS 1 Hub 13 Inner peripheral cylinder part 14 Outer peripheral cylinder part 2 Dry bearing 3 Mass body 3b Chamfer 4 Elastic body 5 Sleeve S Slit

Claims (3)

  A hub attached to the rotary shaft; a bearing concentrically mounted on the hub; a plurality of circumferential mass bodies arranged so as to be in contact with an inner peripheral surface of the bearing; A torsional damper comprising: an elastic body that is connected so as to be movable in a radial direction and a circumferential direction.   A gap exists between the opposing surfaces of each mass body and the bearing in a non-rotating state, and each mass body is brought into close contact with the inner peripheral surface of the bearing by centrifugal force at a predetermined rotational speed or more. Item 2. The torsional damper according to Item 1.   The torsional damper according to claim 1, wherein corner portions at both ends in a circumferential direction of a facing surface of each mass body with respect to the bearing are chamfered.

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