Asymmetric damping automatic tensioner

Abstract

The utility model relates to an asymmetric damping automatic tensioner which comprises a base, a tensioning arm and a tensioning wheel, a sleeve portion is arranged at one end of the tensioning arm, a friction ring is arranged in the base, the sleeve portion is in transmission connection with the friction ring through a ratchet pair, the other end of the tensioning arm is connected with the tensioning wheel, and a torsion spring is arranged between the base and the sleeve portion. And the sleeve part is rotationally matched and connected with the base through a pin shaft. According to the asymmetric damping automatic tensioner, the ratchet pair structure is introduced into the automatic tensioner, and through the structural design of the friction element, the friction damping of the tensioner under the loading working condition can be improved, the friction damping of the tensioner under the unloading working condition can be reduced, and the asymmetry of the friction damping in the tensioner is remarkably improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of automatic tensioner of automobile engine belt tension adjustment and vibration absorption, especially an asymmetric damping automatic tensioner. BACKGROUND

[0002] The automatic tensioner is mainly used in the automobile belt transmission system, or the automobile engine wheel system, or the engine front end accessory drive system (EFEADS for short). The EFEADS is one of the key systems on the engine, which is composed of a driving wheel (crankshaft wheel), a plurality of driven wheels, a tensioner and a transmission belt. The main function is to transmit part of the output power of the engine crankshaft to each accessory of the transmitter, such as fan, water pump, generator and air conditioner compressor, etc., to ensure the normal work of the automobile.

[0003] The automatic tensioner is a key part in the engine front end accessory drive system. Its basic function is to maintain the constant tension of the transmission belt and prevent the belt from slipping. On this basis, it can also provide appropriate damping to attenuate the vibration in the accessory system and suppress the belt shaking to maintain the stability of the system and reduce the vibration and noise.

[0004] In the prior art, the automatic tensioner is mainly composed of a base, a tensioning arm, a tensioning wheel, a spiral spring (also known as a torsion spring or a torsional spring according to the function) and a damping member. The base is fixed on the engine body or a bracket by bolts; the tensioning arm is installed on the base through a mandrel and can rotate reciprocally relative to the base around the mandrel, and a bushing for reducing wear is installed between the tensioning arm and the mandrel; the spiral spring is installed between the base and the tensioning arm for generating a continuous tensioning force; the pulley is installed on the tensioning arm through a bearing, and a dust cover is added on the bearing and fastened with screws. The automatic tensioner also includes a first damping member (generally made of metal) and a second damping member (generally made of plastic) symmetrically arranged on both sides of the mandrel. After the two damping members are matched with the structure of the tensioning arm, they can only move radially along the rotation center of the tensioning arm. When working, the outer wall of the damping member is in contact with the inner wall of the base, and the inner wall of the damping member is in contact with the spiral spring. When the automatic tensioner is loaded or unloaded, the outer diameter of the spiral spring expands or shrinks, and the two damping members independently move radially outward or inward along the mandrel under the action of the increased or decreased expansion force of the spiral spring, so that the force of the damping member pressing against the inner wall of the base increases or decreases, and the friction damping also increases or decreases, realizing the asymmetry of the friction damping.

[0005] In the prior art, the patent with publication number CN108443439A discloses an asymmetric damping tensioner adopting the above structure. When the asymmetric damping tensioner is in a loading or unloading working condition, the end of the coil spring rotates in two opposite directions under stress, the outer diameter of the coil spring expands or shrinks, and the two damping members independently move radially outward or inward under the action of the expanding or shrinking force of the coil spring, so that the force of the damping members pressing against the inner wall of the base increases or decreases, the frictional damping also increases or decreases, and the asymmetricity of the frictional damping is realized. However, the rotation amplitude of the coil spring in the actual working process is very small, which leads to a very small expansion and shrinkage amount of the outer diameter of the coil spring, and further causes a small difference in the frictional damping of the tensioner during loading and unloading, and the asymmetric damping effect is not obvious. SUMMARY

[0006] The utility model discloses to the asymmetric damping tensioner in the background art is the rotation amplitude of the coil spring in the actual working process is very small, which leads to a very small expansion and shrinkage amount of the outer diameter of the coil spring, and further causes a small difference in the frictional damping of the tensioner during loading and unloading, and the asymmetric damping effect is not obvious problem, provide a kind of asymmetric damping automatic tensioner.

[0007] To achieve the above object, the utility model is realized by the following technical scheme:

[0008] An asymmetric damping automatic tensioner, comprising a base, a tensioning arm and a tensioning wheel, one end of the tensioning arm is provided with a sleeve portion, a friction ring is arranged in the base, the sleeve portion and the friction ring are connected by a ratchet pair transmission, the other end of the tensioning arm is connected with the tensioning wheel, a torsion spring is arranged between the base and the sleeve portion, and the sleeve portion and the base are connected by a pin shaft rotation matching.

[0009] In the above scheme, the outer wall of the sleeve portion is provided with a gear, the side wall of the friction ring is provided with a pawl mounting slot, the pawl is arranged in the pawl mounting slot, a blind hole is arranged in the pawl mounting slot, a pawl spring is arranged in the blind hole, the end of the pawl spring abuts against the outer side of the pawl, and the inner side of the pawl is provided with a plurality of teeth, which are engaged with the teeth of the gear. Through this arrangement, the friction ring and the tensioning arm can form one-way torque transmission through the ratchet pair. When the tensioning arm rotates counterclockwise relative to the base, the gear and the pawl remain in engagement, the friction ring is pushed to rotate by the pawl, and the friction force between the friction ring and the base needs to be overcome. The sliding friction force between the friction ring and the base provides frictional damping for the tensioner. When the tensioning arm rotates clockwise relative to the base, the gear pushes the pawl to disengage the engagement therebetween, and the friction ring and the base do not rotate relative to each other, so that the tensioner cannot output frictional damping. In this way, the asymmetric damping of the tensioner is realized.

[0010] In the above scheme, the top plate of the base is provided with a raised upper torsion spring stop on the inner side, the inner bottom surface of the sleeve part is provided with a raised lower torsion spring stop, and the upper end and the lower end of the torsion spring are respectively stopped on the upper torsion spring stop and the lower torsion spring stop. By setting the upper torsion spring stop and the lower torsion spring stop, the upper end and the lower end of the torsion spring can be tightly stopped, so that the torsion between the torsion spring and the base and the tensioning arm can be stably transmitted.

[0011] In the above scheme, the inner side wall of the base is provided with a friction ring assembly part at the lower position, the friction ring is arranged on the friction ring assembly part, a snap spring groove is arranged below the friction ring assembly part, and a snap spring is arranged in the snap spring groove. The inner diameter of the snap spring is smaller than the outer diameter of the friction ring, and the snap spring is used for limiting the axial position of the friction ring. Through this setting, the friction ring can be quickly assembled by the snap spring, and the axial position of the friction ring can be stably limited.

[0012] In the above scheme, the top surface and the outer peripheral surface of the friction ring are in contact with the friction ring assembly part, and the outer surface of the friction ring and the friction ring assembly part are rough surfaces. Through this setting, the friction between the friction ring and the base can be increased, and the friction damping output by the tensioner can be larger.

[0013] In the above scheme, the friction ring is a friction ring with a fracture, and the outer wall of the friction ring is tightly attached to the friction ring assembly part. Through this setting, when installing the friction ring, the friction ring can be first subjected to pressure, so that the fracture of the friction ring is closed, and the radius of the friction ring is also reduced, so that the radius of the friction ring is smaller than the caliber of the open end of the base, facilitating the placement of the friction ring into the base. After the friction ring is placed in the friction ring assembly part, the friction ring is loosened, the pressure is released, the fracture of the friction ring is separated under the elastic force of the material of the friction ring, the outer diameter of the friction ring is increased, the outer wall of the friction ring is tightly attached to the friction ring assembly part, and the assembly of the friction ring is completed.

[0014] In the above scheme, the inner side surface of the top plate of the base is provided with a stand pipe, a bushing is arranged on the base, the top of the bushing is a limiting part, the lower part of the limiting part is a cylindrical pipe, the cylindrical pipe is inserted into the stand pipe, and the pin shaft is fixedly connected with the sleeve part through the bushing. By setting the bushing, the friction between the pin shaft and the base can be reduced, and the pin shaft is protected. By setting the stand pipe, the pin shaft and the bushing can be radially limited, so that the rotation accuracy between the tensioning arm and the base is higher.

[0015] In the above scheme, the middle part of the sleeve part is provided with a boss, a through hole is arranged in the middle part of the boss, and the lower end of the pin shaft is connected with the through hole in an interference fit. By setting the boss, the connection between the pin shaft and the sleeve part can be more stable.

[0016] In the above scheme, the other end of the tensioning arm is provided with a stepped shaft, a bearing is arranged on the stepped shaft, the inner ring of the bearing is fixedly connected with the stepped shaft, and the outer ring of the bearing is fixedly connected with the tensioning wheel. Through the arrangement, the assembly of the tensioning wheel can be facilitated.

[0017] The asymmetric damping automatic tensioner has the positive effects that the asymmetric damping automatic tensioner introduces a ratchet pair structure into the automatic tensioner, and through the structural design of a friction element, the friction damping of the tensioner under a loading working condition can be improved, the friction damping of the tensioner under an unloading working condition can be reduced, and the asymmetry of the friction damping in the tensioner is significantly improved. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 It is a perspective structural schematic view of the asymmetric damping automatic tensioner of the utility model.

[0019] Figure 2 It is a perspective structural schematic view of the asymmetric damping automatic tensioner of the utility model.

[0020] Figure 3 It is a sectional view structure schematic view of A-A in Figure 2 .

[0021] Figure 4 It is a sectional view structure schematic view of B-B in .

[0022] Figure 5 It is a sectional view structure schematic view of C in Figure 4 .

[0023] Figure 6 It is a local enlarged schematic view of C part in Figure 5 .

[0024] Figure 7 It is a structural schematic view of a base.

[0025] Figure 8 It is a structural schematic view of a tensioning arm.

[0026] Figure 9 It is a structural schematic view of a friction ring.

[0027] Figure 10 It is a structural schematic view of a pawl.

[0028] The reference numerals in the figure are as follows: base 1, top plate 11, riser 12, upper torsion spring stop 13, friction ring assembly 14, snap ring groove 15, tension arm 2, sleeve 21, stepped shaft 22, gear 23, boss 24, lower torsion spring stop 25, tension wheel 3, bearing 31, bushing 4, snap ring 5, pin 6, friction ring 7, break 71, pawl mounting groove 72, blind hole 73, pawl 8, notch 81, tooth 82, pawl spring 83, ball 84, torsion spring 9. Detailed Implementation

[0029] The technical solution of this utility model will be clearly and completely described below through embodiments. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0030] like Figure 1 The diagram shows an asymmetric damping automatic tensioner, which includes a base 1, a tensioning arm 2, and a tensioning wheel 3.

[0031] like Figures 2-6 As shown, one end of the tensioning arm 2 is provided with a sleeve part 21, and a friction ring 7 is provided in the base 1. The sleeve part 21 and the friction ring 7 are connected by a ratchet pair. The other end of the tensioning arm 2 is connected to the tensioning wheel 3. A torsion spring 9 is provided between the base 1 and the sleeve part 21. The sleeve part 21 and the base 1 are connected by a pin for rotational engagement.

[0032] like Figure 7 As shown, base 1 can be a cylindrical base, as attached... Figure 1 In the indicated direction, the base 1 includes a top plate 11 and a cylindrical portion disposed below the top plate 11.

[0033] A through hole is provided in the middle of the top plate 11, and a riser 12 is provided in the middle of the inner side of the top plate 11. The riser 12 corresponds to the through hole. A bushing 4 is provided on the top plate 11. The top of the bushing 4 is a limiting part, and the bottom of the limiting part is a cylindrical tube. The cylindrical tube passes through the through hole and is inserted into the riser 12.

[0034] A raised upper torsion spring stop 13 is also provided on the inner side of the top plate 11, and the upper torsion spring stop 13 is located on the radial outer side of the riser 12.

[0035] The lower end of the cylindrical part of the base 1 is open, and a friction ring assembly part 14 is arranged at the lower part of the cylindrical part. The friction ring assembly part 14 can be arranged as a stepped surface. In the internal cavity of the base 1, the inner diameter of the part below the stepped surface is larger than the inner diameter of the part above the stepped surface, and the inner diameter of the part below the stepped surface is adapted to the outer diameter of the friction ring 7. In order to increase the friction between the friction ring 7 and the friction ring assembly part 14, the stepped surface and the part below the stepped surface for assembling the friction ring 7 are arranged as rough surfaces.

[0036] A circlip groove 15 is further arranged inside the cylindrical part of the base 1, below the friction ring assembly part 14.

[0037] In order to facilitate the assembly and fixation of the tensioner, a plurality of fixation ears are connected to the outer wall of the base 1, and assembly holes are arranged on the fixation ears.

[0038] As shown in Figure 8 , the tensioning arm 2 comprises a body at the middle part, a sleeve part 21 and a stepped shaft 22. The sleeve part 21 is arranged at one end of the body, and the stepped shaft 22 is arranged at the other end of the body. The sleeve part 21 is arranged at the left end of the body and at the upper side of the body; and the stepped shaft 22 is arranged at the right end of the body and at the lower side of the body.

[0039] A gear 23 is arranged on the outer wall of the sleeve part 21, and the gear 23 is fixedly connected with the sleeve part 21, preferably integrally formed. A boss 24 is arranged at the middle part of the inner side of the sleeve part 21, and a through hole is arranged at the middle part of the boss 24, which corresponds to the through hole of the base stand pipe 12. A raised lower torsion spring stop 25 is arranged on the inner side bottom surface of the sleeve part 21, outside the boss 24.

[0040] The pin shaft 6 extends through the bushing 4 in the through hole at the middle part of the base 1, the stand pipe 12 in the base 1, and the through hole of the boss 24 at the middle part of the sleeve part 21, and the pin shaft 6 is fixedly connected with the boss 24 of the sleeve part 21, preferably interference fit connection. The top end of the pin shaft 6 is provided with a limiting part, and the diameter of the limiting part is larger than the diameter of the through hole at the top part of the base 1.

[0041] As shown in Figure 9 , the friction ring 7 is an annular member, and the top surface and the outer peripheral surface thereof are rough surfaces. Through this arrangement, the friction between the friction ring 7 and the base 1 can be increased, and the output friction damping of the tensioner can be larger.

[0042] The friction ring 7 can be made of a wear-resistant material with a certain degree of elasticity. For example, it can be made of engineering plastic. A break 71 can be provided on the friction ring 7. When installing the friction ring 7, pressure can be applied to the friction ring 7 first to close the break 71 of the friction ring 7, and the radius of the friction ring 7 will also decrease accordingly, making the radius of the friction ring 7 smaller than the diameter of the opening end of the base 1, so that the friction ring 7 can be placed into the base 1. After the friction ring 7 is placed in the friction ring assembly part 14, the friction ring 7 is released to release the pressure. Under the action of its own material elasticity, the break 71 of the friction ring 7 separates, increasing the outer diameter of the friction ring 7, so that the outer wall of the friction ring 7 fits tightly with the friction ring assembly part 14, thus completing the assembly of the friction ring 7.

[0043] A pawl mounting groove 72 is provided on the inner wall of the friction ring 7. The pawl mounting groove 72 can be designed as an arc. A blind hole 73 is provided in the pawl mounting groove 72, and a pawl spring 83 is provided in the blind hole 73. The pawl spring 83 can be replaced with any part with elastic potential energy, such as a spring or a butterfly spring. In this embodiment, a cylindrical helical spring is selected as the pawl spring 83. The pawl spring 83 is nested in the pawl mounting groove 72. One end of the pawl spring 83 rests on the blind hole 73 of the pawl mounting groove 72, and the other end abuts against the ball 84. The ball 84 presses against the notch 81 on the outside of the pawl 8. The pawl spring 83 is required to have a low spring stiffness.

[0044] The pawl 8 is located within the pawl mounting slot 72, such as... Figure 10 As shown, the outer side of the pawl 8 can be designed as an arc shape that matches the pawl mounting groove 72. A notch 81 is provided on the outer side of the pawl 8, which is opposite to the blind hole 73. Several teeth 82 are provided on the inner side of the pawl 8, for example, two teeth 82 can be designed as shown in the attached figure. When the sleeve part 21 is installed, the height of the gear 23 on the outer side of the sleeve part 21 corresponds to the height of the friction ring 7, and the teeth 82 on the pawl 8 can mesh with the gear 23 on the outer side of the sleeve part 21.

[0045] With this configuration, a unidirectional torque transmission can be formed between the friction ring 7 and the tensioning arm 2 via a ratchet pair. When the tensioning arm 2 rotates counterclockwise relative to the base 1, the gear 23 and the pawl 8 remain engaged. The pawl 8 pushes the friction ring 7 to rotate, which requires overcoming the friction between the friction ring 7 and the base 1. The sliding friction between the friction ring 7 and the base 1 provides frictional damping for the tensioner. When the tensioning arm rotates clockwise relative to the base 1, the gear 23 pushes the pawl 8, disengaging the two. The friction ring 7 and the base 1 will not rotate relative to each other, so the tensioner cannot output frictional damping. In this way, the asymmetric damping of the tensioner is achieved.

[0046] A retaining ring 5 is installed in the retaining ring groove 15 on the base 1. After the friction ring 7 is assembled, the retaining ring 5 can be pressurized to reduce its diameter. Then the retaining ring 5 is installed into the retaining ring groove 15, and the pressure is released to make the retaining ring 5 clamped to the retaining ring groove 15. Because the inner diameter of the retaining ring 5 is smaller than the outer diameter of the friction ring, it can limit the friction ring 7 axially.

[0047] A torsion spring 9 is also provided between the base 1 and the sleeve portion 21. The upper end of the torsion spring 9 abuts against the upper spring stop 13 inside the base 1, and the lower end of the torsion spring 9 abuts against the lower torsion spring stop 25 inside the sleeve portion 21.

[0048] A bearing 31 is provided on the stepped shaft 22 at the right end of the tensioning arm 2. The inner ring of the bearing 31 is fixedly connected to the stepped shaft 22, and the outer ring of the bearing 31 is fixedly connected to the tensioning wheel 3. A threaded hole can be provided on the stepped shaft 22, and the inner ring of the bearing 31 can be fixedly connected to the stepped shaft 22 by bolts, or the inner ring of the bearing 31 can be interference-fitted to the stepped shaft 22. The outer ring of the bearing 31 can be interference-fitted to the tensioning wheel 3. This arrangement facilitates the assembly of the tensioning wheel 3.

[0049] This asymmetric damping automatic tensioner is installed in the belt drive system of an automobile. The drive belt passes over the tensioning pulley, and the asymmetric damping automatic tensioner maintains a constant belt tension to prevent belt slippage. Furthermore, it provides appropriate damping to attenuate vibrations in the accessory system, suppressing belt jitter to maintain system stability and reduce vibration and noise. Moreover, the damping friction provided by this invention has significant asymmetry; when the belt drives the tensioning arm... Figure 2 When rotated clockwise as shown, the pawl on the friction ring can jump on the gear on the outside of the sleeve, without causing the friction ring to rotate. Therefore, the damping force is very small, only the elastic force of the torsion spring. However, when the belt drives the tensioning arm to rotate counterclockwise, the pawl on the friction ring meshes with the gear on the outside of the sleeve, causing the pawl to rotate. The rotation of the pawl causes the friction ring to rotate accordingly. Because the contact surfaces between the friction ring and the friction ring assembly are rough surfaces, there is a large frictional resistance, resulting in a large output damping force. Through the above improvements, the friction damping of the tensioner under loading conditions can be increased, and the friction damping of the tensioner under unloading conditions can be reduced, significantly improving the asymmetry of friction damping in the tensioner.

[0050] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An asymmetrically damped automatic tensioner comprising a base, a tensioning arm, and a tensioner pulley, characterized by: One end of the tension arm is provided with a sleeve part, a friction ring is arranged in the base, the sleeve part and the friction ring are connected through a ratchet pair, the other end of the tension arm is connected with a tension pulley, a torsion spring is arranged between the base and the sleeve part, and the sleeve part and the base are connected through a pin shaft.

2. The asymmetrically damped automatic tensioner of claim 1, wherein: A gear is arranged on the outer wall of the sleeve part, a pawl mounting groove is arranged on the side wall of the friction ring, a pawl is arranged in the pawl mounting groove, a blind hole is arranged in the pawl mounting groove, a pawl spring is arranged in the blind hole, the end of the pawl spring is arranged on the outer side of the pawl, and a plurality of teeth are arranged on the inner side of the pawl and engaged with the gear teeth.

3. The asymmetrical damping automatic tensioner of claim 1, wherein: A protruding upper torsion spring stopper is arranged on the inner side of the top plate of the base, a protruding lower torsion spring stopper is arranged on the inner bottom surface of the sleeve part, and the upper end and the lower end of the torsion spring are respectively arranged on the upper torsion spring stopper and the lower torsion spring stopper.

4. The asymmetrical damping automatic tensioner of claim 1, wherein: A friction ring assembly part is arranged on the lower part of the inner side wall of the base, the friction ring is arranged on the friction ring assembly part, a clamping spring groove is arranged below the friction ring assembly part, a clamping spring is arranged in the clamping spring groove, the inner diameter of the clamping spring is smaller than the outer diameter of the friction ring, and the clamping spring is used for limiting the axial position of the friction ring.

5. The asymmetrical damping automatic tensioner of claim 4, wherein: The top surface and the outer peripheral surface of the friction ring are in contact with the friction ring assembly part, and the outer surface of the friction ring and the friction ring assembly part are rough surfaces.

6. The asymmetrical damping automatic tensioner of claim 4, wherein: The friction ring is a friction ring with a fracture, and the outer wall of the friction ring is tightly attached to the friction ring assembly part.

7. The asymmetrical damping automatic tensioner of claim 1, wherein: A stand pipe is arranged on the inner side of the top plate of the base, a bushing is arranged on the base, the top of the bushing is a limiting part, a cylindrical pipe is arranged below the limiting part, the cylindrical pipe is inserted into the stand pipe, and the pin shaft is fixedly connected with the sleeve part through the bushing.

8. The asymmetrical damping automatic tensioner of claim 7, wherein: A boss is arranged in the middle of the sleeve part, a through hole is arranged in the middle of the boss, and the lower end of the pin shaft is connected with the through hole in an interference fit.

9. The asymmetrical damping automatic tensioner of claim 1, wherein: The other end of the tension arm is provided with a stepped shaft, a bearing is arranged on the stepped shaft, the inner ring of the bearing is fixedly connected with the stepped shaft, and the outer ring of the bearing is fixedly connected with the tension pulley.

Images