JPH068849U - Tensioner - Google Patents

Abstract

(57) [Abstract] [Purpose] To reduce the number of parts, simplify parts management and assembly work, and improve accuracy. [Structure] A substrate 22, a swing shaft 23, and a locking pin 24 are integrally formed by a precision casting method such as a lost wax method. The tension pulley 12 rotatably supported on the tip end of the swing shaft 23 is pressed against the belt 20 by the elasticity of the tension spring 19 whose one end is locked by the locking pin 24.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The tensioner according to the present invention is used, for example, to apply proper tension to a belt for driving an auxiliary machine of an automobile engine or a timing belt for driving a camshaft.

[0002]

[Prior art]

 In the case of automobile engines, auxiliary components such as generators, compressors, cooling water and pumps for power steering are driven by the crankshaft of the engine, so they are fixed to the drive pulley fixed to the crankshaft and the input shaft of the auxiliary machinery. Auxiliary machine drive devices in which a belt is stretched between the driven pulley and the driven pulley have been widely used conventionally, as described in, for example, US Pat. No. 4,721,495. Further, a tensioner that presses a tension pulley on a part of the belt by an elastic force of a spring to give an appropriate tension to the belt has been widely used.

As such a tensioner, one having a structure as shown in FIGS. 5 to 6 is conventionally known. The substrate 1, which is the rocking member, is formed by punching out a thick steel plate. A circular hole 2 and an arc-shaped elongated hole 3 centered on the circular hole 2 are formed in the middle of the substrate 1. On the front surface 4a of the cylinder block 4 to which the tensioner is attached, a pivot 5 is provided so as to project. The substrate 1 has a front surface 4a of the cylinder block 4 with its inner side surface (left side surface in FIG. 5) facing the front surface 4a. 4a is swingably supported. A bolt 6 inserted through the long hole 3 from the outer side (right side in FIG. 5) side is screwed into a screw hole 7 formed in the front surface 4a.

A base end of a swing shaft 8, which is a displacement member and is parallel to the pivot 5, is coupled and fixed to the outer surface 1a of one end of the substrate 1 (lower left end in FIG. 6). ing. That is, with the cylindrical portion 10 formed at the base end portion of the swing shaft 8 inserted into the mounting hole 9 formed at one end portion of the substrate 1, the opening portion of the cylindrical portion 10 is caulked outward in the diametrical direction. The swing shaft 8 is connected to the base plate 1 by expanding it.

A tension pulley 12 is rotatably supported by a rolling bearing 11 at the tip of the swing shaft 8 fixedly coupled to the substrate 1 in this manner. That is, a plurality of balls 16 and 16 are mounted between the inner ring raceway 14 on the outer circumferential surface of the inner ring 13 fitted and fixed to the tip end portion and the outer ring raceway 15 formed on the inner circumferential surface of the tension pulley 12, and the balls 16 and 16 are attached to each other. The tension pulley 12 can freely rotate around the rocking shaft 8.

Further, a base end portion of a locking pin 18 is fitted and fixed in a circular hole 17 formed at the other end portion (upper end portion in FIG. 6) of the substrate 1, and a tip end of the locking pin 18 is fixed. One end of the tension spring 19 is locked to the portion. The other end of the tension spring 19 is locked to another locking pin (not shown) fixed to the front surface 4a. Therefore, the substrate 1 is given a counterclockwise elastic force in FIG.

When tension is applied to the belt, the bolt 6 is loosened, and the tension pulley 12 is pressed by the elasticity of the tension spring 19 toward the belt 20 stretched over the tension pulley 12. As a result, the belt 20 is given an appropriate tension according to the elasticity of the tension spring 19. Therefore, the bolt 6 is tightened, the head 1a of the bolt 6 holds the substrate 1 on the front surface 4a of the cylinder block 4, and the substrate 1 is fixed.

[0008]

[Problems to be solved by the device]

 The present invention is intended to simplify parts management and assembly work by reducing the number of components of the tensioner, reduce costs, and improve durability.

For example, in the case of the conventional tensioner as shown in FIGS. 5 to 6, there are the following points to be improved.

Since the board 1, the swing shaft 8, and the locking pin 18 which are separately manufactured are combined later, parts management and assembly work become complicated, and the circular holes 2, 17 and the mounting hole 9 are formed in the board 1. In addition to the need for work, the production cost increases.

When the swing shaft 8 is lightened to reduce the weight, a dedicated process is required, which also causes an increase in manufacturing cost.

Since the separately manufactured parts are combined later, the dimensional error of each part is likely to be accumulated, and when the total dimensional error becomes large as a result of the integration, the tension applied to the belt 20 is increased. This causes problems such as deviation from the design value.

It is difficult to strictly control the squareness of the swing shaft 8 with respect to the substrate 1, and when the swing shaft 8 is tilted with respect to the substrate 1, the belt 20 stretched around the tension pulley 12 moves in the width direction. Problems such as slippage occur.

The swing shaft 8 and the locking shaft 8 are engaged with the outer surface 1 a of the substrate 1 and the outer peripheral surface 8 a of the swing shaft 8, and the continuous part of the outer surface 1 a and the outer peripheral surface of the locking pin 18. Stress is likely to be concentrated on the basis of the force in the bending direction applied to the pin 18, and it is conceivable that a crack or the like may be generated in the continuous portion with long-term use. In order to prevent stress concentration in order to improve the durability of the tensioner, it is sufficient to make each of the above continuous parts a curved surface having an arcuate cross section, but to separate members 1, 8 and 18 made separately. In the case of the conventional structure in which they are connected, it is difficult to make each of the above continuous parts into a curved surface.

The tensioner of the present invention has been devised in view of the above circumstances.

[0016]

[Means for Solving the Problems]

 The tensioner of the present invention, like the conventional tensioner described above, has a cylindrical outer periphery having a swinging member that is swingably supported by a fixed portion by a pivot and a center that is parallel to the pivot and eccentric to the pivot. A displacement member having a surface and coupled and fixed to a part of the swing member, a tension pulley rotatably supported on the outer peripheral surface via a bearing, and the fixed portion and the swing member. And a spring having elasticity that presses the tension pulley toward the belt to which the tension is applied.

In particular, the tensioner of the present invention is characterized in that at least the swing member and the displacement member are integrally formed by precision casting. Further, if necessary, a spring engaging member or the like fixed to the swinging member or the displacing member can be integrally formed.

[0018]

[Action]

 The tensioner of the present invention configured as described above has the same action as in the case of the conventional tensioner described above when the proper tension is applied to the belt that is stretched around the tension pulley based on the elasticity of the spring. Is.

Particularly, in the case of the tensioner of the present invention, the following effects (1), which cannot be obtained by the conventional structure, can be obtained by integrally forming the swing member and the displacement member.

The parts management and assembly work are simplified, and the manufacturing cost can be reduced.

Since the rocking member and the displacement member can be cast at the same time as the lightening is performed to reduce the weight, the manufacturing cost can be reduced.

Since the oscillating member and the displacing member are integrally molded, the dimensional error of each component is not accumulated, and the tension applied to the belt is not deviated from the design value.

It becomes easy to strictly control the parallelism between the pivot and the center of rotation of the tension pulley, and the belt wound around the tension pulley will not be displaced in the width direction.

Since the continuous portion of the oscillating member and the displacing member can be easily machined to have a curved surface with an arcuate section, stress is prevented from concentrating on the continuous portion, and cracks or the like are generated in the continuous portion. It can be prevented from occurring and the durability of the tensioner can be improved.

[0025]

【Example】

 1 and 2 show a first embodiment of the present invention. The tensioner shown in the present embodiment is similar to the conventional tensioner described above in that both ends of the outer surface 22a of the base plate 22, which is pivotally supported by the pivot shaft 5 on the front surface 4a of the cylinder block 4, are attached to the pivot shaft. 23 and a locking pin 24 are provided. A tension pulley 12 is rotatably supported on the tip of the swing shaft 23 via a rolling bearing 11, and one end of a tension bar 19 is locked to a locking pin 24. A circular hole 2 for inserting the pivot 5 and an elongated hole 3 for inserting the bolt 6 are formed in an intermediate portion of the substrate 22.

Particularly, in the case of the tensioner of the present invention, the substrate 22, the swing shaft 23, and the locking pin 24 are made of a low carbon material such as S15C to S45C that contains only about 0.1 to 0.5% by weight of carbon. It is made as a single body by casting casting steel by precision casting methods such as the lost wax method. The swing shaft 23 is formed in a circular tube shape for the purpose of lightening the weight to reduce the weight. However, in the work of forming the swing shaft 23 in the circular tube shape as described above, the circular hole 2 and the long hole are formed. The work for forming 3 is also performed at the same time when the substrate 22, the swing shaft 23, and the locking pin 24 are cast.

In addition, the outer surface 22a of the base plate 22 and the outer peripheral surface 23a of the swing shaft 23 are continuous with each other, and the outer surface 22a and the outer peripheral surface 24a of the locking pin 24 are continuous with each other. As the quarter-circular curved surfaces 25 and 26, the outer surface 22a and the outer peripheral surfaces 23a and 24a are smoothly continuous.

The other construction and the operation itself when applying an appropriate tension to the belt 20 wound around the tension pulley 12 are the same as in the case of the conventional tensioner described above.

Particularly, in the case of the tensioner of the present invention, since the base plate 22, the swing shaft 23, and the locking pin 24 are integrally formed by a precision casting method, they are separately manufactured as in the conventional structure. It is possible to prevent troubles such as when combining different parts later and the occurrence of defects such as dimensional errors.

Further, by forming the continuous parts into curved surfaces 25 and 26 having an arcuate cross section, stress is concentrated on the continuous parts based on the force in the bending direction applied to the swing shaft 23 and the locking pin 24. Can be prevented. As a result, defects such as cracks are unlikely to occur in each continuous portion even after long-term use. The larger the radius of curvature of each of the curved surfaces 25 and 26 is, the more effective the prevention of cracks is. However, in the case of an automobile tensioner, if it is 0.2 mm or more, practically sufficient durability can be obtained.

Next, FIGS. 3 to 4 show a second embodiment of the present invention. In the case of the present embodiment, a so-called auto tensioner that applies a constant tension to the belt regardless of changes over time such as elongation of the belt over a long period of time is targeted.

A cylindrical shaft 27, which is a swing member, is rotatably supported on the front surface 4 a of the cylinder block 4 by a bolt 28, which is a pivot shaft. A disc 29, which is a displacement member, is formed integrally with the cylindrical portion 27 on the outer peripheral surface of the distal end portion of the cylindrical shaft 27 by a precision casting method such as the lost wax method. A continuous portion of the inner surface 29a of the disk 29 and the outer peripheral surface 27a of the cylindrical shaft 27 is smoothly continuous by a curved surface 31 having a quarter arc shape in cross section.

The center a of the cylindrical shaft 27 and the center b of the disc 29 are parallel to each other but eccentric to each other. Further, the outer surface 29b of the disc 29 is recessed in a crescent shape so as to be lightened to reduce the weight. The tension pulley 12 is rotatably supported on the outer peripheral surface of the disc 29 through a rolling bearing 11 having an inner ring 13 and a plurality of balls 16, 16.

Further, a locking pin 32 is formed on the outer peripheral surface of the intermediate portion of the cylindrical shaft 27 integrally with the cylindrical shaft 27 during casting. Then, one end of a torsion coil spring 33 provided around the base of the cylindrical shaft 27 is locked to the locking pin 32, and the other end of the torsion coil spring 33 is attached to another front surface 4a. By engaging with the stop pin 34, the cylindrical shaft 27 is provided with elastic force in the rotation direction around the bolt 28. The outer peripheral surface of the locking pin 32 and the outer peripheral surface 27a of the cylindrical shaft 27 are smoothly continuous by a curved surface 35 having a quarter arc shape in cross section.

In the case of the present embodiment, the tension pulley 12 is constantly elastically pressed toward the belt based on the elasticity of the torsion coil spring 33. Therefore, regardless of changes over time such as stretching of the belt, the belt is always provided with appropriate elasticity. Other functions are the same as in the case of the first embodiment described above.

[0036]

[Effect of device]

 Since the present invention is constructed and operates as described above, a compact and lightweight tensioner having excellent durability can be manufactured at a low cost.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a view seen from the right side of FIG.

FIG. 3 is a sectional view showing a second embodiment of the present invention.

FIG. 4 is a diagram viewed from the right side of FIG.

FIG. 5 is a sectional view showing an example of a conventional structure.

FIG. 6 is a diagram viewed from the right side of FIG.

[Explanation of symbols]

 1 substrate 1a outer side surface 2 circular hole 3 long hole 4 cylinder block 4a front surface 5 pivot 6 bolt 6a head 7 screw hole 8 rocking shaft 8a outer peripheral surface 9 mounting hole 10 cylindrical portion 11 rolling bearing 12 tension pulley 13 inner ring 14 inner ring raceway 15 outer ring raceway 16 ball 17 circular hole 18 locking pin 19 tension spring 20 belt 21 lightening 22 substrate 22a outer side surface 23 swing shaft 23a outer peripheral surface 24 locking pin 24a outer peripheral surface 25, 26 curved surface 27 cylindrical shaft 27a outer peripheral surface 28 Bolt 29 Disc 29a Inner surface 29b Outer surface 30 Lightening 31 Curved surface 32 Locking pin 33 Torsional coil spring 34 Locking pin 35 Curved surface

Claims (1)

[Scope of utility model registration request] 1. A swing member, which is swingably supported by a fixed portion by a pivot, and a cylindrical outer peripheral surface having a center parallel to the pivot and eccentric to the pivot. A displacement member fixedly coupled to a part, a tension pulley rotatably supported on the outer peripheral surface via a bearing, and a fixed pulley and a swing member are provided between the fixed portion and the swinging member to apply tension to the tension pulley. A tensioner provided with a spring having elasticity to press against a belt to be applied, characterized in that at least the swing member and the displacement member are integrally formed by precision casting.