JPH01320367A - Automatic tensioner for belt - Google Patents

Abstract

PURPOSE:To automatically adjust the tension of a belt and to absorb the impact and vibration caused on a tensioner by bridging the spring for setting tension on a sliding ring and making the distance between the outer diameter of a pulley and the shaft center of a tensioner bearing variable. CONSTITUTION:A sleeve 9 is fitted by its pressure fitting to the outer diameter of the outer wheel 4 of a tensioner bearing 1. A pair of sliding rings 10, 11 are inserted slidably in the axial direction on the outer diameter of the sleeve 9. The spring 17 for setting tension is bridged by the specified energizing force on the sliding rings 10, 11. The tension of a belt is automatically adjusted by making the distance between the outer diameter of the pulley 18 to which the belt is locked and the shaft center of the tensioner bearing 1 variable. The impact and vibration caused on the tensioner can be absorbed with a simple structure without occupying any fitting space.

Description

[Detailed description of the invention] [Industrial application field]

This invention relates to an auto-tensioner for a power transmission belt used in an engine, such as a belt that adjusts the tension of a toothed timing belt stretched between a crankshaft pulley and a camshaft pulley in an automobile engine. It concerns auto tensioners.

[Prior art]

For example, the auto tensioner device shown in Fig. 15 is known as an auto tensioner device that prevents loosening and adjusts the tension of a toothed timing belt stretched between a crankshaft pulley and a camshaft pulley in an automobile engine. ing. (See Japanese Unexamined Patent Publication No. 58-121344.) In this type of device, a placket 71 that rotatably supports the idler 70 is swingably supported by a fixed object such as an engine body 72. A damper 73 is arranged between the bracket 71 and the fixed object 72. The damper 75 is composed of a cylinder 74, a piston 75, and a piston door 6, and has two liquid chambers 77,78 separated by the piston 75, and a throttle 79 that communicates the two liquid chambers 77,78. A coil spring 81 that applies tension to the belt 80 is mounted on the damper 73, and one of the cylinder 74 and the piston 76 is linked to the fixed object 72, and the other is linked to the bracket 71. Therefore, regardless of the ambient temperature, the belt tension is maintained in a substantially constant state, noise at high temperatures, shirting at low temperatures, etc. do not occur, and the tension is not transmitted from the vibrating body such as the belt or engine to the idler. Since the damper exerts a control effect on the vibrations generated, the idler does not resonate.

[Problem to be solved by the invention]

However, with conventional belt auto-tensioner devices, each part must be installed separately on the engine body, which not only improves work efficiency but also requires time and effort to adjust the belt tension, and installation requires a large amount of space. There was an inherent problem in not being able to do so.

[Means to solve the problem]

above! In order to solve one problem, the present invention includes a tensioner bearing, a sleeve fitted on the outer diameter of the tensioner bearing, and a sloped outer diameter surface fitted on the outer diameter of the sleeve so as to be slidable in the axial direction. It consists of a sliding ring having a slanted outer diameter surface, and a pulley that is fitted on the inclined outer diameter surface of the sliding ring, and a tension setting spring is stretched around the sliding ring with a predetermined biasing force, and the belt is locked. The tension of the belt was automatically adjusted by making the distance between the outer diameter of the pulley and the axis of the tensioner bearing variable.

[Effect]

When the sliding ring slides in the axial direction on the sleeve fitted on the outer diameter of the tensioner bearing due to the tension setting spring force,
The outer diameter of the plug that is fitted onto it changes. This change automatically adjusts the belt tension by stopping at a position that balances the tension caused by the contraction and expansion of the belt relative to the engine. On the other hand, the radial load generated on the tensioner via the belt does not change instantaneously. That is, shocks, high-frequency vibrations, etc. that occur in the tensioner are absorbed by this frictional force.

【Example】

Embodiments of the present invention will be described in detail below with reference to FIGS. 1 to 14. FIG. 1 is a vertical cross-sectional view showing the first embodiment of the present invention, and the second
The figure is a side view of the same as above. The tensioner bearing 1 includes an annular inner member 2 and a double row of balls 3.
The inner member 2 is integrally fixed to the arm 5. The inner member 2 is integrally fixed to the arm 5. This arm 5 includes a hole 6 for attaching a bottle (not shown), which is the center of swing, and a spring locking hole 7 for locking a spring (not shown) for setting the initial belt tension. and a long hole 8 into which a bolt (not shown) for fixing the arm 5 is mounted. By selecting the biasing force of the spring for setting the initial belt tension, the initial belt tension, that is, the position of the tensioner, can be automatically set, and once the fixing bolt is tightened and the arm is fixed, This spring is no longer needed. 9 is a sleeve press-fitted to the outer diameter of the outer ring 4;
It is formed wider than the A pair of sliding rings 10 and 11 are fitted onto the outer diameter of the sleeve 9 so as to be slidable in the axial direction, and 12 is the sliding ring 1.
This is a key to prevent rotation of 0.11. The sliding ring 10.11 has an inclined outer diameter surface 13.14, and the pair forms a substantially V-shaped groove. Further, a plurality of axial through holes 15, 16 are formed in the sliding ring 10° 11 at equidistant positions on the circumference, and a belt tension setting spring 17 is installed inside. The belt tension setting spring 17 is locked by appropriate locking means formed at the openings of the through holes 15 and 16, and elastically connects the pair of sliding rings 10 and 11. 18 is an annular pulley fitted around a pair of sliding rings 10 and 11, and has an annular collar 1 at both ends for guiding the belt.
9.19 are integrally formed. 12 out of 18 pulleys
0.21 is formed in a symmetrical taper shape that spreads from the center to the end surface, and is formed so that when the pair of sliding rings 10.11 abut against each other, the entire surface of the sliding ring 10.11 contacts the inclined outer diameter surface thereof. Now, when the temperature around the engine increases and the distance between the belt pulleys increases due to thermal expansion, increasing the belt tension, a radial load is created on the sliding ring 10.11 via the pulley 18. Part of this load is on the inclined outer diameter surface 13.1
The degree of inclination of the belt tension setting spring 17 is distributed to a force that moves the sliding ring 10.11 apart in the axial direction, and stretches the belt tension setting spring 17 to a position where it balances the spring force of the belt tension setting spring 17. The state is shown in FIG. 3, where a pair of sliding rings 1
The outer diameter of the approximately ■-shaped annular groove formed by the inclined outer diameter surfaces 13 and 14 of 0.11 is reduced, and the inner diameter of the pulley 18 is 20.
．． 21, there will be some contact, and other parts will have gaps. That is, the axis O of the tensioner bearing 1 and the pulley 18
The belt is eccentric from the axis O by e to compensate for the increase in the distance between the belt pulleys due to thermal expansion. Therefore, the belt tension is always maintained constant. Reference numeral 22 denotes an annular locking piece protruding from the outer diameter of the sleeve 9 in order to restrict the position of the pair of tW drive rings 10.11. FIG. 4 is a longitudinal cross-sectional view showing a second embodiment of the present invention, in which the same parts and portions are given the same reference numerals and their explanations will be omitted. The sleeve 23 press-fitted onto the outer diameter of the outer ring 4 of the tensioner bearing l is made of pressed steel plate, and has flanges 24.2 at both ends.
4 is formed by bending. A pair of pressed steel sliding rings 25 and 26 are slidably fitted onto the outer diameter of the sleeve 23, and a pair of belt tension setting springs 27 and 28 are interposed between the sleeve 23 and the sleeve 23. There is. The sliding rings 25, 26 have a substantially U-shaped cross section, and the outer diameters 29, 30 are bent at a predetermined angle. The inner diameter of the pulley 31 is 32.33, which is the outer diameter of 29.30.
It is formed at the same angle as the inclination angle of the belt, and the axis is shifted by the tension of the belt. Here, the belt tension setting spring 27
．． A coil spring 28 is selected to maintain a predetermined belt tension, and is fitted onto the sleeve 23. Therefore,
It is not necessary to restrict displacement of the pair of sliding rings 25, 26 in the circumferential direction by means such as the key 12 as in the first embodiment. Furthermore, since the sliding rings 25 and 26 are made of pressed steel plates, even if there are variations in the inclination angle of their outer diameters 29 and 30, their own elasticity absorbs the angle error and ensures good contact with the pulley 31. The torque transmission efficiency can be prevented from decreasing due to slipping. FIG. 5 is a longitudinal sectional view showing a third embodiment of the invention. The sleeve 34 fixed to the outer diameter of the outer ring 4 of the three-tensile bearing 1 is made of pressed steel and has flanges 35 and 36 at both ends.
is formed by bending. One flange 35 is a flange that locks a belt tension setting spring 37, which will be described later, and the other flange 36 forms a guide wall that guides a pulley 38. Reference numeral 39 denotes a sliding ring made of pressed steel plate, the outer diameter 40' of which is bent at a predetermined angle, and the cylindrical inner diameter 41 capable of sliding on the outer diameter of the sleeve 34. The pulley 38 has a cross-sectional shape that outlines a substantially V-shaped annular groove formed by the inclined outer diameter surface 40 of the sliding ring 39 and the guide wall of the sleeve 34, and its axial center shifts due to changes in belt tension. . The belt tension setting spring 37 is fitted onto the sleeve 34 and a sliding ring 39 fitted into the sleeve 34, and an appropriate coil spring having a spring force corresponding to a predetermined belt tension is selected. As described above, the pulley in Embodiment 1.2.3 of this invention is an annular ring made of metal or rubber. It can be formed from a material such as synthetic resin. Also, when it is made of metal, the rigidity is too high, so it is better to embed rubber or the like in the contact surface with the sliding ring to improve the contact force. The pulley is not limited to the annular ring described above, and various types described below can be considered. 6 to 11 show examples of pulleys applied to the present invention. In FIGS. 6 and 7, the pulley 42 is a circumferentially offset ring whose abutting surfaces 43, 44 each have a stepped shape to prevent axial displacement. The respective abutting surfaces 43 and 44 are arranged in the guide portion 4 according to changes in belt tension.
5. Separate while making sliding contact at 46. Reference numeral 47 denotes an annular groove formed on the outer diameter of the pulley 42, into which a spring is attached. The spring 48 is always biased to reduce the diameter of the pulley 42 in order to prevent the abutment surfaces 43, 44 of the pulley from opening, and is in full contact with the outer diameter of the sliding ring mentioned above. In FIG. 8, the pulley 49 is constructed by stacking a large number of metal blocks 51 on a pair of belts 50 made of thin-walled steel plates, and can be freely contracted and expanded in diameter by sliding a sliding ring (not shown). There is. Further, a buffer material may be interposed between the blocks 51 so as to be able to follow dimensional changes in the pulley 49 in the radial direction. Furthermore, a hole is made in the center of the block 51, and a sixth hole is made in the center of the block 51.
Similar to the embodiments shown in Figures and Figure 7, a spring is installed,
The pulley 49 may be operated to always reduce its diameter to the minimum size. In FIGS. 9 and 10, the pulley 52 includes segments 53 made of rubber, synthetic resin, etc., a diameter reducing spring 54 inserted in the center of the segments and connecting each segment 53, and a diameter-reducing spring 54 interposed between the segments 53, respectively. and a buffer spring 55. In FIG. 11, the pulley 56 is a ring-shaped coil spring 57 wound with a trapezoidal cross section, and can be expanded or contracted due to its own elasticity. FIG. 12 is a vertical sectional view showing a fourth embodiment of the present invention;
FIG. 13 is a side view of the same as above. Identical parts are given the same reference numerals and their explanations will be omitted. A sleeve 58 is press-fitted onto the outer diameter of the outer ring 4 of the tensioner bearing 1, and a pair of sliding rings 59 and 60 are fitted onto the outer diameter so as to be slidable in the axial direction. This sliding ring 59.60 has sloped outer diameter surfaces 61, 62 opposite to those of the first embodiment, between which a spring 63 for setting the belt tension is biased. A pair of pulleys 64, 65 fitted onto the inclined outer diameter surfaces 61, 62 of the sliding ring 59, 60 are formed by natural splitting after heat treatment of the integrally processed ring, and after assembling the Tensilona, the rivet 66 is inserted again. It is fixed in one piece. When a radial load is applied to this pulley 64.65 via the belt, the inclined outer diameter surface 61.6 of the sliding ring 59.60
Due to the degree of inclination of 2, part of the load is transferred to the sliding ring 59.6
0 in the axial direction to compress the belt tension setting spring 63. Then, the sliding ring 59, 60 approaches the position where it balances the spring force of the belt tension setting spring 63, and the first
As shown in the operation diagram of FIG. 4, the pulleys 64 and 65 are eccentric from their original axes, and the distance between the outer diameter of the pulleys 64 and 65 and the axes becomes smaller, thereby compensating for the increase in belt tension. Unlike the pulleys used in reduction gears, the pulleys mentioned above are used to adjust belt tension, which changes extremely slowly in response to changes in ambient temperature, so the amount of change is minute and the tensioner is not forced to do so. No significant load will occur.

【effect】

With the above-described configuration, the present invention has a simple configuration, does not take up much installation space, and does not require time and effort to adjust the tension of the belt. Furthermore, it is possible to always apply appropriate tension to the belt, and it is also possible to absorb not only slow changes due to thermal expansion of an engine, etc., but also vibrations and the like.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view showing a first embodiment of a belt auto-tensioner according to the present invention, FIG. 2 is a side view of the same, and FIG.
4 and 5 are longitudinal sectional views showing second and third embodiments of the belt auto-tensioner according to the present invention, and FIG. 6 is a longitudinal sectional view showing the operation of the same as above. 7 is a cross-sectional view of the same as above, FIG. 8 is a perspective view of the second embodiment of the pulley, and FIG. 9 is a plan view of the third embodiment of the pulley. 10 is a cross-sectional view of the same as above, FIG. 11 is a partial perspective view showing a fourth embodiment of the pulley, and FIG. 12 is a longitudinal sectional view showing a fourth embodiment of the present invention. FIG. 13 is a side view of the same, FIG. 14 is a longitudinal sectional view showing the operation of the same, and FIG. 15 is a front view of a conventional example of the present invention.

Claims (1)

[Claims] A tensioner bearing, a sleeve fitted to the outer diameter of the tensioner bearing, a sliding ring fitted to the outer diameter of the sleeve so as to be slidable in the axial direction and having an inclined outer diameter surface, and the sliding ring. a pulley fitted to the inclined outer diameter surface of the ring, a tension setting spring is stretched around the sliding ring with a predetermined biasing force, and the outer diameter of the pulley to which the belt is engaged, and the tensioner bearing. An automatic belt tensioner characterized in that the tension of the belt is automatically adjusted by making the distance from the axis of the belt variable.