JPH0656548U - Tension setting mechanism for endless drive belt - Google Patents

Abstract

(57) [Abstract] [Purpose] An object of the present invention is to provide a tension setting mechanism for an endless drive belt, which can adjust the deviation of the set tension after the belt is assembled. [Structure] An automatic tensioner 5 has a structure in which a tension setting spring 6 can be swung and displaced in a contacting direction with a belt 3 around a mounting bolt as a swing center. A predetermined tension can be applied to the belt 3 by the tensile force of 6. The tension correction tension pulley 4 can be moved forward and backward in the contact direction with the belt 3 around the lower extension portion 7a of the bracket 7, and is moved forward and backward by the screwing mechanism 10.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a tension setting mechanism installed in an accessory drive belt of an automobile engine, a camshaft drive timing belt, and an endless drive belt for general industry.

[0002]

[Prior art]

 As a conventional endless drive belt and its tension setting mechanism, for example, in a timing belt drive system, as shown in FIG. 7, an endless annular belt is provided between a timing pulley 1 on the crank side and a timing pulley 2 on the camshaft side. The timing belt 3 is stretched, and the tension setting mechanism is configured by the idle pulley 16 arranged on the tensioning side of the timing belt 3 and the auto tensioner 5 arranged on the loosening side of the belt 3. .

The idle pulley 16 is axially supported by a fixed shaft fixed to the engine block and is pressed against the tension side of the timing belt 3. Further, the auto tensioner 5 is attached to the engine block and is pressed against the belt 3 by the tension setting spring 6, so that the tension change of the belt 3 is swiftly suppressed to the minimum limit. It is supposed to do.

As shown in FIGS. 8 and 9, the structure of the auto tensioner 5 is such that a fixed shaft 5a having an outer cylindrical shape is fixed to an engine block via a mounting bolt 17, and an outer peripheral surface of the fixed shaft 5a is fixed. The plain bearing 5b is fitted. An inner ring 5c (fixed ring) of the rolling bearing 5f is fitted on the outer peripheral surface of the slide bearing 5b via an eccentric collar 5g in a state where the center is eccentric from the center of the fixed shaft 5a by a predetermined amount. The inner ring 5c and the eccentric collar 5g are fitted and fixed in a press-fitted state. The outer ring 5e is rotatably mounted on the inner ring 5c of the rolling bearing 5f via a ball bearing 5d as a rolling element, and the outer peripheral surface of the outer ring 5e is in contact with the belt 3.

A bracket 18 extending radially upward is fixed to the eccentric collar 5g, and an engaging portion 18a is formed at the tip of the bracket 18. Then, the tension setting spring 6 is arranged between the engaging portion 18a and the spring engaging pin 19 provided on the engine block, and the tensile force of the spring 6 causes the outer ring 5e of the rolling bearing 5f to move. It is urged toward the timing belt 3.

As a result, the autotensioner 5 applies a predetermined initial tension to the belt 3, and the rolling bearing 5f swings in the contact direction with the belt 3 following the tension fluctuation of the belt 3. The tension change of the belt 3 is promptly suppressed to the minimum limit. The tension of the belt 3 is set in consideration of the geometrical force balance such as the distance between the spring engaging pin 19 provided on the engine block and the engaging portion 18a of the bracket 18 and the winding angle of the belt 3 around the outer ring 5e. The position of the spring 6 is determined by calculation.

[0007]

[Problems to be solved by the device]

 However, in the conventional belt tension setting with the above-mentioned configuration, even if the elongation of the spring 6 is designed so as to have the optimum tension in consideration of the desk, in reality, the dimensional tolerances of the respective parts are not uniform. Therefore, the actual set tension is likely to vary considerably, and the tension of the belt 3 is likely to be excessive or excessive.

The main variations in the above dimensional tolerance include variations in belt length and variations between pulley spans on which the belt 3 is stretched due to the engine block being composed of a plurality of members. To be It should be noted that if the tension is excessively large, it may contribute to a decrease in the service life of the belt 3 or noise, and if the tension is excessively small, it may cause noise, fluttering of the belt 3, or skipping. Become.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a tension setting mechanism for an endless drive belt that can adjust the deviation of the set tension after the belt is assembled. .

[0010]

[Means for Solving the Problems]

 In order to achieve the above object, the tension setting mechanism for an endless drive belt of the present invention is installed in a state in which it is installed in a state where it is pressed against the loose side of the belt and in a state where it is pressed against the tension side of the belt. It is characterized in that it is composed of a tension-compensating tension pulley capable of adjusting forward and backward in the contact direction with the belt.

[0011]

[Action]

 Deviation of the tension set by the auto tensioner after the belt is assembled is corrected by slightly moving the belt tension by advancing and retracting the tension compensation tension pulley. That is, when the tension of the belt by the auto tensioner is below the set value, the tension correction tension pulley is advanced to the belt side to increase the tension of the belt, and the tension of the belt by the auto tensioner is over the set value. In this case, the tension correction tension pulley is retracted from the belt side to reduce the belt tension and optimize the set tension of the belt.

[0012]

【Example】

 An embodiment of the present invention will be described with reference to the drawings. In this embodiment, the tension setting mechanism for the timing belt for driving the camshaft is described as an example, but it is of course applicable to the tension setting mechanism for the accessory belt of the engine for automobiles and the endless belt for general industry. Is.

First, the structure will be described. As shown in FIG. 1, an endless annular timing belt 3 is stretched between a timing pulley 1 on the crank side and a timing pulley 2 on the camshaft, and the timing thereof is set. A tension setting mechanism is configured by a tension correction tension pulley 4 provided on the tension side 3 a of the belt 3 and an auto tensioner 5 provided on the slack side 3 b of the belt 3.

The autotensioner 5 has a structure similar to that of the conventional example, and has a structure in which the tension setting spring 6 can swing and displace in the abutting direction with the belt 3 around the mounting bolt as the swing center. A predetermined tension can be applied to the belt 3 by the tension force of the tension setting spring 6 when the belt 3 is assembled. At that time, the elongation of the tension setting spring 6 and the set tension are calculated and set from the dimensions of the respective parts and the balance of the geometrical force.

Further, as shown in FIG. 2, the tension correction tension pulley 4 has a structure in which a bracket 7 extending substantially vertically is fixed to the lower end portion side of the bearing carrier 4 a, and the bracket 7 extends downward. The tip of the portion 7a is pivotally attached to the engine block by a pin 8. Further, the bearing carrier 4a can be fixed to the engine block by inserting a mounting bolt 9 into a bolt hole 4b provided at the center thereof and tightening the mounting bolt 9. The bolt hole 4b extends in the left-right direction to form an arc-shaped elongated hole 4b. When the mounting bolt 9 is loosened, the bearing 7a is swung by the swinging motion of the bracket 7. The mounting bolt 9 relatively moves along the arc-shaped long hole 4b.

A rolling bearing 4c is press-fitted onto the outer peripheral surface of the bearing carrier 4a, and the outer ring of the rolling bearing 4c is pressed against the belt 3. A plate-shaped rod abutting portion 7c is formed on the upper extending portion 7b of the bracket 7 so that the surface thereof faces the right side in the drawing in the right direction. Then, the tip end portion is brought into contact with the contact surface 7d of the rod contact portion 7c, and the rod 10a is arranged.

A male screw is threaded on the outer peripheral surface of the rod 10a, and the axis of the rod 10a is arranged substantially orthogonal to the contact surface. The rod 10a is advanced and retracted in the axial direction, whereby the tip portion 10d of the rod 10a is moved. Moves the bearing carrier 4a and the rolling bearing 4c through the rod contact portion 7c in the contact direction with the belt 3 against the tension of the belt 3. The tip portion 10a is rounded so that the manner of permanent installation during advancing and retracting is as constant as possible.

A nut 10b is screwed onto the rod 10a, and the nut 10b is fixed to the engine block 11 via an L-shaped rod supporting member 10c as shown in FIG. The rod 10a forms a screwing mechanism 10 that can be moved back and forth only in the axial direction by axially rotating. In the timing belt drive system equipped with such a tension setting mechanism, when the belt 3 is assembled, the position of the mounting bolt 9 of the tension correction tension pulley 4 is adjusted so that it is located at the center of the elongated hole 4b of the bearing carrier 4a. 10a is moved back and forth to adjust, and the mounting bolt 9 is once tightened.

As a result, the tension correction tension pulley 4 is pressed against the belt 3 to apply a predetermined tension to the belt 3, and the reaction force from the belt 3 is applied to the tightened bolt 9 and the rod support member 10c. It has been received by. Further, the auto tensioner 5 is also installed at the position calculated in advance so as to apply a desired tension to the belt 3.

At this time, in reality, due to variations in the dimensional tolerances of the respective parts, the amount of elongation of the tension setting spring 6 and the belt tension deviate from the intended set values, and the tension is reduced. It may be over or under the target value. In this case, after loosening the mounting bolt 9 once, the rod 10a is axially rotated and moved back and forth toward the belt 3 so that the tension correction tension pulley 4 is centered on the lower end portion of the bracket 7. It is swung by a predetermined amount, that is, it is moved back and forth in the contact direction with the belt 3.

As a result, the tension applied to the belt 3 by the pulley 4 changes slightly, and the expansion of the tension setting spring 6 and the deviation of the tension of the belt 3 from the initial setting are corrected. For example, when the elongation of the tension setting spring 6 is less than or equal to the set value, the tension of the belt 3 is increased by advancing the tension correction tension pulley 4 toward the belt 3 side. Is greater than the set value, the tension correction tension pulley 4 is retracted from the belt 3 side to reduce the tension of the belt 3, and the amount of expansion of the spring 6 is adjusted to a target value. adjust.

When the set tension is corrected, the mounting bolt 9 is tightened again to fix the tension correction tension pulley 4 to the engine block. In the above embodiment, the tension correction tension pulley 4 is moved forward and backward by the screwing mechanism 10. However, as shown in FIG. 4, instead of the screwing mechanism 10 and the upper extension portion 7b of the bracket, tension A hole or projection 12 for tool engagement such as a tool is provided on the upper surface of the bearing carrier 4a of the correction tension pulley 4, and the tool is attached to the hole or projection 12 It is also possible that an operator adjusts the tension correction tension pulley 4 forwards and backwards toward the contact portion 7c with the belt 3 via a tool.

The operation and effect are similar to those of the above embodiment. Further, the auto tensioner 5 is not limited to the one having the structure of the above embodiment, and may be, for example, an actuator type auto tensioner 5 having a large damper capacity as shown in FIG. In this auto tensioner 5, a bracket 13 fixed to the rotary shaft of a pulley 12 extends downward, and a lower end portion of the bracket 13 is fixed to an engine block by a rotation bolt via a mounting bolt 14 so that the bracket 13 is By the oil 15c filled in the spring 15a and the cylinder 15b of the actuator 15, the pulley 12 is urged to rotate in the direction of contacting the belt 3 and has a vibration damping function. It is configured to be swingably pressed against.

In order to set the tension in this case, first, as shown in FIG. 6A, the pulley 12 and the actuator 15 of the auto tensioner 5 are set so as to be in the most slack side of the belt, and the tension correction is performed. The tension pulley 4 is installed by advancing it so that the tension on the belt 3 is the strongest, that is, the bolt 9 is on the right end side of the elongated hole 4b. From this state, the tension correction tension pulley 4 is retracted until the tension of the belt 3 reaches the target tension, and when the tension of the belt 3 reaches the target setting state, the mounting bolt 9 is tightened to tighten the tension. Fix the tension pulley 4 for correction to the engine block.

[0025]

[Effect of device]

 As described above, the tension setting mechanism for the endless drive belt of the present invention is used for tension correction even if the tension set on the belt by the auto tensioner, which is calculated and set in advance, varies due to the tolerance of the parts. It is possible to set the belt tension to an appropriate value by correcting it to the target value simply by adjusting the tension pulley.

Therefore, it is possible to suppress the flapping of the belt, the noise, and the like, which have conventionally been caused by the deviation of the set tension.

[Brief description of drawings]

FIG. 1 is a diagram showing an endless drive belt and a tension setting mechanism according to an embodiment of the present invention.

FIG. 2 is a front view showing a tension correction tension pulley according to an embodiment of the present invention.

FIG. 3 is a side view of the screwing mechanism according to the embodiment of the present invention.

FIG. 4 is a front view showing a tension correction tension pulley according to a second embodiment of the present invention.

FIG. 5 is a view showing an automatic tensioner of a third embodiment according to the present invention.

FIG. 6 is a view showing adjustment of tension setting of the third embodiment according to the present invention.

FIG. 7 is a diagram showing a conventional endless drive belt and a tension setting mechanism.

FIG. 8 is a side view showing a conventional auto tensioner.

FIG. 9 is an AA cross-sectional view showing a conventional auto tensioner.

[Explanation of symbols]

 3 Timing belt 4 Tension correction tension pulley 5 Auto tensioner

Claims (1)

[Scope of utility model registration request] 1. A mechanism for setting a predetermined tension on a belt in a power transmission structure using an endless drive belt, wherein an automatic tensioner installed while being pressed against a loose side of the belt and a tension side of the belt. A tension setting mechanism for an endless drive belt, which comprises a tension correction tension pulley that is installed in a pressed state and that can be adjusted forward and backward in the contact direction with the belt.