JPH02240434A - Belt tension automatic adjuster device - Google Patents

Abstract

PURPOSE:To smoothly adjust tension of a belt by adapting a rod point end part of an automatic tensioner to an adjusting stopper forming its adapted surface in an involute curve with the swivel center of a tension pulley serving as the original point. CONSTITUTION:A tension pulley 8 is pivotally mounted to a pulley shaft 11 of a swivel arm 10 swiveled with a shaft 9 serving as the center of rotation, and a rod 13a of an automatic tensioner 13 is adapted to an adapted surface 12a of an adapting stopper 12 of the swivel arm 10. The adapted surface 12a is formed in an involute curve based on a base circle with the swivel center 9 of the tension pulley 8 serving as the original point and with a distance between the center 9 and an axial center line of the rod 13a of the automatic tensioner 13 serving as the radius. Accordingly, tension of a belt can be smoothly adjusted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an automatic belt tension adjustment device that controls the tension of a chain or belt of an automobile engine valve drive system and auxiliary machinery drive system to a constant level. More specifically, the present invention relates to an autotensioner that can improve the reliability and durability of an autotensioner that maintains a constant tension by absorbing elongation of a chain or belt length due to changes over time or temperature changes.

[Conventional technology]

In general, a timing belt is wound around a pulley attached to the crankshaft in the valve drive system that drives the camshaft of an automobile engine and the auxiliary drive system that drives water pumps, generators, air conditioner compressors, etc. As the number of auxiliary parts driven by a single timing belt has increased, and the belt layout has become more complex,
It has become strongly desired to maintain belt tension approximately constant.

In addition, when a belt is used for a long time, it loses its initial tension due to aging and temperature changes, as well as due to elongation and wear of the belt, causing belt flapping and cam timing to be out of order. There are problems such as generation of noise from the parts being driven by the belt and damage to the durability of the belt itself.

Conventionally, in order to keep the tension of the belt constant,
A tensioner installed with a screw type or spring type tensioner, or Utility Model No. 62-68067
As shown in the above publication, many prior art techniques are known in which an autotensioner applies a constant pressing force to a belt to press it.

[Problem that the invention seeks to solve]

However, in conventional examples including the above-mentioned prior art, as shown in FIG. 105
Even if the abutment surface is formed on a plane of , or is set to abut on a perpendicular plane at the initial stage, as the belt 106 stretches, the abutment surface of the adjustment stopper 105 will be on the auto tensioner 101. The rod 102 is held down by the tip of the rod 102 and inclined, and the tip of the rod 102 and the adjustment stopper 105 make partial contact at point A. For this reason rod 10
2, the resultant force F1 of the axial pressing forces F and 1 of the rod 102 acts on the autotensioner 101, causing the autotensioner 101 to become distorted, making it impossible to make smooth adjustments, and also causing wear and tear, resulting in malfunctions and other unreliable conditions. There are problems with durability and durability.

Also, due to changes over time, the heald 106 may stretch;7;'
, 1 When the adjustment stopper is swung by 105 degrees α, the adjustment stroke δ of the rod tip 102 becomes large, causing problems such as poor adjustment.

The present invention has been proposed to address the above-mentioned problems, and includes an adjustment stopper that the rod tip of an auto-tensioner comes into contact with, regardless of the swing angle of the tension pulley that swings in accordance with the stretch of the belt. The contact surface between the auto tensioner rod tip and the tension pulley adjustment stopper is always perpendicular because the contact surface is formed by an involute curve based on the base circle with the origin at the swing center of the tensioner pulley. By holding the tensioner in this condition, bending force is not applied to the rod of the autotensioner, and it also improves the belt tension adjustment function regardless of the adjustment stroke of the rod, and improves reliability and durability. It is an object of the present invention to provide an automatic belt tension adjustment device as described above.

[Means to solve the problem]

In order to achieve this object, the belt tension automatic adjustment device according to the present invention is designed to adjust the tension of the timing belt on the slack side of the timing belt wound around the valve drive system of an automobile engine and the drive system of auxiliary machinery.
a swinging arm swingably supported by a shaft disposed on the engine side; a tension pulley rotatably supported by a pulley shaft of the swinging arm; In a device equipped with an automatic belt tension adjustment device consisting of an auto tensioner that presses the tension pulley against the timing belt side by swinging, the rod tip of the auto tensioner comes into contact and rotates the swing arm. The contact surface of the stopper is formed by an involute curve based on a basic circle whose origin is the swing center of the tension pulley and whose radius is the distance between the swing center of the tension pulley and the center line of the rod of the auto tensioner. It is characterized by:

[For production]

In such a configuration, the contact surface of the adjustment stopper that the auto tensioner's rod end comes into contact with is formed by an involute curve based on a base circle with the origin at the swing center of the tension pulley, thereby controlling the elongation of the belt. Regardless of the swing angle of the tension pulley, which swings in accordance with the tension, the axial center of the rod tip of the auto-tensioner is always in perpendicular contact with the contact surface of the tension pulley with the adjustment stopper.

Therefore, the tension of the belt can be adjusted smoothly without any bending force acting on the rod of the autotensioner.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a schematic configuration diagram showing an automatic adjustment device for a timing belt in a horizontally opposed engine according to an embodiment of the present invention, and FIG. 2 is an enlarged view showing the main parts of FIG.

In the figure, to explain the outline of the timing belt drive system, numeral 1 is a crank pulley, 2a, 2b, 3a, and 3b are cam pulleys that drive the left and right valve mechanisms, respectively, and 4 is a water pump drive pulley.
An idler pulley 6a is placed between these.

A timing belt 7 is wound around the timing belt 11ib and Be. A tension pulley 8 for adjusting tension is installed on the slack side of the timing belt 7. As shown in FIG. 3, the tension pulley 8 is rotatably supported by a pulley shaft 1 of a swing arm 10 which is swingably supported by a shaft 9 disposed on the side of the engine body 5. 7 is pressed.

Further, at a predetermined position of the swing arm 10, as shown in FIGS. 2 and 3, a tension pulley 8 is attached to a shaft 9.
An adjustment stopper 12 is fixedly installed in the direction in which tension is applied by swinging around the timing belt 7 and pressing the timing belt 7, and an adjustment stopper 12 is fixedly installed on the engine body 5 side in the direction in which the adjustment stopper 12 is pressed. auto tensioner 13
is installed.

That is, the telescopic rod 13a provided in the auto-tensioner 13 is configured such that the axial center line of the rod 13a always contacts the contact surface 12a of the adjustment stopper I2 in the vertical direction.

Here, as shown in FIG. 4, the contact surface 12a of the adjustment stopper 12 that swings the tension pulley 8 is connected to the swing center Po of the tension pulley 8 with the swing center Po of the tension pulley 8 as the origin. It is formed by an involute curve from the base end 'So on the base circle S with the radius being the distance a from the axial center line A-A of the rod 13a.

That is, when the tangent at the point of the base end So of the base circle S is the perpendicular line of the X axis connecting the swing center PO of the X axis 9 and the base end So, the contact of the adjustment stopper 12 is The point a□ where the contact surface 12a contacts the rod 13a is X - a (cos θ + θ sin θ) '1' - a
(slnθ-cosθ) is formed along the involute curve ■.

The rod 13a of the autotensioner 13 that presses the abutment surface 12a of the adjustment stopper 12 acts perpendicularly to the abutment surface 12a of the adjustment stopper 12 at point a□.

In the embodiment configured as described above, when the timing belt 7 stretches over time and the rod 13a of the auto tensioner 13 presses the contact surface 12a of the adjustment stopper 12, the swing arm IO moves to the tension pulley 8.
The rotation center R0 of the tension pulley 8 moves to R1 by rotating α around the swing center Po, and at the same time, the tension pulley 8 moves to the tension pulley 81 position and the timing belt 7 moves to the position 71. to apply the specified tension.

At this time, the contact point a□ of the contact surface 12a of the adjustment stopper 12 integrated with the swing arm 10 is at position 81 of the involute curve ■ with so as the base point.

Therefore, the contact point a1 is the rod 1 of the auto tensioner 13.
3a is on the axis center line, the contact surface 12a of the adjustment stopper 12 and the rod 13a of the auto tensioner 13 are always at the JiQ point on the axis center line of the rod 13a of the auto tensioner 13, and the contact surface 12a of the adjustment stopper 12 and the rod 13a of the auto tensioner 13 are always on the axis center line. It acts perpendicularly to the contact surface 12a.

〔Effect of the invention〕

As described above in detail, according to the present invention, the contact surface of the adjustment stopper that the rod tip of the autotensioner contacts is formed to be an involute curve with the origin of the swing center of the tension pulley. As a result, the tip of the rod of the auto-tensioner always contacts the contact surface of the adjustment stopper in a perpendicular state, regardless of the swing angle of the tension pulley that swings in accordance with the extent of belt extension.

Therefore, the reaction force of the adjustment stopper acts on the rod of the auto tensioner in the direction of the rod axis center line.
The auto tensioner smoothly adjusts the belt tension.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an automatic adjustment device for a timing belt in a horizontally opposed engine according to an embodiment of the present invention, FIG. 2 is an enlarged view showing the main parts of FIG.
The sectional view taken along the line ■-■ in the figure, Figure 44 is an explanatory diagram of the main part according to the present invention, and Fig. 5 is a front view of the main part showing the conventional embodiment. 7... Timing belt, 8... Tension pulley, 9... Shaft, 10... Swing arm, 11...
・Pulley shaft, 12...adjustment stopper 1.12a...
・Abutment surface, 13...Auto tensioner, 13a...
rod. Patent applicant Fuji Heavy Industries Co., Ltd. Agent Patent attorney Jundo Kobashi Patent attorney Susumu Murai

Claims (1)

[Scope of Claims] A timing belt that is swingably supported by a shaft disposed on the engine side on the slack side of a timing belt wound around a valve drive system of an automobile engine and a drive system of auxiliary machinery. A swing arm, a tension pulley rotatably supported on a pulley shaft of the swing arm, and an auto tensioner that presses the tension pulley against the timing belt by swinging the swing arm about the shaft. In a device equipped with an automatic belt tension adjustment device, the contact surface of the adjustment stopper that the rod tip of the auto tensioner comes into contact with and rotates the swing arm is set at the center of swing of the tension pulley as the origin. An automatic belt tension adjustment device, characterized in that it is formed by an involute curve based on a basic circle whose radius is the distance between the center of swing of the tension pulley and the center line of the rod axis of the auto tensioner.