JPH0942393A - Hydraulic auto tensioner unit - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a hydraulic auto tensioner unit at low cost. A pulley (6) is rotatably attached to an arm (4) swingably supported by an engine block (1). Insert rod 10 into cylinder 8 and insert rod 1 into cylinder 8.
The cylinder 8 of the actuator 7 incorporating the spring 11 that presses 0 outward and the hydraulic damper mechanism 12 is swingably supported by the engine block 1. An insertion hole 22 is provided in the arm 4, and a bearing 23 is assembled in the insertion hole 22. The rod 1 is inserted into the conical recess 24 provided in the bearing 23.
The hemispherical surface 25 at the tip of 0 is pressed to press the arm 4 toward the belt tension side. Both ends of a pin 27 that radially penetrates the tip of the rod 10 are supported by the arm 4,
The diameter of the pin hole 26 provided in the above is made larger than the diameter of the pin 27 to prevent the pin 27 from being loaded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic type automatic tensioner unit, and more particularly to a hydraulic type automatic tensioner unit for maintaining a constant tension of a belt for driving an auxiliary machine such as a timing belt for driving a cam shaft of an automobile engine or an alternator. It concerns auto tensioners.

[0002]

2. Description of the Related Art As a hydraulic type automatic tensioner unit for keeping the tension of a belt constant, the one shown in FIG. 7 has been conventionally known. In this hydraulic auto tensioner unit, a fulcrum shaft 32 is attached to a base 30 fixed to an engine block by tightening bolts 31, and a pulley 34 is attached to a tip end portion of an arm 33 that is swingably provided around the fulcrum shaft 32. Rotatably attached to the pulley 34
Pushes the arm 33 with the actuator 36 in the direction to stretch the belt 35.

Here, the actuator 36 is the base 30.
A cylinder 38 swingably supported by a pin 37 on the
And a rod 39 inserted into the cylinder 38, and the rod 39 is pressed outward by a spring of the illustrated cylinder incorporated in the cylinder 38.

Further, a hydraulic damper mechanism is incorporated in the cylinder 38 to buffer the load in the pushing direction applied to the rod 39 by the hydraulic damper mechanism.

The actuator 36 connects the tip of the rod 39 to the arm 33 and presses the arm 33 toward the belt tension side.

[0006]

By the way, in the conventional hydraulic autotensioner, a connecting boss 40 is provided at the tip end portion of the rod 39 of the actuator 36, and the boss 40 is superposed on the arm 33 to form a shaft member such as a bolt. Since the structure is connected by 41, the shaft member 41 comes into contact with the inner peripheral surface of the shaft insertion hole provided in the arm 33 and the boss 40 due to the swing of the arm 33 due to the fluctuation of the tension of the belt 35. The contact part is easily worn.

Therefore, conventionally, as a measure against wear of the contact portion, a sliding member is incorporated between the shaft member 41 and the shaft insertion hole, or a wear-resistant surface treatment is performed on the shaft member 41, which results in cost reduction. There was the problem of being expensive.

An object of the present invention is to reduce the cost of a hydraulic type automatic tensioner unit.

[0009]

In order to solve the above problems, according to the present invention, an arm swingably supported by a fixed portion and a swing side end of the arm are rotatably supported. A pulley, and an actuator that pushes the arm in the direction in which the pulley stretches the belt, and a cylinder in which the actuator is swingably supported by a fixed portion,
A structure having a rod inserted into the cylinder, a spring for pressing the rod outward in the cylinder, and a hydraulic damper mechanism for buffering the pushing force when the rod is pushed; In the hydraulic autotensioner unit that pushes the arm toward the belt tension side with the rod, a hemispherical surface is provided at the tip of the rod, and the arm is formed with an insertion hole into which the tip of the rod is inserted. A conical or hemispherical recess is provided in the hole where the hemispherical surface of the rod is pressed. The rod and the arm are connected to each other by inserting a pin penetrating the tip of the rod in the radial direction. The pin hole is larger than the outer diameter of the pin.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

As shown in FIGS. 1 and 2, a first fulcrum shaft 3 is attached to an engine block 1 as a fixed portion by tightening a bolt 2, and an aluminum light alloy is used around the first fulcrum shaft 3 as a center. The arm 4 is swingably supported.

A pulley 6 for guiding the movement of the belt 5 is rotatably supported at the swinging end of the arm 4.

An actuator 7 presses the arm 4 in a direction in which a pulley 6 stretches the belt 5.

The actuator 7 has a cylinder 8. An oil seal 9 is attached to the inner upper part of the cylinder 8, and a rod 10 is slidably inserted in the oil seal 9.

Inside the cylinder 8, the rod 10
A spring 11 for pressing the rod 10 outward and a hydraulic damper mechanism 12 for cushioning the pushing force of the rod 10 are incorporated.

In the hydraulic damper mechanism 12, the plunger 13 connected to the lower end of the rod 10 is swingably inserted into the sleeve 14 incorporated in the lower inside of the cylinder 8, and the plunger 13 and the lower end of the rod 10 are connected. A passage 17 is provided which connects the pressure chamber 15 formed below the plunger and the reservoir chamber 16 provided above the plunger.

The pressure chamber 15 and the reservoir chamber 16 are filled with hydraulic oil to provide an air reservoir on the surface of the hydraulic oil in the reservoir chamber 16, and the hydraulic oil in the pressure chamber 15 flows into the reservoir chamber 16 in the passage 17. A check valve 18 for preventing the above is provided, and when the pushing force acts on the rod 10, the pushing force is buffered by the hydraulic oil in the pressure chamber 15.

The lower end of the cylinder 8 of the actuator 7 is swingably supported about a second fulcrum shaft 19 bolted to the engine block 1, and is provided at the second fulcrum shaft 19 and the lower end of the cylinder 8. A slide bearing 21 is incorporated between the inner circumferences of the shaft insertion holes 20.

The tip of the rod 10 is inserted into an insertion hole 22 formed in the arm 4. A bearing 23 is incorporated in the insertion hole 22, and a hemispherical surface 25 provided at the tip of the rod 10 comes into contact with a conical recess 24 formed in the bearing 23,
The contact absorbs the relative movement of the arm 4 and the actuator 7.

A pin hole 26 is formed at the tip of the rod 10 so as to penetrate in the radial direction, and both ends of a pin 27 inserted into the pin hole 26 are supported by the arm 4.

The pin hole 26 has a larger diameter than the outer diameter of the pin 27, and prevents the pin 27 from coming into contact with the inner circumference of the pin hole 26 when the rod 10 and the arm 4 move relative to each other.

When the pin hole 26 is provided at a position passing through the center of the hemispherical surface 25 at the tip of the rod, the pin 27 and the pin hole 2 are provided.
The contact with 6 can be completely prevented.

In the hydraulic type automatic tensioner unit having the above structure, when the tension of the belt 5 becomes strong, the pulley 6 is pushed by the belt 5 and the arm 4 swings around the first fulcrum shaft 3.

The swing of the arm 4 causes the rod 10 to move.
Is pushed in and the plunger 13 descends, and at this time, the pressure in the pressure chamber 15 increases, so that the check valve 18 closes the passage 17.

When the plunger 13 is pushed further in,
The hydraulic oil in the pressure chamber 15 is transferred to the plunger 13 and the sleeve 14.
Flows into the reservoir chamber 16 through the gap between the sliding portions of the.

Therefore, the plunger 13 and the rod 1
0 slowly descends to buffer the pushing force of the rod 10, and when the force of the spring 11 pressing the rod 10 and the force of the belt 5 pressing the pulley 6 are balanced, the pulley 6
Stops.

When the belt 5 becomes loose, the rod 10 moves outward due to the elasticity of the spring 11.
At this time, since the plunger 13 also moves upward together with the rod 10, the pressure in the pressure chamber 15 decreases, and when the pressure becomes lower than the pressure in the reservoir chamber 16, the check valve 18 opens the passage 17 and the reservoir chamber The hydraulic oil in 16 flows into the pressure chamber 15.

Therefore, the rod 10 rapidly moves outward, and the arm 4 swivels toward the belt tension side quickly to absorb the looseness of the belt 5.

According to the embodiment shown in FIG. 2, the arm 4 and the actuator 7 are connected to each other by the hemispherical surface 2 at the tip of the rod 10.
5 is a connection for press-contacting the recess 5 of the bearing 23,
Even if the arm 4 swings due to the change in the tension of the belt 5 and wear occurs at the contact portion between the hemispherical surface 25 of the rod 10 and the recess 24 of the bearing 23, the elasticity of the spring 11 causes the rod 10 to project outward. Is added, the rod 10 is held in contact with the bearing 23.

As described above, since the rod 10 and the bearing 23 are always kept in contact with each other even when wear occurs, the pulley 6 can always follow the fluctuation of the tension of the belt 5, and the rod 10 Since it is not necessary to take special measures against wear on the contact portion between the bearing 23 and the bearing 23, the cost can be reduced.

Further, since both ends of the pin 27 that radially penetrates the tip of the rod 10 are supported by the arms 4, the tip of the rod 10 is inserted into the insertion hole 22 due to vibration or the like.
It is possible to reliably prevent it from coming out.

Then, the pin hole 26 formed in the rod 10
Since the diameter of the pin 27 is larger than the outer diameter of the pin 27, no load is applied to the pin 27 when the tension of the belt 5 is adjusted, and it is possible to prevent the pin 27 from being worn or damaged.

4 and 5 show the rod 10 and the arm 4
Another example of the connection will be shown. In the example shown in FIG. 4, the arm 4 is made of iron, a conical recess 24 is formed in the bottom surface of the insertion hole 22 formed in the arm 4, and the rod 10 is inserted in the recess 24.
The hemispherical surface 25 is pressed.

In the example shown in FIG. 5, the arm 4 is formed of an aluminum light alloy, the bearing 23 is incorporated in the insertion hole 22 of the arm 4, and the recess 24 of the bearing 23 is formed into a hemispherical shape, and the rod 24 is inserted into the recess 24. It is made to come into pressure contact with the hemispherical surface 25 at the tip of the.

Generally, in a hydraulic autotensioner unit used for adjusting the tension of a belt that drives an automobile accessory such as an alternator, when the belt 5 is stretched, the rod 10 is held in a pushed state to stretch the belt 5. It was installed, and the tensioning of the belt 5 was troublesome.

In order to eliminate such inconvenience, in the example shown in FIG. 6, a pin hole 28 is formed in the tip portion of the rod 10 and the tip portion of the cylinder 8, and the set pin 29 is inserted into the pin hole 28. The rod 10 is held in the pushed state.

As described above, the rod 1 is set by the set pin 29.
When 0 is held in the pushed state, the rod 1 is pulled by pulling out the set pin 29 after the belt is stretched.
Since 0 moves outward and tension can be applied to the belt 5 via the pulley 6, the belt 5 can be stretched very easily.

[0038]

As described above, according to the present invention, the insertion hole provided in the arm is provided with the conical or hemispherical recess,
Since the hemispherical surface provided at the tip of the rod is brought into pressure contact with the depression, relative movement between the arm and the actuator can be smoothly performed, and even if the contact portion between the rod and the depression is worn, Since there is no backlash between the connecting portion of the rod and the arm and no special surface treatment is required for the contact portion, the cost can be reduced.

Further, by incorporating a bearing having a recess into the insertion hole, it is possible to employ an arm made of a light aluminum alloy as the arm, so that the weight of the auto tensioner unit can be reduced.

Further, by connecting the rod and the arm with a pin that penetrates the rod in the radial direction, the arm and the actuator can be held in a non-separated state, and the pin hole provided in the rod can be formed into By making it larger, no load is applied to the pin, and damage to the pin can be prevented.

Further, since the rod is held in the pushed-in state by inserting the set pin, the work of stretching the belt can be facilitated.

[Brief description of drawings]

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

2 is a vertical side view of FIG.

FIG. 3 is an enlarged sectional view showing a connecting portion between the rod and the arm of the above.

FIG. 4 is a sectional view showing another example of the connection between the rod and the arm.

FIG. 5 is a sectional view showing still another example of the connection between the rod and the arm.

FIG. 6 (I) is a front view showing another embodiment of the present invention, and (II) is a sectional view taken along line VI-VI of (I).

FIG. 7 is a front view showing a conventional hydraulic type automatic tensioner unit.

[Explanation of symbols]

 4 arm 5 belt 6 pulley 7 actuator 8 cylinder 10 rod 11 spring 12 hydraulic damper mechanism 22 insertion hole 23 bearing 24 recess 25 hemispherical surface 26 pin hole 27 pin 28 pin hole 29 pit pin

Claims (4)

[Claims] 1. An arm swingably supported by a fixed portion, a pulley rotatably supported by a swing side end of the arm, and an actuator for pushing the arm in a direction in which the pulley stretches the belt. And a rod in which the actuator is swingably supported by a fixed portion and a rod inserted in the cylinder, and a spring for pushing the rod outward in the cylinder and a rod pushed in. In the hydraulic autotensioner unit in which a hydraulic damper mechanism that buffers the pushing force is incorporated, the rod is pressed by the rod toward the belt tension side. Has an insertion hole into which the tip of the rod is inserted, and a conical or hemispherical recess into which the hemispherical surface of the rod is pressed is provided in the insertion hole. A hydraulic autotensioner unit characterized in that the rod and the arm are connected by inserting a pin that penetrates the tip end portion of the rod in the radial direction, and the pin hole provided in the rod is larger than the outer diameter of the pin. 2. The hydraulic autotensioner according to claim 1, wherein a bearing is incorporated in the insertion hole, and a recess is provided in the bearing. 3. The hydraulic automatic tensioner unit according to claim 1, wherein a recess is provided on the bottom surface of the insertion hole. 4. A pin hole penetrating in a radial direction is formed at a tip portion of the pin and a tip portion of the cylinder, and a rod is held in a pushed state by inserting a set pin inserted into the pin hole. The hydraulic auto tensioner unit according to claim 1.