JPH04136550A - Autotensioner - Google Patents

Abstract

PURPOSE:To prevent resonance of an idler, keep tensile force of a belt at a specified value, and simplify the operation of incorporating a spring by filling the inside of a one way clutch with high viscous oil. CONSTITUTION:In state where force of a spring 22 for energizing an eccentric member 16 counterclockwise and tensile force of a belt 25 are in balance, a high frequency vibration load acts in the direction of locking and releasing a one way clutch 14 by vibration of an idler 20 and the eccentric member 16 due to vibration of the belt 25 and vibration of an engine. However, by action of silicone oil 01 in the one way clutch 14, a roller 14a is prevented from moving against force of a plate spring 30 to a released position (indicated by chain lines) at which it does not contact a cylindrical part 10a and an outer ring 14b. Thus, the occurrence of delay in blocking the rotation of an intermediate member 13 is prevented, and tensile force of the belt 25 is kept at a specified value. Further, there is no need to increase force of the plate spring 30 for energizing the roller 14a.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to an autotensioner, and more specifically, to an autotensioner that applies a predetermined tension to a timing belt, etc., which is hung between the crankshaft boob and the camshaft pulley of an automobile engine. Regarding auto tensioners that provide

Conventional Technology The above-mentioned timing belt uses an idler with an elastic force such as a spring to absorb the expansion and contraction of the belt due to changes in engine temperature and the elongation of the belt due to use, and to apply a predetermined tension to the belt. An autotensioner is provided that presses against the belt.

As such an auto tensioner, the first tensioner on the fixed part side
a second member eccentrically and rotatably attached around the first member; an idler rotatably attached around the second member and in contact with the belt; a spring that urges the second member in the direction of contact with the roller; a spring that is provided between the first member and the second member and remains as a clutch member and urges the roller; the second in the direction of pressing against the belt
A one-way clutch is known that allows rotation of a second member but prevents rotation of a second member in a direction that separates the idler from the belt (see Utility Model Application No. 2-81951).

According to this autotensioner, when the belt suddenly loosens due to factors such as sudden acceleration of the engine, the second member rotates relative to the first member at the one-way clutch portion, causing the idler to loosen the belt. The tension quickly follows the loosening and is maintained at a predetermined value; conversely, if the engine temperature rises and the distance between the boars on which the belt is hooked increases, causing the belt tension to increase, 2nd member for 1st member
The tension is maintained at a predetermined value because the rotation of the member is prevented by the rollers of the one-way clutch biting into the inner and outer wheels. Therefore, especially when an autotensioner is applied to a timing belt, it is possible to prevent tooth skipping of the timing belt and apply pressing force in accordance with the belt tension.

Problems to be Solved by the Invention However, the above autotensioner has the following problems. In other words, when the tension of the belt is balanced with the force of the spring that biases the second member in the direction in which the idler contacts the belt, vibrations of the idler and the second member due to belt vibration or engine vibration cause When a high-frequency vibration load is applied to the one-way clutch in the lock direction and the one-way direction, the rollers of the one-way clutch resist the force of the spring that urges the one-way clutch between the inner and outer wheels. It vibrates at a high frequency between the lock standby position where it is pressed to the lock standby position and the free position where it is not in contact with both the inner and outer wheels, and is substantially in the same state as being held in the free position.

Therefore, when the tension of a timing belt fluctuates at a high frequency, the first
Since there is a delay in preventing the rotation of the second member with respect to the second member, the idler may also resonate in response to fluctuations in tension, and there is a possibility that the tension of the belt cannot be maintained at a predetermined value.

In order to solve this problem, it is possible to increase the force of the spring that biases the rollers of the one-way clutch, but assembling such a spring is extremely difficult.

An object of the present invention is to provide an autotensioner that solves the above problems.

Means for Solving the Problems The autotensioner according to the present invention includes a first member on the fixed portion side, a second member eccentrically and rotatably attached around the first member, and a second member on the fixed portion side. an idler rotatably attached around the member and in contact with the belt; a spring biasing the second member in a direction in which the idler contacts the belt; and a spring provided between the first member and the second member. , and has a clutch member and a spring that biases the clutch member, and allows rotation of the second member in the direction of pressing the idler against the belt, but prevents rotation of the second member in the direction of separating the idler from the belt. An auto tensioner equipped with a directional clutch is characterized in that the interior of the one-way clutch is filled with high-viscosity oil.

When a high-frequency vibration load is applied in the locking direction and the freeing direction of the one-way clutch due to the vibration of the idler and second member due to vibration of the working belt or engine vibration, the high viscosity filled inside the one-way clutch is The action of the oil prevents the clutch member of the -direction clutch from moving to a free position where it does not come into contact with both the inner and outer wheels against the force of the spring that urges the clutch member to press against both the inner and outer wheels. Therefore, even if the tension of the belt increases in this state, a delay in preventing the rotation of the second member relative to the first member is prevented. Furthermore, there is no need to increase the force of the spring that biases the clutch member.

Embodiments Hereinafter, embodiments in which the present invention is applied to a timing belt for an automobile engine will be described with reference to the drawings.

In Figures 1 to 3, the auto tensioner is connected to a fixed part of the engine (for example, a cylinder block) (11) by a single bolt-shaped fixed shaft (fixed member (10)).
) is fixed.

An intermediate cylindrical portion (10a) is provided at one end of the fixed shaft (10).
A threaded portion (10b) having a slightly smaller outer diameter is provided, and a collar portion (10c) and a head portion (10d) are formed in a negative shape at the other end. On the threaded part (10b) of the fixed shaft (10),
A side plate (I2) in the form of a perforated disk having approximately the same outer diameter as the flange (10c) is press-fitted. And the fixed part (11)
By screwing the threaded portion (10b) into the fixed shaft (10) and fixing the fixed shaft (10), the side plate (12) is held between the cylindrical portion (10a) and the fixed portion (11) of the fixed shaft (10).

Around the cylindrical part (10a) of the fixed shaft (10), there is a cylindrical part (
A cylindrical intermediate member (13) that is slightly shorter than 10a) and has a smaller outer diameter than the collar portion (10c) and the side plate (12) is concentrically attached via a one-way clutch (14). The inner diameter of the intermediate member (13) is larger than the outer diameter of the cylindrical portion (LOA) of the fixed shaft (10), and the annular space between the cylindrical portion (LOA) of the fixed shaft (10) and the intermediate member (13) is unidirectionally A clutch (14) is provided. This one-way clutch (14) includes, for example, a roller (1
4a) is a known one-way roller clutch using
The clutch (14) becomes free and allows rotation of the intermediate member (13) in the counterclockwise direction in the figure 1 with respect to the fixed shaft (10), but the clutch (14) locks and allows the rotation in the clockwise direction in the figure. It is designed to prevent it. One-way clutch (14
) is press-fitted into the intermediate member (13), and a plurality of roller-shaped rolling elements (14c) that receive a load in the radial direction are interposed between the outer ring (14b) and the fixed shaft (10). I'm forced to. In addition, the cylindrical part (
10a) also serves as the inner ring of the one-way clutch (14). As shown by the solid line in FIG.
) is biased counterclockwise in FIG.
b) is pressed so as to be in contact with the locking standby position. And the inside of the one-way clutch (14),
In other words, the outer ring (14b) and the cylindrical portion (1) of the fixed shaft (10)
, 0a) is filled with high viscosity oil such as silicone oil (01). One-way clutch (14)
On both sides, oil seals (15) for sealing out oil (01) are provided between the cylindrical portion (10a) of the fixed shaft (10) and the intermediate member (13).

A short cylindrical movable eccentric member (16) having the same length as the intermediate member (13) is eccentrically and rotatably attached around the intermediate member (13). An eccentric hole (17) is formed in the eccentric member (16), and the intermediate member (13) is fitted into this eccentric hole (17). The outer peripheral surface of the intermediate member (13) and the eccentric member (
16) and the inner surface of the eccentric hole (17) is kept to a minimum, and this part has a viscosity of, for example, 100,000e.
The rotational torque of the eccentric member (1B) is increased by intervening the silicone oil (02) with a temperature of St (25° C.) or higher. Note that this rotational torque is set by the outer diameter and length of the intermediate member (13), and the size of the gap between it and the eccentric member (16), in addition to the viscosity of the oil. In addition,
An O-ring (18) for sealing oil (02) is provided between both ends of the intermediate member (13) and both ends of the eccentric member (16).
19) is provided.

A cylindrical idler (20) is attached to the outer periphery of the eccentric member (16).
is mounted so that it can rotate via a plurality of spherical rolling elements (21) but hardly move in the axial direction.

A fixed shaft (10) is attached to the side plate (12) side of the eccentric member (16).
A boss portion (lea) is formed substantially concentric with the boss portion (lea), and a torsion coil spring (22) is attached around the boss portion (16a). One end Q2a) of the spring (22) is connected to the boss part (16a) of the eccentric member (16) and the eccentric part (1) on the opposite side.
pin (23) fixed to the step (lee) between 6b)
The other end (22b) is hung on a bottle (24) fixed to the fixed part (11). This spring (22) biases the eccentric member (16) counterclockwise in FIG.
is pressed against the surface without teeth (26).

A pin insertion hole (27) is formed in the eccentric part (1Bb) of the eccentric member (16) and passes through it in the axial direction. A set pin (28) is inserted from the lc) side.This set pin (28) protrudes from the stepped portion (16c) of the eccentric member (16) to the outside of the boss portion (lea).
Spring (2) hung on pin (24) of fixed part (11)
The end (22b) of 2) is hung on this set pin (28). Note that at this time, the spring force of the spring (22) is set to an appropriate value in advance.

In this state, the fixed shaft (1
0) and the side plate (12) to the fixed part (11), remove the set bin (28) from the eccentric member (16) and attach the end (22b) of the spring (22) to the fixed part (1]).
The auto tensioner can be easily assembled by hooking it onto the pin (24).

If the belt (25) suddenly loosens due to factors such as sudden acceleration of the engine and the tension of the belt (25) decreases, the elastic force of the spring (22) causes the eccentric member (16) to move in the counterclockwise direction as shown in Figure 1. The intermediate member (13) also tries to rotate in the same direction due to the viscous resistance of the oil (02). The rotation of the intermediate member (13) in this direction is allowed by the one-way clutch (14) becoming free, so that the eccentric member (16) and the intermediate member (13) are integrated as shown in FIG. The idler (20) rapidly follows the loosening of the belt (25) and is pressed against it, maintaining a predetermined tension. Therefore, the problem of tooth skipping of the timing belt (25) does not occur. Conversely, as the engine temperature rises, the distance between the belts (25) and the belts (25) increases.
When the tension of the spring (22) increases, the eccentric member (16) tries to rotate clockwise in FIG.
) will also try to rotate in the same direction. However, the rotation of the intermediate member (13) in this direction is caused by the stiffness (14a) of the one-way clutch (14) biting into and locking between the cylindrical portion (10a) of the fixed shaft (JO) and the outer ring (14b). Therefore, only the eccentric member (16) is exposed to oil (0
The idler (20) rotates slowly clockwise in FIG. 1 against the viscous resistance of 2), and moves slowly until the tension of the belt (25) is maintained at a predetermined value. In addition, vibrations of the belt (25) and the idler (20) due to engine vibration may
) is suppressed by the viscous resistance of the silicone oil (02) to rotation.

A spring (
22) and the tension of the belt (25) are in balance, the idler (20) and the eccentric member (1B) vibrate due to the vibration of the belt (25) and engine vibration,
Even if a high-frequency vibration load acts on the one-way clutch (14) in the lock direction and the one-way direction, the one-way clutch (14)
) Due to the action of silicone oil (01) in the roller (
14a) resists the force of the leaf spring (30) and the cylindrical part (10a
) and the free position (third position) where it does not contact the outer ring (14b)
This prevents the device from moving to the position indicated by the chain line in the figure. Therefore, a delay in preventing the rotation of the intermediate member (I3) as described above when the tension of the belt (25) becomes large is prevented, and the tension of the belt (25) is maintained at a predetermined value. Ru. Moreover, the leaf spring (
30) There is no need to increase the force.

If the inside of the one-way clutch (14) is not filled with oil (01), the lock (14a) will resist the force of the leaf spring (30) and move to the lock standby position shown by the solid line in Figure 3. It vibrates at a high frequency between the free position shown by the chain line in , and is essentially held in the free position. Therefore, when the tension of the belt (25) vibrates at a high frequency in this state, there is a delay in stopping the rotation of the intermediate member (13) at the moment when the tension becomes large, causing the idler (20) to resonate. There is a possibility that the tension of the belt (25) cannot be maintained at a predetermined value.

Note that the autotensioner according to the present invention can of course be applied to belts other than the timing belt of an automobile engine.

In the above embodiment, the fixed shaft (10) and the eccentric member (1
Although an intermediate member (13) is interposed between B), the intermediate member (13) is not necessarily required.

Effects of the Invention According to the autotensioner of this invention, as described above,
Even if the tension of the belt increases due to vibrations of the idler and eccentric members due to belt vibrations and engine vibrations, the first member Since a delay in preventing the rotation of the second member relative to the second member is prevented, resonance of the idler can be prevented and the tension of the belt can always be maintained at a predetermined value.

Moreover, since there is no need to increase the force of the spring that biases the clutch member, the work of assembling the spring can be done easily.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view (cross-sectional view taken along line 1-1 in FIG. 1) of an autotensioner showing a first embodiment of the present invention, FIG. 2 is a cross-sectional view taken along line U-rl in FIG. 1, and FIG. 2 is an enlarged view of a part of FIG. 2. FIG. (10)...Fixed shaft, (11)...Fixed part, (1
4)... One-way clutch, (14a)... Roller (clutch member), (16)... Eccentric member, (20)...
・Idler, (22)... Spring, (25)... Timing belt, (30)... Leaf spring, (01)...
silicone oil. Figure 2 3N and above

Claims (1)

[Claims] A first member on the fixed portion side, a second member eccentrically and rotatably attached around the first member, and rotatably attached around the second member. an idler that contacts the belt; a spring that biases a second member in a direction in which the idler contacts the belt; an autotensioner having a biasing spring and a one-way clutch that allows rotation of the second member in the direction of pressing the idler against the belt but prevents rotation of the second member in the direction of separating the idler from the belt; An auto tensioner characterized in that a one-way clutch is filled with high-viscosity oil.