JPH03181645A - Automatic tensioner - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] (Field of Application in Industry A) The auto tensioner according to the present invention applies appropriate tension to a timing belt of an automobile engine or a belt for driving auxiliary equipment such as an alternator or a compressor. Used to give.

(Prior art) The camshaft of an OHC type or DOHC type engine is
A drive mechanism using a timing belt 1 as shown in FIG. 14 has been widely known for rotationally driving in synchronization with the crankshaft, as disclosed in, for example, Japanese Patent Application Laid-Open No. 180759/1983.

In this Figure 4, 2 is a drive pulley that is rotationally driven by the engine crankshaft, 3 is a driven pulley fixed to the end of the camshaft, and 4 is a timing belt 1.
This is a tension pulley to apply appropriate tension to the

As shown in detail in FIG. 5, the tension pulley 4 is pivotally supported around a swinging member 6 that swings about a fixed shaft 5. One end of a tension spring 8 is connected to the distal end of the arm piece 7 whose base end is fixed to the swinging member 6, and the tension pulley 4 is connected to the timing belt 1 (FIG. 4).
By elastically pressing the timing belt 1 toward the , the tension of the timing belt 1 can be kept constant regardless of changes in dimensions of the timing belt 1 due to temperature changes, vibrations caused by engine operation, etc. I make it look like it's dripping.

(Problems to be Solved by the Invention) However, in the case of the conventional autotensioner configured and operated as described above, there were problems to be solved as described below.

That is, in the case of a conventional auto tensioner, the tension spring 8
, or because the tension pulley 4 is pressed against the belt to which tension is to be applied, such as the timing belt 1, by the elasticity of the torsion coil spring, if the tension of the belt changes suddenly, this belt may flap. was unavoidable.

In the case of a so-called fixed tensioner, which fixes the shaft that supports the tension pulley while applying appropriate tension to the belt, the belt will not flap even if the belt tension changes suddenly. However, in the case of a fixed tensioner, if the tension of the belt is reduced due to elongation of the belt due to use, it cannot be compensated for.

In the case of an auto-tensioner, the reduction in tension as described above can be compensated to some extent, but in addition to the flapping of the C belt as described above, as the belt stretches, the tension spring 8
Alternatively, it is inevitable that the elasticity of the torsion coil spring that presses the tension pulley 4 against the belt will decrease, and as the belt stretches, the tension applied to the belt will inevitably decrease little by little.

The autotensioner of the present invention eliminates all of the above-mentioned disadvantages.

(Means for Solving the Problems) The autotensioner of the present invention includes a fixed shaft, a swinging member rotatably supported around the fixed shaft, and a part of the swinging member parallel to the fixed shaft. a tension pulley supported by a pivot provided on the fixed part; an electric motor supported on the fixed part; and a transmission that causes the swinging member to swing about the fixed shaft based on the rotation of the output shaft of the electric motor. and is configured to press the tension pulley toward a belt stretched around the tension pulley based on energization of the electric motor.

(Function) When applying appropriate tension to a belt such as an engine timing belt using the autotensioner of the present invention configured as described above, the electric motor is energized to move the swinging member to the transmission means. The tension pulley, which is pivoted to this swinging member by a pivot, is pushed toward the belt.

The force that presses the tension pulley toward the belt is proportional to the drive torque of the electric motor, so by appropriately adjusting the amount of electricity supplied to the electric motor, the appropriate tension can always be applied to the belt. I can continue.

(Example) Next, the present invention will be explained in more detail while explaining the illustrated embodiment.

Figures 1 to 3 show examples of the present invention, where Figure 1 is a sectional view, Figure 2 is a view seen from the left of Figure 1, and Figure 3 is a view similarly seen from the right. be.

Reference numeral 9 denotes a fixed shaft formed in a cylindrical shape, which is fixed to the front surface of the cylinder block 11 of the engine (in the case of an autotensioner for a timing belt) etc. with a bolt 10 when the autotensioner is used.

One end portion (lower end portion in FIGS. 1 to 3) of a swinging member 13 is pivotally supported on the outer circumferential surface of the fixed shaft 9 via a sliding bearing 12.12.

That is, the cylindrical portion 14 formed at one end of the swinging member 13 is
The swinging member 13 is pivotally supported on the fixed shaft 9 by being externally fitted onto the fixed shaft 9 via the sliding bearings 12.12.

In this way, a pivot shaft 15 parallel to the fixed shaft 9 is protruded from the front surface of the intermediate portion (right side in FIG. 1) of the swinging member 13 pivotally supported by the fixed shaft 9, and rolling bearing 1
A tension pulley 17 is supported via 6. The tension pulley 17 has an inner cylindrical portion 17a and an outer cylindrical portion 17b that are concentric with each other by press-forming a metal plate such as a stainless steel plate or an aluminum plate. By fitting and fixing the belt to the outside, the belt is pivotally supported on the pivot shaft 15, and a belt to be applied tension is stretched around the outer peripheral surface of the outer cylindrical part 17b.

In the illustrated embodiment, the outer cylindrical portion 17b is formed to have a sufficiently large diameter so that the fixed shaft 9 can be attached to the outer cylindrical portion 1.
Space 1 between the inner peripheral surface of 7b and the outer peripheral surface of inner cylindrical portion 17a
9 and due to the stress exerted by the belt on the tension pulley 17, the fixed shaft 9 has a sliding bearing 12.1
This prevents the application of torsional stress that could lead to uneven wear.

Further, an arc-shaped driven gear io is fixed to the tip end of the swinging member 13 (upper end in FIGS. 1 to 3) with a screw 21. The outer peripheral edge of the driven gear 20 is an arcuate edge centered on the fixed shaft 9, and teeth are formed on the arcuate edge.

On the other hand, a motor constituting an electric motor 23 is attached to the distal end of a support arm 22 extending from the outer peripheral edge of the base end (left end in FIG. 1) of the fixed shaft 9 in substantially the same direction as the swinging member 13. The housing 24 is integrally formed with C, and this motor housing 2
4 and a pair of rolling bearings 26 and 26.
It is rotatably supported. A rotor 27 is fixed to the outer circumferential surface of the intermediate portion of the output shaft 25, and a stator 28 is fixed to the inner circumferential surface of the motor housing 24 at a portion facing the rotor 27, thereby moving the output shaft 25 in a specific direction. It can be rotated freely.

A drive gear 29 is formed on the outer circumferential surface of the portion protruding from the motor housing 24 at the tip end (right end in FIG. 1) of the output shaft 25 constituting the electric motor 23 as described above. is meshed with the driven gear 20.

As a result, as the electric motor 23 is energized, the swinging member 13 swings about the fixed shaft 9.
The rotation direction of the electric motor 23 is determined so that the tension pulley 17, which is pivotally supported by the pivot shaft 15, is pressed against the belt in accordance with this displacement.

Furthermore, ratchet teeth 30 are formed at the base end (left end in FIG. 1) of the output shaft 25, and ratchet pawls 31 that engage with the ratchet teeth 30 are formed on the inner peripheral surface of the motor housing 24. has been established. This ratchet i3
Due to the action of a ratchet mechanism 32 consisting of a ratchet claw 31 and a ratchet pawl 31, the output shaft 25 is rotatable only in the direction in which the tension pulley 17 is pressed against the belt when the electric motor 23 is energized. That is, even if the electric motor 23 is not energized and the swinging member 13 supporting the tension pulley 17 based on the tension from the belt tries to swing in the direction of moving the tension pulley 17 away from the belt, The action of the ratchet mechanism 32 prevents the output shaft 25 from rotating.

The autotensioner of the present invention constructed as described above operates as described below.

When applying appropriate tension to a belt such as an engine timing belt, the electric motor 23&: is energized with an appropriate voltage, and the output shaft 25 of the electric motor 23 is rotated with a torque commensurate with the voltage.

As the output shaft 25 rotates, the driven gear 20 fixed to the tip of the swinging member 13 is displaced via the drive gear 29, and the swinging member 13 swings about the fixed shaft 9. As a result, the pivot 15 at the front of the intermediate portion of the swinging member 13
A tension pulley 17 pivotally supported is pressed toward the belt, applying tension to the belt.

The force that presses the tension pulley 17 toward the belt is
Since it is proportional to the rotational torque of the output shaft 25, which is determined by the voltage applied to the electric motor 23, by appropriately adjusting the voltage applied to the electric motor 23, an appropriate tension can be applied to the belt. I can do it.

Once the proper tension is applied to the belt as the electric motor 23 is energized, the ratchet mechanism 32 will keep the tension pulley 17 in the same position even if the electric motor 23 is no longer energized. The belt remains under proper tension.

That is, the ratchet mechanism 32 is connected to the electric motor 23.
Since only the rotation of the output shaft 25 based on the energization is allowed,
Even if the electric motor 23 is not energized and the swinging member 13 supporting the tension pulley 17 based on the tension from the belt tries to swing in the direction of moving the tension pulley 17 away from the belt, the output shaft 25 does not rotate, and the swinging member 13 to which the driven gear 20 meshed with the drive gear 29 at the tip of the output shaft 25 is fixed does not displace regardless of the stress applied to the tension pulley 17 from the belt.

Therefore, once an appropriate tension is applied to the -degree belt, the tension of the belt can be maintained within an appropriate range without continuing to energize the electric motor 23.

In addition, even if the belt tension changes suddenly in this state, the tension pulley 17 will not be displaced in the direction away from the belt running position, so as in the case of the fixed tensioner described above, the belt will not fluctuate. It can be suppressed to

If the tension of the belt decreases due to elongation of the belt due to long-term use, etc., the tension pulley 17 can be directed toward the belt by energizing the electric motor 23 again for a predetermined period of time (several seconds). Apply appropriate tension to this belt. After applying tension, the ratchet mechanism 32
As mentioned above, the proper tension is maintained due to the action of the .

Note that the following method can be considered as a method for determining the timing for energizing the electric motor 23.

The first method is to provide a detection means (clock or odometer) for detecting the elapsed time or distance traveled by the vehicle;
It is conceivable that a separately provided control means controls the energization of the electric motor 23 based on the signal from this detection means.

In this case, the control means causes a current of a predetermined magnitude to flow through the electric motor 23 for a predetermined time when a predetermined time has elapsed or when the vehicle has traveled a predetermined distance.
7 is pressed against the belt with a predetermined force, and if the belt is slack, this slack is compensated for.

Next, as a second method, a temperature detection means (such as a water temperature gauge) for detecting the temperature of the engine of the vehicle is provided, and a separately provided control means controls the electric motor 23 based on a signal from this temperature detection means. It is conceivable to control the energization of the

In this case, when the temperature of the engine rises above a certain value, the control means causes a current of a predetermined magnitude to flow through the electric motor 23 for a predetermined time, and presses the tension pulley 17 against the belt with a predetermined force. If the belt is slack, C compensates for this slack.

In the two methods described above, the tension pulley 17 is pressed against the belt by energizing the electric motor 23, regardless of whether the belt is slack, and if the belt is slack, this slack is compensated for. However, next, a case will be described in which the presence or absence of slack in the belt is detected and the electric motor 23 is energized only when the belt is slack.

First, the first method in this case is to install a load cell to detect the stress applied to the axis of one of the pulleys (a guide pulley is suitable) around which the belt is stretched. It is conceivable that a tension detection means for detecting a decrease in the tension applied to the electric motor is provided, and a separately provided control means controls energization to the electric motor based on a signal from the tension detection means.

In this case, the control means causes a current of a predetermined magnitude to flow through the electric motor 23 for a predetermined period of time to press the tension pulley 17 against the belt with a predetermined strength when the tension of the belt falls below a certain value. , to compensate for belt slack.

A second method for detecting slack in the belt and controlling energization to the electric motor 23 is based on the rotation speed of the engine that drives the belt and the rotation of auxiliary equipment such as a generator that is driven by the belt. It is possible to detect that the belt is slack due to the discrepancy with the number.

In other words, the engine rotation speed and the auxiliary machine rotation speed are in a proportional relationship to each other when the belt tension is appropriate.
If the belt loosens and the engine rotation is not sufficiently transmitted to the auxiliary equipment, it will no longer be proportional.

Therefore, in the case of this method, the rotation speed of the engine and the rotation speed of the auxiliary equipment are observed and compared, and if the rotation speed of the auxiliary equipment is lower than the engine speed, the belt is loosened. In this case, a separately provided control means causes a current of a predetermined magnitude to flow through the electric motor 23 for a predetermined period of time, and presses the tension pulley 17 against the belt with a predetermined force to compensate for slack in the belt.

Note that the output shaft 25 of the electric motor 23 directly connects the driven gear 2.
0, the output of the electric motor 23 is insufficient,
If sufficient tension cannot be obtained, a reduction gear may be provided between the electric motor 23 and the drive gear 29.

In addition, the output shaft 25 is disposed in the front and back directions in FIG. Alternatively, the transmission means can be configured by supporting a nut member on a part of the swinging member 13 and screwing a threaded rod torsionally rotated by the electric motor 23 onto the nut member. , it is sufficient (
The swinging member 13 can be displaced with a large force. However, in this case, the nut member is placed against the swinging member 13,
The screw rods are supported by fixed parts so as to be able to swing slightly, so that the threaded state of the nut member and the screw rod is secured regardless of the displacement of the swing member 13.

Furthermore, a ratchet mechanism 32 for preventing the tension pulley 17 from retreating from the belt running position when the electric motor 23 is de-energized is connected to the swinging member 13 and the support arm 22, as shown by the chain line in FIG. It can also be placed between.

In addition, in FIG. 1, 33 indicates the driven gear 20 and the driving gear 2.
In order to prevent dust and the like from entering the meshing portion with the support arm 9, boots are provided at the tip of the swinging member 13 and the tip of the support arm 22.

(Effects of the Invention) Since the autotensioner of the present invention is constructed and operates as described above, it is possible to reliably prevent the belt from flapping even when the tension of the belt changes rapidly.
Furthermore, even if the tension of the belt is reduced due to elongation of the belt during use, this can be reliably compensated for.

[Brief explanation of drawings]

1 to 3 show embodiments of the present invention, FIG. 1 is a sectional view, FIG. 2 is a view seen from the left side of FIG. 1, and FIG. 3 is a view similarly seen from the right side. FIG. 4 is a front view of a belt drive mechanism provided with an auto-tensioner, and FIG. 5 is an enlarged front view of only the auto-tensioner. 1: Timing belt, 2: Drive pulley, 3: Driven pulley, 4: Tension pulley, 5: Fixed shaft, 6: Swing member, 7: Arm piece, 8: Tension spring, 9: Fixed shaft, 10: Bolt, 11 Niji cylinder block, 12: Slide bearing, 13
: Swinging member, 14: Cylindrical part, 15: Pivot, 16: Rolling bearing, 17: Tension pulley, 17a: Inner cylindrical part, 1
7b: outer cylindrical part, 18: outer ring, 19: space, 20: driven gear, 21: screw, 22: support arm, 23: electric motor,
24: Motor housing, 25: Output shaft, 26: Rolling bearing, 27: Rotor, 28: Stator, 29: Drive gear, 30: Ratchet tooth, 31: Ratchet pawl, 32: Ratchet mechanism, 33: Boot.

Claims (13)

[Claims] (1) a fixed shaft, a swinging member rotatably supported around the fixed shaft, and a tension pulley supported on a part of the swinging member by a pivot provided parallel to the fixed shaft; It consists of an electric motor supported by a fixed part, and a transmission means for swinging the swinging member about the fixed shaft based on the rotation of the output shaft of the electric motor, and based on the energization of the electric motor. An auto tensioner that presses the tension pulley toward a belt that is stretched around the tension pulley. (2) Transmission is transmitted by fixing an arc-shaped driven gear centered on the fixed shaft on a part of the swinging member, and meshing the driving gear fixed to the output shaft of the electric motor with the driven gear. The autotensioner according to claim 1, wherein the autotensioner is used as a means. (3) The auto tensioner according to claim 2, wherein the electric motor is supported at the tip of the support arm fixed to the fixed shaft. (4) The rotation of the output shaft or the displacement of the swinging member occurs only in the direction in which the tension pulley faces the belt between the motor housing and the output shaft that constitute the electric motor, or between the support arm and the swinging member. 4. The auto tensioner according to claim 3, further comprising a ratchet mechanism that allows for. (5) Supporting a nut member on a part of the swinging member, and
2. The auto tensioner according to claim 1, wherein the transmission means is a screw rod that is twisted and rotated by an electric motor and is screwed into the nut member. (6) The autotensioner according to any one of claims 1 to 5, wherein the transmission means is surrounded by a boot made of a flexible material. (7) The auto tensioner according to any one of claims 1 to 6, wherein the transmission means is provided inside the outer peripheral surface of the tension pulley. (8) The auto tensioner according to any one of claims 1 to 7, wherein the fixed shaft is provided inside the outer peripheral surface of the tension pulley. (9) It has a detection means for detecting the elapsed time or the distance traveled by the vehicle, and a control means for controlling the energization of the electric motor based on the signal from the detection means, and the control means is configured to detect the elapsed time or the distance traveled by the vehicle. The auto tensioner according to any one of claims 4 to 5, wherein a current of a predetermined magnitude is caused to flow through the electric motor for a predetermined period of time when the vehicle is traveling a certain distance or when the vehicle has traveled a certain distance. (10) Temperature detection means for detecting the temperature of the engine of the vehicle; and control means for controlling energization of the electric motor based on a signal from the temperature detection means, and the control means is configured to detect the temperature of the engine. The auto tensioner according to any one of claims 4 to 5, wherein a current of a predetermined magnitude is caused to flow through the electric motor for a predetermined period of time when the tensioner increases to a predetermined value or more. (11) A tension detection means for detecting a decrease in the tension applied to the belt; and a control means for controlling energization of the electric motor based on a signal from the tension detection means; 6. The auto tensioner according to claim 4, wherein a current of a predetermined magnitude is caused to flow through the electric motor for a predetermined time when the tension of the tensioner falls below a certain value. (12) The autotensioner according to claim 11, wherein the tension detection means detects the tension of the belt based on a load applied to any pulley that is in contact with the belt. (13) The autotensioner according to claim 11, wherein the tension detection means detects the tension of the belt based on a difference between the rotation speed of the engine and the rotation speed of an auxiliary machine driven by the belt.