JP2002364721A - Eccentric pulley and belt tension adjustment device using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an eccentric pulley having a means detecting a swing position of a tension pulley, capable of notifying replacement timing of a timing belt or abnormality of an auto tensioner with high reliability, and allowing easy replacement work or maintenance and inspection for the detection means, and to provide a belt tension adjustment device using it. SOLUTION: In this eccentric pulley, the tension pulley 21 is rotatably supported by a bearing 22, the bearing 22 is supported by an eccentric ring 23 turnably supported by a fixing bolt 26 such that a position of the tension pulley 21 can be freely shifted, to freely adjust tension of a belt A. In the belt tension adjustment device using the eccentric pulley, a position of the tension pulley 21 is adjusted by a hydraulic damper 28 and a spring 51 provided inside the pulley, and a position detection mechanism comprising a magnet 91 provided in a face opposite to an installation member 34 of an eccentric ring 23, and a magnetic sensor 93 provided in a face opposite to the eccentric ring 23 of the installation member 34. For the purpose of the maintenance of reliability of the position detection of the tension pulley 21, an O-ring 27 is inserted as a means suppressing fluctuation of a gap between the eccentric ring 23 and the fixing bolt 26.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for adjusting the tension of a timing belt for driving a camshaft of an automobile, etc., and is provided with a means for detecting the movement of a pulley rolling on the belt. The present invention relates to a pulley and a belt tension adjusting device using the same.

[0002]

2. Description of the Related Art A belt transmission device for driving a camshaft incorporated in an internal combustion engine of an automobile has a timing belt with a change in the distance between pulley cores due to thermal expansion of the internal combustion engine main body during operation and an elongation of the belt due to aging. The tension changes.
In order to keep the tension of the timing belt constant, a belt tension adjusting device generally called an auto tensioner having a spring and a hydraulic damper is used. FIG. 14 shows an example of a layout in which such a belt tension adjusting device is used.

As shown, a timing belt 4 includes a pulley 1 for a crankshaft, pulleys 2a and 2b for a camshaft,
A tension pulley 5 of an automatic tensioner is provided so as to be stretched between pulleys 3 of a drive shaft for an oil pump, and to a slack side of the timing belt 4. The illustrated auto-tensioner is disclosed in, for example,
This is a compact auto-tensioner disclosed in Japanese Patent No. 338488, in which a hydraulic damper is accommodated in an umbrella of a tension pulley 5 to reduce the size of the whole.

[0004] The auto tensioner is provided so as to freely swing the tension pulley 5 about the shaft 6 against the timing belt 4, and keeps the tension of the timing belt constant by the tension adjusting force of a spring and a hydraulic damper. When the tension is excessive, the tension pulley 5 swings counterclockwise to reduce the tension, and conversely, when the tension is low, swings clockwise to adjust the tension. The overall length of the timing belt 4 increases as the period of use increases, due to aging. Therefore, the tension pulley 5 of the auto-tensioner swings clockwise as the operation time or the use period becomes longer.

In general, when such an automatic tensioner is not provided, the timing belt 4 is replaced with a travel distance of 100,000 km as a guide. However, when the automatic tensioner is provided, the tension of the timing belt 4 becomes stable, and the operation time is reduced. And the effect of extending the life of the timing belt 4 can be ensured, and it is possible to guarantee that the timing belt 4 exceeds 100,000 km.

[0006]

By the way, the swing angle of the tension pulley in the above-mentioned auto tensioner is limited, and if the operation exceeding the swing limit point is continued, the tension of the timing belt cannot be kept constant. In this case, the timing belt has a low tension, and the belt is deteriorated due to flapping of the timing belt and the like, and eventually, the belt is damaged.

However, at present, there is no mechanism for detecting the swing angle of the tension pulley to detect whether the operation has exceeded the swing limit point. You can't tell if it's kept properly. For this reason, it is not possible to appropriately judge when to replace the timing belt, and it is not possible to know in advance even if there is an abnormality in the auto tensioner.

For this reason, the present inventors have disclosed a belt tension adjusting device which is provided with a means for detecting the swing position of a tension pulley in the prior application and which can notify a timing belt replacement time or an abnormality of an auto tensioner. Proposed. However, when such a detecting means is provided,
Considering the ease of manufacture, the ease of maintenance and inspection, and the ease of replacement work, as shown in FIG. 15, the magnetic sensor 93 of the detecting means is attached to the mounting member 34, and the magnets 91a, 91
It is most rational to provide the space between the end surface of the inner member and the surface where the mounting member faces, such as attaching 1b to the end surface of the eccentric ring 23 of the inner member.

However, when assembling the actual parts, the length L ₂ of the large-diameter portion of the fixing bolt 26 is made extremely longer than the length L ₁ of the slide bearing 25 in order to make the eccentric ring 23 rotatable. It is made slightly longer, and the fixing bolt 26 is attached to the end face 2 of the large diameter portion.
At 6a, the mounting member 34 including the hydraulic damper 28 is pressed against the side wall of the engine block EW to be fixed. Therefore, the distance between the eccentric wheel 23 and the bolt 26 is slightly different depending on the dimensional tolerance of each part, but is about 0.1 to 0.8 m.
There is a gap δ of m. For this reason, the eccentric wheel 23 moves in the axial direction of the bolt by this gap δ, and under this influence, the magnetic sensor 93 of the sensor unit 97a and the magnet 91 (91
a, 91b) also varies with the surface of the magnetic sensor 93.
Causes an error in the detection accuracy.

As described above, when the detecting means is mounted in a direction corresponding to the measuring direction in which the movement of the eccentric ring in the axial direction affects the detecting accuracy of the detecting means, the influence of the gap on the detecting means is taken into consideration. There is a need to. The above gap is indispensable to rotatably support the inner member with respect to the fixed member, and cannot be eliminated, but can be suppressed to a minimum while maintaining free rotation. It is.

The detecting means is capable of detecting a change in the swinging position of the tension pulley in principle on the assumption that the gap does not fluctuate greatly.
Actually, the gap fluctuates, so that a large error occurs in the detection result of the oscillating position, and the reliability is not obtained. Therefore, the significance of providing the detection means is lost. However, there has not been a proposal in the related art that even detects the swinging state of the tension pulley by providing the above-described detection means, and there is no example that discusses the detection accuracy of the detection means as described above.

The present invention is provided with a means for detecting the swing position of the tension pulley in consideration of the problem in the conventional tension adjusting means, and can notify the timing of replacing the timing belt or the abnormality of the auto tensioner.
An object of the present invention is to provide an eccentric pulley in which a gap set between a fixed member and an inner member is minimized to ensure the reliability of detection by a detection unit, and a belt tension adjusting device using the same. I do.

[0013]

According to the present invention, a tension pulley is rotatably supported by an inner member rotatably supported by a fixed member inserted at an eccentric position. A magnetic sensor for detecting the position of the pulley and a working piece are provided, and a suppressor for suppressing a change in a gap set between the inner member and the fixed member is provided to suppress a change in a gap between the magnetic sensor and the working piece. This is an eccentric pulley configured to perform the above operation.

The eccentric pulley of the above construction is provided with a tension adjusting spring for displacing the tension pulley via an inner member and a hydraulic damper so that the tension can be adjusted freely, and is used as a belt tension adjusting device. In this belt tension adjusting device, if the belt tension fluctuates during normal operation, the belt tension is always adjusted by the tension adjusting spring and the hydraulic damper. In the adjustment of the belt tension, the fluctuation of the tension is canceled in accordance with the expansion and contraction of the belt depending on the load state, and the fluctuation of the belt tension is attenuated by the hydraulic damper. In such a normal operation, a position detecting mechanism including an operating piece and a magnetic sensor is provided between the fixed member and the inner member to detect a change in the position of the tension pulley due to a change in the tension of the belt.

While the position of the tension pulley is being detected by the above detection mechanism, if the timing belt stretched around the tension pulley is extended due to aging,
The swing position of the tension pulley changes little by little, and the swing range increases. Since such a swing position of the tension pulley is detected by the position detecting mechanism, even if the swing range becomes large, a change in the position is detected continuously or in multiple points. When the swing range becomes large and reaches the limit position where the tension pulley can swing, the timing belt needs to be replaced.However, a caution, warning signal, If an alarm signal is generated, the timing of replacing the timing belt or an abnormality of the auto tensioner can be notified.

An eccentric pulley having such a function is provided with a suppressing means for suppressing a change in a gap between the inner member and the fixed member, whereby the change in the gap is used when detecting the position of the tension pulley. The effect on the detection accuracy is minimized, and the reliability of the detection operation indicating that the position of the tension pulley has changed is guaranteed. If the gap between the inner member and the fixed member in the axial direction is large, and the variation of this gap affects the accuracy of the position detection of the tension pulley by the magnetic sensor, the magnetic sensor and the operating piece are attached in a direction in which This is because it is necessary to suppress the fluctuation of the value and to minimize its influence.

An elastic member is used as the above-mentioned suppressing means.
It also has the function of minimizing the gap without increasing the dimensional accuracy of components used as inner members and fixing members. Generally, it is necessary to increase the dimensional accuracy of the component in order to suppress the change in the gap. However, in the present invention, since the elastic deformation of the elastic member is used, the dimensional accuracy can be suppressed without increasing the dimensional accuracy of the component.

In the case where the operating piece is a magnet, the magnet is fixed to the inner member via a non-magnetic member, so that the magnetic sensor can detect magnetism generated by the magnet with high sensitivity. The detection accuracy of the position of the pulley can be improved.

In addition, a sleeve having an eccentric hole is rotatably inserted into the hole provided at the eccentric position of the inner member so that the swing angle after the eccentric pulley is assembled can be reduced. The belt tension adjusting device can be provided so that it can be assembled so as to obtain the maximum, and the timing belt replacement time can be extended.

[0020]

Embodiments of the present invention will be described below. 1 to 4 show the configuration of a belt tension adjusting device including an eccentric pulley according to the first embodiment. As shown in the figure, the tension pulley 21 is mounted so as to be rotatable around an eccentric wheel 23 via a rolling bearing 22. The eccentric wheel 23 is fastened to the engine block EW by a fixing bolt 26 penetrating through a slide bearing 25 fitted in an eccentric hole 24 provided in the eccentric wheel 23. A hydraulic damper 28 is disposed between the eccentric wheel 23 and the opposing surface of the engine block EW so as to be accommodated in the umbrella of the tension pulley 21. The eccentric pulley configured as described above includes a tension adjusting spring 51 described later to form a belt tension adjusting device.

As shown in FIG. 2, the hydraulic damper 28 accommodates a plunger 31 movably in the axial direction in a liquid chamber 30 provided in a damper cylinder 29, and is coupled to one side of the damper cylinder 29. The sub-reservoir chamber 33 and a mounting member 34 are provided on the side of the sub-reservoir chamber 33. The plunger 31 is provided so that the left end of a reservoir chamber 35 provided inside along the axis communicates with a pressure chamber 36 formed at the left end of the liquid chamber 30 via a passage 37. A check valve 38 is provided at the left end of the passage 37 with respect to the plunger 31.
The return coil spring 39 is contracted.

The right end of the plunger 31 has a rod insertion hole, and the rod 6 having the left end inserted into the rod insertion hole.
2 is loosely guided by the wear ring 63 so as to be freely movable in the axial direction, and the right end portion penetrates the oil seal 65 and protrudes outward (to the right end) from the damper cylinder 29. The sub-reservoir chamber 33 is provided at a right angle to the liquid chamber 30, and the opening end of the sub-reservoir chamber 33 is in close contact with a rubber cap 42. The hydraulic damper 28 is filled with an amount of hydraulic oil (oil) that fills the whole of the reservoir chamber 35 and the pressure chamber 36 and a part of the inside of the sub-reservoir chamber 33, and the upper space of the sub-reservoir chamber 33 becomes the air chamber. It is arranged so that it becomes.

As shown in FIG. 2, the hydraulic damper 28 has a mounting member 34 through which the fixing bolt 26 penetrates, and
2 is fixed so that the sub-reservoir chamber 33 faces upward, the hydraulic oil is set to such an amount as to leave an air space above the sub-reservoir chamber 33, and the rod projecting portion is Abuts on a pin 47 projecting from The hydraulic damper 28 has a sub-reservoir chamber 33 at a side of the liquid chamber 30.
, The entire length of the rod 62 can be shortened, whereby the entire hydraulic damper 28 can be reduced in size and housed in the umbrella of the tension pulley 21, and the clearance W 1 between the tension pulley 21 and the engine block 27 can be reduced.
Can be reduced (see FIG. 1).

On the other hand, the eccentric wheel 23 supporting the tension pulley 21 is provided with a pin 46 having the projection 32 penetrated.
A concave hole 48a is provided in which a loose fit is provided. In this concave hole 48a, as shown in FIG. A spring 51 is contained. A sliding member 71 formed of a synthetic resin in a cylindrical shape is provided in the lateral hole 49, and a tip end of a tension adjusting spring 51 provided in the sliding member 71 is provided in the axial direction with respect to the sliding member 71. The cap member 72 held movably is fitted inside, and the cap member 72 is brought into contact with the pin 46.

In FIG. 3, the tension adjusting spring 51 is a double coil spring. However, a single coil spring may be used. The cap member 72 is inserted into the sliding member 71 so as to be movable in the axial direction, and these are embedded in a concave hole 48 a provided in the eccentric ring 23.

Reference numeral 53 in the drawing denotes a hexagonal hole for resetting provided in the eccentric ring 23, and the eccentric ring 2 is provided by a hexagon wrench.
When the plunger 31 is pushed in by applying a torque to the belt 3, the belt A is hung on the pulley 21 in this state, and when the hexagon wrench is released, the pulley 21 moves in the direction in which the belt A is pushed, and the set state is established. FIG. 4 is an exploded perspective view for easy understanding of the above mechanical configuration. The relationship with the hydraulic damper 28 incorporated in the tension pulley 21 is understood from FIG.

The belt tension adjusting device is provided with a position detecting mechanism for detecting the movement (displacement) of the position of the pulley 21. As shown in the figure, a magnet 91 swings around the fixing bolt 26 in conjunction with the movement of the tension pulley 21.
Is detected by a magnetic sensor 93, and an eccentric wheel 23 which is an inner member in the pulley 21 and a hydraulic damper 2
The mounting members 34 are mounted using the respective opposite end surfaces of the mounting members 34. This means ease of production, maintenance and inspection,
The ease of replacement work is taken into account.

The magnetic sensor 93 and the magnet 91 (91a, 91a,
In the position detecting mechanism 91b), the rotational movement amount of the tension pulley 21 is measured by the magnetic sensor 93 as an analog amount. The measurement signal is detected by the detection circuit 10 and is output to the engine control unit after performing electrical processing. Note that the detection circuit 10 is omitted,
The measurement signal may be output directly to the engine control unit.

The magnetic sensor 93 and the magnet 91 (91a,
The mounting position of the magnet 91b is
Is provided so that the magnetic sensor 93 responds to magnetism directed in the axial direction of the eccentric wheel 23 of the inner member. Further, the magnetic sensor 93 is located at a predetermined radius position from the eccentric position of the eccentric wheel 23.
And a magnet 9 is provided on a trajectory moving along the predetermined radius.
1 is provided. As the magnetic sensor, a type using a Hall element is used, and a magnet is used as an operating piece that has a magnetic effect to detect a change in movement of an object with respect to the magnetic sensor.

The mounting member 34 of the hydraulic damper 28 has a hole 98.
a is opened, and a sensor unit 97a in which the magnetic sensor 93 is molded is attached thereto. An eccentric wheel 23 made of an iron-based magnetic material has two magnets 9 on its end face.
1a and 91b are embedded, and a ring (O-ring) 92 made of a nonmagnetic material is embedded around the magnet. FIG. 7A is a partially enlarged view of FIG. The magnets 91a and 91b are magnetized in the axial direction of the eccentric wheel 23, and are arranged so that the polarities appearing on the surfaces thereof are different.

The reason for this is that the presence of the non-magnetic material prevents the magnetic path from leaking without closing the magnetic path in the eccentric ring 23, thereby making it easier to reach the magnetic sensor 93. The magnet may be a ferrite-based or neodymium-based magnet.
It is preferable to use a system, and the output change with respect to a temperature change is small.

The ring 92 may be made of non-magnetic stainless steel. In this case, the inner diameter of the ring 92 and the magnets 91a,
A gap is provided with the outer diameter of the eccentric ring 1b and the eccentric ring 23 is fixed with an adhesive. As a method for fixing the ring 92 without using an adhesive, a resin ring 92 ′ may be used as shown in FIG. 7B. It is fixed using the elastic deformation of the resin ring. The resin material is nylon or PBT
An engineering plastic such as a resin that can sufficiently withstand the use environment of the engine is preferable.

To mount the magnets 91a and 91b and the ring 92, a hole smaller than the outer diameter of the resin ring 92 'is provided in the eccentric ring 23, and the inner diameter of the resin ring 92' is
a, slightly larger than the outer diameter of 91b. Magnet 91
a, 91b in the center of the hole, the eccentric ring 2
3 adsorbed. When the resin ring 92 'is pressed into the gap between the magnet and the hole, the resin ring 92' is fixed to the eccentric ring, and the magnet is also fixed by deformation of the resin at the time of press-fitting.

In order to secure the detection accuracy when detecting the movement of the position of the pulley 21 by the position detection mechanism, in this embodiment, an eccentric wheel of one of the types shown in FIGS. Suppression means for suppressing a change in the gap between the bolt and the fixing bolt. (A) In the form of the figure, the fixing bolt 26
Large-diameter portion shorter form the width L ₁ of the sliding bearing 25 from L _2, is inserted an O-ring 27 into the gap δ as an elastic member. Determining the dimensional relationship of L ₁ and L ₂ the flange portion 26b of the fixing bolt 26 in relation to press as to abut directly on the O-ring 27 slightly elastically deform the O-ring 27.

The sliding bearing 25 can be made of PTFE resin or the like. The sliding bearing 2 is provided by such a restraining means.
5, the end surface of the bearing 25 is attached to the mounting member 34.
, And the fluctuation of the eccentric ring 23 is suppressed within a small fluctuation range within the elastic deformation of the O-ring 27, whereby the axial distance between the magnets 91 a and 91 b and the magnetic sensor 93 is made substantially constant. Can be kept. (B) The figure is (a)
It is a partial modification of the figure. In this example, it is provided with O-ring 27 and the washer 27a in the gap δ between the width dimension L ₁ of the larger diameter portion L ₂ and the bearing 25.

The washer 27a is also made of BEAREE resin. Depending on the amount of elastic deformation of the O-ring 27, the end surface (right side in the figure) of the eccentric shaft 23 is in a state of being slightly separated from the surface of the washer 27a, or the washer 27a.
Lightly in contact with the surface of. (C) is a partially modified example of the example shown in (b), and includes an O-ring 27 and a washer 27.
a is provided on both sides of the slide bearing 25.

(D) shows an example in which the members shown in (a) and (b) are used together, and an O-ring 27 and a washer 27 are shown on the left side.
a, an example in which only the O-ring 27 is provided on the right side. In the above four examples, the large-diameter portion dimension L ₂ of the fixing bolt 26 is used.
The movement of the eccentric ring 23 in the axial direction is restricted within a predetermined range via an elastic member within the range described above, and the detection accuracy by the position detection mechanism can be ensured.

The predetermined range in which the axial movement of the eccentric ring 23 is suppressed is determined by a displacement which can be detected within a range permitted by the magnetic sensor to detect the rotational movement (displacement) of the tension pulley. It must be set to be inside. Specifically, it is desirable to set the amount of displacement of the eccentric wheel 23 to 0.1 mm or less.

The first type of the compact type constructed as described above
The operation of the belt tension adjusting device provided with the eccentric pulley of the embodiment is as follows. When the tension of the belt A increases in the state shown in FIG. 2, the tension pulley 21 and the eccentric wheel 23 rotate clockwise in FIG.
The rod 62 and the plunger 31 are pushed in. When the plunger 31 is pushed in, the hydraulic oil in the pressure chamber 36 moves from the leak gap between the plunger 31 and the inner peripheral surface of the liquid chamber 30 to the reservoir chamber 35 to buffer the operation of the plunger 31. The hydraulic oil that has moved to the reservoir chamber 35 passes through the passage 4
1 enters the sub reservoir chamber 33. The plunger 31
It stops at the balance point between the tension of the belt A and the spring force of the tension adjusting spring 51.

On the other hand, when the tension of the belt A decreases, the tension pulley 21 and the eccentric wheel 23 rotate counterclockwise from the state shown in FIG. 2, and as shown in FIG.
1 is extended, and the swing of the tension pulley 21 stops at the balance point between the tension adjusting spring 51 and the tension of the belt A. At this time, since the pin 47 of the eccentric wheel 23 moves in a direction away from the plunger 31, the plunger 31 moves in a direction in which the rod 62 follows the movement of the pin 47 by the pressing of the return coil spring 39. In this case, since the check valve 38 opens the communication passage 37, the reservoir chamber 35
The hydraulic oil in the sub-reservoir chamber 33 flows into the pressure chamber 36 and the hydraulic oil in the sub-reservoir chamber 33 flows into the reservoir chamber 35.
1 follows the movement of the pin 47 promptly.

When the belt tension adjusting device operates as described above, the position detecting mechanism detects the movement (displacement) of the eccentric wheel 23 based on a change in the operation of the magnetic sensor 93 and the magnet 91.
Thus, a change in the position of the pulley 21 is detected. Although not shown, the tension of the belt A increases and the eccentric ring 23
Rotate, and the amount of eccentricity becomes maximum when the pulley 21 moves to the left most. In the initial state shown in FIGS. 2 and 3, one of the magnets 91a and the magnetic sensor 93 are closest to each other. The penetrating magnetic flux is maximum. As the belt A extends from this state, the magnet 91a and the magnetic sensor 93 are separated, and the magnetic flux passing through the magnetic sensor decreases.

FIG. 5 shows the positional relationship between the other magnet 91b and the magnetic sensor 93 when the rod 62 projects to the maximum. As described above, the tension pulley 21 swings and the magnetic flux passing through the magnetic sensor 93 decreases as the belt A extends, but when a certain point (near the middle between both magnets) is exceeded, the magnets 91b having different polarities approach each other. The magnetic flux passing through the magnetic sensor 93 is in the opposite direction. Therefore, if an analog output Hall sensor is used as the magnetic sensor 93, the position of the eccentric wheel 23 can be continuously detected at all times.

As described above, the amount of movement of the eccentric wheel 23 by the belt tension adjusting device is detected continuously or in multiple points by the magnetic sensor 93, whereby the change in the position of the pulley 21 can be detected. when the maximum protruding point to the eccentric wheel 23 of the rod 62 of Figure 5 from the initial state shown in 3 illustrating a movement of the center position 23 _P of the eccentric wheel 23 in the case where the mobile is shown in FIG. Center position 23 _P is fixed bolt 2
The horizontal axis X passing through the center position 23 _P in the initial state around the center 6
The maximum movement amount moves to the position 23 _PL where the intersection occurs, which indicates the limit position.

Accordingly, the movement amount of the rod 62 and the eccentric ring 23
The relationship between the center position 23 _{P and} the movement amount (X axis) is determined by the geometric shape of the fixing bolt 26, the eccentric ring 23, and the pulley 21. In this case, the position of the eccentric wheel 23 can be detected by converting the amount of movement of the eccentric wheel 23 into an electric signal.

When detecting the movement of the position of the eccentric wheel 23 by the position detecting mechanism, the magnetic sensor 93 provided on the mounting member 34 and the magnet 9 mounted on the end face of the eccentric wheel 23 are used.
Although the above-mentioned suppressing means is provided so as to prevent the axial distance from 1a and 91b from changing, the effect of providing such a suppressing means is examined. The detection results obtained by the position detection mechanism were compared for the case where no means was provided. FIG. 9 shows the detection results. In the figure, the detection results indicated by symbols a, b, and c indicate the following states.

A: When the mounting member 34 and the eccentric wheel 23 are closest to each other (the gap δ in FIG. 8 or δ ₁ and δ ₂ are designed dimensions)
(The magnetic sensor 93 and the magnets 91a and 91b are closest to each other in the axial direction.) B: When the gap δ or δ ₁ + δ ₂ is 0.4 mm larger than a. C: Gap δ or δ ₁ + δ ₂ compared to a. Is 0.8 mm larger. The graph of the measurement results shows the amount by which the center of the pulley 21 (point 23p in FIG. 6) rotates and moves in accordance with the extension of the rod of the hydraulic damper 28. Shows the relationship with the output when using.

As can be seen from the figure, curves b and c are obtained by changing the distance between the magnet surface and the magnetic sensor with respect to curve a.
When the position of the tension pulley is calculated from the value of the sensor, if the gap δ (δ ₁ + δ ₂ ) fluctuates in the axial direction, the calculated value may cause an error. Is shown. Accordingly, if the amount of movement of the pulley 21 in the axial direction is strictly suppressed by providing the suppression means so that the rotational movement amount of the pulley 21 becomes the curve a, the accurate movement amount of the center of the pulley 21 can be obtained with high reliability. Obtainable.

FIG. 10 shows another modification of the suppression means of FIG. In this example, the width L of the sliding bearing 25 is
₁ and the length L ₂ of the large diameter portion of the fixing bolt 26 (L ₂ > L ₁ )
Between the washer 27a and the disc spring 2 as an elastic member.
7 'is inserted. A wave washer may be used instead of the disc spring. Further, the washer 27a may be omitted.

In the above-described embodiment, various types of elastic members are used as the suppressing means for suppressing the axial movement of the eccentric ring 23. The reason for providing this elastic member is to suppress the fluctuation of the gap described above. In addition, it has the following significance.

That is, as described above, the eccentric wheel 23 is fixed by the fixing bolt 26. However, in order to make the eccentric wheel 23 swingable, it is necessary to provide a gap in the axial direction and loosely mount the eccentric wheel 23. . The distance between the sensor 93 and the magnets 91 (91a, 91b) also fluctuates by the amount of the gap, but since this fluctuation affects the detection accuracy of the sensor, it is desirable to minimize the fluctuation. However, increasing the dimensional accuracy of the component to reduce the gap increases the cost. Therefore, in this embodiment, it is possible to set the gap to be small by interposing an elastic member and utilizing its elastic deformation without increasing the dimensional accuracy of each component such as the eccentric wheel 23 and the fixing bolt 26. It was done.

FIGS. 11 to 13 show the configuration of the belt tension adjusting device according to the second embodiment. This embodiment is an example in which a hydraulic damper 28 ′ having a tension adjusting spring is arranged outside the umbrella of the tension pulley 21, and the position detecting means is provided in the tension pulley 21. The same functional members as in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted. The description will focus on the characteristic configuration of this embodiment. The main configuration of the tension pulley 21, the rolling bearing 22, and the eccentric ring 23 is the same as that of the first embodiment, but the mounting means of the tension pulley 21 is slightly different.

The eccentric ring 23 has an eccentric hole 2 provided at an eccentric position.
A sleeve 81 is provided in the slide bearing 25 fitted to the mounting member 4, and the fixing bolt 26 is inserted through a through hole provided at an eccentric position of the sleeve 81 via a washer 82, and the mounting member 34 is provided.
And is screwed into the engine block EW via the mounting hole.

The sleeve 81 provided at an eccentric position with respect to the eccentric wheel 23 is fixed to the fixing bolt 26 through the eccentric position.
As shown in FIG. 12, the center of the eccentric ring 23, the center of the sleeve 81, and the center of the fixing bolt 26 are on the same vertical line as shown in FIG. Since the belt lengths are different at the time of assembling and mounting the eccentric pulley, the center is moved so that the center of the sleeve 81 can be adjusted to the position corresponding to the belt length. The assembly procedure will be further described later.

As shown in FIG. 13B, the sleeve 81 protrudes from the eccentric ring 23 and has a length that can be inserted into the mounting member 34. A circumferential groove is provided on the outer periphery of the insertion end, and a plurality of pins are fitted into small holes provided on the outer periphery of the mounting member 34 toward the center of the sleeve 81 so that the sleeve 81 is attached to the mounting member 34. Fixed to An arm 21a is attached to an end surface of the eccentric wheel 23 on the attachment side by a bolt 21b.
a extends to the outside of the tension pulley 21.

The outer end of the arm 21a has an L-shaped receiving member 2
1a 'is provided, and the rod 62 of the hydraulic cylinder 28' abuts on the receiving member 21a ', whereby the arm 21a
By pressing, the tension pulley 21 rotates around the sleeve 81. Hydraulic cylinder 2
Although not shown in detail, 8 'is a known type having a tension adjusting spring in a cylinder unlike the first embodiment, and the auxiliary reservoir chamber 23 is not provided.

As shown in FIG. 12 and FIG.
4, a sensor block 34a is integrally formed, and a sensor unit 97a in which a magnetic sensor 93 is molded with resin in a hole 98a provided in the block 34a.
Is inserted and fixed. Two magnets 91a and 91b are embedded at a predetermined interval in the end face of the eccentric wheel 23 so as to face the magnetic sensor 93.
Reference numeral 91 b is fixed by a resin ring 92.

The two magnets 91a and 91b are positioned at the reference position shown in FIG.
3 and a position where the other magnet 91 b faces the magnetic sensor 93 when the tension pulley 21 rotates around the sleeve 81 and moves a maximum distance so as to protrude rightward from the reference position. It is arranged in. The sensor block 34a shown in FIG.
However, the eccentric ring 23 is slidable in a state where there is no gap on the surface facing the end face of the eccentric ring 23, and the two are not integrally formed.

As shown in FIG. 13B, the eccentric ring 2
O-rings 27 are provided on both sides of the slide bearing 25 as means for suppressing the amount of movement of the eccentric ring 23 in the axial direction between the slide bearing 25 interposed between the sleeve 3 and the sleeve 81 and the fastening portion with the fixing bolt 26. Are provided respectively. Fixing bolt 26
Is an O-ring 2 at the end face of the head 26b through a washer 82.
7, the elastic bearing presses the sliding bearing 25 to abut the end face of the mounting member 34 via the other O-ring 27.

The width L ₁ of the slide bearing 25 and the two O-rings 2
7, the width of the eccentric ring 23 including the gaps δ ₁ and δ ₂ is L _2, and the width of the eccentric ring 23 is formed to be slightly smaller than L _2. Although it is rotatable via the contact surface 23a, it is designed so that movement in the axial direction is minimized. Reference numeral 83 in FIG. 12 is a small hole for inserting a pin (not shown) for temporarily fixing the mounting member 34 and the eccentric ring 23 so as not to rotate relatively until the assembly is completed.

When attaching the tension pulley 21 to the engine block, as shown in FIG. 13B, a bearing 22, an eccentric ring 23,
The slide bearing 25 and the sleeve 81 are inserted, the attachment member 34 is attached to the tip of the sleeve 81, and the attachment member 34 and the eccentric ring 23 are connected by pins so as not to rotate relative to each other. Is inserted into the sleeve 81, attached to the engine block EW, and fixed by screwing the fixing bolt 26.

At this time, before the tension bolt 21 is fixed by final tightening with the fixing bolt 26, the sleeve 81 is still loosened while the fixing bolt 26 is still loose.
The sleeve 81 is slightly rotated about the center to adjust the position of the sleeve 81. The rotation of the sleeve 81 is performed by rotating the tip of a washer 82 press-fitted and fixed to the outer surface of the sleeve. Even if the belts are manufactured with the same dimensions, the lengths of the individual belts have individual differences and do not always exactly match the design dimensions.

For this reason, if the sleeve 81 is fixed at the reference position shown in FIG. 12, if the belt length is longer or shorter than the reference length, it cannot be optimally handled. Therefore, at the time of actual mounting, the position of the tension pulley 21 is adjusted until the tension of the belt becomes appropriate.
The belt tension is adjusted by rotating the fixing bolt 26 located at an eccentric position with respect to 1 and rotating it.

During the above-mentioned position adjusting operation, since the pin is inserted between the eccentric wheel 23 and the mounting member 34, the relative rotation is locked, and thus the tension of the belt is adjusted. Even if the sleeve 81 is rotated,
The positional relationship between 1a and 91b and the magnetic sensor 93 does not change.

When the adjustment is completed and the tension pulley 21 is fixed to the engine block EW by the fixing bolt 26, the mounting member 34 and the sleeve 81 are fixed to the fixing bolt 26.
As a result, the mounting member 34 and the sleeve 81 cannot be rotated. In this state, the pin inserted between the eccentric ring 23 and the mounting member 34 is pulled out, and the eccentric ring 2
3 enables relative rotation.

Accordingly, when the belt subsequently extends due to the operating distance or aging, the rod 62 of the hydraulic cylinder 28 ′ extends to push the arm 21 a of the tension pulley 21, and the pulley 21 rotates around the sleeve 81. Therefore, the positions of the magnets 91a and 91b relatively change with respect to the magnetic sensor 93, and the output of the magnetic sensor 93 changes, so that the change in the position of the pulley 21 is detected continuously or in multiple points. Become.

The basic operation of the belt tension adjusting device having the above-described configuration is the same as that of the first embodiment, and therefore, the description of the first embodiment will not be repeated.
Further, the configuration example of the suppressing means in FIG. 8 and the format different from that in FIG. 13B and the configuration example in FIG. 10 are also applied to the second embodiment. Further, the setting of the predetermined range in which the movement of the eccentric wheel 23 in the axial direction is suppressed by the suppression means is the same as that in the first embodiment. Magnetic sensor 93, magnet 91 (91
It goes without saying that the arrangement relationship of a, 91b) is set similarly. Further, the elastic member of the restraining means also has a function of keeping the gap constant without increasing the dimensional accuracy of the component, as in the first embodiment.

[0067]

As described above in detail, the eccentric pulley according to the present invention rotatably supports the tension pulley with the inner member, and detects the position of the tension pulley with the magnetic sensor. The belt tension adjusting device using this eccentric pulley is provided with a tension adjusting spring and a hydraulic damper so that the tension can be adjusted freely. By detecting the movement of the tension pulley to the limit position, it is possible to know the timing belt replacement time. The detection signal is sent to the control circuit (computer) and displayed on the display, so that the timing belt replacement time and abnormality are detected. Can be displayed. In addition, since the change in the gap between the fixing member and the inner member is suppressed to a minimum by the suppression means, the above display can be performed with high reliability, and the maintenance and inspection and replacement of the detection means can be performed. Advantages such as easy work can be obtained.

Further, when the operating piece is a magnet, this magnet is fixed to the inner member via a non-magnetic member,
The magnetism generated by the magnet can be detected by the magnetic sensor with high sensitivity, and the detection accuracy of the position of the eccentric pulley can be improved.

Further, a sleeve having an eccentric hole is rotatably inserted into the hole provided at the eccentric position of the inner member so that the swing angle after the eccentric pulley is assembled can be reduced. The belt tension adjusting device can be provided so that it can be assembled so as to obtain the maximum, and the timing belt replacement time can be extended.

[Brief description of the drawings]

FIG. 1 is a main cross-sectional view of a belt tension adjusting device according to a first embodiment.

FIG. 2 is a side view taken along the line II-II in FIG.

FIG. 3 is a side view as viewed from an arrow III-III in FIG. 1;

FIG. 4 is an exploded perspective view of the same device.

FIG. 5 is an explanatory diagram of an operation.

FIG. 6 is an explanatory diagram of an operation.

FIG. 7 is a partially enlarged view of an arrangement configuration of a magnetic sensor and a magnet.

FIG. 8 is a partially enlarged view of a basic example and a modified example of the configuration of the suppressing means for suppressing the gap between the slide bearing and the fixing bolt.

FIG. 9 is a graph of a measurement result of a gap between the slide bearing and the fixing bolt.

FIG. 10 is a partially enlarged view of another modified example of the suppressing means of FIG. 8;

FIG. 11 is a side view of a belt tension adjusting device according to a second embodiment.

FIG. 12 is a side view corresponding to FIG.

FIG. 13 is a sectional view taken along arrows aa and bb in FIG. 12;

FIG. 14 is a schematic layout diagram in which a belt tension adjusting device is used.

FIG. 15 is a main sectional view of a conventional belt tension adjusting device.

[Explanation of symbols]

 21 Tension Pulley 23 Eccentric Wheel 26 Fixing Bolt 27 Engine Block 28 Hydraulic Damper 29 Damper Cylinder 30 Liquid Chamber 31 Plunger 33 Sub Reservoir Chamber 35 Reservoir Chamber 36 Pressure Chamber 38 Check Valve 39 Return Coil Spring 46 Fixing Pin 47 Pin 51 Tension Adjusting Spring 62 Rod 63 Wearing

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3J049 AA03 BB05 BB12 BB16 BB17 BB23 BB26 BC03 BC08 BG10 CA02

Claims (11)

[Claims] An inner member rotatably supported by a fixed member at an eccentric position rotatably supports a tension pulley, and a magnetic sensor for detecting a position of the tension pulley and an operation piece are provided. An eccentric pulley configured to suppress a change in a gap set between fixed members and to suppress a change in a gap between the magnetic sensor and the operation piece. 2. The method according to claim 1, wherein the suppressing means is an elastic member interposed between the inner member and the fixed member, and the elastic member is elastically deformed to reduce a gap in the pulley axial direction between the inner member and the fixed member within a predetermined range. 2. The method according to claim 1, wherein
The eccentric pulley according to 1. 3. The magnetic sensor according to claim 1, wherein the inner member is attached to the mounting member so as to face the mounting member, and the magnetic sensor responds to magnetism generated by the operating piece on the opposite end surface of the mounting member and the inner member. The eccentric pulley according to claim 1 or 2, wherein a rotational change of the tension pulley is detected by detecting a change in magnetism due to rotation of the inner member. 4. A magnetic sensor is provided at a predetermined radius position from the eccentric position of the inner member, and the acting piece rotates along the predetermined radius and the magnetic sensor responds to detect the rotational displacement of the tension pulley. 2. The method according to claim 1, wherein
An eccentric pulley according to any one of claims 1 to 3. 5. A predetermined range in which the gap in the pulley axial direction is suppressed by the elastic member is within a displacement that can be detected within a range of an error allowed in the detection accuracy of the rotational displacement of the tension pulley by the magnetic sensor. The eccentric pulley according to any one of claims 2 to 4, wherein the eccentric pulley is set as follows. 6. The eccentric pulley according to claim 2, wherein the elastic member is an O-ring. 7. The eccentric pulley according to claim 2, wherein said elastic member is a disc spring or a wave washer. 8. The eccentric pulley according to claim 1, wherein the action piece is a magnet, and the magnet is fixed to an inner member via a non-magnetic member. 9. The eccentric pulley according to claim 8, wherein the non-magnetic member is a synthetic resin molded product. 10. The inner member according to claim 1, wherein a sleeve having an eccentric hole is rotatably inserted into the hole provided at the eccentric position of the inner member. Eccentric pulley. 11. A belt tension adjusting device provided with a tension adjusting spring and a hydraulic damper for displacing the eccentric pulley according to any one of claims 1 to 10 via an inner member so that the tension can be adjusted.