JPH01247859A - Automatic tensioner - Google Patents

Abstract

PURPOSE:To facilitate fitting work for an automatic tensioner and to obtain required tension setting characteristics by providing an engaging arm portion projecting outside at the end of a fixing member and providing the screw hole of a fixing portion on the turning track of the bolt hole of the fixing member. CONSTITUTION:An engaging arm portion 14b projecting outside is provided at the end portion of the fixing portion 10 side of a fixing member 11. A pin hole 15 in which a pin 16 is fitted is formed in the arm portion 14b. The screw hole 10a of the fixing portion 10 is provided on the turning track of the bolt hole 15 of the fixing member when the fixing member 11 is turned round the engaging pin 16 under a state that the pin hole 15 of the arm portion 14b is fitted to the engaging pin 16. Thus, fitting work is easy and the fixing member 11 is easily fixed to a position where required tension setting characteristics can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to an autotensioner, more specifically, to tensioning a timing belt or the like applied between a crankshaft boob and a camshaft boob of an automobile engine. Regarding the auto tensioner to be adjusted.

BACKGROUND OF THE INVENTION Timing belts are used in automobile engines to rotate the crankshaft and camshaft in synchronization, and autotensioners have been developed to adjust the tension of the timing belts.

As an example of this type of auto-tensioner, a movable eccentric member corresponding to the inner ring of a bearing is attached around a cylindrical fixed member fixed with bolts to a fixed part such as an engine block so that the movable eccentric member can rotate freely. An idler corresponding to the outer ring of the bearing is rotatably attached to the outside of the eccentric member.
It is known that the idler is brought into pressure contact with the timing belt by a spring attached between a fixed part and an eccentric member, and the tension of the belt is adjusted by swinging the idler about a fixed shaft.

Problems to be Solved by the Invention When assembling the auto tensioner as described above to an engine, place the fixing member on top of the engine block, approximately align the bolt holes of the fixing member with the screw holes of the engine block, and insert the bolts into the fixing member. After passing it through the bolt hole, you need to find the screw hole in the engine block. At this time,
Since the bolts are passed through bolt holes in the fixing member, the screw holes in the engine block cannot be visually confirmed, making assembly difficult.

Furthermore, when tightening the bolt, the fixing member may rotate together, and as will be explained next, the autotensioner may not be able to be used within the appropriate tension setting range as designed. In other words, the above-mentioned autotensioner is used so that a desired constant characteristic (tension setting characteristic) can be obtained between the rotational displacement of the movable eccentric member and the tension of the belt, and within an appropriate tension setting range. Designed to be. The fixed member may be eccentric with respect to the bolt, and a stopper or the like may be provided between the fixed member and the movable eccentric member to restrict the rotation range of the movable eccentric member. In such a case, if the fixing position of the fixing member changes, the tension setting characteristics and tension setting range will change. Therefore, if the fixing member rotates when the bolt is tightened and its fixing position changes, the desired tension setting characteristic cannot be changed, and the autotensioner cannot be operated within the proper tension setting range.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an autotensioner that solves the above problems, is easy to assemble, and allows a fixing member to be easily fixed at a position where desired tension setting characteristics can be changed.

Means for Solving the Problems An autotensioner according to the present invention includes: a cylindrical movable eccentric member is eccentrically and rotatably attached around a cylindrical fixed member fixed to a fixed part by a bolt, and contacts the belt. In an auto tensioner, a cylindrical idler is rotatably mounted around a movable eccentric member, and a spring is provided between a fixed part and the movable eccentric member to bias the movable eccentric member in a direction in which the idler comes into pressure contact with a belt. , An engagement arm part protruding outward is fixedly provided at the end of the fixed part side of the fixed member, and a pin hole into which a pin fixed to the fixed part fits is formed in this arm part. When the pin hole is fitted into the engagement pin of the fixed part and the fixed member is rotated around this engagement pin, the screw hole of the fixed part is provided on the turning trajectory of the bolt hole of the fixed member. It is characterized by:

Function When assembling the auto tensioner, pass the pin hole of the engaging arm on the fixed member side through the pin on the fixed part, rotate the auto tensioner around this pin, and insert it through the bolt hole of the fixed member. Screw the bolt into the screw hole in the fixing part to secure it. At this time, since the screw hole of the fixing part is provided on the turning trajectory of the bolt hole of the fixing member, it can be easily found and the assembly operation is easy. Also, when tightening the bolt, the pin on the fixed part is passed through the pin hole in the engagement arm, so the fixed member does not rotate together. Therefore, the fixing position accuracy of the fixed member is improved, and the automatic The tensioner can be used within the appropriate tension setting range as designed.

Embodiments Hereinafter, embodiments in which the present invention is applied to a timing belt placed between a crankshaft and a camshaft of an automobile engine will be described with reference to the drawings.

1 to 4 show a first embodiment.

Fixed parts of the engine (e.g. engine block) (
10), a cylindrical fixing member (11) is attached to one bolt (
12). The bolt (12) is passed through the bolt hole (lla) of the fixing member (11), and the fixing part is closed! 0) is screwed into the screw hole (LOA).

A first side plate (13) is attached to the step formed at the distal end of the fixing member (11), and a second side plate (14) is attached to the step formed at the proximal end.
) are each fixed by press fitting.

The first side plate (13) has a disk shape, and its outer diameter is slightly larger than the outer diameter of the fixing member (11). The second side plate (14) is
A disc portion (14a) having a slightly larger outer diameter than the fixing member (11)
) is integrally formed with an engaging arm portion (14b) that protrudes radially outward. A pin hole (15) is formed in the arm portion (14b), and an engagement pin (1B) fixed to the fixed portion (lO) is passed through this hole (15). When the bolt (12) is not attached to the fixed part (lO), the fixed member (11) is attached to the engagement pin (
16), and at this time the fixed member (11)
Fixed part (lO) on the turning trajectory of the bolt hole (lla) of
A screw hole (10a) is provided.

A bushing (17) is fitted around the fixing member (11). The length of the bush (17) is the side plate (13) (1
4), and the outer diameter is slightly shorter than the mutual spacing of the first side plate (13).
and smaller than the outer diameter of the disk portion (14a) of the second side plate (14). Side plate (13) C14) around the bush (17)
In between, a short cylindrical movable eccentric member (18) is eccentrically and rotatably attached. A boss portion (18a) approximately concentric with the fixing member (11) is formed on the base end side of the eccentric member (18), and this boss portion (18a) and the eccentric portion (1
8b), an annular step (18c) is formed between them. A first side plate (13) is attached to the outer periphery of the tip surface of the eccentric member (18).
An annular protrusion (18d) located on the outside is integrally formed.

The gap between the outer peripheral surface of the bushing L (17) and the inner surface of the eccentric hole of the eccentric member (18) is kept to a minimum, and this part is filled with silicone oil with a viscosity of 100,000 cSt (25°C) or more. 0) is interposed, and the eccentric member (
The rotational torque of 18) is increased. Also Bushi:
Fixing member (11) and eccentric member (1B) on both sides of L (17)
) is provided with a seal (19) for sealing off the oil (0).

A cylindrical idler (20) is placed around the eccentric member (18).
is mounted so that it can rotate via a plurality of spherical rolling elements (21) but hardly move in the axial direction.

A short cylindrical portion (22a) of the bracket (22) is fitted around the boss portion (18a) of the eccentric member (18).

The bracket (22) is attached to the stepped portion (18) of the eccentric member (18).
The fixing pin (23) inserted into the eccentric member (c)
18) so as not to rotate.

A portion of the bracket (22) is bent toward the fixed portion (10) and then protrudes outward in the radial direction, and this portion serves as a spring attachment portion (22b). This spring mounting part (
22b) is provided with a hole (20) for mounting the spring;
24) and a spring attachment fixed to the fixed part (lO), both ends of the tension coil spring (20) are attached to the pin (25). The spring (2B) is attached to the eccentric member (18) by pulling the spring mounting portion (22b) of the bracket (22) clockwise in FIGS. 1 and 3.
energize the idler (20) and the timing belt (27
) is pressed against the surface without teeth (28) on the loose side.

The distance between the engine's crankshaft and camshaft varies with temperature, which causes the relative belt (2
7) Length changes. The belt (27) also expands and contracts due to changes in its own temperature, and elongates due to long-term use. As a result, the tension of the belt (27) tends to change, but the auto tensioner operates as follows to maintain the tension at a predetermined value.

First, when the tension of the belt (27) starts to decrease,
Due to the elastic force of the spring (28), the eccentric member (18) rotates around the fixed member (11) in a direction that approaches the belt (27) and increases the tension (counterclockwise in FIGS. 1 and 3). ,
Tension is maintained at a predetermined value.

On the other hand, if the tension of the belt (27) increases,
The eccentric member (18) moves away from the belt (27) against the elastic force of the spring (2B) and rotates in a direction to reduce the tension (counterclockwise in the figure), and the tension is maintained at a predetermined value. This °
When the belt (27) expands or contracts very slowly, the silicone oil (0) is applied to the eccentric member (18).
) rotation is not constrained. Also, belt (27)
The vibrations of the idler (20) and the eccentric member (18) due to the vibrations of the engine and vibrations of the engine are suppressed by the viscous resistance (shear resistance) of the silicone oil (0) against rotation.

The autotensioner described above is assembled, for example, as follows.

First, the pin hole (15) of the arm part (14b) on the fixed part (10) side of the auto tensioner is fitted into the engagement pin (1G) of the fixed part (10), and the belt (27) is hung on the engine. Note that the belt (27) may be put on first. Next, one end of the spring (28) is attached to the bracket (22), and the other end of the spring (28) is attached to the fixed part (
10) Spring installation is done by attaching it to the pin (25), and then attaching this spring (
2B), the idler (lO) is brought into pressure contact with the belt (27). Next, the bolt hole (lla) of the fixing member (11) is
), rotate the auto tensioner around the engagement pin (16), find the screw hole (10a) in the fixed part (to), and insert the bolt (12) into this screw hole (10a). and screw in the fixing member (11) to the fixing part (
1G). At this time, since the screw hole (lea) of the fixed part (lO) is provided on the turning trajectory of the bolt hole (lla) of the fixed member <11) centered on the engagement pin (15), this can be easily done. Easy to assemble.

5 to 8 show a second embodiment.

A fixing member (31) consisting of a cylindrical part (31a) and a flange part (31b) fitted into the distal end of the cylindrical part (31a) is attached to the fixed part (30) of the engine through the screw hole (31) of the fixed part (30).
It is fixed by a single bolt (32) screwed into 30a). One diameter above the flange part (atb),
A long piece (33
) is formed. The width of this long hole (33) is the bolt (
32) is slightly larger than the outer diameter of the shaft (32a) of the head (32).
32b) is slightly smaller than the outer diameter. Flange part (31b)
The space between the elongated part (33) and the cylindrical part (31a) serves as a bolt hole (34). A short cylindrical portion (35a) of a bracket (35) is fitted onto the base end of the fixing member (31). The bracket (35) has a fixing member (3
An engagement arm part (35b) extending in a direction perpendicular to the axis of 1) and the elongated hole (33) is integrally formed, and an engagement pin (35b) fixed to the fixed part (30) is attached to the tip end of the engagement arm part (35b).
A pin hole (37) is formed to be fitted in B). When the bolt (32) is not attached to the fixed part (3G), the fixed member (31) is attached to the engagement pin (3G).
), and at this time, on the turning trajectory of the bolt hole (30) of the fixed member (31), the screw hole (30) of the fixed part (30)
30a) is provided. In addition, the bolt (32) is passed through the bolt hole (30) of the fixing member (31) and the fixing part (
When the fixing member (31) is loosely fixed to the
) can pivot by the length of the elongated hole (33) around the engagement pin (3B).

A sleeve (38) is fitted around the fixing member (31) on the bracket (35) side. Fixing member (31
) is attached to the end of the sleeve (38) on the flange part (31b) side of the flange part (3
8a) are integrally formed, and these flange parts (31b
> A bush (39) is fitted between (38a). The length of the bush (39) is the flange portion (31b) (
38a), and the outer diameter is slightly shorter than the mutual spacing of 38a).
31b) smaller than the outer diameter of (Ha). A short cylindrical movable eccentric member (40) that is slightly shorter than the mutual spacing between the flange portions (31b) and (38a) is eccentrically and rotatably attached around the bush (39), and a portion of the movable eccentric member (40) is attached to the flange portion (38a).
31b> Extrudes from (38a). Bush (39
) and the inner surface of the eccentric hole of the eccentric member (40) is minimized, and silicone oil (0) with a viscosity of 100,000 cSt (25°C) or more is interposed in this part, for example. As a result, the rotational torque of the eccentric member (40) is increased.

In addition to the viscosity of the oil (0), this rotational torque is determined by the outer diameter and length of the bushing (39) and the size of the gap between it and the eccentric member (40). Also, bush (39
) between the fixing member (31) and the eccentric member (40) on both sides thereof, an O-ring (42) for sealing out oil (0) is provided.

A cylindrical idler (4) is arranged around the movable eccentric member (40).
4) is mounted so that it can rotate via a plurality of spherical rolling elements (45) but hardly move in the axial direction.

A torsion coil spring (4B) is attached around the short cylindrical portion (35a) of the sleeve (38) and the bracket (35). One end (46a) of the spring (46) is fixed to the end face of the eccentric member (40) on the fixed part (30) side.
b) The second spring receiver fixed to the fixed part (30) is hung on the pin (48). This spring (4B) biases the eccentric member (40) in the counterclockwise direction in FIGS.
) is pressed against the (1) surface of the teeth (50).

A semicircular pin engagement notch (51) is formed on the outer peripheral edge of the flange portion (31b) of the fixed member (31), and a corresponding pin insertion hole (52) is formed on the end surface of the eccentric member (40).
) is formed.

Assembling the belt (49) and the autotensioner are performed, for example, as follows.

First, fit the set pin (53) into the notch (51) of the flange portion (31b) of the fixing member (31), and insert it into the pin insertion hole (52) of the eccentric member (40). and the eccentric member (40) are fixed so that they do not rotate relative to each other. Also, one end (46a) of the spring (40)
) on the pin (47) of the first spring holder.

Fit the pin hole (37) of the arm part (35b) of the bracket (35) of this auto tensioner into the engagement pin (3B) of the fixed part (30), and as shown by the chain line in FIG. ), and with the auto tensioner turned and retracted to a position away from the belt (49), hang the belt (49) on the engine. At this time, since the entire autotensioner can rotate around the engagement pin (8B), even if the amount of eccentricity between the running member (31) and the eccentric member (40) is small, the idler (49) )
can be sufficiently separated from the belt (49), making the work easier. Once the belt is assembled, press the auto tensioner against the belt (49) and tighten the end of the spring (46) to the second
The spring receiver is fixed to the pin (48). In this way, the spring (4B) presses the autotensioner against the bell (49) with a constant force, so the fixing member (31
Pass the bolt (32) through the bolt hole (34) of ) and screw it into the screw hole (30) of the fixing part (30) to fix it. At this time as well, since the screw hole (30a) of the fixed part (30) is provided on the rotation locus of the bolt hole (34) of the fixed member (31) with the engagement pin (36) as the center, the bolt (30) 32) is easy to install. Finally, insert the set pin (53) into the pin insertion hole (52) and the notch (51).
extract from. This allows the eccentric member (40) to rotate around the fixed member (31), and the autotensioner starts operating. In this way, the fixing member (31)
The initial tension of the belt (49) can be easily set with the eccentric member (40) fixed with the set pin (53), and the auto tensioner is activated by simply removing the set pin (53) after setting. .

The operation of the autotensioner of the second embodiment is also similar to that of the first embodiment.

In order to interpose silicone oil in the gap between the bushing and the movable eccentric member, silicone oil may be applied to either or both of the outer peripheral surface of the bushing and the inner surface of the eccentric hole of the eccentric member, and then these are fitted together. In addition, a small spiral groove or a small groove parallel to the axis is provided on the outer peripheral surface of the bushing or the inner surface of the eccentric hole, and silicone oil is poured into this groove by placing the eccentric member in the bushing and rotating it. It is also possible to make it pervasive throughout. Furthermore, an annular groove may be provided on the outer circumferential surface of the bushing or on the inner surface of the eccentric hole to store silicone oil.

In the case of the autotensioner of the above embodiment, the vibration damping effect is exhibited by the viscous resistance of the silicone oil, so the performance is stable over a long period of time and there is no need to replenish the oil. Further, since the damper is built into the bush of the stationary member and the rotating portion of the movable eccentric member, the structure is extremely simple and compact, and is inexpensive and requires less space for installation.

In the above embodiment, the movable eccentric member is attached around the bush fixed to the fixed member, but the movable eccentric member may be attached directly around the fixed member. Furthermore, the configurations of other parts of the autotensioner are not limited to those of the above embodiments, and can be modified as appropriate.

Note that the autotensioner according to the present invention can of course be applied to belts other than timing belts for automobile engines.

Effects of the Invention According to the autotensioner of this invention, as described above,
Assembly is easy, especially bolt attachment, and the fixing member can be easily fixed at a position where desired tension setting characteristics can be changed.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an autotensioner showing a first embodiment of the present invention (FIG. 2 is a sectional view taken along the line 1-1), and FIG.
Figure 3 is a cross-sectional view taken along line ■-■ in Figure 2, Figure m4 is a cross-sectional view taken along line IV-IV in Figure 2, and Figure 5 is a cross-sectional view taken along line IV-IV in Figure 2.
A cross-sectional view of an autotensioner showing an embodiment (Fig. 6v-
Figure 6 is a cross-sectional view taken along line Vl--Vl in Figure 5, Figure 7 is a cross-sectional view taken along line ■-■ in Figure 6, and Figure 8 is a cross-sectional view taken along line Vl--■ in Figure 6.
It is a sectional view taken along the line -■. (1G) (80)...Fixed part, (11) (31)
... Fixed member, (12) (32) ... Bolt, (1
4b) ('15b)...Engagement arm part, (15) (
37)... Pin hole, (16) (36)... Engaging pin, (18) (40)... Movable eccentric member, (2G)
(44)...Idler, (26) (4B)...Spring, (27) (49)...Timing belt. Above Figure 6 Procedural Amendment Written October 7, 1988 Patent Office Commissioner Yoshi 1) Bun Yi va j-1, Indication of the case 1988 Patent Application No. 81528 2, Name of the invention Auto tensioner 3.11a correct Relationship with the case of the person who filed the patent application Patent applicant 4, name of agent (6087) Patent attorney Einosuke Kishimoto J'+ 4 others C., -'-1 5. Date of amendment order
(,<4.+,;- Number of claims increased due to 6.1. 8. Figure 3 of the amendment content sheet is amended as shown in the attached sheet.)

Claims (1)

[Claims] A cylindrical movable eccentric member is attached eccentrically and rotatably around a cylindrical fixed member fixed to a fixed part with a bolt, and a cylindrical idler that contacts the belt is the movable eccentric member. In an auto tensioner that is rotatably mounted around the fixed part and is provided with a spring between the fixed part and the movable eccentric member that biases the movable eccentric member in the direction in which the idler comes into pressure contact with the belt, An engaging arm part that protrudes outward is fixedly provided at the end, and a pin hole is formed in this arm part to fit a pin fixed to the fixed part. An auto tensioner characterized in that a screw hole in a fixed part is provided on a turning trajectory of a bolt hole in the fixed member when the fixed member is rotated around the engaging pin while being fitted on the pin.