JPH0842647A - Auto tensioner - Google Patents

Abstract

(57) [Abstract] [Purpose] The center line of the fixed shaft 2 and the center line of the pulley 10 are prevented from being non-parallel to each other, and the outer peripheral surface of the pulley 10 and the belt are prevented from being unbalanced. [Structure] A tip of a bolt 3 for fixing the fixed shaft 2 to a substrate is supported by a support bracket 18, and the fixed shaft 2 is supported in a double-sided manner. Further, the pressing arm 1 for transmitting the pressing force of the plunger 15 of the actuator 13 to the swing member 7.
2a is also supported on the swing member 7 in a double-sided manner.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The automatic tensioner according to the present invention is used, for example, to apply a predetermined tension to a timing belt of an automobile engine.

[0002]

2. Description of the Related Art In the case of an OHC type engine or a DOHC type engine, a timing belt is provided in order to rotate a camshaft provided in an upper part in synchronization with a crankshaft provided in a lower part of the engine. In order to keep the tension of the timing belt proper, a tension applying device called an auto tensioner has been conventionally used. 7-8,
1 shows an example of a conventionally known auto tensioner. First, this conventional structure will be described.

This auto tensioner is mounted on the front side (not shown) of a cylinder block, which is a fixed substrate, on the side portion of the timing belt 1 to which tension is applied. A cylindrical fixed shaft 2 is fixed to the front surface by a bolt 3 and a spacer 4. A slide bearing 6 made of oil-impregnated metal, synthetic resin, or the like is mounted between the collar portion 5 formed at the tip portion (lower end portion in FIG. 8) of the fixed shaft 2 and the spacer 4. The sliding bearing 6 supports the swinging member 7 swingably around the fixed shaft 2.

The rocking member 7 is formed of a heat-resistant material such as an aluminum alloy into a thick disk shape, and an outer peripheral surface 8 and an inner peripheral surface 9 are eccentric to each other. The inner peripheral surface 9 and the slide bearing 6 are in sliding contact with each other.
Therefore, when the swing member 7 swings around the fixed shaft 2, the outer peripheral surface 9 is displaced in a direction in which the outer peripheral surface 9 moves toward and away from the timing belt 1. A pulley 10 is rotatably supported by a bearing 11 around the swing member 7.
As the bearing 11, a deep groove type ball bearing is generally used, and an inner ring forming the ball bearing is externally fitted and fixed to the swing member 7. The outer ring may be omitted by fitting it inside the pulley 10 and forming an outer ring raceway directly on the inner peripheral surface of the pulley 10.

Further, a base end portion of the pressing arm 12 is fixedly coupled to a portion of the axial end surface of the swing member 7 which is separated from the fixed shaft 2. In the illustrated example, the pressing arm 12 is formed integrally with the swinging member 7, but a separate member may be joined and fixed by a screw or the like. The pressing arm 12 is bent in a substantially J-shape, and its tip end is positioned radially outward of the outer peripheral surface of the pulley 10.

Further, an actuator 13 for pressing the pulley 10 against the timing belt 1 is provided on the side of the pulley 10. This actuator 13
Is provided with a case 14 and a plunger 15. The plunger 15 is provided with an elastic force in a direction projecting from the inside by a spring built in the case 14. In addition, as such an actuator 13, preferably, an actuator having a built-in damper device is used. This damper device does not become a resistance when the plunger 15 is displaced in a direction projecting from the case 14, but becomes a resistance when the plunger 15 is pushed into the case 14. For an actuator incorporating such a damper, see, for example, Japanese Utility Model Laid-Open No. 60-182553.
It is well known in the past as described in Japanese Patent No.
Further, since it is not the gist of the present invention, detailed illustration and description thereof will be omitted.

The actuator 13 as described above is fixed to the front surface of the cylinder block by the bolts 17 and 17 which are inserted through the mounting flanges 16 and 16 provided on the outer surface of the case 14. And in this state, the plunger 1
The tip of 5 is elastically brought into contact with the tip of the pressing arm 12. In this state, the pulley 10 is pressed against the timing belt 1 by the elastic force of the spring built in the actuator 13, and the timing belt 1 is
Tension is applied according to the elasticity of the spring.

[0008]

However, in the case of the conventional auto tensioner configured and operating as described above,
A force in a direction that makes the center line of the pulley 10 and the center line of the fixed shaft 2 non-parallel is likely to be applied. When these center lines are not parallel to each other, the contact state between the outer peripheral surface of the pulley 10 and the outer peripheral surface of the timing belt 1 becomes non-uniform across the width direction, so-called one-side contact. Occurs, which causes the life of the timing belt 1 and the bearing 11 to be shortened.

The above non-parallelism between the center lines, which causes such inconvenience, occurs due to the following causes. A fixed shaft 2 for pivotally supporting the swing member 7 is supported in a cantilever manner on a substrate such as the front surface of the cylinder block. A pressing arm 12 for transmitting the pressing force of the plunger 15 to the swing member 7 is supported by the swing member 7 in a cantilever manner.

First, the reason why the above two centerlines are not parallel to each other will be described. The fixed shaft 2 is supported on the substrate in a cantilever manner, while a radial force is applied to the fixed shaft 2 from the timing belt 1 to push the fixed shaft 2 in a direction inclined with respect to the substrate. Be done.
As a result, unless the rigidity of the fixed shaft 2, the bolt 3 and the spacer 4 is increased, the fixed shaft 2 is inclined and the center lines are non-parallel to each other. Improving the rigidity of each of these members 2, 3 and 4 causes an increase in weight and a high cost.
Not preferred.

Next, the reason why the center lines are not parallel to each other will be described. For example, when the center of the contact portion between the plunger 15 and the pressing arm 12 is displaced from the center line α (FIG. 8) in the width direction of the contact portion between the outer peripheral surface of the pulley 10 and the outer peripheral surface of the timing belt 1. Is applied to the pulley 10 in a direction in which the center line of the pulley 10 is inclined with respect to the center line of the fixed shaft 2. As a result, unless the clearance precision of the plain bearing 6 is increased, the non-parallelism between the center lines occurs. This improvement in accuracy of the slide bearing 6 causes a cost increase, which is not preferable.

The moment does not theoretically occur if the center of the abutting portion is located on the center line α, but the tip end of the cantilever type pressing arm 12 is as shown in FIG. Easy to elastically deform. When elastically deformed, the direction of the force transmitted from the plunger 15 to the pressing arm 12 is inclined with respect to the center line of the plunger 15. As a result, an undesired thrust load or moment load is generated in the swing member 7 including the pressing arm 12, and the center lines are also non-parallel to each other. Even if the center lines are not parallel to each other due to such a cause, the rigidity of each of the members 2, 3, 4 is improved, or the clearance precision of the slide bearing 6 is improved,
Although it can be suppressed to such an extent that there is no practical problem, it is not preferable because it causes increase in weight and cost. The autotensioner of the present invention was invented in view of such circumstances.

[0013]

All of the autotensioners of the present invention, like the conventional autotensioner described above, include a fixed shaft having a base end portion coupled and fixed to a fixed substrate,
A swing member swingable around the fixed shaft, a pulley rotatably supported on the outer peripheral surface of the swing member via a bearing, and an axial end surface of the swing member from the fixed shaft. A pressing arm having a proximal end portion coupled and fixed to the disengaged portion, and a distal end portion thereof projecting outward in the diametrical direction from the outer peripheral surface of the pulley, and a plunger imparted with elasticity in a projecting direction from the inside of the case are provided. And an actuator fixed to the substrate at a position radially outward of the outer peripheral surface of the pulley. The tip of the plunger is elastically brought into contact with the tip of the pressing arm.

In particular, the autotensioner according to claim 1 was invented to prevent the center line of the fixed shaft and the center line of the pulley from becoming non-parallel due to the above-mentioned causes. And a support bracket having a base end portion fixedly coupled thereto. The tip of the fixed shaft is supported by the tip of the support bracket.

Further, the autotensioner according to a second aspect of the present invention is invented to prevent the center lines from being non-parallel to each other due to the cause described above. The pressing arms are separated from each other. A pair of connecting arm portions and a connecting portion that connects the base end portions of both the connecting arm portions are provided. And
One end of one coupling arm of the pair of coupling arms is on one end face in the axial direction of the swinging member, and the other end of the coupling arm is on the other end face in the axial direction of the swinging member. Each of them is fixedly coupled, and the tip of the plunger is in contact with the middle of the connecting portion.

[0016]

According to the autotensioner of the present invention configured as described above, the rigidity of each component is not particularly enhanced, or the precision of the bearing portion between the fixed shaft and the swing member is not improved. Also, it is possible to prevent the center line of the fixed shaft and the center line of the pulley from becoming non-parallel. First, in the case of the autotensioner according to claim 1, since the fixed shaft is supported by both the tip end portion and the base end portion in a double-sided manner, a radial belt is applied from a belt that applies tension such as a timing belt. The fixed shaft is unlikely to tilt regardless of the force applied in the direction. Therefore, the center line of the fixed shaft and the center line of the pulley are unlikely to be non-parallel.

Further, in the case of the autotensioner according to the second aspect, even if the tip end of the pressing arm is elastically deformed by being pushed by the tip of the plunger, this elastic deformation extends in the width direction of the swing member. Is symmetric. Therefore, regardless of the elastic deformation of the pressing arm, no moment is generated in the direction of inclining the center line of the swing member. Therefore, the center line of the fixed shaft and the center line of the pulley are unlikely to be non-parallel.

[0018]

1 and 2 show a first embodiment of the present invention corresponding to claim 1. The feature of the present invention is that a support bracket 18 for supporting the tip of the fixed shaft 2 is provided in order to prevent the fixed shaft 2 from tilting. Since the configuration and operation of the other parts are the same as those of the conventional structure described above, the same parts are designated by the same reference numerals, and the overlapping description will be omitted. Hereinafter, the characteristic part of the present invention will be mainly described.

The support bracket 18 is formed by pressing a metal plate having sufficient rigidity such as a steel plate into a crank shape. That is, the support bracket 18 includes a mounting plate portion 19 and a support plate portion 20 which are flat and parallel to each other.
A continuous plate portion 21 that is substantially perpendicular to both plate portions 19 and 20.
It is made continuous by. A pair of circular holes 22 and 22 are formed in the mounting substrate portion 19 among them. The distance between the two circular holes 22, 22 is equal to the case 1 of the actuator 13.
4 The intervals of the circular holes formed in the mounting flanges 16, 16 provided on the outer surface are matched. Further, one circular hole 23 is formed at the tip of the support plate portion 20, and the bolt 3 for fixing the fixed shaft 2 to the front surface of the cylinder block can be inserted into the circular hole 23.

When the autotensioner of the present invention having the support bracket 18 as described above is mounted on a fixed substrate such as the front surface of a cylinder block, the mounting substrate portion 19 is used.
The bolts 17 and 17 are inserted into the pair of circular holes 22 and 22 formed in 1. and the bolts 17 and 17 are directly inserted into the circular holes formed in the mounting flanges 16 and 16, respectively. Then, the bolts 17, 17 are screwed into the screw holes formed in the substrate and further tightened. In this state, the actuator 13 and the support bracket 18 are fixed to the substrate. Further, in this state, the circular hole 23 formed at the tip of the support plate portion 20 of the support bracket 18 is a screw hole formed on the substrate for screwing the bolt 3 for fixing the fixed shaft 2 into another screw hole. opposite.

When the fixed shaft 2 is fixed to the substrate, the bolt 3 inserted into the circular hole 23 at the tip of the support plate 20 is
Further, the fixed shaft 2 and the spacer 4 are inserted. Then, the bolt 3 is screwed into the other screw hole and further tightened. As a result, the fixed shaft 2 has its base end fixed to the substrate via the spacer 4, and its tip end fixed to the support bracket 1.
It is fixed to the support plate portion 20 of No. 8. That is, in the case of the present invention, the fixed shaft 2 is supported in a so-called double-supported type in which it is supported at two points, that is, the base end portion and the tip end portion.

As described above, in the autotensioner of the present invention, since the fixed shaft 2 is supported by both the front end and the base end in a double-sided manner, it is possible to use a tension belt such as a timing belt. The fixed shaft 2 is unlikely to tilt regardless of the force applied in the radial direction. Therefore, the center line of the fixed shaft 2 and the center line of the pulley 10 are unlikely to be non-parallel. As a result, even if the rigidity of the fixed shaft 2, the bolt 3, the spacer 4, etc. is not increased, it is possible to prevent the outer peripheral surface of the pulley 10 from hitting the belt in one-sided contact.

Next, FIGS. 3 to 4 correspond to claim 2.
2 shows a second embodiment of the present invention. The pressing arm 12a, whose base end is fixed to the swing member 7a, is made by press-molding a metal plate having sufficient rigidity such as a steel plate. The pressing arm 12a includes a pair of coupling arm portions 24, 24 that are parallel to each other and a coupling portion 25 that couples the proximal end portions (the left end portions in FIGS. 3 to 4) of the coupling arm portions 24, 24. Prepare The distance D between the two connecting arm portions 24, 24 is set to be larger than the thickness T of the pulley 10 (D> T), and the two connecting arm portions 2 are
The pulleys 4 and 24 do not interfere with the pulley 10.

Further, the tip ends of the two connecting arm portions 24, 24 are bent in a crank shape toward the axial end surface of the swinging member 7a to form connecting plate portions 26, 26, respectively. Then, these two connecting plate portions 26, 26 are connected and fixed to both axial end surfaces of the swinging member 7a by two screws, two screws in total. Such pressing arm 12
The rocking member 7a to which a is coupled and fixed is the same as in the case of the conventional structure described above, and the actuator 13 (see FIGS.
8 and 9) together with mounting on a substrate such as the front surface of the cylinder block to form the auto tensioner of the present invention. That is, the tip of the plunger 15 of the actuator 13 is abutted against the central portion of the connecting portion 25 to the swing member 7a,
Elasticity is applied in the direction of rotation around the fixed shaft 2.

In the case of the autotensioner of the present invention configured as described above, even if the connecting portion 25, which is the tip of the pressing arm 12a, is elastically deformed by being pushed by the tip of the plunger 15, this The elastic deformation is symmetrical over the width direction of the swing member 7a. Therefore, regardless of the elastic deformation of the pressing arm 12a, no moment is generated in the direction of inclining the center line of the swinging member 7a. Therefore, the center line of the fixed shaft 2 and the center line of the pulley 10 are unlikely to be non-parallel.

Next, FIGS. 5 to 6 show a third embodiment of the present invention in which the invention described in claim 1 and the invention described in claim 2 are combined. In the case of this embodiment,
The support bracket 18 supports the fixed shaft 2 in a two-sided manner to prevent the fixed shaft 2 from inclining due to the force applied to the pulley 10 from the belt, and at the same time, the pressing arm 12a having the pair of coupling arm portions 24, 24. Is used so that no moment is generated in the direction of inclining the center line of the swinging member 7. That is, in the case of the present embodiment, the working effect obtained by the first embodiment and the working effect obtained by the second embodiment are combined. The pressing arm 12a used in this embodiment is made by die-cast molding of an aluminum alloy, and its specific shape is slightly different from that of the above-described second embodiment.

[0027]

Since the autotensioner of the present invention is constructed and operates as described above, a high-performance autotensioner which does not cause partial contact between the pulley and the belt can be constructed in a light weight and the manufacturing cost is increased. Nothing.

[Brief description of drawings]

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

FIG. 2 is a plan view seen from above in FIG.

FIG. 3 is a partial plan view showing a second embodiment of the present invention.

FIG. 4 is a front view of a pressing arm.

FIG. 5 is a front view showing a third embodiment of the present invention.

FIG. 6 is a plan view seen from above in FIG.

FIG. 7 is a front view showing a conventional structure.

FIG. 8 is a plan view seen from above in FIG.

FIG. 9 is a partially enlarged plan view showing an elastically deformed state of a pressing arm.

[Explanation of symbols]

 1 Timing belt 2 Fixed shaft 3 Bolt 4 Spacer 5 Collar part 6 Sliding bearing 7, 7a Swing member 8 Outer peripheral surface 9 Inner peripheral surface 10 Pulley 11 Bearing 12, 12a Pressing arm 13 Actuator 14 Case 15 Plunger 16 Mounting flange 17 Bolt 18 Support Bracket 19 Mounting Substrate 20 Support Plate 21 Continuous Plate 22, 23 Circular Hole 24 Coupling Arm 25 Coupling 26 Coupling Plate

Claims (2)

[Claims] 1. A fixed shaft having a base end portion fixedly coupled to a fixed base plate, a swinging member swingable about the fixed shaft, and a rotating member mounted on a peripheral surface of the swinging member via a bearing. A freely supported pulley and a base end portion of the swing member are coupled and fixed to a portion of the swing member which is away from the fixed shaft at an axial end surface of the swing member, and a tip portion of the pulley is located radially outward of the outer peripheral surface of the pulley. The plunger has a projecting pressing arm and a plunger to which elasticity is applied in a direction projecting from the case, and an actuator fixed to the substrate at a position radially outward of the outer peripheral surface of the pulley. In an autotensioner in which the tip end of is elastically brought into contact with the tip end of the pressing arm, a support bracket having a base end portion coupled and fixed to the base plate is provided, and the tip end portion of the fixed shaft is of this support bracket. Supported by the tip Auto tensioner that features things. 2. A fixed shaft having a base end portion coupled and fixed to a fixed base plate, a swinging member swingable about the fixed shaft, and an outer peripheral surface of the swinging member which is rotated via a bearing. A freely supported pulley and a base end portion of the swing member are coupled and fixed to a portion of the swing member which is away from the fixed shaft at an axial end surface of the swing member, and a tip portion of the pulley is located radially outward of the outer peripheral surface of the pulley. The plunger has a projecting pressing arm and a plunger to which elasticity is applied in a direction projecting from the case, and an actuator fixed to the substrate at a position radially outward of the outer peripheral surface of the pulley. In an autotensioner in which the tip of the pressing arm is elastically brought into contact with the tip of the pressing arm, the pressing arm connects a pair of coupling arms separated from each other and a coupling connecting the proximal ends of these coupling arms. And the above 1
The tip of one of the pair of coupling arms is coupled to one end face of the swinging member in the axial direction, and the tip of the other coupling arm is coupled to the other end face of the swinging member in the axial direction. The automatic tensioner is fixed, and the tip of the plunger is in contact with the middle of the connecting portion.