JP3424737B2 - Auto tensioner - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an auto-tensioner for use in applying an appropriate tension to a timing belt of an automobile engine, for example. 2. Description of the Related Art A proper tension is applied to a belt such as a timing belt for rotating a camshaft of an OHC type or DOHC type engine in synchronization with a crankshaft by an auto tensioner. ing. Figures 5-7
An example of an auto tensioner used for such a purpose is described in JP-A-8-61446. An auto-tensioner 2 that elastically presses an intermediate portion of the belt 1 and applies a predetermined tension to the belt 1,
By combining the components as shown in FIG.
It is configured as shown in FIG. FIG. 7 shows the disassembled state.
Here, for the sake of simplicity, the number of some members is drawn smaller than that in FIG. 6 showing an actual case. Further, the swing member 5 shown in FIGS. 5 and 6 and the swing member 5 shown in FIG. 7 have slightly different shapes at the tip end portion (left end portion in FIGS. 6 and 7). Are the same, and are substantially the same. First, a fixing member 3 is fixed to a bolt 16 (FIG. 7).
Thereby, it is fixed to the front surface of a cylinder block (not shown) which is a fixed portion. The fixed member 3 is provided with a cylindrical fixed shaft 4, and a swing member 5 is provided around the fixed shaft 4.
Are rotatably supported via slide bearings 6a and 6b. The outer peripheral surface of the tip (the left end in FIGS. 6 and 7) of the swing member 5 forms a cylindrical surface eccentric with respect to the fixed shaft 4. A pulley 7 is provided around the tip of the swing member 5.
Is rotatably supported via a rolling bearing 8 such as a deep groove ball bearing. Also, the base end of the swing member 5 (FIGS.
(Right end of 7) A bracket 9 is externally fitted and fixed to the outer peripheral surface. A locking portion 10 is provided on a part of the bracket 9 so as to protrude outward in the diameter direction. A tension spring 24 (FIG. 5) is provided between the locking portion 10 and another locking portion provided on the front surface of the cylinder block. The tension spring 24 imparts elasticity to the swing member 5 in a direction of pressing the pulley 7 toward the belt 1. A cylindrical closed space 1 is provided between the outer peripheral surface of the intermediate portion of the fixing member 3 and the inner peripheral surface of the intermediate portion of the swinging member 5.
1 is provided. Both ends in the axial direction (the left-right direction in FIG. 6) of the closed space 11 are closed by seal rings 12a and 12b, respectively. And in the inner part of this closed space 11,
A plurality of inner circular plates 13, 13 and outer circular plates 14, 14 are arranged alternately in the axial direction (the left-right direction in FIGS. 6 and 7). Of these two annular plates 13, 14, the inner annular plates 13, 13 have their inner peripheral edges fixed to the outer peripheral surface of the fixing member 3. That is, the fixing member 3
Between the flange portion 15 formed at the base end portion and the inner annular plate 13 located at one end side (the right end side in FIGS. 6 and 7), between the adjacent inner annular plates 13, 13, and at the other end. Annular spacers 18 are interposed between the inner annular plate 13 located on the side (left end side in FIGS. 6 and 7) and the fixing plate 17 which is externally fixed to the fixing member 3. Then, the fixing plate 17
Is strongly pressed toward the flange portion 15. On the other hand, a plurality of engaging projections 19, 19 (FIG. 7) are formed on the outer peripheral edge of each of the outer annular plates 14, 14, respectively. To
Engagement grooves 20 formed on the inner peripheral surface of the swing member 5
(FIG. 6), it is displaceably engaged in the axial direction (left and right directions in FIGS. 6 and 7). The thickness dimension of each of the spacers 18 is slightly larger than the thickness dimension of each of the outer annular plates 14. Therefore, as described above, in a state where the inner and outer circular plates 13 and 14 are alternately arranged, a minute gap is formed between the side surfaces of the adjacent circular plates 13 and 14. As described above, the viscous liquid such as silicone oil is filled in the sealed space 11 in which the inner and outer circular plates 13 and 14 are alternately arranged. The filling of the viscous liquid is performed through the injection hole 22 formed in the swinging member 5, and after the filling, the opening of the injection hole 22 is closed by pushing a steel ball 23. [0006] The auto tensioner 2 configured as described above.
By elastically pressing the pulley 7 toward the belt 1 by the elastic force of the tension spring 24, the belt 1 can be moved regardless of the dimensional change of the belt 1 due to a temperature change or the like and the vibration caused by the operation of the engine. Always keep the tension constant. or,
The side surfaces of the plurality of inner circular plates 13 and 13 and the side surfaces of the outer circular plates 14 and 14 respectively face each other via a minute gap, and a viscous liquid exists in the minute gap. Therefore, abrupt displacement between the two annular plates 13 and 14 is prevented by the shearing force applied to the viscous liquid existing in the minute gap. Therefore, even when the tension of the belt 1 partially rises sharply, the pulley 7 is not immediately displaced. As a result, even when the tension of the belt 1 suddenly increases and then suddenly decreases when the tension suddenly changes, the belt 1 can be prevented from loosening. However, in the case of the conventional auto-tensioner constructed and operated as described above, the displacement of the pulley 7 cannot be regulated as it is. On the other hand, when the tension of the belt 1 suddenly increases, it is necessary to suppress the belt 1 by restricting the excessive displacement of the pulley 7. The reason for this is that if the pulley 7 is retracted in response to a sudden rise in the tension of the belt 1 in part, the tension in the other parts of the belt 1 becomes too low. If the tension of the belt 1 is too low, so-called tooth skipping occurs when the belt 1 is a timing belt. In addition, in all types of belts, the fluttering that the belt vibrates greatly occurs, which leads to a reduction in the life of the belt 1 and an increase in noise of the belt driving unit. [0008] This point will be described in detail with reference to FIG. A driving pulley 25 fixed to the end of the crankshaft 21 and rotating clockwise in FIG. 8 during operation of the engine as indicated by an arrow α, and a driven pulley 27 fixed to the ends of the camshafts 26 and 26, 27, the belt 1 is stretched. In the middle of the belt 1, a guide pulley 28 whose position is fixed and an auto tensioner 2 which is an object of the present invention are provided. And this auto tensioner 2
Is elastically pressed toward the belt 1 by the elastic force of the tension spring 24, and this belt 1
To the appropriate tension. When the engine is stopped, the driving pulley 2
With the sudden stop of 5, the tension in the section A where the auto tensioner 2 is installed rises rapidly in a part of the belt 1, and the pulley 7 is pushed in the direction of arrow β. When the pulley 7 of the auto tensioner 2 is retracted from the position indicated by the solid line in FIG. 8 to the position indicated by the dashed line in FIG. 8 in response to the increase in the tension of the belt 1, the tension in the section B where the guide pulley 28 is provided becomes excessively high. And tooth skipping occurs as described above. In order to prevent the timing belt from skipping due to such a cause, the swing amount of the swing member 5 supporting the pulley 7 has been conventionally known, for example, as described in JP-A-8-61446. It has been performed to provide a stopper for limiting the pressure. [0010] However, Japanese Unexamined Patent Publication No.
In the case of the conventional structure described in Japanese Patent No. 61446, it is necessary to perform a special processing on a part of a member for installing an auto tensioner, such as forming an arc-shaped engagement hole on the front surface of an engine cylinder block. is there. For this reason, not only does the cost increase, but it is necessary to design a dedicated auto-tensioner for each engine. In other words, the versatility of the auto-tensioner is poor, which causes an increase in cost. The auto-tensioner of the present invention has been made in view of such circumstances. An auto tensioner according to the present invention comprises a fixing member fixed to a fixed portion and a fixed shaft provided on the fixing member, similarly to the above-described conventional auto tensioner. An oscillating member rotatably supported around the fixed shaft, a pulley rotatably supported at a portion of the oscillating member eccentric to the fixed shaft, and the fixed portion or fixed portion. A spring is provided which locks both ends of the member and the swinging member so as to impart elasticity in a direction of pressing the pulley toward the belt to the swinging member. In particular, in the auto tensioner of the present invention, the fixed-side engaging portion protruding from a part of the fixed-side bracket fixed to the fixed member, and the swing-side bracket fixed to the swingable member. A swing-side engaging portion projecting at a position where the swing-engaging member engages with the fixed-side engaging portion in accordance with the swing of the swing member; and a fixed-side engaging portion and a swing-side engaging portion. Hang between
And a displacement limiting means comprising a connected member . The displacement limiting means is such that the connecting member is
Tension between the mating portion and the swing-side engaging portion has a function of restricting swinging displacement of the pulley in a direction to retreat from the belt. The automatic tensioner of the present invention having the above-described structure swings the swing member about the fixed shaft by the elastic force of the spring, presses the pulley against the belt, and applies an appropriate tension to the belt. The operation at the time of applying is the same as that of the above-described conventional auto tensioner. In particular, in the case of the auto-tensioner of the present invention, a fixed-side engaging portion protruding from a part of the fixed-side bracket and a part of the swinging-side bracket associated with the swinging movement of the swinging member. A swing-side engaging portion protruding from a position where the engaging portion engages with the fixed-side engaging portion, and a connecting portion bridged between the two engaging portions.
The displacement limiting means made of a material can limit the displacement of the swing member and the pulley pivotally supported by the swing member.
Therefore, the positions where the fixed side engaging portion and the swing side engaging portion are formed.
If the installation state of the connecting member is regulated, the displacement of the pulley is regulated to a desired value, so that even when the belt tension suddenly increases, the pulley can be prevented from retreating excessively. It is easy to project the fixed-side engaging portion on a part of the fixed-side bracket and the swing-side engaging portion on a part of the swing-side bracket, and to install the connecting member. . Therefore, the cost increase of the auto tensioner provided with the displacement limiting means can be slightly suppressed. 1 to 3 show the technical scope of the present invention.
Reference examples that deviate from are shown. The feature of this embodiment is that a displacement limiting means is provided between the fixed member 3 and the swinging member 5 to limit the displacement of the swinging member 5 and the pulley 7 pivotally supported by the swinging member 5. It is in the point which did. Since the configuration and operation of the other parts are the same as in the conventional structure described above,
The same parts are denoted by the same reference numerals, and redundant description will be omitted or simplified. Hereinafter, the description will focus on the characteristic parts of this embodiment . Base end of the fixing member 3 (right end in FIG. 3)
, The fixed bracket 29 is fixed. This fixed side bracket 29, which is formed by pressing a metal plate having sufficient rigidity, is formed by fitting a cylindrical portion 30 formed at the center portion to the base end portion of the fixed member 3 by interference fit. It is fixed to this fixing member 3. Further, at two positions on the outer peripheral edge of the fixed side bracket 29, an arm piece 31 and a tongue piece 32 are provided so as to project outward in the diameter direction. A small circular hole 33 is formed at the tip of the arm piece 31 among them. When the auto tensioner 2a of this embodiment is fixed to the front of the cylinder block of the engine, the small circular hole 3
The fixed side bracket 29 is reliably prevented from rotating around the fixed member 3 by, for example, screwing a screw inserted into the fixed member 3 into a screw hole formed on the front surface of the cylinder block. On the other hand, the first half of the tongue piece 32 is bent at a substantially right angle toward the swing-side bracket 34 described later to form a fixed-side engaging portion 35. A swing-side bracket 34 is fixed to the base end (the right end in FIG. 3) of the swing member 5. The swing side bracket 34 formed by pressing a metal plate having sufficient rigidity has a cylindrical portion 36 formed at the center.
Is fixed to the rocking member 5 by being fitted to the base end of the rocking member 5 by interference fit. The arm piece 37 is provided at two positions on the outer peripheral edge of the swing side bracket 34.
The tongue-shaped swing-side engaging portion 38 is provided so as to project radially outward. A hexagonal square hole 40 is formed in the tip end surface of the swing member 5 among them. The square hole 40 swings the swing member 5 against the elasticity of the tension spring 24 (see FIG. 5) whose one end is locked to the locking portion 10 so that the belt 1 is wound around the pulley 7. At this time, it is used to lock the tip of a tool such as a hexagon wrench. In the case of the auto-tensioner 2a of the present embodiment constructed as described above, the fixed-side engaging portion 35 protruding from the outer peripheral edge of the fixed-side bracket 29 and the outer peripheral edge of the swing-side bracket 34 Displacement limiting means comprising a swing-side engaging portion 38 formed in the portion limits the displacement amount of the swing member 5 and the pulley 7 pivotally supported by the swing member 5. In other words, regardless of the force applied to the pulley 7 in the direction of the arrow FF in FIGS. The swing displacement amount is limited. That is, when the force applied in the direction of the arrow FF becomes large, and the swing member 5 swings in the counterclockwise direction in FIG. 1 and the clockwise direction in FIG. 2 against the elastic force of the extension spring 24. In this case, the fixed side engaging portion 35 and the swing side engaging portion 38 abut against each other so that the pulley 7 is not further displaced in the direction of retreating from the belt 1. Therefore,
If the positions where the fixed side engaging portion 35 and the swing side engaging portion 38 are formed are regulated, the displacement amount of the pulley 7 is regulated to a desired value, and the tension of the belt 1 in the section A in FIG. , The pulley 7 can be prevented from retreating excessively from the belt 1. As a result, the tension in the section B (see FIG. 8) of the part of the belt 1 facing the fixed guide pulley 28 is prevented from excessively decreasing, and the above-described problem such as the tooth skipping occurs. To prevent The fixed-side engaging portion 35 is formed on the outer peripheral edge of the fixed bracket 29 formed by press-forming a metal plate, and the outer peripheral edge of the swing-side bracket 34 is formed by press-forming a metal plate. Protruding the swing-side engaging portions 38 can be easily performed. Therefore, the fixed side engaging portion 3
The cost increase of the auto-tensioner 2a including the displacement limiting means, which is composed of the swinging-side engaging portion 38 and the swing-side engaging portion 38, can be suppressed slightly. Next, FIG. 4 shows an example of the embodiment of the present invention. In the case of the above-described reference example , when the tension of the belt 1 is increased, the fixed-side engaging portion 35 and the swing-side engaging portion 38 are directly abutted. On the other hand, in the case of this example, a connecting member 41 such as a cable or a rod is bridged between the fixed side engaging portion 35 and the swing side engaging portion 38. Normally, the connecting member 41 is loosened between the fixed-side engaging portion 35 and the swing-side engaging portion 38, or is slidably displaced with respect to any of the engaging portions. 3, the swinging displacement of the swinging member 5 (see FIGS. 1 and 3) is allowed. On the other hand, when the tension of the belt 1 is increased, the connecting member 41 is tightened between the fixed side engaging portion 35 and the swinging side engaging portion 38, and the swinging displacement of the swinging member 5 is reduced. Block. Therefore, in the case of this example, the installation positions of the fixed side engaging portion 35 and the swing side engaging portion 38 in the circumferential direction are the same as those described above.
The opposite is the case with the reference example . Other configurations and operations are the same as those of the above-described reference example . Since the present invention is constructed and operates as described above, an auto tensioner which can prevent the occurrence of inconvenience such as tooth skipping can be realized at low cost.

[Brief description of the drawings] FIG. 1 is a front view showing a first example of an embodiment of the present invention. FIG. 2 is a rear view of the same. FIG. 3 is a sectional view taken along line AA of FIG. 1; FIG. 4 is a rear view showing a second example of the embodiment of the present invention. FIG. 5 is a front view showing an example of a conventional structure. FIG. 6 is a sectional view of the same. FIG. 7 is an exploded perspective view of the same. FIG. 8 is a schematic front view showing an installation portion of the auto tensioner. [Explanation of symbols] 1 belt 2, 2a Auto tensioner 3 Fixing member 4 Fixed axis 5 Swing member 6a, 6b sliding bearing 7 Pulley 8 Rolling bearing 9 Bracket 10 Locking part 11 enclosed space 12a, 12b Seal ring 13 inner circular plate 14 Outside circular plate 15 Tsubabe 16 volts 17 Fixing plate 18 Spacer 19 Engagement projection 20 Engagement groove 21 Crankshaft 22 Injection hole 23 steel ball 24 Extension spring 25 Drive pulley 26 camshaft 27 driven pulley 28 Guide pulley 29 Fixed side bracket 30 cylindrical part 31 arm piece 32 tongue piece 33 small circular hole 34 Oscillating side bracket 35 Fixed side engaging part 36 cylindrical part 37 arms 38 Oscillating side engaging part 40 square hole 41 Connecting member

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-8-61446 (JP, A) JP-A-9-137851 (JP, A) JP-A-61-140661 (JP, A) 102046 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) F16H ^7/ 00-7/24 F02B 67/06

Claims (1)

(57) [Claim 1] A fixing member fixed to a fixed portion, a fixed shaft provided on the fixing member, and a swing supported rotatably around the fixed shaft. A member, a pulley rotatably supported by a part of the swinging member that is eccentric to the fixed shaft, and locking both ends of the fixed portion or the fixed member and the swinging member. As a result, in the auto-tensioner provided with a spring that applies elasticity in a direction of pressing the pulley toward the belt to the swinging member, a fixing member protruding from a part of the fixed-side bracket fixed to the fixing member is provided. A side engaging portion, and a swinging side member projecting from a part of the swinging side bracket fixed to the swinging member, the position being engaged with the fixed side engaging portion along with the swinging of the swinging member. Joint part and these
Connection spanned between the fixed side engaging portion and the swing side engaging portion
And a displacement limiting means, wherein the connecting member is connected to the fixed side engaging portion and the swing side engaging portion.
An auto tensioner having a function of restricting swinging displacement of the pulley in a direction of retreating from the belt by tensioning the pulley.