JP2005133830A - Hydraulic tensioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ratchet type tensioner which can operate smoothly a ratchet when a plunger is stroked, which compacts the tensioner by a size reduction of a housing body, which can reduce a weight of the tensioner and which can manufacture simply a spring holding hole for the ratchet of the housing body. <P>SOLUTION: The ratchet type tensioner includes a ratchet pawl 141 of the ratchet 140 rockably engaged with rack teeth 122 notched on a side face of the plunger 120 to prevent a backward displacement of the plunger 120. A spring containing hole 113 for the ratchet for disposing the spring 150 for the ratchet in parallel with the plunger 120 is provided in the housing body 110. A circular arc-like contact surface 142 for receiving the spring 150 for the ratchet displaceably is provided on the ratchet 140. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a ratchet type tensioner used for applying an appropriate tension to a timing belt or a timing chain of a vehicle engine.

  Conventionally, a chain transmission device that transmits rotation between a crankshaft and a camshaft of a vehicle engine is used to suppress vibrations that occur during traveling by applying appropriate tension to the slack side of the timing belt or timing chain. Ratchet type tensioners are widely used (see Patent Document 1).

  As shown in FIG. 4, a conventional ratchet type tensioner 500 has a tensioner lever in which a plunger 520 protrudes from the front surface of a housing body 510 so that the plunger 520 can protrude and retract, and a tip end of the plunger 520 is swingably supported on the engine body side. The tensioner lever is slidably brought into contact with the slack side of the chain to apply tension by pressing the back surface in the vicinity of the swing end of the chain.

  At this time, the plunger urging spring 530 elastically mounted in the plunger receiving hole 511 of the housing main body 510 constantly urges the plunger 520 in a direction protruding from the housing main body 510. A ratchet claw 541 that meshes with a rack tooth 522 formed on the side surface of the plunger 520 is formed on the ratchet 540 that is pivotally supported by the ratchet shaft 512 of the housing body 510.

  The ratchet 540 is provided with a rotational biasing force around the ratchet shaft 512 in a direction in which the ratchet pawl 541 meshes with the rack teeth of the plunger 520 by a ratchet spring 550 provided in the housing body 510. And the rack teeth prevent the plunger 520 from moving in the backward direction. When the chain is extended by long-term use and the plunger 520 is further displaced in the protruding direction beyond the backlash range, the ratchet pawl 541 is engaged with a new rack tooth, and the tensioner lever is pushed against the plunger 520. Then, it swings and displaces so as to follow the elongation of the chain.

Further, the housing main body 510 is provided with a ratchet spring accommodating hole 513 for accommodating the ratchet spring 550 so as to be inclined with respect to the stroke direction of the plunger 520. On the other hand, the ratchet 540 is formed with a spring receiving plane 542 that abuts the ratchet spring 550. This spring receiving plane 542 is in the raised state where the ratchet is most often used, that is, the plunger 520 is in the protruding direction. It is designed on the assumption that the ratchet 540 and the ratchet spring 550 are brought into contact with each other at an angle close to a right angle in a state of being displaced.
Japanese Patent Laid-Open No. 11-344086 (first page, FIG. 1 to FIG. 2)

  However, in the conventional ratchet type tensioner 500 as described above, the ratchet spring accommodating hole 513 is provided to be inclined with respect to the stroke direction of the plunger 520. Therefore, when manufacturing the housing main body 510 by casting or the like, The ratchet spring accommodating hole 513 cannot be formed at the same time as the plunger accommodating hole 511, and there is a troublesome problem in manufacturing the tensioner that must be formed by machining such as drilling which is another processing step.

Further, in the conventional ratchet type tensioner 500, the ratchet spring accommodating hole 513 is provided to be inclined with respect to the stroke direction of the plunger 520, so that the distance between the opening end of the ratchet spring accommodating hole 513 and the plunger 520 approaches. There is a problem in the tensioner design in that it is difficult to reduce the size and weight of the housing body 510.
If the ratchet spring accommodating hole 513 is provided in parallel with the plunger 520, the distance between the ratchet spring 550 and the ratchet shaft 512 is reduced, and the change in the angle at which the ratchet spring 550 abuts on the spring receiving plane 542 increases. In the worst case, the ratchet spring 550 may be dropped, and the possibility of dropping the ratchet spring 550 increases as the backlash amount of the ratchet 540 increases. There was a problem in operating the tensioner.

  Therefore, the problem to be solved by the present invention, that is, the object of the present invention is to solve the problems of the prior art as described above, and the ratchet can operate smoothly when the plunger strokes, It is an object of the present invention to provide a ratchet type tensioner which can realize a compact and light weight of the tensioner by downsizing the housing body and can easily manufacture a ratchet spring accommodating hole of the housing body.

  The present invention includes a plunger that is urged and slid so as to protrude forward from a plunger receiving hole of the housing body, and a ratchet that is pivotally supported by the ratchet shaft of the housing body and is urged by a ratchet spring, In the ratchet type tensioner in which the ratchet pawl of the ratchet is swingably engaged with the rack teeth engraved on the side surface of the plunger to prevent the plunger from moving backward, the ratchet spring is provided in the housing body in parallel with the plunger. The ratchet spring accommodating hole to be disposed is provided, and the ratchet is provided with an arcuate contact surface that receives the ratchet spring in a displaceable manner, thereby solving the above-described problems.

  The ratchet type tensioner according to the present invention is provided with a ratchet spring accommodating hole for arranging the ratchet spring in parallel with the plunger in the housing body, so that when the housing body is manufactured by casting or the like, the ratchet spring is provided. Since the receiving hole can be molded, it is possible to omit extra machining for punching the ratchet spring receiving hole as in the prior art, and the housing main body ratchet spring receiving hole can be easily manufactured, Moreover, the tensioner can be made compact and light by reducing the size of the housing body that occupies most of the tensioner structure.

  Further, since the ratchet is provided with an arcuate contact surface that receives the ratchet spring in a displaceable manner, the ratchet spring is less affected by the ratchet movement, and the ratchet is moved when the plunger strokes. It can operate smoothly.

  The present invention relates to a ratchet-type tensioner in which a ratchet pawl of a ratchet is swingably engaged with a rack tooth carved on a side surface of a plunger so as to prevent a backward displacement of the plunger. The ratchet spring receiving hole is provided in parallel with each other, and the ratchet is provided with an arc-shaped contact surface that receives the ratchet spring so that the ratchet can be moved smoothly. In addition to being operated, the size and weight of the tensioner can be reduced by reducing the size of the housing body, and the ratchet spring accommodating hole of the housing body can be easily manufactured.

  The ratchet type tensioner of the present invention is a ratchet type tensioner in which the ratchet pawl of the ratchet is swingably meshed with the rack teeth carved on the side surface of the plunger so as to prevent the plunger from moving backward. Any type of ratchet type tensioner can be used. For example, a conventionally known hydraulic mechanism, that is, a check valve unit that prevents backflow of pressure oil flowing from the pressure oil supply passage of the housing into the high pressure chamber is provided in the plunger receiving hole. It may be a ratchet type tensioner that is accommodated in a check valve unit accommodation hole that is continuously recessed in the bottom of the cylinder, or a ratchet type tensioner that is not provided with such a hydraulic mechanism.

A ratchet tensioner 100 according to an embodiment of the present invention will be described with reference to FIGS.
Here, FIG. 1 is a schematic view showing how the ratchet type tensioner according to this embodiment is used, FIG. 2 is a cross-sectional view of the ratchet type tensioner 100 according to this embodiment, and FIG. FIG. 4A shows an operating state, in which (A) is a partially enlarged explanatory view of the ratchet biting state, and (B) is a partially enlarged explanatory view of the ratchet raised state.

As shown in FIG. 1, the ratchet type tensioner 100 of this embodiment is stretched between a driving side sprocket S1 rotated by an engine crankshaft and a driven side sprocket S2 fixed to the camshaft. It is attached to the engine body on the slack side of the timing chain C, and the plunger 120 protrudes from the front surface of the housing 110 so that the plunger 120 can swing freely. By pressing the back surface near the moving end, tension is applied to the slack side of the timing chain C via the movable lever L. A fixed guide G for guiding the travel of the timing chain C is attached to the tension chain side of the timing chain C on the engine body side.
The driving side sprocket S1 and the driven side sprocket S2 are driven when the driving side sprocket S1 rotates in the direction of the arrow, and the timing chain C travels in the direction of the arrow. The side sprocket S2 rotates in the direction of the arrow, and the rotation of the driving side sprocket S1 is transmitted to the driven side sprocket S2.

  Therefore, in the ratchet type tensioner 100 of this embodiment shown in FIG. 2, a cylindrical plunger 120 is slidably inserted into a plunger receiving hole 111 formed in the housing body 110, and one end of the plunger 120 is inserted into the plunger 120. An open hollow portion 121 is formed. A plunger urging spring 130 is accommodated across the plunger accommodation hole 111 and the hollow portion 121, and the plunger urging spring 130 projects the tip of the plunger 120 to the outside of the plunger accommodation hole 111. Always energized.

  A ratchet shaft 112 provided in the housing main body 110 is pivotally supported by a ratchet 140 that is urged by a ratchet spring 150 so as to prevent the plunger 120 from moving backward. Reference numeral 140 includes a ratchet pawl 141 that can swingably engage with a rack tooth 122 engraved on the side surface of the plunger, and an arcuate contact surface 142 that receives the ratchet spring 150 movably. As a result, the distance between the rotation center of the ratchet 140 and the point of action of the ratchet spring 150 approaches and the rotational moment generated in the ratchet 140 is kept small, so that the ratchet 140 is smoothly moved when the plunger 120 strokes. To work.

  The housing main body 110 is provided with a ratchet spring accommodating hole 113 for arranging the ratchet spring 150 in parallel with the plunger 120. When the housing main body 110 is manufactured by casting or the like, the ratchet spring accommodating hole is formed. The housing body 110, which molds 113 and occupies most of the tensioner structure, is made smaller than the outer shape shown by the phantom lines in FIG. 2.

Further, a high pressure chamber R is formed by the plunger receiving hole 111 and the hollow portion 121 of the plunger 120, and pressure oil flows into the high pressure chamber R in the high pressure chamber R by facing the hollow portion 121 of the plunger 120. A known check valve unit 160 is incorporated.
In the ratchet type tensioner 100 of the present embodiment, the check valve unit 160 has been described for the ratchet type tensioner in which the check valve unit 160 is housed in the bottom of the plunger housing hole 111. However, the ratchet type tensioner 100 is not provided with such a hydraulic mechanism. It may be a tensioner.

According to the ratchet type tensioner 100 of this embodiment obtained in this way, when the tension of the timing chain C is loosened and the plunger 120 moves forward, the ratchet 140 is pushed by the rack teeth 122 of the plunger 120 that moves forward. It rotates clockwise in the figure. At this time, the ratchet spring 150 is attached in parallel to the plunger 120. However, in this embodiment, the ratchet 140 is connected to the ratchet spring 150 as shown in FIGS. Since the abutting arc-shaped contact surface 142 is provided, even when the ratchet 140 is rotated, there is little change in how the ratchet 140 and the ratchet spring 150 come into contact, and the ratchet 140 operates smoothly.
Also, as shown in FIG. 3A, when the plunger 120 is retracted due to an impact from the timing chain C side and the backstop acts, as shown in FIG. Similarly, when the plunger 120 moves forward due to the looseness on the side, the ratchet 140 operates smoothly.

  Therefore, the ratchet type tensioner 100 of this embodiment can mold the ratchet spring accommodation hole 113 simultaneously with the plunger accommodation hole 111 when manufacturing the housing body 110 by casting or the like. It is possible to omit extra machining for drilling the ratchet spring accommodating hole, and it is possible to easily manufacture the ratchet spring accommodating hole of the housing body, and in addition, a conventional one having an outer shape indicated by an imaginary line in FIG. Compared to the tensioner, the tensioner can be made compact and light by reducing the size of the housing body that occupies most of the tensioner structure.

  Further, since the ratchet 140 is provided with the arcuate contact surface 142 that receives the ratchet spring 150 so as to be displaceable, there is little change in how the ratchet spring 150 contacts the movement of the ratchet 140, and the plunger 120 The effect is enormous, for example, the ratchet 140 can operate smoothly during a stroke.

Schematic which shows the usage condition of the ratchet type tensioner which is this invention. Sectional drawing of the ratchet type tensioner which is a present Example. FIG. 7 shows the operating state of the ratchet in the present embodiment, where (A) is a partially enlarged illustration of the ratchet biting state, and (B) is a partially enlarged illustration of the ratchet raised state. . Sectional drawing of the conventional ratchet type tensioner.

Explanation of symbols

100, 500 ... Ratchet type tensioner 110, 510 ... Housing body 111, 511 ... Plunger receiving hole 112, 512 ... Ratchet shaft 113, 513 ... Ratchet spring receiving hole 120, 520 ... Plunger 121: hollow portion 122, 522 ... rack tooth 130, 530 ... plunger biasing spring 140, 540 ... ratchet 141, 541 ... ratchet pawl 142 ... arc contact Surface 542 ... Spring receiving plane 150, 550 ... Ratchet spring 160 ... Check valve unit S1 ... Drive side sprocket S2 ... Driven side sprocket C ... Timing chain L ... Movable lever G ・ ・ ・ Fixed guide R ・ ・ ・ High pressure chamber

Claims (1)

A ratchet pawl of the ratchet, comprising: a plunger that is urged and slid so as to protrude forward from a plunger receiving hole of the housing body; In the ratchet type tensioner which is configured to prevent the plunger from moving backward by swingably meshing with the rack teeth engraved on the side surface of the plunger,
The housing body is provided with a ratchet spring receiving hole for arranging the ratchet spring in parallel with the plunger, and the ratchet is provided with an arcuate contact surface for receiving the ratchet spring movably. Ratchet tensioner.

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