JP3127374U - Chain tensioner - Google Patents

Abstract

A chain tensioner including a plunger protrusion prevention mechanism having a compact and simple structure and excellent handleability is provided.
A housing 10 having a bottomed cylinder part, a plunger 13 slidably incorporated in the cylinder part 10, and a spring 12 for applying a biasing force in a direction in which the plunger 13 protrudes from the cylinder part 11 are provided. A chain tensioner having a locking member 17 which is rotatably provided on the opening side of the cylinder part 11 and has a plunger insertion hole having the same inner diameter as the inner diameter of the cylinder part 11. When the locking member 17 is pivoted to a predetermined position, the center of the cylinder portion 11 and the inner diameter center of the plunger insertion hole are concentric with each other. Allow 13 protrusions.
[Selection] Figure 6

Description

  The present invention relates to a chain tensioner used for preventing a transmission chain from slackening.

  In the transmission mechanism that transmits the rotation of the crankshaft to the camshaft, a chain tensioner is provided on the slack side of the chain, and the tension of the chain tensioner is applied to the chain to keep the chain tension constant.

  A typical chain tensioner is constructed by incorporating a spring and plunger into a cylinder part formed in the housing. When the chain is slack, the chain is pressed by the plunger biased by the spring. Acts so as to maintain an appropriate tension, and when the chain is tensioned and a pushing force against the plunger is generated, it acts to buffer the backward movement of the plunger by the hydraulic pressure of the hydraulic oil filled in the back of the plunger. .

  By the way, in this type of chain tensioner, since the plunger is biased by a spring, a mechanism for preventing the plunger from protruding when not in use, such as at the time of delivery, is required. Conventionally, as a generally used plunger restraining mechanism, an engagement hole is provided in the plunger and the housing, a pin is communicated and set to each engagement hole, and the plunger is prevented from protruding, There is a mechanism that prevents the plunger from protruding by providing a locking groove on the plunger and locking the protrusion prevention plate attached via a spring pin to the locking groove (for example, see Patent Document 1).

JP-A-2005-344872

  However, the conventional mechanism for preventing the plunger from protruding has a large number of parts, and requires a space for processing the plunger such as a hole and a groove, which has a problem of hindering the compactness of the chain tensioner. In addition, with regard to the one using the above pin, for example, when removing the chain tensioner from the engine during maintenance, it is necessary to set the pin again to prevent the plunger from protruding, and it is difficult to say that the handle is excellent. .

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a chain tensioner including a plunger protrusion prevention mechanism having a compact and simple structure and excellent handleability.

  A chain tensioner according to the present invention includes a housing having a bottomed cylinder portion, a plunger slidably incorporated in the cylinder portion, and a spring that applies a biasing force in a direction in which the plunger projects from the cylinder portion. A chain tensioner provided on the opening side of the cylinder portion so as to be rotatable, and having a locking member having a plunger insertion hole having the same inner diameter as the inner diameter of the cylinder portion. Centering on the position eccentric from the rotation center of the stop member, when the locking member is rotated to a predetermined position, the inner diameter center of the cylinder portion and the inner diameter center of the plunger insertion hole become concentric, The protrusion of the plunger is allowed.

  According to the present invention, it is possible to restrict the protrusion of the plunger or to allow the protrusion of the plunger with a simple operation by simply rotating the locking member, and the handleability is excellent. In addition, since it is not necessary to perform special processing on the plunger and the plunger can be prevented from protruding, the plunger stroke can be reduced to the minimum length, and the size of the plunger can be reduced.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a chain tensioner 1 according to the present embodiment. FIG. 1 (a) is a plan view, FIG. 1 (b) is a side cross-sectional view, and FIG. is there.

  As shown in the figure, a cylinder portion 11 is formed in a housing 10 formed by aluminum die casting or the like. A return spring 12 and a plunger 13 are incorporated in the cylinder portion 11. The maximum outer diameter of the plunger 13 is substantially the same as the inner diameter of the cylinder part 11, and the plunger 13 is slidably incorporated in the cylinder part 11.

  A hydraulic chamber 14 communicating with the cylinder portion 13 is formed in the housing 10, and hydraulic oil flowing from a check valve 16 described later is held in the hydraulic chamber 14.

  Furthermore, mounting holes 15a and 15b are formed in the housing 10, and are used when the chain tensioner 1 is mounted in the engine.

  The check valve 16 includes a valve seat 16a having an oil port communicating with the outside from the hydraulic chamber 14, a ball 16b disposed on the valve seat 16a, and a stopper 16c for restricting the protrusion of the ball 16b. This check valve 16 controls the hydraulic oil flowing into the hydraulic chamber 14, and when the chain extends and the plunger 13 protrudes, the ball 16b is separated from the valve seat 16a and flows into the hydraulic oil. When the force is applied in the direction in which the plunger 13 is pushed, the ball 16b closes the oil port of the valve seat 16a to prevent the backflow of the working oil in the hydraulic chamber 14 and hold the working oil.

  A locking member 17 is rotatably engaged on the opening side of the cylinder portion 11 of the housing 10, that is, on the side in which the plunger 13 protrudes. By rotating the locking member 17, the plunger 13 can be prevented from protruding or the plunger 13 can be allowed to protrude. Hereinafter, the details of the locking member 17 will be described with reference to FIGS. 2 and 3.

  2 shows the locking member 17, FIG. 2 (a) is a front view, FIG. 2 (b) is an arrow view seen from the arrow A in FIG. 2 (a), and FIG. 2 (c) is FIG. It is the arrow view seen from the arrow B of (a).

  As shown in FIG. 2, the locking member 17 is formed in a hollow cylindrical shape with a flange, and has a lever 19 that protrudes from a part of the outer periphery of the flange 18. The plunger insertion hole 20 formed in the locking member 17 is centered on a position that is eccentric by a predetermined distance L1 from the center of the locking member 17 (that is, the rotation center of the locking member 17). Is set to be approximately the same as the inner diameter.

  Further, two pieces of arc-shaped claw portions 22 protruding outward are provided on the outer peripheral surface of the cylindrical portion 21 stepped down from the flange portion 18. In the present embodiment, the claw portions 22 are provided at positions that are 180 degrees out of phase on the outer peripheral surface of the cylindrical portion 21, but are not limited to this arrangement.

  Next, FIG. 3 shows the housing 10, and is a front view showing a state where the return spring 12, the plunger 13, and the locking member 17 are not incorporated in the cylinder portion 11. For convenience, FIG. 3 shows a state rotated 90 degrees clockwise from the state shown in FIG.

  As shown in FIG. 3, an engagement portion 23 for engaging the locking member 17 is provided on the opening side of the cylinder portion 11 of the housing 10, that is, on the side in which the plunger 13 projects (see FIG. 3). See also 1). More specifically, the engaging portion 23 is formed in a circular concave shape communicating with the cylinder portion 11 at the bottom portion. In this case, the circular recessed engaging portion 23 is not formed coaxially with the cylinder portion 11 but is formed around a position eccentric from the center of the inner diameter of the cylinder portion 11 by a predetermined distance L1.

  A pair of arcuate guide portions 24 projecting inward are provided on the inner peripheral surface of the engaging portion 23 in the vicinity of a substantially intermediate position in the depth direction. A space is formed between the pair of guide portions 24 at a position shifted in phase by 180 degrees on the inner peripheral surface of the engagement portion 23, and the arc length of each space is the length of the claw portion 22 of the locking member 17. It is set to be longer than the arc length.

  Further, the inner diameter of the engaging portion 23 is set larger than the outer diameter formed by the claw portions 22 of the locking member 17, and the inner diameter formed by the guide portions 24 is formed by the claw portions 22 mutually. It is set smaller than the outer diameter.

  The mark 10a shown in the figure is a mark indicating a position where the protrusion of the plunger 13 is allowed, as will be described in detail later. By aligning the lever 19 of the locking member 17 with the mark 10a, the mark 10a Protrusion is allowed.

  Hereinafter, a state in which the locking member 17 is engaged with the engaging portion 23 to prevent the plunger 13 from protruding or to allow the plunger 13 to protrude will be described with reference to FIG. 4. In addition, in the locking member 17 shown in each of FIGS. 4A to 4C, the claw portion 22 is shown to be exposed for convenience.

  FIG. 4A shows an initial step of engaging the locking member 17 with the engaging portion 23 after incorporating the return spring 12 and the plunger 13 into the cylinder portion 11. That is, a state in which the claw portion 22 of the locking member 17 is inserted into the space formed between the guide portions 24 is shown. In this state, the bottom surface of the locking member 17 is located behind the guide portion 24 of the engaging portion 23. In the drawing, the black arrow indicates the position of the claw portion 22, and the white arrow indicates a space formed between the guide portions 24. Further, in this state, the inner diameter center of the cylinder portion 11 and the inner diameter center of the plunger insertion hole 20 of the locking member 17 are not concentric, and the region of the maximum outer diameter of the plunger 13 interferes with the bottom surface of the locking member 17. Thus, the protrusion of the plunger 13 is prevented.

  FIG. 4B shows a state in which the locking member 17 is rotated counterclockwise from the state of FIG. Specifically, it is rotated 45 degrees, and in this state, the claw portion 22 of the locking member 17 is located on the back side of the guide portion 24 and the locking member 17 cannot be pulled out. Further, in this state, the inner diameter center of the cylinder portion 11 and the inner diameter center of the plunger insertion hole 20 of the locking member 17 are concentric, and the portion of the plunger 13 having the maximum outer diameter interferes with the bottom surface of the locking member 17. As a result, the plunger 13 is allowed to protrude. At this time, the lever 19 overlaps the mark 10a described above. Thus, usability improves by making it easy to understand the position where the protrusion of the plunger 13 is allowed.

  FIG. 4C shows a state in which the locking member 17 is further rotated counterclockwise from the state of FIG. Specifically, it is further rotated by 45 degrees, and even in this state, the claw portion 22 of the locking member 17 is located on the back side of the guide portion 24 and the locking member 17 cannot be pulled out. Further, in this state, the inner diameter center of the cylinder portion 11 and the inner diameter center of the plunger insertion hole 20 of the locking member 17 are not concentric, and the region of the maximum outer diameter of the plunger 13 interferes with the bottom surface of the locking member 17. Thus, the protrusion of the plunger 13 is prevented.

  Here, with reference to FIG. 5, the relationship between the cylinder part 11 and the plunger insertion hole 20 of the locking member 17 is demonstrated. The state shown in FIG. 5A is a diagram showing the relationship between the cylinder portion 11 corresponding to FIG. 4A and the plunger insertion hole 20 of the locking member 17. A region indicated by diagonal lines in this drawing indicates a region where the bottom surface of the locking member 17 covers the cylinder part 11. That is, the center of the inner diameter of the cylinder portion 11 and the center of the inner diameter of the plunger insertion hole 20 of the locking member 17 are not concentric, and the region of the maximum outer diameter of the plunger 13 interferes with the bottom surface of the locking member 17. The protrusion of the plunger 13 is prevented.

  The state shown in FIG. 5B is a diagram showing the relationship between the cylinder portion 11 corresponding to FIG. 4B and the plunger insertion hole 20 of the locking member 17. In this figure, the inner diameter center of the cylinder portion 11 and the inner diameter center of the plunger insertion hole 20 of the locking member 17 are concentric, and the portion of the plunger 13 having the maximum outer diameter and the bottom surface of the locking member 17 are shown. And the plunger 13 is allowed to protrude.

  The state shown in FIG. 5C is a diagram showing the relationship between the cylinder portion 11 corresponding to FIG. 4C and the plunger insertion hole 20 of the locking member 17. A region indicated by diagonal lines in this drawing indicates a region where the bottom surface of the locking member 17 covers the cylinder part 11. That is, the center of the inner diameter of the cylinder portion 11 and the center of the inner diameter of the plunger insertion hole 20 of the locking member 17 are not concentric, and the region of the maximum outer diameter of the plunger 13 interferes with the bottom surface of the locking member 17. The protrusion of the plunger 13 is prevented.

  Here, with reference to FIG. 6, the part of the plunger 13 having the maximum outer diameter, that is, the part that interferes with the bottom surface of the locking member 17 of the plunger 13 will be described. As shown in FIG. 6, a set wall 25 having an outer diameter substantially the same as the inner diameter of the cylinder portion 11 is formed on the outer peripheral surface of the plunger 14. The set wall 25 is a part for initially setting the C ring 26 that elastically tightens the outer peripheral surface of the plunger 13, and is a part that interferes with the bottom surface of the locking member 17. The C-ring 26 is an elastic ring that is partially opened, and can expand and contract.

  The state shown in this figure is a state in which the bottom surface of the locking member 17 abuts against the set wall 25, that is, interferes with it, and the plunger 13 is prevented from protruding (FIG. 4 (a) or FIG. 4 (c)). Corresponding).

  A plurality of circumferential grooves 27 are formed at equal intervals on the outer peripheral surface of the plunger 13 behind the set wall 25. Each circumferential groove 27 has a rear taper surface 27a and a front engagement surface 27b. Further, on the inner peripheral surface of the cylinder portion 11, a stopper surface 28 having an angle just facing the engaging surface 27 b of the circumferential groove 27 is formed. In a state where the plunger 13 is allowed to move in the protruding direction, the C-ring 26 attached to the plunger 13 expands along the tapered surface 27a of the circumferential groove 27 so that the plunger 13 moves stepwise. . Further, when the plunger 13 moves in the retreating direction, the C-ring 26 is sandwiched between the stopper surface 28 and the engagement surface 27b to prevent the plunger 13 from retreating and the amount of retreating movement is limited.

  FIGS. 7A to 7C are diagrams showing the state in which the plunger 13 moves in the protruding direction in a stepwise manner. FIG. 7A shows a state in which the plunger 13 is allowed to move by rotating the locking member 17 (corresponding to FIG. 4B). In this state, the contact state between the bottom surface of the locking member 17 and the set wall 25 is released, so that the plunger 13 protrudes and the C ring 26 set on the set wall 25 is connected to the bottom surface of the locking member 17. Abut. And since the plunger 13 moves while expanding the diameter along the taper surface 27a of the circumferential groove 27 by the C ring 26 coming into contact with the locking member 17, it moves in a stepwise manner without suddenly protruding. (See FIG. 7B and FIG. 7C).

  FIG. 7D shows how the plunger 13 is prevented from coming off. A stopper groove 29 is formed on the outer peripheral surface of the plunger 13 behind the rearmost circumferential groove 27. A side surface 29 a formed on the rear side of the stopper groove 29 is a wall substantially perpendicular to the axial direction of the plunger 13. Therefore, when the C ring 26 reaches the side surface 29a, the C ring 26 is sandwiched between the side surface 29a and the bottom surface of the locking member 17, and the plunger 13 is prevented from coming off (see FIG. 8).

  In the chain tensioner 1 according to the present embodiment described above, for example, at the time of delivery, the plunger 13 is pushed in, and the plunger 13 is prevented from protruding by a simple operation of simply rotating the locking member 17. can do. And the protrusion of the plunger 13 can be permitted by a simple operation of merely rotating the locking member 17, and the handleability is excellent.

  In addition, since it is not necessary to perform special processing on the plunger 13 and the protrusion of the plunger 13 can be prevented, the stroke of the plunger 13 can be set to the minimum necessary length, and the size reduction can be achieved.

  In the configuration in which a plurality of circumferential grooves 27 are formed in the plunger 13 as in the present embodiment and the amount of movement of the plunger 13 when the plunger 13 is retracted is limited by the C ring 26, The diameter of the ring 26 can be increased, and the number of parts can be reduced.

  The present invention is not limited to this embodiment, and can be changed within the scope of the present invention. For example, in the present embodiment, a plurality of circumferential grooves 27 are formed on the outer peripheral surface of the plunger 13, and the return amount of the plunger 13 is limited by cooperation with the C ring 26. However, the present invention is not limited to this. is not. For example, it is good also as a structure which restrict | limits the return amount of the plunger 13 by a ratchet system, and the structure itself which restrict | limits the return amount of the plunger 13 does not need to be provided.

  Further, in the present embodiment, the locking member 17 is accommodated in the housing 10 to further reduce the size, but the present invention is not limited to this. For example, as shown in FIG. 9, the engaging portion 30 may be formed so as to protrude from the housing 10, and the locking member 31 may be formed in a cap shape and exposed to the outside. Also in this case, it is preferable that the positional relationship of the center of the cylinder portion 11, the rotation center of the locking member 31, the center of the plunger insertion hole of the locking member 31 is basically the same as that in the above embodiment. Implementation is possible.

It is a figure which shows the chain tensioner which concerns on embodiment of this invention. It is a figure which shows the latching member of the chain tensioner which concerns on embodiment of this invention. It is a figure which shows the housing of the chain tensioner which concerns on embodiment of this invention. It is a figure for demonstrating operation of the latching member of the chain tensioner which concerns on embodiment of this invention. In the chain tensioner which concerns on embodiment of this invention, it is a figure for demonstrating a mode that the protrusion of a plunger is prevented and permitted. In the chain tensioner which concerns on embodiment of this invention, it is a figure for demonstrating the state by which protrusion of the plunger was restrict | limited. In the chain tensioner which concerns on embodiment of this invention, it is a figure for demonstrating the state in which protrusion of the plunger was accept | permitted. In the chain tensioner which concerns on embodiment of this invention, it is a figure for demonstrating removal prevention of a plunger. It is a figure which shows the modification of the chain tensioner of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Chain tensioner 10 Housing 11 Cylinder part 12 Return spring 13 Plunger 17 Locking member 23 Engagement part 25 Set wall 26 C ring 27 Circumferential groove 27a Tapered surface 27b Engagement surface 30 Engagement part 31 Locking member

Claims (4)

A chain tensioner having a housing having a bottomed cylinder part, a plunger slidably incorporated in the cylinder part, and a spring for applying a biasing force in a direction in which the plunger projects from the cylinder part,
A locking member provided rotatably on the opening side of the cylinder part, and having a plunger insertion hole having the same inner diameter as the inner diameter of the cylinder part;
The plunger insertion hole is centered on a position eccentric from the rotation center of the locking member. When the locking member is rotated to a predetermined position, the inner diameter center of the cylinder portion and the inner diameter center of the plunger insertion hole And a chain tensioner characterized in that the plunger is allowed to protrude.   The housing is formed with a circular recessed engaging portion communicating with the cylinder portion at the bottom, and the hollow cylindrical locking member is rotatably inserted in the engaging portion, 2. The chain tensioner according to claim 1, wherein the engaging portion is centered at a position eccentric from an inner diameter center of the cylinder portion.   The chain tensioner according to claim 1 or 2, wherein a mark is provided on the housing to indicate a position where an inner diameter center of the cylinder portion and an inner diameter center of the plunger insertion hole are concentric. A plurality of circumferential grooves formed on the outer peripheral surface of the plunger, each having a front engagement surface and a rear taper surface;
An elastic ring assembled in one of the circumferential grooves;
A stopper surface formed on the inner peripheral surface of the cylinder part,
When the plunger protrudes, the elastic ring comes into contact with the locking member and expands along the tapered surface of the circumferential groove, and when the plunger moves backward, the ring The chain tensioner according to any one of claims 1 to 3, wherein the chain tensioner is sandwiched between an engaging surface and a stopper surface of the groove to prevent the plunger from moving backward.

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