JP3577033B2 - Hydraulic tensioner - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a hydraulic tensioner for applying an appropriate tension to a chain or a belt, and more particularly, to a hydraulic tensioner having a ratchet mechanism for preventing the plunger from retracting when the hydraulic pressure decreases.
[0002]
[Prior art and its problems]
A hydraulic tensioner generally comprises a housing, a plunger slidably inserted into a hole formed in the housing and urged in a projecting direction by a spring, and a fluid chamber defined by a hole in the housing and the plunger. Have been. During operation of the tensioner, the pressing force acting on the tip of the plunger from the chain or the belt is balanced with the hydraulic pressure in the chamber and the drag due to the elastic repulsion of the spring.
[0003]
By the way, in a hydraulic tensioner applied to a timing system for an automobile, a pressing force is applied from the chain to the tip of the plunger when sufficient hydraulic pressure is not applied to the chamber, such as when starting an engine. When actuated, the plunger is easily pushed into the housing and the plunger retracts, which may result in noise and vibration.
[0004]
In order to prevent such plunger contraction, for example, a hydraulic tensioner provided with a ratchet mechanism as disclosed in Japanese Patent Application Laid-Open Nos. 2000-136859 and 2001-304360 has been proposed. .
[0005]
Japanese Patent Application Laid-Open No. 2000-136859 discloses a rack member slidably supported in a vertical hole formed in a housing, and a rack member slidably supported in a horizontal cavity formed in a housing. And a spring housed in the cavity and biasing the ratchet in a direction to engage with the rack member.
[0006]
The engagement of the rack member and the ratchet allows the plunger to move in the protruding direction, while preventing the plunger from moving in the retracting direction. In this case, the plunger is separated from the plunger. Since the rack member is provided, the structure is complicated.
[0007]
On the other hand, Japanese Patent Application Laid-Open No. 2001-304360 discloses a rack groove formed on an outer peripheral surface of a piston and a claw member slidably supported by a lateral hole formed in a housing and engaged with the rack groove of the piston. And a spring that is housed in the lateral hole and biases the claw member in a direction that engages with the rack groove.
[0008]
In this case, although the rack groove is integrally formed on the outer peripheral surface of the piston, the structure is simplified, but a spring for urging the claw member in the direction of engaging with the rack groove is still required, There are many parts.
[0009]
The present invention has been made to solve such a conventional problem, and an object of the present invention is to provide a hydraulic tensioner having a ratchet mechanism capable of reducing the number of parts and simplifying the structure.
[0010]
[Means for Solving the Problems]
The hydraulic tensioner according to the first aspect of the present invention has a housing having a hole formed at one end and a housing slidably inserted into the hole to form a fluid chamber between the housing and the rack teeth. It includes a plunger formed at least in part, a biasing member for biasing the plunger in a protruding direction, and a ratchet member. The ratchet member is disposed in the opening of the hole in the housing, and includes a substantially ring-shaped main body, and an engaging piece extending inward from the main body and capable of elastically engaging with the rack teeth of the plunger. I have.
[0011]
According to the first aspect of the present invention, during operation of the tensioner, when the plunger moves in the protruding direction, the movement of the plunger is performed in a state where the engagement piece of the ratchet member elastically abuts the rack teeth of the plunger. Done. On the other hand, when the plunger moves in the retracting direction, the engagement piece of the ratchet member acts as a strut or strut between the wall surface in the opening and the rack teeth of the plunger. Degeneration can be prevented.
[0012]
In this case, the engagement piece of the ratchet member has an elastic action, so that it is not necessary to provide an urging member separately from the ratchet member. Thereby, the number of parts can be reduced and the structure can be simplified. Further, since the ratchet member can be integrated with the plunger, the tensioner can be easily assembled.
[0013]
According to the first aspect of the present invention, since the biasing member is disposed on the outer periphery of the plunger, the plunger does not need to be a hollow member, and the capacity of the chamber can be reduced. Accordingly, the oil can be filled in the chamber in a short time at the start of the operation, and the response characteristics of the tensioner can be improved. In addition, since the main body of the ratchet member is disposed at the opening of the hole of the housing in the compartment formed by the wall surface in the opening and the rear end surface of the locking member with an axial gap therebetween, , The amount of backlash of the tensioner can be increased. This makes it possible to provide a tensioner suitable for a chain system requiring a relatively large backlash amount and having a long center-to-center distance.
[0014]
Furthermore, according to the first aspect of the present invention, when the plunger is at its maximum extension, the contact surface of the outer peripheral surface of the plunger contacts the stopper surface of the locking member via the engagement piece of the cheet member. This makes it possible to reliably prevent the plunger from falling off.
[0015]
Locking member, as described in the invention of claim 2, preferably attached to the mounting holes of large diameter formed at the opening of the housing bore. In this case, the bottom wall surface of the mounting hole forms the wall surface in the opening. Thus, when the engaging piece of the ratchet member acts as a strut, the base end portion of the engaging piece, that is, the main body of the ratchet member is stably supported by the bottom wall surface of the mounting hole.
[0016]
The engagement piece of the ratchet member preferably extends obliquely toward the distal end of the plunger with respect to the axis of the plunger, as described in the third aspect of the present invention. As a result, the engagement piece effectively exerts a ratchet function on the rack teeth of the plunger.
[0017]
It is preferable that the engagement piece is constituted by a pair of engagement pieces arranged to face each other, as described in the invention of claim 4 . In this case, particularly when the plunger is retracted, the plunger is supported by the engagement pieces in a well-balanced manner without prying inside the hole of the housing.
[0018]
According to the fifth aspect of the present invention, the rack teeth of the plunger are provided on the outer peripheral surface of the plunger corresponding to the circumferential positions of the engagement pieces of the ratchet member. Then, by rotating the plunger about its axis, the plunger is disengaged from the engaging position where the rack teeth are engaged with the engaging pieces and the rack teeth are separated from the engaging pieces. In a disengaged position. That is, in this case, a reset structure of the ratchet member is provided.
[0019]
Thus, even when the plunger is once extended, the engagement state between the rack teeth of the plunger and the engagement pieces of the ratchet member is released by rotating the plunger by a predetermined angle, and the plunger is moved into the housing from this state. By pushing the plunger, the plunger can be easily brought into the retracted state again. Utilizing this reset structure, the assembly of the plunger, the incorporation of the plunger into the engine, and the replacement of the plunger can be easily performed.
[0020]
In the invention of claim 6 , the retainer pin is inserted into the through hole formed in the housing and the retainer pin is locked in the locking hole of the plunger, so that the plunger can be held in the maximum retracted state before the tensioner is installed. Become. After the tensioner is installed, the tensioner is put into an operable state by removing the retainer pin.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
1 and 2 are longitudinal sectional views of a hydraulic tensioner according to an embodiment of the present invention. FIG. 1 is a diagram showing a state when the plunger is fully retracted, FIG. 2 is a diagram showing a state when the plunger is fully extended, 3A is a front view of a plunger in the hydraulic tensioner of FIG. 1, FIG. 3B is a plan view of the plunger, FIG. 4A is a right side view of a ratchet member in the hydraulic tensioner of FIG. 7 (b) is a cross-sectional view taken along the line BB of FIG. 7 (a), FIG. 5 is a view showing a state where the plunger is extended during tensioner operation, FIG. 6 is a view showing a state where the plunger is retracted during tensioner operation, FIG. FIG. 8 is a view showing a state in which the ratchet mechanism is reset when the plunger is fully extended, FIG. 8 is a view showing a state in which the engagement state by the ratchet member is released when the plunger is fully retracted, and FIG. Cross sectional view showing the engagement state is released, FIG. 10 is a cross-sectional view showing an engagement state by the ratchet member.
[0022]
As shown in FIGS. 1 and 2, a hydraulic tensioner 1 is provided on a housing 2, a solid plunger 3 slidably inserted into a hole 2 a formed in the housing 2, and an outer periphery of the plunger 3. And a spring 4 for urging the plunger 3 in a direction protruding from the hole 2a.
[0023]
In the housing 2, a fluid chamber 20 is formed from the rear end surface 3a of the plunger 3 and the inner wall surface of the hole 2a. Rack teeth 3 b are formed on a part of the outer peripheral surface of the plunger 3. The rack teeth 3b are formed on two opposing surfaces on the outer peripheral surface of the plunger 3 (see FIGS. 3A and 3B). At the tip of the plunger 3, there is provided a contact portion 30 for contacting a chain (not shown). One end of the spring 4 is in pressure contact with the contact portion 30.
[0024]
At the opening of the hole 2 a of the housing 2, a mounting hole 22 having a larger diameter than the hole 2 a is formed, and a locking member 5 for locking the other end of the spring 4 is formed in the mounting hole 22. Installed. The distal end portion of the plunger 3 is slidably supported in a through hole 5 a formed in the center of the locking member 5.
[0025]
A ratchet member 6 for preventing the plunger 3 from retracting is provided in the mounting hole 22. As shown in FIG. 4A, the ratchet member 6 includes a ring-shaped main body 6a, and a pair of substantially rectangular engaging pieces 6b extending inward from the main body 6a and arranged to face each other. Have been. Each engagement piece 6b extends to the plunger tip side in a direction obliquely intersecting the center axis C, that is, the axis L of the plunger 3 (FIG. 1), as shown in FIG. Further, each tip of the engagement piece 6 b of the ratchet member 6 is elastically engaged with the rack teeth 3 b of the plunger 3.
[0026]
With such a configuration, the ratchet member 6 allows the plunger 3 to move in the protruding direction while effectively exerting a ratchet function of preventing the plunger 3 from moving in the retreating direction. Further, since the engagement piece of the ratchet member 6 is constituted by a pair of engagement pieces 6b arranged opposite to each other, the plunger 3 does not pry inside the hole 2a of the housing 2 particularly when the plunger 3 is retracted. The pieces 6b are supported in a well-balanced manner.
[0027]
Further, the main body portion 6a of the ratchet member 6 has an axial gap in the compartment defined by the bottom wall surface 22a of the attachment hole 22 and the rear end surface 5b of the locking member 5 in the attachment hole 22. I have.
[0028]
An inclined stopper surface 5c is formed at the rear end side opening of the through hole 5a of the locking member 5. On the other hand, on the outer peripheral surface of the plunger 3, an inclined contact surface 3c corresponding to the stopper surface 5c is formed.
[0029]
The housing 2 is formed with a lateral through hole 21 for inserting a retainer pin (not shown) for holding the plunger 3 in the maximum retracted state before installing the tensioner. The plunger 3 has a locking hole 31 for locking the retainer pin.
[0030]
Next, the operation of the ratchet member 6 during the operation of the tensioner will be described.
When the engine starts, oil is supplied to the chamber 20 of the tensioner 1 from an external oil pump. When the chamber 20 is filled with oil, the pressing force due to the combination of the oil pressure and the elastic repulsive force of the spring 4 is applied from the contact portion 30 at the tip of the plunger via a tensioner arm (not shown). Act on the chain.
[0031]
When the plunger 3 moves in the projecting direction due to elongation of the chain during operation, that is, when the plunger 3 is extended, as shown in FIG. 5, the engagement piece 6b of the ratchet member 6 and the rack teeth of the plunger 3 are moved. The ratchet member 6 moves in the mounting hole 22 in the protruding direction of the plunger 3 in the mounting hole 22 to the right through the elastic contact state with the engagement piece 6b, that is, through the drag of the engagement piece 6b by the elastic force. Then, the main body 6a of the ratchet member 6 comes into contact with the rear end face 5b of the locking member 5.
[0032]
When the plunger 3 is further extended from this state, the engaging piece 6b of the ratchet member 6 moves the rack teeth 3b of the plunger 3 while the main body 6a of the ratchet member 6 is in contact with the locking member 5. The plunger 3 moves in the protruding direction while getting over.
[0033]
When the plunger 3 is fully extended, as shown in FIG. 2, the contact surface 3c of the plunger 3 comes into contact with the stopper surface 5c of the locking member 5 via the engagement piece 6b of the ratchet member 6. ing. Thereby, it is possible to reliably prevent the plunger 3 from falling out of the housing hole 3a.
[0034]
On the other hand, when the plunger 3 moves in the retreating direction from the state shown in FIG. 5 when a pressing force acts on the contact portion 30 at the tip of the plunger from the chain due to an increase in chain tension or the like, FIG. As shown in FIG. 6, the tip of the engagement piece 6b of the ratchet member 6 engages with the rack teeth 3b of the plunger 3, whereby the ratchet member 6 moves integrally with the plunger 3 to the left in the drawing. As a result, the main body 6 a of the ratchet member 6 comes into contact with the bottom wall surface 22 a in the mounting hole 22. In this state, the engagement piece 6b of the ratchet member 6 acts as a strut between the bottom wall surface 22a and the rack teeth 3b of the plunger 3, that is, a rod, so that the plunger 3 is reliably prevented from retreating. .
[0035]
Next, if a pressing force is applied from the chain to the contact portion 30 at the tip of the plunger in a situation where sufficient fluid pressure is not acting in the chamber 20, such as when starting the engine, the same applies. Since the engagement piece 6b of the ratchet member 6 acts as a strut between the bottom wall surface 22a and the rack teeth 3b of the plunger 3 (see FIG. 6), the retraction of the plunger 3 can be reliably prevented.
[0036]
Next, at the time of assembling the tensioner, when holding the plunger 3 in the maximum retracted state, the housing 2 is engaged with the engagement piece 6b of the ratchet member 6 in engagement with the rack teeth 3b on the front end side of the plunger 3. In this state, a retaining pin is inserted into the through hole 21 of the housing 2 and locked in the locking hole 31 of the plunger 3 from this state. Thereby, the plunger 3 can be easily maintained in the maximum contracted state. After assembling the tensioner to the chain, by pulling out the retaining pin from the through hole 21, the plunger 3 is extended and the tensioner is in an operable state.
[0037]
When the plunger placed in the maximum extension state is again brought into the maximum contraction state, the contact portion 30 at the tip of the plunger is gripped from the state shown in FIG. 2 and the plunger 3 is moved through the contact portion 30. Rotate about 90 degrees about axis L. Then, as shown in FIG. 7, the engagement piece 6b of the ratchet member 6, which has been in contact with the contact surface 3c of the plunger 3, moves away from the contact surface 3c and onto the outer peripheral surface of the cylindrical plunger.
[0038]
At this time, the positional relationship between the engagement pieces 6b of the ratchet member 6 and the rack teeth 3b of the plunger 3 is as shown in FIG. 9, and the rack teeth 3b are located between the opposed engagement pieces 6b. Is arranged. As shown in FIG. 9, the contact portion 30 of the plunger 3 has a pair of notches 30a facing each other, and the contact portions 30 are easily gripped by these notches 30a. The position of the rack teeth 3b of the plunger 3 can be easily grasped by the position of the notch 30a.
[0039]
Next, as shown in FIG. 8, the plunger 3 is pushed into the housing 2 via the contact portion 30 of the plunger 3. At this time, the rack teeth 3b of the plunger 3 and the engaging pieces 6b of the ratchet member 6 are still in the disengaged state where the engaged state has been released.
[0040]
From this state, the contact portion 30 at the tip of the plunger is grasped, and the plunger 3 is rotated about its axis L by about 90 degrees via the contact portion 30. Then, as shown in FIG. 1, the rack teeth 3b of the plunger 3 move toward the engagement piece 6b of the ratchet member 6, and the engagement piece 6b engages with the rack tooth 3b. At this time, the positional relationship between the contact portion 30, the rack tooth 3b, and the engagement piece 6b at the tip of the plunger is as shown in FIG.
[0041]
In this case, even if the plunger is once extended, the plunger can be easily brought into the retracted state even if the plunger is once extended by providing the reset mechanism which can release the engagement state of the ratchet member 6 with the rack teeth 3b. can do. This facilitates assembly of the plunger, installation of the plunger in the engine, replacement of the plunger, and the like.
[0042]
As described above, according to the present embodiment, when the plunger 3 moves in the protruding direction during operation of the tensioner, the engagement piece 6b of the ratchet member 6 elastically abuts the rack teeth 3b of the plunger 3. The plunger 3 is moved in this state. On the other hand, when the plunger 3 moves in the retracting direction, the engagement piece 6b of the ratchet member 6 acts as a strut between the bottom wall surface 22a in the mounting hole 22 and the rack teeth 3b of the plunger 3, thereby. Thus, the plunger 3 can be prevented from contracting.
[0043]
In this case, the engagement piece 6b of the ratchet member 6 itself has an elastic action, and therefore, there is no need to provide an urging member separately from the ratchet member 6. Thereby, the number of parts can be reduced and the structure can be simplified. In addition, since the ratchet member 6 can be integrated with the plunger 3, the tensioner can be easily assembled. The number of the engagement pieces 6b provided on the ratchet member 6 may be one or more at equal intervals in the circumferential direction according to the plunger diameter or the like. It is also possible to arrange only.
[0044]
Further, in this embodiment, since the spring 4 is disposed on the outer periphery of the plunger 3, it is not necessary to make the plunger 3 a hollow member, and the capacity of the chamber 20 can be reduced. Thus, the oil can be filled into the chamber 20 in a short time at the start of the operation, and the response characteristics of the tensioner can be improved. Further, since the main body 6a of the ratchet member 6 is disposed in the compartment formed by the bottom wall surface 22a of the mounting hole 22 and the rear end surface 5b of the locking member 5 with an axial gap therebetween, The amount of backlash of the tensioner can be increased by the amount. This makes it possible to provide a tensioner suitable for a chain system requiring a relatively large backlash amount and having a long center-to-center distance.
[0045]
【The invention's effect】
As described above, according to the hydraulic tensioner according to the present invention, since the ratchet member having the engagement piece that can be elastically engaged with the rack teeth of the plunger is provided, the urging member is provided separately from the ratchet member. Need not be provided, thereby reducing the number of parts and simplifying the structure.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a hydraulic tensioner according to an embodiment of the present invention, showing a state at the time of maximum retraction of a plunger.
FIG. 2 is a longitudinal sectional view of a hydraulic tensioner according to an embodiment of the present invention, showing a state in which a plunger is fully extended.
3A is a front view of a plunger in the hydraulic tensioner of FIG. 1, and FIG. 3B is a plan view of the plunger.
4A is a right side view of a ratchet member in the hydraulic tensioner of FIG. 1, and FIG. 4B is a cross-sectional view taken along line BB of FIG.
FIG. 5 is a diagram showing a state when a plunger is extended during tensioner operation.
FIG. 6 is a diagram illustrating a state in which the plunger is retracted during the operation of the tensioner.
FIG. 7 is a view showing a disengaged state in which the engaged state by the ratchet member is released when the plunger is fully extended.
FIG. 8 is a diagram showing a non-engaged state in which the engaged state by the ratchet member is released at the time of maximum retraction of the plunger.
FIG. 9 is a cross-sectional view showing a disengaged state in which the engaged state by the ratchet member is released.
FIG. 10 is a cross-sectional view showing an engagement state by a ratchet member.
[Explanation of symbols]
1: hydraulic tensioner 2: housing 2a: hole 20: fluid chamber 21: through hole 22: mounting hole 22a: bottom wall 3: plunger 3b: rack teeth 3c: contact surface 31: locking hole 4: spring 5: engagement Stop member 5b: Rear end surface 5c: Stopper surface 6: Ratchet member 6a: Main body 6b: Engagement piece

Claims (6)

A hydraulic tensioner for applying tension to the chain,
A housing having a hole opened at one end;
A plunger slidably inserted into the hole to form a fluid chamber between the hole and a rack tooth formed on at least a part of an outer peripheral surface;
An urging member for urging the plunger in a protruding direction;
A substantially ring-shaped main body is disposed in the opening of the hole of the housing, and has an engagement piece extending inward from the main body and capable of elastically engaging with the rack teeth of the plunger. The plunger is allowed to move in the protruding direction, and when the plunger is retracted, the engaging piece acts as a strut between the wall surface in the opening and the rack teeth of the plunger, thereby acting on the plunger. and a ratchet member for preventing degeneration,
The urging member is disposed on the outer periphery of the plunger, and one end of the urging member is locked to a tip end of the plunger,
The opening of the hole of the housing has a through hole through which the plunger is inserted, and a locking member for locking the other end of the biasing member is provided,
The main body of the ratchet member is disposed at an opening of the hole of the housing in a compartment formed by a wall surface in the opening and a rear end surface of the locking member via an axial gap. And
A stopper surface for preventing the plunger from falling out of the hole of the housing is formed at a rear end side opening of the through hole of the locking member, and an outer peripheral surface of the plunger is formed on the outer peripheral surface of the plunger. A contact surface is formed corresponding to the stopper surface of the locking member, and a contact surface that contacts the stopper surface via the engagement piece of the ratchet member when the plunger is fully extended,
A hydraulic tensioner characterized in that: In claim 1 ,
The locking member is attached to a mounting hole formed in the opening of the hole of the housing and having a larger diameter than the hole, and a bottom wall surface of the mounting hole forms the wall surface in the opening. are doing,
A hydraulic tensioner characterized in that: In claim 1 or 2 ,
The extending direction of the engagement piece in the ratchet member extends obliquely toward the distal end side of the plunger with respect to the axis of the plunger.
A hydraulic tensioner characterized in that: In claim 3 ,
The engagement piece is constituted by a pair of engagement pieces arranged to face each other,
A hydraulic tensioner characterized in that: In claim 3 or 4 ,
The rack teeth of the plunger are provided on the outer peripheral surface of the plunger at positions corresponding to circumferential positions of the engagement pieces of the ratchet member. By rotating the plunger about its axis, the plunger is rotated. Takes an engagement position where the rack teeth are engaged with the engagement piece and is in an engaged state, and a non-engagement position where the rack teeth are separated from the engagement piece and the engagement state is released. Is to gain,
A hydraulic tensioner characterized in that: In claim 1,
The housing has a lateral through-hole into which a retaining pin for holding the plunger in the maximum retracted state before the tensioner is installed, and the retaining pin is engaged with the plunger. Locking holes are formed,
A hydraulic tensioner characterized in that:

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