JP4451314B2 - Hydraulic tensioner - Google Patents

Description

  The present invention relates to a hydraulic tensioner that applies tension to a target member such as an endless transmission belt represented by an endless chain or an endless belt. The hydraulic tensioner drives a valve operating device or an auxiliary machine in an internal combustion engine, for example. It is used for a drive device having an endless transmission band.

In the hydraulic chamber of the hydraulic tensioner, there is a small gap such as air mixed in the oil supplied to the hydraulic chamber or a sliding part when the oil supply to the hydraulic chamber is stopped when the tensioner is not operating. Air that has entered the hydraulic chamber from there accumulates. Various techniques for exhausting this air are known because the air in the hydraulic chamber reduces the damper function for suppressing the flutter of the endless transmission band that occurs when the tensioner receives a load from the endless transmission band that is tensioned, for example. It has been. For example, in the hydraulic tensioner disclosed in Patent Document 1, an orifice is formed between an outer periphery of an orifice member that is press-fitted into a plunger that forms an oil chamber together with a housing and the plunger. The orifice is formed by a spiral groove formed on the outer periphery of the orifice member, and when the plunger receives a load from the chain and the oil pressure in the oil chamber rises, air is discharged together with the oil through the orifice.
Japanese Patent No. 3243226 (FIG. 1)

  By the way, in the prior art, since it is necessary to press-fit the orifice member in order to form the orifice, it takes time to assemble the tensioner, and it cannot be said that the assemblability is good. In addition, the formation of the spiral groove becomes an increase factor of the processing cost. In order to minimize the amount of oil leaking through the orifice as much as possible, it is not easy to set the flow path area to an appropriate value and keep the amount of leakage within a desired range in an orifice composed of a spiral groove. Absent. In addition, the oil in the hydraulic chamber is mixed with foreign matter such as wear powder generated at the sliding part of the tensioner, and shavings generated when the oil passage leading the oil to the hydraulic chamber is formed by machining. If such foreign matter enters a relatively small-diameter orifice such as a spiral groove, the foreign matter may impede air flow and prevent smooth discharge of air in the hydraulic chamber. .

The present invention, all SANYO been made in view of such circumstances, the hydraulic tensioner air vent passage is formed, to improve the assembly property of the tensioner, the oil through the air vent passage leak amount of the desired It is intended to make it easy to fit within the range, and to make the air discharge function of the air vent passage less susceptible to the influence of foreign matter mixed in the oil. The invention described in claim 4 further aims to facilitate the discharge of the air in the hydraulic chamber to the outside, and the invention described in claim 3 further aims to reduce the cost of the tensioner. To do.

According to the first aspect of the present invention, there is provided a housing, a plunger that is slidably fitted to the housing and forms a hydraulic chamber between the housing, and the plunger is disposed in the hydraulic chamber so that the plunger is attached in the advance direction. An urging member that urges and a sheet member that is held by the plunger by being urged by the urging member, and the plunger acts on the target member by the urging force of the urging member and the hydraulic pressure in the hydraulic chamber. in hydraulic tensioner for imparting tension, it said plunger communicating hole for communicating the outside of the hydraulic chamber and the hydraulic chamber is formed in the sheet over preparative member includes a fitting portion to be loosely fitted to the communication hole And an air vent passage formed integrally by the plunger and the seat member for discharging the air in the hydraulic chamber. A throttle passage formed on the basis of a cylindrical gap formed between the wall surface and the outer peripheral surface of the fitting portion of the communication hole is formed on at least one of the abutting surfaces of mutual between the plunger and the flange And an introduction passage configured by a groove that allows the hydraulic chamber and the throttle passage to communicate with each other , and the throttle passage defines the amount of oil leaking from the hydraulic chamber to the outside, and the outer diameter of the flange Is smaller than the diameter of the hydraulic chamber, a gap is formed between the outer peripheral surface of the flange and the inner peripheral surface of the plunger, and the central axis of the fitting portion and the central axis of the communication hole are coaxial. In this state, the radial width of the gap between the outer peripheral surface of the flange and the inner peripheral surface of the plunger is larger than the radial width of the gap between the wall surface of the communication hole and the outer peripheral surface of the fitting portion. hydraulic, characterized in that the larger Is Nshona.

According to this, the throttle passage of the air vent passage is formed by loosely fitting the insertion portion of the sheet member that is urged by the urging member and held by the plunger into the communication hole. As compared with the case where the member is press-fitted into the plunger, the assembly of the tensioner in which the throttle passage is formed is facilitated. Further, since the throttle passage is a passage formed based on a cylindrical gap formed between the wall surface of the communication hole and the outer peripheral surface of the insertion portion, the size of the communication hole or the insertion portion is changed. By changing the width between the wall surface and the outer peripheral surface in the gap, it is possible to change the amount of oil leaking from the hydraulic chamber to the outside. Furthermore, since the cross-sectional shape of the flow path of the throttle passage is an annular shape or a substantially annular shape surrounding the insertion portion, even if foreign matter such as friction powder mixed in the oil flowing through the throttle passage enters the throttle passage, it is blocked by the foreign matter. The rate of reduction of the flow passage area of the throttle passage due to peeling is extremely small, and the degree to which the smooth flow of air in the throttle passage is hindered by foreign substances is small.
Also, the air in the hydraulic chamber can easily escape from the hydraulic chamber to the throttle passage through the introduction passage. Further, a gap (recess) is formed outside the flange regardless of the position of the seat member in the radial direction, and this gap (recess) is formed at the upper position in the hydraulic chamber. It will be in the position where air is easy to collect. In other words, the gap as the inlet of the air vent passage is secured at a position where air easily accumulates in the hydraulic chamber, and the gap is not filled, so that the air can flow quickly to the outside without being obstructed. .

According to a second aspect of the present invention, there is provided a housing, a plunger that is slidably fitted to the housing and forms a hydraulic chamber between the housing, and the plunger that is disposed in the hydraulic chamber and attaches the plunger in the advance direction. An urging member that urges and a sheet member that is held by the plunger by being urged by the urging member, and the plunger acts on the target member by the urging force of the urging member and the hydraulic pressure in the hydraulic chamber. In the hydraulic tensioner that applies tension, the plunger is formed with a communication hole that communicates the hydraulic chamber and the outside of the hydraulic chamber, and the seat member has a fitting portion that is loosely fitted into the communication hole; An air vent passage formed integrally by the plunger and the seat member and exhausting air in the hydraulic chamber is provided in front of the flange abutting the plunger. A throttle passage formed based on a cylindrical gap formed between the wall surface of the communication hole and the outer peripheral surface of the fitting portion, and the air vent passage further supports the biasing member at the flange An inlet opening to the support surface which is a surface on the side to be closed, an axial hole having a closed end extending in the central axial direction of the fitting portion, and extending outward from the axial hole along the radial direction to the outer peripheral surface An introduction passage configured to open and communicate the hydraulic chamber with the throttle passage, and an amount of oil leaking from the hydraulic chamber to the outside is defined by the throttle passage; The outer diameter is smaller than the diameter of the hydraulic chamber, a gap is formed between the outer peripheral surface of the flange and the inner peripheral surface of the plunger, and the central axis of the fitting portion and the central axis of the communication hole The outer periphery of the flange The radial width of the gap between the inner peripheral surface of the plunger and the plunger is formed smaller than the radial width of the gap between the wall surface of the communication hole and the outer peripheral surface of the fitting portion. It is a hydraulic tensioner.

According to this, the inlet of the introduction passage is provided at a higher position in the hydraulic chamber, so that air is easily collected in the hydraulic chamber, and without collecting the air accumulated in the hydraulic chamber as the inlet of the air vent passage. It makes it possible to discharge quickly. In addition, a gap is formed between the outer peripheral surface of the flange and the inner peripheral surface of the plunger in a state where the central axis of the fitting portion and the central axis of the communication hole are coaxial. The insertion part of the sheet member can be easily inserted into the communication hole of the plunger without causing interference with the surface.

According to a third aspect of the present invention, in the hydraulic tensioner according to the first or second aspect, the wall surface of the communication hole and the outer peripheral surface of the fitting portion are cylindrical surfaces.

According to this, since the throttle passage is cylindrical or substantially cylindrical, the communication between the introduction passage and the throttle passage becomes easy, and there are few restrictions on the arrangement of the introduction passage for smoothly guiding air to the throttle passage. Become. Further, since the wall surface of the communication hole forming the throttle passage and the outer peripheral surface of the fitting portion are cylindrical surfaces, the processing cost is reduced as compared with the case where a spiral groove is formed on the wall surface or the outer peripheral surface.

According to a fourth aspect of the present invention, in the hydraulic tensioner according to the first or second aspect, the throttle passage extends on the outer peripheral surface of the insertion portion in the insertion direction of the insertion portion and communicates with the introduction passage. It has the wide part comprised from the insertion direction groove | channel to do, It is characterized by the above-mentioned.

According to this, the air in the hydraulic chamber can easily escape from the hydraulic chamber to the throttle passage through the introduction passage, and the restriction on the arrangement of the introduction passage for smoothly guiding the air to the throttle passage is reduced. Further, in the throttle passage, the flow passage area is increased by the widened portion, so that air easily passes.

According to invention of Claim 1, the following effect is show | played. That is, in order to form the throttle passage, it is only necessary to loosely fit the insertion portion of the sheet member into the communication hole of the plunger, so that the assemblability of the tensioner in which the air vent passage is formed is improved. In addition, since the amount of oil leakage can be changed by changing the size of the cylindrical gap formed by the communication hole and the fitting portion, the amount of oil leakage through the air vent passage is within a desired range. Easy to fit. Furthermore, since the degree of hindering the smooth air flow in the throttle passage by the foreign matter mixed in the oil is small, the air flow in the throttle passage is less affected by the foreign matter, and consequently the air exhaust function of the air release passage. Is less susceptible to foreign objects.
Also, the air in the hydraulic chamber can easily escape from the hydraulic chamber to the throttle passage through the introduction passage. Further, a gap (recess) is formed outside the flange regardless of the position of the seat member in the radial direction, and this gap (recess) is formed at the upper position in the hydraulic chamber. It will be in the position where air is easy to collect. In other words, the gap as the inlet of the air vent passage is secured at a position where air easily accumulates in the hydraulic chamber, and the gap is not filled, so that the air can flow quickly to the outside without being obstructed. .

According to the second aspect of the present invention, the inlet of the introduction passage is provided at a higher position in the hydraulic chamber, so that the air is easily collected in the hydraulic chamber, and collected in the hydraulic chamber as the inlet of the air vent passage. It is possible to discharge quickly without accumulating air. In addition, a gap is formed between the outer peripheral surface of the flange and the inner peripheral surface of the plunger in a state where the central axis of the fitting portion and the central axis of the communication hole are coaxial. The insertion portion of the sheet member can be easily inserted into the communication hole of the plunger without causing interference with the surface.

According to the third aspect of the present invention, since the throttle passage is cylindrical or substantially cylindrical, the communication between the introduction passage and the throttle passage is facilitated, and the introduction passage for smoothly introducing air into the throttle passage is provided. There are fewer constraints on placement. Further, since the wall surface of the communication hole forming the throttle passage and the outer peripheral surface of the fitting portion are cylindrical surfaces, the processing cost is reduced as compared with the case where a spiral groove is formed on the wall surface or the outer peripheral surface.

According to the fourth aspect of the present invention, the air in the hydraulic chamber can easily escape from the hydraulic chamber to the throttle passage through the introduction passage, and there are restrictions on the arrangement of the introduction passage for smoothly guiding the air to the throttle passage. Less. Further, in the throttle passage, the flow passage area is increased by the widened portion, so that air easily passes.

Hereinafter, embodiments of the present invention will be described with reference to FIGS.
1 to 4 are for explaining the first embodiment. Referring to FIG. 1, in a vehicle internal combustion engine as a machine provided with a hydraulic tensioner T to which the present invention is applied, a drive device for driving a valve operating device includes a crankshaft of the internal combustion engine and the dynamic shaft. An endless chain C serving as an endless transmission band is provided between the camshaft of the valve device and a tensioner T applies tension to the chain C.

  The tensioner T includes a housing 1 having an opening 5a that opens to the outside S of the tensioner T at one end and a receiving hole 5 having a bottom 5b at the other end, and is accommodated in the receiving hole 5 and extends from the opening 5a to the tip 2b. And a plunger 2 that is slidably supported by the housing 1 in a state of projecting and a hydraulic chamber 3 formed by the housing 1 and the plunger 2 and disposed between the housing 1 and the plunger 2. A tensioner spring 4 comprising a compression coil spring as a biasing member, a restricting means 30 for restricting movement in the retracting direction while permitting movement of the plunger 2 relative to the housing 1, and supplying oil to the hydraulic chamber 3 And a relief valve 40 as a hydraulic pressure release means for preventing the hydraulic pressure in the hydraulic chamber 3 from becoming excessive. Further, in the tensioner T, an oil supply path 6 that guides oil from an oil pump as a hydraulic pressure source to the hydraulic chamber 3, a relief passage 7 in which a relief valve 40 is disposed, and air accumulated in the hydraulic chamber 3 is supplied to the hydraulic chamber 3. An air vent passage 50 is formed to be discharged to the outside S as the outside.

  Referring also to FIG. 2, the housing 1 is composed of a first housing 1a in which a receiving hole 5 and a mounting portion 1a1 are formed, and a second housing 1b fixed to the end of the first housing 1a by a bolt B. Is done. The housing 1 is fixed to the mounting portion E1 of the internal combustion engine provided with the drive device by a bolt (not shown) inserted through the insertion hole 1a2 of the mounting portion 1a1. Here, it is preferable that the housing 1 is fixed to the internal combustion engine in a posture in which air tends to accumulate in the vicinity of the inlet 51 a (see FIG. 3) of the air vent passage 50 in the hydraulic chamber 3.

  The oil supply passage 6 is formed in the first housing 1a and the first oil passage 6a into which oil from the oil passage E2 provided in the internal combustion engine flows, and the second housing 1b is formed in the first oil passage 6a. The second oil passage 6b guides oil to the check valve 10. High-pressure oil discharged from the oil pump driven by the power of the crankshaft is supplied to the hydraulic chamber 3 through the oil passage E2 and the first and second oil passages 6a and 6b. The oil pump supplies lubricating oil to a lubricating portion such as a sliding portion of the internal combustion engine through a number of oil passages, and the oil supplied to the hydraulic chamber 3 is a part of the lubricating oil. The first oil passage 6a is formed by machining, for example.

  The plunger 2 composed of a cylindrical member having a central axis L2 coaxial with the central axis L1 in a state of being fitted into the cylindrical accommodation hole 5 having the central axis L1 is combined with the accommodation hole 5 in the hydraulic chamber 3. And a base 2a that can be positioned in the receiving hole 5 and a tip 2b that is continuous with the base 2a and also serves as a wall that closes the inner hole 8. The plunger 2 is urged in the advancing direction which is parallel to the central axis L2 by the urging force of the tensioner spring 4 and the hydraulic pressure of the hydraulic chamber 3, and is supported by the internal combustion engine so as to be swingable and slips on the chain C. The chain C is pressed through the shoe D, which is an intermediate member that comes into contact, and tension is applied to the chain C as the target member.

  The check valve 10 includes a valve seat member 11 that is press-fitted and fixed to a portion 1a3 that forms the bottom portion 5b of the housing hole 5 in the first housing 1a, and a spherical valve that can be seated on the valve seat 11a of the valve seat member 11 A body 12 and a valve body 13 that accommodates the valve body 12 and restricts the amount of movement when the valve body 12 is opened are provided. The check valve 10 is opened when the hydraulic pressure in the hydraulic chamber 3 is reduced by the plunger 2 moving in the advance direction, and allows the oil to flow from the oil supply passage 6 into the hydraulic chamber 3. When the hydraulic pressure in the hydraulic chamber 3 rises by moving in a backward direction that is parallel to the central axis L2, the valve is closed to prevent the oil from flowing out from the hydraulic chamber 3 to the oil supply passage 6.

  The tensioner spring 4 is supported by the seat member 20 at one end and supported by the valve body 13 of the check valve 10 as the seat member at the other end. The seat member 20 and the valve body 13 are held in contact with the distal end portion 2b and the valve seat member 11 by being urged by the tensioner spring 4 in the hydraulic chamber 3, respectively.

  Referring to FIGS. 1 and 3 together, in the restricting means 30, the annular inner groove 31 extending over the entire circumference on the outer peripheral surface of the plunger 2 is in the direction A of the central axis L2 (hereinafter referred to as “axial direction A”). However, a plurality of annular inner engagement portions 32 formed by being formed at intervals in a certain advancing / retreating direction and engageable with each inner engagement portion 32 while being accommodated in the inner groove 31 A C-shaped clip 33 that can be expanded as a simple engaging member, and an annular outer groove 34 that is press-fitted into the end 1a4 where the opening 5a is formed in the first housing 1a and accommodates the clip 33. Is provided with an outer engaging portion 35 formed of a cylindrical ring formed on the inner peripheral surface. The plunger 2 is slidable on the first housing 1a and the outer engagement portion 35, and the outer groove 34 is formed in the radial direction centered on the central axis L2 (hereinafter simply referred to as “radial direction”). Opposite the inner engagement portion 32.

  Each inner engagement portion 32 has an inner groove adjacent to the inner engagement portion 32 in the axial direction A, the clip 33 engaging with the advancement engagement portion 35a of the outer engagement portion 35 when the plunger 2 advances. The advancing side engaging portion 32a having a gently sloping surface for allowing it to be housed in 31, and a clip that engages with the retracting side engaging portion 35b of the outer engaging portion 35 when the plunger 2 is retracted 33 has a receding side engaging portion 32b having a steeply inclined surface for making it impossible to get over the inner engaging portion 32. Thereby, the advancement of the plunger 2 corresponding to the looseness of the chain C is allowed by the engagement of the advancement side engaging portions 32a and 35a, while the plunger 2 retracts due to the load acting on the chain C due to the tension of the chain C. After retreating by the amount of movement until the retreat-side engagement portions 32b and 35b are engaged with each other, further retreat is prevented by the engagement of the retreat-side engagement portions 32b and 35b. Further, the advance side limit engaging portion 32c (see FIG. 1) that defines the maximum advance position of the plunger 2 has an inclined surface on which the clip 33 that engages with the advance side engaging portion 35a cannot get over.

1 and 2, the relief passage 7 formed in the first housing 1a opens to the hydraulic chamber 3 at the upstream end and opens to the outside S at the downstream end. The relief valve 40 accommodated in the hole 9 formed in the first housing 1a has a valve seat 41a and a valve seat member 41 inserted into the first housing 1a, and a spherical valve body that can be seated on the valve seat 41a. 42, a relief spring 43 that biases the valve body 42 in the valve closing direction to set the relief pressure, and a retainer 44 that supports the relief spring 43 and defines the amount of movement of the valve body 42 when the valve is opened. Is done. The retainer 44 screwed into the first housing 1a presses the valve seat member 41 through the collar 45, thereby fixing the valve seat member 41 to the first housing 1a. The relief valve 40 is opened when the hydraulic pressure exceeding the relief pressure is generated in the hydraulic chamber 3 due to the retraction of the plunger 2, and the oil is discharged to the outside S through the relief passage 7, so that the hydraulic pressure in the hydraulic chamber 3 is excessive. To prevent becoming.

Referring to FIG. 3, the air vent passage 50 for discharging the air in the hydraulic chamber 3 is formed by the plunger 2 and the seat member 20.
The plunger 2 is formed with a communication hole 60 for communicating the hydraulic chamber 3 and the outside S at the tip 2b. The communication hole 60 includes a small-diameter portion 61 having an opening that opens to the outer surface 2c of the tip end portion 2b and forms an outlet 53b of the air vent passage 50, and a large-diameter portion 62 that is larger in diameter than the small-diameter portion 61. . The large-diameter portion 62 is a cylindrical hole having a wall surface 63a formed of a cylindrical surface, and is a first hole portion 63 that opens to an inner surface 2d described later, and a conical surface between the first hole portion 63 and the small-diameter portion 61. And a second hole 64 which is a conical hole having a wall surface made of The small diameter portion 61 is a cylindrical hole having a wall surface 61a made of a cylindrical surface. The communication hole 60 has a central axis L3 coaxial with the central axis L2.

  Referring also to FIG. 4, the sheet member 20 supports the insertion portion 21 that is loosely fitted into the first hole portion 63 of the communication hole 60 and the tensioner spring 4 that abuts, and is pressed by the tensioner spring 4 to move the plunger 2. And a flange 22 that abuts in the axial direction A. A cylindrical insertion portion 21 having an outer peripheral surface 21a made of a cylindrical surface is inserted into the first hole 63 in an insertion direction that is a direction parallel to the axial direction A from the hydraulic chamber 3 side. When the seat member 20 is held by the plunger 2 in a state where the central axis L4 of the fitting portion 21 is coaxial with the central axis L3 (the state shown in FIG. 3), there is a gap between the wall surface 63a and the outer peripheral surface 21a. A cylindrical gap having a predetermined width W1 in the radial direction, here, a cylindrical gap 65 is formed. Then, in a state where the contact surface 22b of the flange 22 is in contact with the inner surface 2d of the tip 2b that is the contact surface of the plunger 2, a gap 65 is formed between the wall surface 63a and the outer peripheral surface 21a. A throttle passage 52 is formed. When the fitting portion 21 occupies a position eccentric with respect to the first hole 63, the throttle passage 52 is a substantially cylindrical gap formed in a state where the wall surface 63a and the outer peripheral surface 21a are partially in contact with each other. Sometimes it becomes. Therefore, the flow passage cross-sectional shape of the throttle passage 52 is an annular shape or a substantially annular shape surrounding the fitting portion 21, and is an annular shape or a substantially annular shape here.

  The outer diameter of the flange 22 is smaller than the diameter of the inner hole 8 (that is, the inner diameter of the base portion 2a), and the inner surface 2d is connected to the bottom wall surface between the outer peripheral surface 22a of the flange 22 and the inner peripheral surface 2e of the plunger 2. An annular recess 3a is formed. With the center axis L4 of the fitting portion 21 and the center axis L3 of the first hole 63 being coaxial, the width W2 in the radial direction of the recess 3a is larger than the width W1, and the movement of the sheet member 20 in the radial direction is The concave portion 3a is radially outward with respect to the flange 22 regardless of the radial position of the seat member 20 because it is defined by the contact between the fitting portion 21 in the first hole 63 and the plunger 2. It is formed. And the recessed part 3a is formed in the position which becomes the upper part in the hydraulic chamber 3, and is formed in the position where air tends to accumulate in the hydraulic chamber 3. FIG.

  In the contact surface 22 b of the flange 22, an introduction passage 51 is formed that includes one or a plurality of linear grooves 23 that allow the hydraulic chamber 3 and the throttle passage 52 to communicate with each other. In this embodiment, four grooves 23 are formed at equal intervals in the circumferential direction along the radial direction. The upstream end of each groove 23 opens to the outer peripheral surface of the flange 22 to form the inlet 51a of the introduction passage 51. The introduction passage 51 is open to the hydraulic chamber 3 by opening the inlet 51a into the recess 3a.

  The air vent passage 50 includes an introduction passage 51, a throttle passage 52, and a lead-out passage 53 extending from the throttle passage 52 in the communication hole 60 to the outlet 53b. The lead-out passage 53 includes a portion including the second hole portion 64 that is positioned closer to the small-diameter portion 61 than the fitting portion 21 in the large-diameter portion 62 and the small-diameter portion 61. The flow path area of the small diameter portion 61 is larger than the flow path area of the throttle passage 52, and the amount of oil leakage in the hydraulic chamber 3 leaking to the outside S through the air vent passage 50 is defined by the flow path area of the throttle passage 52. Is done.

Next, operations and effects of the embodiment configured as described above will be described.
When the chain C travels, the chain C is slackened and tensioned due to tension fluctuations caused by torque fluctuations, and is also slackened due to elongation caused by wear of the chains C and wear of sprocket teeth. When the slack associated with the decrease in tension occurs in the chain C, the plunger 2 moves in the advance direction by the urging force of the tensioner spring 4 and the hydraulic pressure in the hydraulic chamber 3 to increase the tension of the chain C. At this time, oil flows into the hydraulic chamber 3 through the check valve 10 into the hydraulic chamber 3. On the other hand, when tension is generated in the chain C due to an increase in tension, the plunger 2 is increased in the hydraulic pressure in the hydraulic chamber 3 by closing the check valve 10 within a range in which retraction is prevented by the regulating means 30. As a result, the chain C moves slowly in the backward direction to reduce the tension of the chain C. Further, when shocking tension is generated in the chain C and a shocking load is applied to the plunger 2, the hydraulic pressure in the hydraulic chamber 3 rapidly increases due to the rapid retraction of the plunger 2. At this time, when the hydraulic pressure in the hydraulic chamber 3 exceeds the relief pressure, the relief valve 40 is opened, the hydraulic pressure is reduced, and excessive tension is prevented from being generated in the chain C.

  Then, the air mixed in the oil supplied to the hydraulic chamber 3 and the air that has entered the hydraulic chamber 3 through a slight gap such as the sliding portion of the plunger 2 with respect to the first housing 1a accumulate in the hydraulic chamber 3. When the plunger 2 moves backward, the air passes through the air vent passage 50, that is, through the inlet passage 51, the throttle passage 52, and the outlet passage 53, and is discharged together with oil from the outlet 53b to the outside S.

  The air vent passage 50 includes a wall surface 63a of the first hole 63 of the communication hole 60 formed in the distal end portion 2b of the plunger 2 and an outer peripheral surface of the insertion portion 21 of the sheet member 20 that is loosely fitted in the first hole 63. By having the throttle passage 52 formed between 21a and the throttle passage 52 of the air vent passage 50, the insertion portion 21 of the sheet member 20 that is urged by the tensioner spring 4 and held by the plunger 2 is formed in the communication hole 60. Therefore, as compared with the case where the member is press-fitted into the plunger as in the prior art, assembly of the tensioner T in which the throttle passage 52 is formed is facilitated. As a result, in order to form the throttle passage 52, the fitting portion 21 of the seat member 20 only needs to be loosely fitted in the communication hole 60 of the plunger 2, so that the assemblability of the tensioner T in which the air vent passage 50 is formed is improved. . Further, since the sheet member 20 forming the throttle passage 52 is held by the plunger 2 by the urging force of the tensioner spring 4, the sheet member 20 can be easily held.

  The amount of oil leaked from the hydraulic chamber 3 to the outside S by the throttle passage 52 formed based on the cylindrical gap 65 formed between the wall surface 63a of the communication hole 60 and the outer peripheral surface 21a of the insertion portion 21. Is defined. Accordingly, since the throttle passage 52 is a passage formed based on the cylindrical gap 65, the size of the communication hole 60 or the fitting portion 21 is changed, and the space between the wall surface 63a and the outer peripheral surface 21a in the gap 65 is changed. By changing the width W1, the amount of oil leaking from the hydraulic chamber 3 to the outside S can be changed, so that the amount of oil leaking through the air vent passage 50 can be easily kept within a desired range. Become.

  The oil in the hydraulic chamber 3 may be mixed with foreign matter such as wear powder generated at the sliding portion of the tensioner T or shaving powder generated when forming an oil passage for guiding the oil to the hydraulic chamber 3. However, since the throttle passage 52 is formed based on the cylindrical gap 65, the flow passage cross-sectional shape of the throttle passage 52 becomes an annular shape or a substantially annular shape surrounding the fitting portion 21, so that the oil flowing through the throttle passage 52 Even if the mixed foreign matter enters the throttle passage 52, the reduction rate of the flow passage area of the throttle passage 52 due to the blockage by the foreign matter is extremely small, and the smooth flow of air in the throttle passage 52 is caused by the foreign matter. The degree of obstruction is small. As a result, the air flow in the throttle passage 52 is less affected by foreign matter, and the air discharge function of the air vent passage 50 is less affected by foreign matter, so that the air in the hydraulic chamber 3 can be discharged well. become.

  The air vent passage 50 has an introduction passage 51 formed in a contact surface 22b of the flange 22 with the plunger 2 and configured to communicate with the hydraulic chamber 3 and the throttle passage 52. Air can easily escape from the hydraulic chamber 3 to the throttle passage 52 through the introduction passage 51, and discharge of the air in the hydraulic chamber 3 to the outside S is facilitated. Moreover, since the throttle passage 52 is cylindrical or substantially cylindrical, the communication between the introduction passage 51 and the throttle passage 52 is facilitated, and there are restrictions on the arrangement of the introduction passage 51 for smoothly guiding air to the throttle passage 52. Less. As a result, since the degree of freedom of the arrangement of the introduction passage 51 with respect to the throttle passage 52 is large, the introduction passage 51 can be formed at a position where air easily accumulates in the hydraulic chamber 3, so that air can be easily discharged.

  Since the annular recess 3a is formed between the outer peripheral surface 22a of the flange 22 where the inlet 51a of the air vent passage 50 opens and the inner peripheral surface 2e of the plunger 2, air easily collects in the recess 3a. Air in the hydraulic chamber 3 can be more easily removed through the introduction passage 51.

  Since the wall surface 63a of the communication hole 60 forming the throttle passage 52 and the outer peripheral surface 21a of the fitting portion 21 are cylindrical surfaces, the throttle passage is compared with the case where a spiral groove is formed on the wall surface 63a or the outer peripheral surface 21a. Since the processing cost for forming 52 is reduced, the cost of the tensioner T is reduced.

  Next, a second embodiment of the present invention will be described with reference to FIG. The second embodiment is different from the first embodiment mainly in the structure of the introduction passage of the air vent structure, and the rest has basically the same configuration. Therefore, description of the same part is omitted or simplified, and different points will be mainly described. In addition, about the member same as the member of 1st Embodiment, or the corresponding member, the same code | symbol was used as needed.

  In the introduction passage 55 corresponding to the introduction passage 51 of the first embodiment, an inlet 55a, which will be described later, which is an upstream end is opened to the hydraulic chamber 3 at the flange 22 of the seat member 20, and a downstream end 55b is formed in the tip portion 2b. The hole 25 is open to the throttle passage 52 on the outer peripheral surface 21a of the fitting portion 21 that is loosely fitted into the first hole portion 63 of the communication hole 60. Specifically, the hole 25 has an opening that opens to a support surface 22c that is a surface of the flange 22 that supports the tensioner spring 4 and constitutes the inlet 55a of the air vent passage 50, and the central axis L4 is the central axis. An axial hole 26 having a closed end extending in parallel with the axial direction A, and a single hole extending outward from the axial hole 26 along the radial direction and opening to the outer peripheral surface 21a near the hydraulic chamber 3 in the throttle passage 52 or In this embodiment, it is composed of two linear radial holes 27 formed at equal intervals in the circumferential direction. Here too, the inlet 55a of the introduction passage 55 is formed at a position at the top of the hydraulic chamber 3, so that air is easily collected in the hydraulic chamber 3.

  Further, the radial width W3 between the outer peripheral surface 22a of the flange 22 and the inner peripheral surface 2e of the plunger 2 is smaller than the width W1 when the central axis is coaxial (the state shown in FIG. 5). Preferably, the width W3 is set to be as small as possible within a range in which the sheet member 20 is easily inserted into the inner hole 8. Thereby, the throttle passage 52 is always maintained in a cylindrical shape, and the accumulation of air between the outer peripheral surface 22a and the inner peripheral surface 2e of the flange 22 is suppressed.

  According to the second embodiment, the same operation and effect as in the first embodiment can be obtained. Further, with respect to the introduction passage 55 of the air vent passage 50, the introduction passage 55 is connected to the hydraulic chamber 3 at the flange 22 at the inlet 55a. By opening and forming the hole 25 formed in the sheet member 20 so as to open to the throttle passage 52 on the outer peripheral surface 22a at the downstream end 55b, the hydraulic pressure passes through the introduction passage 55 as in the first embodiment. Since it becomes easy to escape from the chamber 3 to the throttle passage 52, the air in the hydraulic chamber 3 can be easily discharged to the outside S.

Hereinafter, an embodiment in which a part of the configuration of the above-described embodiment is changed will be described with respect to the changed configuration.
As shown by a two-dot chain line in FIG. 4, the throttle passage 52 (see FIG. 3) has a radially widened portion 52 a configured by a groove 29 formed in the outer peripheral surface 21 a of the fitting portion 21. May be. The grooves 29 formed in the same number as the grooves 23 communicate with the grooves 23 at the upstream end, and are linear insertion directions extending parallel to the insertion direction so as to open to the outlet passage 53 (see FIG. 3) at the downstream end. It is a groove.
Thus, since the air vent passage 50 has the introduction passage 51 and the throttle passage 52 has the widened portion 52a, the flow passage area is increased by the widened portion 52a in the throttle passage 52, so that air easily passes. The discharge of the air in the hydraulic chamber 3 to the outside S is further facilitated.

Instead of the groove 23, the groove constituting the introduction passage 51 may be a plunger side groove formed on the inner surface 2d of the plunger 2 to allow the hydraulic chamber 3 and the throttle passage 52 to communicate with each other. May be configured.
The wall surface 63a of the first hole 63 that forms the throttle passage 52 and the outer peripheral surface 21a of the fitting portion 21 may be configured by a conical surface. Further, the insertion portion 21 may have a columnar shape with a cross section other than circular, and the shape of the first hole 63 may also be a columnar shape other than a columnar shape corresponding to the shape of the insertion portion, for example. .
The plunger 2 is configured by a single member in the above-described embodiment, but may be configured by a plurality of members that are coupled or assembled so as to be integrally movable.
The internal combustion engine may be used in a marine vessel propulsion apparatus such as an outboard motor having a crankshaft oriented in the vertical direction. The tensioner T may be provided in a machine other than the internal combustion engine. The endless transmission band may be an endless belt.

FIG. 3 is a cross-sectional view of the hydraulic tensioner according to the first embodiment of the present invention, taken along line Ia-Ia and part Ib-I in FIG. 2. It is II arrow directional view of FIG. It is a principal part expanded sectional view in the Ia-Ia line | wire of FIG. It is a perspective view of the sheet | seat member of the tensioner of FIG. FIG. 4 shows a second embodiment of the present invention and is a cross-sectional view corresponding to FIG. 3.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Housing, 2 ... Plunger, 3 ... Hydraulic chamber, 4 ... Tensioner spring, 5 ... Accommodating hole, 6 ... Refueling passage, 7 ... Relief passage, 8 ... Inner hole, 9 ... Hole, 10 ... Check valve, 11 ... Valve seat member, 12 ... Valve body, 13 ... Valve body, 20 ... Seat member, 21 ... Insertion part, 22 ... Flange, 23 ... Groove, 25, 26, 27 ... Hole, 30 ... Restricting means, 31, 34 ... Groove 32 ... engagement part 33 ... clip 40 ... relief valve 41 ... valve seat member 42 ... valve body 43 ... relief spring 44 ... retainer 45 ... collar 50 ... air vent passage 51,55 ... introduction passage , 52 ... throttle passage, 53 ... outlet passage, 60 ... communication hole, 61 ... small diameter portion, 62 ... large diameter portion, 63, 64 ... hole portion, 63a ... wall surface, 65 ... gap, T ... tensioner, C ... chain, S ... External, L1-L4 ... Center axis, A ... Axial direction, W1-W3 ... Width.

Claims (4)

A housing, a plunger slidably fitted to the housing and forming a hydraulic chamber between the housing, a biasing member disposed in the hydraulic chamber and biasing the plunger in the advance direction, A hydraulic tensioner that includes a seat member that is held by the plunger by being biased by a biasing member , and the plunger applies tension to the target member by the biasing force of the biasing member and the hydraulic pressure in the hydraulic chamber. ,
Wherein the plunger is formed a communication hole for communicating the outside of the hydraulic chamber and the hydraulic chamber, the sheet over preparative member includes a fitting portion to be loosely fitted to the communication hole, the abutting flange to the plunger Have one,
An air vent passage formed by the plunger and the seat member for discharging air in the hydraulic chamber is formed based on a cylindrical gap formed between the wall surface of the communication hole and the outer peripheral surface of the fitting portion. A throttle passage, and an introduction passage formed on at least one of the contact surfaces of the plunger and the flange and configured to communicate with the hydraulic chamber and the throttle passage. Defines the amount of oil leaking from the hydraulic chamber to the outside ,
The outer diameter of the flange is smaller than the diameter of the hydraulic chamber, and a gap is formed between the outer peripheral surface of the flange and the inner peripheral surface of the plunger.
The radial width of the gap between the outer peripheral surface of the flange and the inner peripheral surface of the plunger is in a state where the central axis of the fitting portion and the central axis of the communication hole are coaxial. A hydraulic tensioner, wherein the tensioner is formed larger than a radial width of a gap between the outer peripheral surface of the fitting portion . A housing, a plunger slidably fitted to the housing and forming a hydraulic chamber between the housing, a biasing member disposed in the hydraulic chamber and biasing the plunger in the advance direction, A hydraulic tensioner that includes a seat member that is held by the plunger by being biased by a biasing member , and the plunger applies tension to the target member by the biasing force of the biasing member and the hydraulic pressure in the hydraulic chamber. ,
Wherein the plunger is formed a communication hole for communicating the outside of the hydraulic chamber and the hydraulic chamber, the sheet over preparative member includes a fitting portion to be loosely fitted to the communication hole, the abutting flange to the plunger Have one,
An air vent passage formed by the plunger and the seat member for discharging air in the hydraulic chamber is formed based on a cylindrical gap formed between the wall surface of the communication hole and the outer peripheral surface of the fitting portion. The air vent passage further has an inlet opening in a support surface that is a surface of the flange that supports the biasing member, and a closed end that extends in the direction of the central axis of the fitting portion. An introduction passage composed of an axial hole and a radial hole extending outwardly in the radial direction from the axial hole and opening in the outer peripheral surface to communicate the hydraulic chamber with the throttle passage; The amount of oil leaking from the hydraulic chamber to the outside is defined by the throttle passage ,
The outer diameter of the flange is smaller than the diameter of the hydraulic chamber, and a gap is formed between the outer peripheral surface of the flange and the inner peripheral surface of the plunger.
The radial width of the gap between the outer peripheral surface of the flange and the inner peripheral surface of the plunger is in a state where the central axis of the fitting portion and the central axis of the communication hole are coaxial. The hydraulic tensioner, wherein the tensioner is formed smaller than a radial width of a gap between the outer peripheral surface of the fitting portion . The hydraulic tensioner according to claim 1 or 2, wherein a wall surface of the communication hole and an outer peripheral surface of the fitting portion are cylindrical surfaces. The throttle passage, the outer peripheral surface of the fitting portion, extending in the fitting direction of the fitting portion, claim 1 or claim characterized in that it comprises a composed widened portion of the fitting groove which communicates with the introduction passage Item 3. The hydraulic tensioner according to Item 2 .

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