JPH0135089Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a sealed autotensioner that maintains the tension of a wrapped power transmission member such as an endless belt or an endless chain at a set tension.

[Conventional technology]

In belt transmission devices built into internal combustion engines such as automobiles, belt tension changes due to changes in the distance between pulley cores and torque fluctuations due to thermal expansion of the engine body during engine operation. As shown in FIG. 3, a tension roller 32 is brought into contact with the slack side of the endless belt 31, and an adjusting force is applied to the swingable roller arm 33 that supports this roller 32 to press the roller 32 against the belt 31, thereby tightening the belt. 31 is kept constant.

A conventional tensioner for maintaining the tension of the belt 31 at a constant level is disclosed in, for example, Japanese Unexamined Patent Publication No. 59-208251.

The tensioner (gap elimination unit) shown in the above publication has a cylinder slidably inserted inside the housing, a plunger installed inside the cylinder, and a pressure regulating spring installed between the cylinder and the plunger. The cylinder is moved forward and the roller arm connected to the cylinder is deflected in a direction that applies tension to the belt, and the elasticity of the spring is used as a tension adjustment force for the belt. In addition, oil is filled in each of the sealed pressure chamber formed between the cylinder and the plunger and the supply chamber provided inside the plunger, so that when the pressure rises in the pressure chamber due to the backward movement of the cylinder, The oil in the pressure chamber leaks into the supply chamber from the gap formed between the cylinder and the plunger sliding surface, and when the pressure in the pressure chamber decreases, it leaks from the valve hole formed in the plunger and opened and closed by the check valve. The oil from the supply chamber is supplied to the pressure chamber to suppress the backward movement of the cylinder due to oil leakage, thereby alleviating the impact load acting on the cylinder.

[Problem that the invention attempts to solve]

By the way, in the above tensioner, the supply chamber formed inside the plunger is sealed by an air bag built into the plunger, so after filling the pressure chamber and supply chamber with oil, , you need to install an air bag. For this reason, it is extremely difficult to fill the appropriate amount of hydraulic oil without including air, and the air bladder must be secured to the plunger by tightening a band, etc., making assembly of the tensioner extremely time-consuming. There is an inconvenience that it costs a lot of money.

Therefore, this idea solves the above disadvantages,
The purpose is to provide a sealed autotensioner that is easy to assemble.

[Means for solving problems]

In order to achieve the above object, this invention incorporates a slideable plunger inside a cylindrical body whose one end is closed and the other end is open, and a pressure regulating spring that pushes out this plunger. A pressure chamber compressed by the backward movement of the plunger is provided between the closed ends, and is adjacent to this pressure chamber via a damper, and is connected to the pressure chamber through a gap formed around the damper. A supply chamber is provided that communicates with the supply chamber, and a sealing member is slidably fitted to the outside of a rod whose end is located in the supply chamber to seal the supply chamber, and a fluid is sealed in the supply chamber and the pressure chamber. However, a spring is provided to press the sealing member toward the supply chamber.

[Effect]

Due to the above structure, the auto tensioner maintains the tension of the belt at a constant level by the elasticity of the pressure regulating spring that presses the plunger in the axial direction, and prevents leakage of the fluid filled in the pressure chamber. This buffers the impact force acting on the plunger. When filling the autotensioner with fluid, first fill the pressure chamber with fluid, insert a damper, and then insert a sealing member to expel air and excess fluid from the center hole of the sealing member. , insert the rod into the hole in the seal member to seal the supply chamber.

〔Example〕

Hereinafter, embodiments of this invention will be described based on the accompanying drawings.

As shown in FIG. 2, a screw 2 is provided on the outer peripheral surface of a cylindrical body 1 that is closed at one end and open at the other end. Further, a plunger 3 is slidably inserted inside the body 1, and the plunger 3
A pressure regulating spring 4 is installed between the closed end of the body 1 and the plunger 3 is pressed toward the opening of the body 1, and a stopper shaft 5 attached to the inner peripheral surface of the opening of the body 1 prevents the plunger 3 from coming off. I'm trying to figure it out.

The plunger 3 is formed with a damper storage hole 6 that opens on the back side, and a damper 7 is slidably inserted into the damper storage hole 6 to create a press between the closed end of the damper storage hole 6 and the damper 7. Yamba 8
has been formed.

A rod 10 is disposed between the back surface of the damper 7 and a protrusion 9 provided on the inner surface of the closed end of the body 1, and a seal member 11 is slidably fitted on the outside of the rod 10.

The sealing member 11 has two conical lips 11' on the inner diameter side and the outer diameter side of the end facing the damper 7.
11' is formed, and the tip of the inner lip 11' is in close contact with the outer circumferential surface of the rod 10, while the tip of the outer lip 11'' is in close contact with the inner circumferential surface of the damper housing hole 6, and the sealing member is 11, a sealed supply chamber 12 is formed between the seal member 11 and the damper 7. This supply chamber 12 is formed between the outer peripheral surface of the damper 7 and the inner peripheral surface of the damper storage hole 6. Fluid is sealed in both chambers 8 and 12, which communicate with each other through a gap formed therein.The pressure chamber 8 also incorporates a damper spring 13 that presses the damper 7 against the end surface of the rod 10. It is.

Although any fluid can be used to fill the chambers 8 and 12, oil is used here.

A pressure receiving plate 14 made of a material with good slip properties such as tetrafluoroethylene resin is in contact with the back surface of the sealing member 11, and a spring 15 installed between the pressure receiving plate 14 and the protrusion 9 is Seal member 11
is pressed toward the supply chamber 12.

The autotensioner shown in the embodiment has the above structure, and as shown in FIG. 1, the body 1 is screwed into the screw hole 35 formed in the bracket 34, and the tip of the plunger 3 can be pivoted. The tension roller 32 supported by the roller arm 33 is pressed against the slack side of the belt 31 by the elasticity of the pressure regulating spring 4 which contacts the roller arm 33 and presses the plunger 3 in the axial direction.
The elasticity of the pressure regulating spring 4 is used as a tension adjusting force to tension the belt 31.

Under the usage conditions shown in Figure 1, due to changes in the distance between pulley cores due to torque fluctuations and temperature changes, etc.
When the belt 31 becomes slack, the pressure regulating spring 4
The plunger 3 moves forward due to the elasticity of the tension roller 32 and presses the belt 31 against the belt 31.
Keep the tension constant. At this time, the oil pressure in the pressure chamber 8 is equal to the pressure in the supply chamber 12.
As a result, the oil in the supply chamber 12 leaks into the pressure chamber 8 from the gap around the damper 7, and the oil in the seal member 1
1 moves toward the supply chamber 12 due to the elasticity of the spring 15.

Furthermore, when the center-to-center distance of the pulleys increases due to temperature rise and the tension of the belt 31 becomes greater than a set value, the plunger 3 is pushed by the belt 31 and retreats. Therefore, the pressure regulating spring 4 contracts, and the tension of the belt 31 is relieved by the contraction. At this time, the oil pressure in the pressure chamber 8 becomes higher than the oil pressure in the supply chamber 12, so the oil in the pressure chamber 8 leaks into the supply chamber 12, and due to this oil leakage,
The impact force acting on the plunger 3 is absorbed.

From the above structure, when filling the autotensioner with oil, the opening of the damper storage hole 6 of the plunger 3 faces upward, and after filling the damper storage hole 6 with an appropriate amount of oil, the damper spring 13 and the damper 7 are assembled. After pressurizing the damper 7 to leak oil to the upper side of the damper, insert the seal member 11 into the damper storage hole 6, remove air from the center of the seal member 11, and then insert the seal member 11 into the center hole of the seal member 11. Insert rod 10 and supply chamber 12
Seal it tightly.

The autotensioner can be assembled by inserting the above assembly into the inside of the body 1 and attaching the retaining ring 5 to the inner peripheral surface of the opening of the body 1. In this case, a pressure regulating spring 4 is previously inserted inside the body 1, and a spring 15 is also fitted on the outside of the rod 10.

In the embodiment shown in FIG. 2, two conical lips 11' and 11'' are formed as the seal member 11 for sealing the supply chamber 12, but the seal member 11 is not limited to this, and for example, Seal member 11 as shown in FIGS. 4 and 5
can be used.

The sealing member 11 shown in FIG.
3 are fitted, and an annular elastic body 24 having a dish-shaped cross section is fitted into each fitting groove 22. This seal member 11 is
The O-ring 23 on the outer diameter side and the elastic body 24 are brought into close contact with the inner peripheral surface of the damper storage hole 6, and the O-ring 23 on the inner diameter side
3 and the elastic body 24 are brought into close contact with the outer peripheral surface of the rod 10 to seal the supply chamber 12.

Further, the sealing member 11 shown in FIG. 5 has a pair of pole pieces 41 provided on both sides of a ring-shaped permanent magnet 40. When using this sealing member 11, magnetic fluid is sealed in each of the pressure chamber 8 and the supply chamber 12, and between the sealing member 11 and the body 1 and between the sealing member 11 and the rod 10. The magnetic flux lines formed magnetically seal the supply chamber.

FIG. 6 shows another embodiment of the sealed autotensioner according to this invention. This autotensioner has a cylinder 16 that is open at one end and closed at the other end fitted into the closed end of the body 1, and has a spring 13 and a damper 7 installed inside the cylinder 16. A pressure chamber 8 is provided between the closed ends of 16. Further, the end of the rod 10 connected to the back surface of the plunger 3 is brought into contact with the damper 7, and the seal spring 15 and the seal member 11 are fitted on the outside of the rod 10, so that the seal member 11 and the damper 7 are connected to each other. A sealed supply chamber 12 is formed in between, and a fluid is sealed in the supply chamber 12 and the pressure chamber 8.

In the autotensioner configured as described above, when a load is applied to the plunger 3 in the pushing direction, the damper 7 moves to the right in FIG. 6 together with the plunger 3, and the fluid in the pressure chamber 8 is compressed. A portion of the fluid leaks into the supply chamber 12 from the gap around the damper 7, and the impact force acting on the plunger 3 is absorbed by the leakage.

Further, when the fluid expands thermally, the sealing member 11 moves to the left in FIG. 6, and this movement absorbs the expansion of the fluid.

〔effect〕

As described above, this invention provides a pressure chamber that is compressed by the backward movement of the plunger,
A supply chamber is provided adjacent to the pressure chamber via a damper and adjacent to the pressure chamber via a gap formed around the damper,
A sealing member was slidably fitted to the outside of the rod whose end was inserted into the supply chamber to seal the supply chamber, so that when the fluid sealed in the pressure chamber and the supply chamber thermally expanded, the sealing member The expansion of the fluid can be absorbed by the movement, and the conventional air bladder described above can be made unnecessary. In addition, by filling a pressure chamber with fluid, inserting a spring and a damper into the pressure chamber, and further inserting a seal member, air is expelled from the center hole of the seal member, and excess fluid is removed from the center of the pressure chamber. Since the fluid can be removed from the hole, an appropriate amount of fluid can be filled in each chamber, and the supply chamber can be sealed by inserting a rod into the center hole, making assembly of the autotensioner extremely easy. It's easy.

[Brief explanation of the drawing]

Fig. 1 is a front view showing how the tensioner according to the invention is used, Fig. 2 is a longitudinal sectional front view showing an embodiment of the above tensioner, and Fig. 3 is a sectional view showing the sealed portion of the supply chamber shown above. , FIG. 4 and FIG. 5 are cross-sectional views showing other embodiments of the seal member, and FIG. 6 is a longitudinal sectional front view showing another embodiment of the tensioner. 1... Body, 3... Plunger, 4... Pressure adjustment spring, 7... Damper, 8... Pressure chamber, 10... Rod, 12... Supply chamber, 15... Spring.

Claims (1)

[Scope of utility model registration request] A plunger and a pressure regulating spring that pushes the plunger outward are installed inside a cylindrical body that is closed at one end and open at the other end, and the plunger is moved backwardly between the plunger and the closed end of the body. A pressure chamber to be compressed is provided, adjacent to the pressure chamber via a damper,
A supply chamber is provided that communicates with the pressure chamber through a gap formed around the damper, and a seal member is slidably fitted on the outside of a rod whose end is located in the supply chamber. A sealed autotensioner that seals a supply chamber and a pressure chamber, seals fluid in the supply chamber and a pressure chamber, and is provided with a spring that presses the sealing member toward the supply chamber.