JP4465738B2 - Sealing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sealing device used for a shaft seal portion of various devices, for example, and particularly relates to a device for dealing with a negative pressure generated on a fluid to be sealed.
[0002]
[Prior art]
Conventionally, as this type of sealing device used as a high-pressure seal for power steering, for example, there is a device as shown in FIG.
[0003]
That is, the sealing device 100 seals an annular gap between a housing 101 as two members assembled so as to be movable relative to each other and a reciprocating shaft 102 inserted into the housing 101.
[0004]
The sealing device 100 includes an annular seal body 103 fitted to the inner periphery of the housing 101, and a wedge-shaped seal lip 104 that slidably comes into sealing contact with the outer peripheral surface of the shaft 102. The seal lip 104 is made of a material such as a rubber-like elastic body.
[0005]
On the outer periphery of the seal lip 104, a spring 105 for applying a pressing force to the seal lip 104 is attached. A backup ring 106 is provided on the atmosphere side A of the seal lip 104 so as to face the shaft 102.
[0006]
Then, the sealing lip 104 is slid on the shaft 102 to seal the sealing target fluid on the sealing target fluid side S.
[0007]
In a shaft seal portion in which such a sealing device 100 is used as a high pressure seal for power steering, a negative pressure may be generated on the sealing target fluid side S when the steering direction is changed depending on the model. When this negative pressure is generated and the seal lip 104 of the sealing device 100 is lifted by the negative pressure, bubbles such as air are mixed into the fluid to be sealed S, causing a reduction in assist performance.
[0008]
For this reason, the seal lip 104 or the spring 105 is adjusted to prevent the seal lip 104 from being lifted by a negative pressure.
[0009]
[Problems to be solved by the invention]
However, the conventional sealing device as described above has the following problems.
[0010]
Since the lift of the seal lip 104 with respect to the negative pressure is determined by the tightening force, rigidity, pressure receiving area, etc. of the seal lip 104, even if the shape of the seal lip 104 or the tightening force of the spring 105 is adjusted, The lift of the seal lip 104 could not be prevented.
[0011]
Further, the adjustment of the seal lip 104 and the spring 105 is caused by the deterioration of the sealing performance at low temperature due to the increase in rigidity of the seal lip 104, and the decrease in the durable wear of the seal lip 104 due to the increase in the tension of the spring 105. In addition, the sealing device 100 has been deteriorated in performance, such as turning over the seal lip 104 when the shaft 102 is inserted.
[0012]
The present invention has been made to solve the above-described problems of the prior art, and an object of the present invention is to provide a highly reliable sealing device that prevents the seal lip from lifting when negative pressure is generated. .
[0013]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention, a sealing device including a sealing lip that slidably seals and contacts one member of two members that are assembled so as to be movable relative to each other. And a ring that is drawn to the fluid to be sealed by negative pressure when negative pressure is generated on the fluid to be sealed, and is drawn to the fluid to be sealed by negative pressure. And a pressing portion that presses the back surface of the seal lip to apply a pressing force to the seal lip.
[0014]
Therefore, when the negative pressure is generated, the ring pulled toward the fluid to be sealed presses the back surface of the seal lip at the pressing part to apply a compressive force to the seal lip. The seal lip can be prevented from lifting.
[0015]
It is preferable that the pressing portion is a tapered portion in which the atmosphere side is inclined in the seal lip direction.
[0016]
As a result, the back surface of the seal lip can be pressed by the taper portion to apply a tightening force to the seal lip.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Exemplary embodiments of the present invention will be described in detail below with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified. Absent.
[0022]
(First embodiment)
FIG. 1 is a diagram illustrating a sealing device according to the first embodiment, and FIG. 2 is a diagram illustrating a state in which the sealing device of FIG. 1 is subjected to negative pressure.
[0023]
1 and 2, the sealing device 1 is a shaft seal portion as in the prior art, and includes a housing 2 as two members assembled so as to be relatively movable relative to each other, and a reciprocating shaft 3 inserted into the housing 2. The annular gap is sealed.
[0024]
The sealing device 1 generally includes a seal body 4 fitted to the inner periphery of the housing 2, and a seal lip 5 slidably in contact with the outer peripheral surface of the shaft 3.
[0025]
The seal body 4 includes a reinforcing ring 7 that prevents deformation of the sealing device 1 due to a fluid pressure to be sealed, and a rubber-like elastic body 6 that is integrally baked and fixed to the reinforcing ring 7.
[0026]
The reinforcing ring 7 is a cylindrical member having a cylindrical portion 71 and an inward flange portion 72 extending in the inner diameter direction. The rubber-like elastic body 6 is integrally baked and fixed continuously to the atmosphere side A end surface of the inward flange portion 72 of the reinforcing ring 7, the outer peripheral surface of the cylindrical portion 71 and the sealing target fluid side S end surface.
[0027]
In the seal body 4, the cylindrical portion 71 of the reinforcing ring 7 is fitted to the inner peripheral surface of the housing 2 via the rubber-like elastic body 6.
[0028]
On the other hand, a rubber-like elastic seal lip 5 is provided at the inner end of the inward flange portion 72 of the reinforcing ring 7.
[0029]
The seal lip 5 has a cross-sectional wedge shape extending in the inner diameter direction while inclining toward the sealing target fluid side S on the sealing target fluid side S of the inward flange portion 72 while being inclined toward the sealing target fluid side S. A sliding surface is formed in slidable and sealing contact with the outer peripheral surface of the plate.
[0030]
On the back surface on the outer peripheral side of the seal lip 5, a spring 8 is provided that applies a pressing force to the seal lip 5.
[0031]
Further, a backup ring 9 is disposed on the atmosphere side A of the seal lip 5 so as to be opposed to the shaft 3 while being sandwiched between the seal lip 5 and the inward flange portion 72. The backup ring 9 prevents excessive deformation of the seal lip 5 toward the atmosphere side A due to the fluid pressure to be sealed.
[0032]
A ring 10 is fitted into a recess in the seal target fluid side S of the seal lip 5 where the seal target fluid side S provided by the seal body 4, the seal lip 5, and the spring 8 is opened.
[0033]
The ring 10 is slidable in the axial direction, and moves to the sealing target fluid side S when negative pressure is generated.
[0034]
The ring 10 is formed with an inner diameter taper portion 10a that is a pressing portion that prevents the seal lip 5 from lifting when a negative pressure is generated when the ring 10 moves to the fluid to be sealed S side.
[0035]
The inner diameter taper portion 10 a is provided on the inner diameter side of the ring 10, and has a shape in which the inner diameter distance of the atmosphere side A end portion is smaller than the maximum outer diameter of the spring 8.
[0036]
A stopper 11 that prevents the ring 10 from slipping out to the sealing target fluid side S is fixed to the seal body 4 on the sealing target fluid side S of the ring 10.
[0037]
About the sealing device 1 of the above structure, the characteristic operation | movement of this invention is demonstrated.
[0038]
When a negative pressure is generated on the sealing target fluid side S, the sealing device 1 instantaneously draws the ring 10 toward the sealing target fluid side S as shown in FIG.
[0039]
When the seal lip 5 tends to float due to negative pressure, the inner diameter taper portion 10a of the ring 10 drawn toward the sealing target fluid side S causes the spring 8 disposed on the back surface of the seal lip 5 to move in the axial direction (inner diameter). Direction) to apply tension.
[0040]
In this way, when the negative pressure is generated, the inner diameter tapered portion 10a of the ring 10 attracted to the fluid side S to be sealed presses the back surface of the seal lip 5 through the spring 8 in the axial center direction. As a result, the seal lip 5 can be prevented from being lifted when negative pressure is generated.
[0041]
Therefore, the seal lip 5 does not float against the negative pressure generated on the sealing target fluid side S, and suction of air or the like to the sealing target fluid side S due to the negative pressure is prevented.
[0042]
For this reason, when the sealing device 1 is used as a high pressure seal for power steering, bubbles such as air are not mixed in the fluid to be sealed S, and assist performance is not lowered, and stable power steering performance can be maintained. it can.
[0043]
Further, since it is not necessary to adjust the seal lip 5 or the spring 8 in consideration of the negative pressure, the wear resistance, the low temperature resistance, etc. are not impaired, and the performance of the sealing device 1 can be prevented from being deteriorated.
[0044]
The inner diameter taper portion 10a of the ring 10 may be a pressing portion that is not particularly limited only to the taper angle and the taper shape as long as the spring 8 can be pressed against the fluid to be sealed S when negative pressure is generated.
[0045]
Alternatively, the stopper 11 may be provided integrally with the seal body 4 or may be configured such that the stopper 11 is not provided by setting the dimensions so that the ring 10 does not come out.
[0046]
In the present embodiment, the spring 8 is provided on the back surface of the seal lip 5, but without providing the spring 8, the seal lip 5 is shaped so that the ring 10 can directly press the back surface of the seal lip 5 when negative pressure is generated. It can also be provided.
[0047]
In this embodiment, the sealing device provided in the reciprocating shaft sealing portion has been described. However, even a rotary sealing device in which the shaft rotates is provided with a sealing lip that is slidably sealed and sealed. The present invention can be applied as long as a negative pressure is generated on the fluid side S, and the seal lip 5 may slide on the housing 2.
[0048]
( Reference Example ) The first embodiment has a configuration including a ring 10 that moves by negative pressure. However, the reference example is a resin ring 12 as a sealing lip support means having a fixed high rigidity. The seal lip 5 that is lifted by the negative pressure is directly supported.
[0049]
In the reference example , only the characteristic part will be described. In addition, about the same structure as 1st Embodiment, the same code | symbol as 1st Embodiment is attached | subjected and the description is abbreviate | omitted.
[0050]
In this reference example , as shown in FIG. 3A, a resin ring 12 having high rigidity is fitted and fixed to the waist of the seal lip 5. A clearance T is provided between the inner circumference of the resin ring 12 and the back surface of the seal lip 5 facing the resin ring 12.
[0051]
Even in the sealing device having the above-described configuration, when the negative pressure is generated, the seal lip 5 is lifted, and when the clearance T between the inner periphery of the resin ring 12 and the back surface of the seal lip 5 is eliminated, The seal lip 5 is supported by the resin ring 12 in contact with the inner periphery of the resin ring 12.
[0052]
In this way, the resin ring 12 contacts the seal lip 5 that is lifted by the negative pressure, and the seal lip 5 supported by the resin ring 12 can be prevented from being lifted.
[0053]
Therefore, not only can the same effect as that of the first embodiment be obtained, but also the resin ring 12 is fixed, so that even if negative pressure is repeatedly generated, it is difficult to be damaged and durability is improved.
[0054]
The resin ring 12 is provided on the waist of the seal lip 5 and is fixed to the seal body 4 as shown in FIG. 3B, and is provided with a spring 8 and a clearance T provided on the back surface of the seal lip 5. It can also be provided. At this time, the inner peripheral shape of the resin ring 12 is preferably provided in a shape along the outer peripheral arc of the spring 8.
[0055]
Further, the present reference example is not limited to the above example, and may be any member that supports a seal lip 5 that is fixed and has a high rigidity and that floats due to negative pressure.
[0056]
【The invention's effect】
As described above, according to the present invention, when the negative pressure is generated, the pressing portion of the ring that is drawn toward the fluid to be sealed presses the seal lip to apply the compressive force to the seal lip. The seal lip can be prevented from lifting when negative pressure occurs.
[0057]
Pressing unit, by air side is the tapered portion inclined in the seal lip direction, Ru can give straining force on the seal lip to press the back of the sealing lip in the tapered portion.
[0059]
For this reason, inhalation of air or the like to the sealed fluid side S due to negative pressure is prevented, and there is no need to adjust the seal lip, spring, etc. in consideration of negative pressure, so wear resistance, resistance to low temperatures, etc. The performance of the sealing device can be prevented from deteriorating.
[Brief description of the drawings]
FIG. 1 is a half sectional view showing a sealing device according to a first embodiment.
FIG. 2 is a half sectional view showing a state when a negative pressure is generated in the sealing device according to the first embodiment.
FIG. 3 is a half sectional view showing a sealing device according to a reference example .
FIG. 4 is a half cross-sectional view showing a prior art sealing device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Sealing device 2 Housing 3 Shaft 4 Seal main body 5 Seal lip 5a Parallel protrusion 6 Rubber elastic body 7 Reinforcement ring 71 Cylindrical part 72 Inward flange part 8 Spring 9 Backup ring 10 Ring 10a Inner diameter taper part 11 Stopper 12 Resin ring T clearance

Claims (2)

In a sealing device including a seal lip that slidably comes into contact with one member of two members assembled so as to be movable relative to each other,
A ring disposed on the back side of the sealing lip on the side of the fluid to be sealed, the ring being drawn toward the side of the fluid to be sealed by negative pressure when negative pressure is generated on the side of the fluid to be sealed;
A sealing device, wherein the ring is provided with a pressing portion that presses the back surface of the seal lip and applies a pressing force to the seal lip when pulled toward the fluid to be sealed by negative pressure.   2. The sealing device according to claim 1, wherein the pressing portion is a tapered portion in which an atmosphere side is inclined in the seal lip direction.

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