JPH0645105Y2 - Sealing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a sealing device having a seal lip made of a rubber-like elastic body such as an oil seal, and more particularly to a sealing device used in a low temperature environment.

(Prior Art) Conventionally, as a sealing device of this type, for example, there is an oil seal as shown in FIG. That is, the oil seal 100 is of a so-called outer peripheral rubber type with a spring, the outer peripheral fitting portion 101 is fitted and fixed to the inner periphery of the housing 102, and the seal lip 103 made of a rubber-like elastic body extends toward the sealing fluid O side. The lip tip 104 is in sealing contact with the outer periphery of the shaft 105.

Thus, the seal lip 103 follows the eccentricity even when the shaft 105 is eccentric, and the neck portion thereof flexes to perform a good sealing function.

(Problems to be solved by the invention) However, in the case of the above-mentioned conventional technology, the seal lip 103 is hardened at a low temperature as a characteristic of the rubber material, and the eccentricity following property of the lip is deteriorated, and oil leakage and lip It has the drawback of causing damage.

Although such a problem of low temperature curing can be prevented to some extent by a compounding technique of a rubber material, the low temperature resistance is limited only by the compounding technique.

Further, when the low temperature property is increased by the compounding technique, the heat resistance is lowered, and the heat resistance must be sacrificed.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a sealing device capable of improving sealing performance at low temperature without sacrificing heat resistance. It is in.

(Means for Solving the Problems) In order to achieve the above object, in the present invention, in a sealing device including a seal lip made of a rubber-like elastic body, a seal lip is provided from a waist portion to a vicinity of a sliding contact portion. It is characterized by fixing a rubber heater.

(Operation) Thus, at a low temperature, the heating element positively warms the seal lip to prevent the rubber-like elastic body from hardening at a low temperature.

(Example) Below, this invention is demonstrated based on the Example shown in figure. First
The figure shows a sealing device according to an embodiment of the present invention. In the present embodiment as well, description will be made by taking as an example an outer peripheral rubber type oil seal with a spring similar to the conventional example.

In the figure, reference numeral 1 denotes the entire sealing device. A metal ring 4 having an L-shaped cross section which is fitted and fixed to an inner circumference of a housing 3 via a rubber portion 2 at a substantially outer circumference, and a metal ring 4 is sealed from an inner diameter end portion. The seal lip 5 is made of a rubber-like elastic body and extends toward the fluid O side. The lip tip 6 of the seal lip 5 slidably sealingly contacts the surface of the movable shaft 7 that rotates or reciprocates to seal the sealing fluid O. A spring member 8 is attached to the outer periphery of the lip tip 6 to apply a tightening force to the seal lip 5.

Inside the seal lip 5, a rubber heater 9 as a heating element is arranged. The rubber heater 9 is configured to generate heat when an electric current is supplied from the outside. Further, a temperature sensor 21 is attached to the tip of the seal lip 5 to measure the temperature in the sealed fluid O. The rubber heater 9 has a power supply for supplying an electric current from the outside of the sealing device 1.
11 is connected, and a control box 22 is attached to the power supply 20 and the temperature sensor 21.

The sealing device 1 configured as described above operates as follows. When the sealing device 1 is placed in a low temperature environment, the sealing fluid O
The temperature will also drop. When the temperature drops, the signal detected by the temperature sensor 21 attached to the tip of the seal lip 5 is supplied to the control box 22. The control box 22 supplies a current from the power supply 20 to the rubber heater 9 based on the signal. As a result, the rubber heater 9 generates heat and heats the seal lip 5. Since the seal lip 5 does not lose its rubber elasticity due to the low temperature environment around it due to the heating by the rubber heater 9, the sealability is not deteriorated even by the shaft eccentricity.

2 and 3 show a second embodiment of the sealing device of the present invention.

In the present embodiment, a planar rubber heater 9 is provided on the atmosphere side surface on the inner peripheral side of the seal lip 5. As the rubber heater 9, in this embodiment, a flexible conductive rubber in which conductive carbon is uniformly mixed in a polymer is used. The shape of the rubber heater 9 is formed into a tubular shape whose diameter is gradually reduced following the inclination of the seal lip 5, and is fixed to the seal lip 5 by adhesion or the like.

The length of the rubber heater 9 is the length from the position of the end surface on the atmosphere side of the seal lip 5 to the neck 10 of the lip tip 6, and is provided over the entire length of the neck 11 of the seal lip 5, and the end on the neck 10 side. The edge is bent inward in the radial direction in an arc shape following the angular shape of the neck 10.

Further, the rubber heater 9 is formed to have a uniform thickness over its entire length so that the entire surface can be heated uniformly.

The rubber heater 9 converts electric energy into heat energy, and in this embodiment, it utilizes Joule heat generated when an electric current is passed. In this embodiment, EPDM
Based on (ethylene propylene diene terpolymer) blended with conductive carbon, the volume resistivity is 2
Ω · cm was used. FIG. 4 shows the characteristics of power density and temperature rise when a conductive rubber material is used as a sheet heating element.

As the electric heat, in addition to Joule heat, methods such as dielectric heating and induction heating can be used.

Although other conductive polymer materials may be used as the rubber heater, it is desirable that the rubber heater is a flexible material that does not impair the flexibility of the seal lip 5.

A power input unit 13 is connected to the rubber heater 9 via a lead wire 12, and a control device 14 incorporating a temperature control circuit for controlling the temperature of the seal lip 5 is provided. A signal from a temperature sensor 15 such as a thermistor embedded in the seal lip 5 is input to the control device 14, and the temperature of the seal lip 5 is controlled by controlling the power supply to the rubber heater 9 based on the input signal. It is supposed to do.

Next, the operation of the sealing device of the second embodiment will be described. The lip tip 6 of the seal lip 5 is in sliding contact with the surface of the movable shaft 7, and when the movable shaft 7 is eccentric, the neck portion 11 of the seal lip 5 follows the eccentricity and bends.

In this embodiment, the rubber heater 9 is attached to the neck portion 11 of the seal lip 5.
However, since the rubber heater 9 has a flexible rubber elasticity, the eccentricity followability of the seal lip 5 is not impaired.

On the other hand, the temperature sensor 15 constantly detects the temperature of the seal lip 5, especially the temperature near the base of the neck 11 which greatly affects the eccentricity following property, and when the detection signal becomes lower than a predetermined temperature, the control device 14 As a result, the rubber heater 9 is energized, and Joule heat generated by the internal resistance of the rubber heater 9 causes the rubber heater 9 to generate heat to heat the seal lip 5.

Therefore, even under a low temperature where the rubber of the seal lip 5 is cured at a low temperature, the flexibility is maintained by the heat from the rubber heater 9, and the eccentricity of the movable shaft 7 is followed to maintain a good sealing performance.

In the second embodiment, the rubber heater 9 is attached to the seal lip 5.
Although it is partially provided up to the position of the neck 10 on the inner circumference, it may be provided up to the position of the lip tip as shown in FIG. 5, and the rubber heater 9 may be brought into contact with the movable shaft 7.

FIG. 6 shows a third embodiment of the sealing device 1 of the present invention. In this embodiment, the rubber heater 9 is attached to the outer surface of the seal lip 5 on the side of the sealed fluid. Other configurations and operations are similar to those of the first and second embodiments described above, and thus description thereof will be omitted.

In each of the above embodiments, the rubber heater 9 is provided inside the seal lip 5, the side surface on the atmosphere side, and the side surface on the sealed fluid side. However, the rubber heater 9 is provided on both the inside of the seal lip 5 and the side surface on the atmosphere side. It is also possible to adopt a configuration in which it is provided on both the inside and the side surface of the sealed fluid, and further on all of the inside, the atmosphere side and the side surface of the sealed fluid. Further, the seal lip 5 itself may be formed by the rubber heater 9.

Although the oil seal has been described as an example of the sealing device in the above embodiment, the sealing device is not limited to the oil seal.
It can be similarly applied to various lip packings having a seal lip using a rubber-like elastic body in which low temperature curing is a problem.

(Effect of the Invention) The present invention has the above-described configuration and operation. Since the rubber heater is fixedly attached from the waist of the seal lip to the vicinity of the sliding contact part, the waist of the seal lip moves to the sliding part, that is, the seal lip. The temperature of the entire movable part can be adjusted, and the thermal energy of the rubber heater is efficiently transmitted to the seal lip without damaging the elasticity of the seal lip due to the elasticity of the rubber heater, preventing low temperature curing, and reducing the operating temperature. The range can be expanded.

[Brief description of drawings]

FIG. 1 is a schematic vertical cross-sectional view of a sealing device according to a first embodiment of the present invention in use, and FIG. 2 is a schematic vertical cross-sectional view of a sealing device according to a second embodiment of the present invention in use. FIG. 4 is a vertical cross-sectional view of the main part of the apparatus of FIG. 1 taken out, FIG. 4 is a graph showing the relationship between the power density and temperature rise of an example of the rubber heater of the apparatus of FIG. 1, and FIG. FIG. 6 is a longitudinal sectional view of an essential part of another embodiment of the device shown in FIG. 6, FIG. 6 is a longitudinal sectional view of an essential part of a sealing device according to a third embodiment of the present invention, and FIG. It is a figure. DESCRIPTION OF SYMBOLS 1 ... Oil seal, 2 ... Outer peripheral rubber part 4 ... Metal ring, 5 ... Seal lip 6 ... Lip tip, 7 ... Movable shaft 8 ... Spring member, 9 ... Rubber heater 10 ... Jaw part, 11 ... Neck part 14 … Controller, 15… Temperature sensor 20… Power supply, 21… Temperature sensor 22… Control box

Claims (1)

[Scope of utility model registration request] 1. A sealing device provided with a rubber-like elastic seal lip, wherein a rubber heater is fixed to the seal lip from a waist portion to a vicinity of a sliding contact portion.