JPH0962098A - Bearing toner seal mechanism - Google Patents

Abstract

(57) [PROBLEMS] To provide a toner seal mechanism for a bearing, which is capable of maintaining good sealability for a long period of time and has an inexpensive and compact structure. SOLUTION: A ring-shaped space 5 is formed by scooping a part of the inner surface side of a bearing 4 supporting a rotary shaft 2 in a ring shape. A ring-shaped sealing material 6 having an annular main lip projecting on the outside in the axial direction and an annular sub lip projecting on the inside is fixed to the inner surface of the bearing 4 so as to be housed in the ring-shaped space 5. There is. Of the above lips, the tip of the sub-lip is the rotating shaft 2
Are arranged in close proximity to each other so that the main lip tip is always in contact with the rotary shaft 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner seal mechanism for a bearing of an electrophotographic apparatus, and more particularly to a toner seal mechanism for a bearing of a rotary shaft in a developing section, a cleaning section and the like.

[0002]

2. Description of the Related Art In order to maintain smooth rotation, a clearance of 5 to several tens of .mu.m or less is usually provided between a rotary shaft of a developing section, a cleaning section, etc. of an electrophotographic apparatus and a bearing. However, since the clearance and the particle diameter of the toner are almost the same, the toner may infiltrate into the bearing portion and may be melted and solidified by frictional heat due to sliding, so that the rotating shaft may not rotate smoothly. Further, the toner may leak from the clearance to contaminate the surroundings, and may cause trouble in operation. Since the toner particle size tends to become smaller with the recent demand for improvement in image quality, it is not easy to prevent toner leakage. As a sealing technique for preventing such a problem, for example, the following are known.

As shown in FIG. 3, the developing machine main body frame 1
The bearing 13 supporting the rotating shaft 12 of No. 1 has a metal ring 14 and a lip seal 1 made of synthetic rubber such as NBR or FKM.
A toner seal mechanism having a structure in which a seal member 5 is mounted is known (hereinafter referred to as "conventional toner seal mechanism 1"). FIG. 4 is an enlarged view of the seal member.

Further, as shown in FIG. 5, Japanese Patent Laid-Open No. 60-28673 discloses a method for preventing iron powder called a carrier from being attracted by a magnetic force to prevent the iron powder from entering the bearing portion. In a developing machine of an electronic copying machine including a toner bottle 16, a blender 18 that rotates around a shaft 17 provided on both side walls of the toner bottle 16, and a magnet roll, a pair of ring-shaped magnets 19 are used as a bearing portion of the blender 18. An invention relating to a developing device characterized in that the same poles are provided so as to face each other with 20 in between (hereinafter referred to as "conventional toner seal mechanism 2").

Further, as a technique for preventing toner from entering the bearing portion by interposing a seal member having a pressure contact surface with a small friction coefficient between the bearing portion and the bearing, as a technique of Japanese Utility Model Laid-Open No. 62-35362. In the publication, as shown in FIG. 6, "a surface of a rotary shaft 21 disposed inside a developing device and an inner end surface of a bearing 22 that supports the rotary shaft have a friction coefficient of a surface facing each other. The sealing mechanism for the bearing in the developing device is characterized in that the seal members 23 and 24 having elasticity formed as small surfaces are fixed and the surfaces having a small friction coefficient of the seal members are brought into pressure contact with each other. It is disclosed (hereinafter referred to as "conventional toner seal mechanism 3").

[0006]

However, the seal member of the conventional toner seal mechanism 1 is originally for the oil seal, and basically the oil to be sealed is present between the lip portion and the rotary shaft. It is designed on the premise that it is in a fluid lubrication state, and no consideration is given to maintaining good friction and wear characteristics in sliding with fine powder such as toner. However, the lip seal 15 shown in FIG.
In the initial stage, a large pressure is locally applied due to elastic deformation. With the operation of the apparatus, the toner pressure F shown in FIG. 7 causes the toner to infiltrate between the lip seal 15 and the rotating shaft 12 and rotate. By sliding the shaft 12 and the lip seal 15 as shown in FIG.
As shown by the dotted line portion 25, the lip seal 15 may be worn, and eventually the lip seal 15 loses the tightening force, and toner leakage may occur due to the clearance between the rotating shaft 12 and the worn lip seal 15. It was Further, the synthetic rubber used for the lip portion of the lip seal 15 is generally nitrile rubber, and the plasticizer in the rubber may exude to the outside due to sliding heat generation with the toner and accelerate coagulation of the toner. is there.

Further, in the conventional toner seal mechanism 2, since the pair of ring-shaped magnets 19 are provided so that the same poles face each other, the number of parts and the number of assembling steps increase, and the space for mounting is increased. Need.

Further, in the conventional toner seal mechanism 3, since the elastic seal members 23 and 24 are made of polyurethane foam or the like, they are pressed against each other when used for a long time or when the rotary shaft 21 rotates. The seal member is turned over, and as a result, the rotary shaft 21 and the seal members 23, 2
There is a case that a gap is generated between the toner and the toner 4 and the toner enters the bearing 22.

The present invention has been made in view of the above problems of the prior art, and an object thereof is to maintain a good sealing property for a long period of time, and to have an inexpensive and compact structure. To provide a toner seal mechanism for a bearing.

[0010]

In order to achieve the above-mentioned object, the gist of the present invention is to form a ring-shaped space by scooping a part of the inner surface side of a bearing that supports a rotary shaft in a ring shape, A ring-shaped sealing material having an annular main lip protruding from the outside and an annular sub-lip protruding from the inside is fixed to the inner surface of the bearing so as to be housed in the ring-shaped space. The first invention is a toner seal mechanism for a bearing, characterized in that the sub-lip tip portion is arranged extremely close so as to be able to come into contact with the rotating shaft, and the main lip tip portion is always brought into contact with the rotating shaft. In the first invention, the angle at which the main lip comes into contact with the rotary shaft is 30 with respect to the axial direction of the rotary shaft.
The bearing of the present invention is characterized in that the toner sealing mechanism of the bearing is at a angle of about 45 °, and the ring-shaped sealing material is a thermoplastic elastomer in the first or second invention. The toner sealing mechanism of is a third invention.

As the thermoplastic elastomer, for example,
NBR-based thermoplastic elastomer, urethane-based thermoplastic elastomer, polyester-based thermoplastic elastomer, polyamide-based thermoplastic elastomer, and fluorine-based thermoplastic elastomer can be used.

The hardness of the ring-shaped sealing material is preferably 50 to 90 ° in Shore A hardness for the reason described later.

[0013]

According to the present invention, since the annular main lip projects from the portion where the ring-shaped sealing material abuts, and the annular sub-lip projects from the inside, the intrusion of the toner due to the toner pressure. Is almost completely blocked by the secondary lip,
The toner pressure applied to the main lip is extremely small, and a reliable sealing operation is performed by the main lip which is always in contact with the rotating shaft. As described above, the amount of toner existing in the main lip portion can be substantially ignored, so that the progress of wear of the main lip is suppressed and the life of the main lip can be extended. When the angle at which the main lip comes into contact with the rotary shaft is 30 to 45 ° with respect to the axial direction of the rotary shaft, the sealing property is further improved. This is because if the angle is less than 30 °, the contact area becomes large and the surface pressure required for sealing cannot be secured. On the other hand, if the angle exceeds 45 °, the surface pressure increases but the contact pressure increases. This is because it is not possible to maintain a sufficient sealing property because the area is reduced. Therefore, it is preferable that the angle at which the main lip contacts the rotary shaft is 30 to 45 ° with respect to the axial direction of the rotary shaft.

If the ring-shaped sealing material is a thermoplastic elastomer, the soft segment of the thermoplastic elastomer elastically abuts the rotating shaft and tightens the rotating shaft with an appropriate pressure, so that there is no toner leakage. , Does not damage the rotating shaft. Furthermore, since the ring-shaped sealing material is structured to be housed in the ring-shaped space on the inner surface side of the bearing, it is not necessary to provide a special space for sealing, and a compact design is possible.

The hardness of the ring-shaped sealing material is Shore A.
When the hardness is less than 50 °, it becomes difficult to obtain the surface pressure required for sealing. On the other hand, its hardness is 90 Shore A.
If it exceeds °, the tightening force on the rotating shaft will be increased and the rotating torque will be increased. Therefore, the hardness of the ring-shaped sealing material is preferably between 50 and 90 ° in Shore A hardness.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a side sectional view of a toner seal mechanism for a bearing according to the present invention, and FIG. 2 is a partially enlarged view of FIG. In the figure, 1 is a main body frame side plate of the developing machine unit, 2 is a rotary shaft partially embedded in the developer and toner 3, and a bearing 4 fitted in the main body frame side plate 1 is a rotary shaft 2
The end of the is supported. A part of the inner surface side of the bearing 4 is engraved in a ring shape to form a ring-shaped space 5, and the ring-shaped space 5 is fixed to the inner surface of the bearing 4 with an adhesive as shown in an enlarged view in FIG. Further, a ring-shaped sealing material 6 (Shore A hardness 60 °) made of a urethane-based thermoplastic elastomer having an annular main lip 6a and an auxiliary lip 6b is housed.

Of the above-mentioned lips, the tip of the main lip 6a on the outer side in the axial direction is always in contact with the rotary shaft 2, while the tip of the auxiliary lip 6b is extremely close to the rotary shaft 2 so that it can come into contact therewith. However, the rotating shaft 2 is not always in contact with the rotating shaft 2. The rotating shaft 2 of the main lip 6a in this embodiment.
The contact angle θ with respect to is 32 °.

In the bearing toner seal mechanism constructed as described above, when the rotary shaft 2 such as the developing roller contacting the developer and the toner 3 is rotating, the pressure of the toner 3 is applied in the arrow F direction. The invasion of the toner due to the pressure of the toner 3 is almost completely blocked by the sub lip 6b,
The toner pressure on the main lip 6a becomes substantially negligible, and leakage of the toner to the outside is reliably prevented by the main lip 6a which is always in contact with the rotating shaft 2. In this way, since it is possible to substantially prevent the toner from entering the main lip 6a, it is possible to suppress the progress of wear of the main lip 6a and prolong the life of the main lip 6a.

[0019]

As described above, the present invention has the following advantages. Due to the double sealing mechanism of the main lip and the sub-lip, extremely excellent sealing performance can be maintained for a long period of time, and it is suitable for use as a toner sealing member for bearings of rotary shafts in the developing section, cleaning section, etc. of electrophotographic devices. can do. Since the ring-shaped sealing material has a structure that is housed in the ring-shaped space on the inner surface of the bearing, it is not necessary to provide a special space for sealing, and a compact design is possible. If the ring-shaped sealing material is made of a thermoplastic elastomer, it is elastically deformed by the action of the soft segment of the thermoplastic elastomer, and an appropriate sealing pressure is secured. The ring-shaped sealing material having the above shape can be efficiently obtained by injection molding or extrusion molding.

[Brief description of drawings]

FIG. 1 is a side sectional view of an embodiment of the present invention.

FIG. 2 is a partially enlarged view of FIG.

FIG. 3 is a side sectional view of a conventional toner seal mechanism 1.

FIG. 4 is an enlarged view of the seal member shown in FIG.

FIG. 5 is a side sectional view of a conventional toner seal mechanism 2.

FIG. 6 is a side sectional view of a conventional toner seal mechanism 3.

FIG. 7 is a partially enlarged view of FIG. 3;

[Explanation of symbols]

 1 ... Main body frame side plate 2 ... Rotating shaft 3 ... Toner 4 ... Bearing 5 ... Ring-shaped space 6 ... Ring-shaped sealing material 6a ... Main lip 6b ... Sub-lip

Claims (3)

[Claims] 1. A ring-shaped space is formed by engraving a part of the inner surface side of a bearing that supports a rotating shaft in a ring shape, and an annular main lip is projected on the outer side in the axial direction and an annular main lip is formed on the inner side. A ring-shaped sealing material provided with a protruding sub-lip is fixed to the inner surface of the bearing so as to be housed in the ring-shaped space, and the tip of the auxiliary lip of the lip is extremely close to the rotary shaft so that it can come into contact with the rotary shaft. The toner seal mechanism of the bearing is characterized in that the tip of the main lip is always in contact with the rotating shaft. 2. The toner seal mechanism for a bearing according to claim 1, wherein an angle at which the main lip contacts the rotary shaft is 30 to 45 ° with respect to the axial direction of the rotary shaft. 3. The toner sealing mechanism for a bearing according to claim 1, wherein the material of the ring-shaped sealing material is a thermoplastic elastomer.