JPH103212A - Toner sealing mechanism for bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain excellent sealing performance for a long time and to make structure inexpensive and compact by disposing a toner sealing member consisting of a shaft sealing part, a housing sealing part, and a side surface coating part making a bearing get out of contact with toner and connecting and integrating both sealing parts on the bearing. SOLUTION: A contact side on the inner surface of the bearing 1 with the toner is cylindrically hollowed out so as to form a space. In the space, the shaft sealing part 7 having an elastic lip 6 is arranged in an abutting state on a rotary shaft so that the edge of the lip 6 is faced to a toner housing side. The toner sealing member 2 is composed of the shaft sealing part 7, the side surface coating part 8 and the housing sealing part 9, attached so that the contact side surface of the bearing 1 with the toner may be coated, and a projected part 9a is formed on the housing sealing part 9. The housing part 9 is allowed to lie in a gap between the housing side plate and the outer periphery of the bearing 1 and the projected part 9a is fit in the recessed part of the housing side plate, so that airtightness is secured.

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.
The present invention relates to a toner seal mechanism for a rotating shaft in a toner storage unit such as a developing unit, a cleaning unit, and a toner supply unit.

[0002]

2. Description of the Related Art Usually, a clearance of 5 to several tens μm or less is usually provided between a bearing and a rotating shaft of a developing unit, a cleaning unit, a toner replenishing unit, etc. of an electrophotographic apparatus in order to maintain smooth rotation. However, since the clearance and the particle diameter of the toner are almost the same, the toner enters the sliding portion of the bearing with the rotating shaft, and is melted and solidified by frictional heat generated by the sliding, so that the rotating shaft does not rotate smoothly. Sometimes. Further, the toner may leak from the clearance to contaminate the surroundings, and may cause trouble in operation.
With the recent demand for improved image quality, the particle size of the toner tends to be further reduced, so it is not easy to prevent toner leakage. For example, the following technology is known as a sealing technology for preventing such a problem.

As shown in FIG. 3, a metal ring 14 is mounted on a bearing 13 for supporting a rotating shaft 12 of a main body housing 11 of a developing machine or the like.
A toner seal mechanism having a structure in which a seal member made of a lip seal 15 made of synthetic rubber such as NBR or fluorine rubber is mounted (hereinafter, referred to as "conventional toner seal mechanism 1"). FIG. 4 is an enlarged view of such a seal member.

In order to prevent toner leakage from a fitting portion between the outer periphery of the bearing and the housing of the developing machine, Japanese Patent Laid-Open No.
Japanese Patent Application Laid-Open No. 3-169676 discloses, as shown in FIG. 5, in a toner storage device provided with a stirring member for stirring stored toner or a conveying member for conveying toner, a bearing member 16 for supporting each of the above members is provided. Of the present invention, wherein a ring-shaped sealing member 17 is interposed between an outer periphery of the toner container and an inner periphery of a bearing housing for accommodating the bearing member 16. Sealing mechanism 2 ").

Furthermore, Japanese Patent Laid-Open Publication No. Sho 62-35362 discloses a technique in which a seal member having a pressure contact surface having a small friction coefficient is interposed between the bearing and the bearing to prevent toner from entering the bearing. As shown in FIG. 6, as shown in FIG. 6, "a shaft end of a rotating shaft 18 disposed inside a developing device and an inner end surface of a bearing 19 supporting the rotating shaft 18 are frictionally opposed to each other. By fixing the elastic sealing members 20 and 21 formed as surfaces having a small coefficient,
There is disclosed a device relating to "a sealing mechanism of a bearing in a developing device, characterized in that surfaces of the sealing member having a small coefficient of friction are pressed against each other (hereinafter referred to as" conventional toner sealing mechanism 3 ").

[0006]

However, the seal member of the conventional toner seal mechanism 1 is originally used for an oil seal, and basically the oil to be sealed is interposed between the lip portion and the rotary shaft. It is designed on the assumption that it will be in a fluid lubricated state, and no consideration is given to maintaining good friction and wear characteristics when sliding with fine powder such as toner. The synthetic rubber used for the lip portion of the toner seal member is generally NBR. However, when the rotation speed of the rotating shaft is increased, the plasticizer in the rubber is heated by the sliding heat with the rotating shaft. The toner bleeds and promotes coagulation of the toner, and this toner mass may cause a defect on an image. In addition, since the toner seal member is press-fitted into the bearing to form a product, a press-fitting step is required, resulting in an increase in processing cost.

Further, in the conventional toner seal mechanism 2, since the ring-shaped seal member 17 is mounted on the outer peripheral surface of the bearing, there is an inconvenience that the number of parts and the number of assembling steps are increased.

Further, in the conventional toner seal mechanism 3, since the elastic seal members 20, 21 are formed of foamed polyurethane or the like, they are pressed against each other when they are used for a long time or when the rotary shaft 18 rotates. As a result, the rotating shaft 18 and the sealing members 20, 2
In some cases, a gap is formed between the bearing 19 and the toner, and the toner may enter the bearing 19.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and has as its object to maintain a good sealing performance for a long period of time, and to realize a low-cost and compact structure. The present invention provides a toner seal mechanism for a bearing.

[0010]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a shaft seal portion, a housing seal portion, and a side surface in which contact between a bearing and toner is cut off and the two seal portions are connected and integrated. The toner seal member composed of the covering portion is disposed on the bearing. And good sealing performance is maintained by this toner seal member.

[0011]

More specifically, the present invention relates to a toner seal mechanism for a bearing having a toner seal member for preventing toner from leaking through a bearing for supporting a rotating shaft mounted on a developing device and a toner storage device. The toner seal member includes a shaft seal portion having an elastic lip that comes into contact with the rotating shaft, a housing seal portion interposed in a gap between the housing of the device in which the bearing is fitted and the outer peripheral surface of the bearing; A first aspect of the present invention is a toner sealing mechanism for a bearing, which comprises a side surface covering portion that cuts off contact and connects and integrates the shaft seal portion and the housing seal portion. The toner sealing mechanism of the bearing is characterized in that the material of the member is a thermoplastic elastomer as the second invention, in the first or second invention, A third invention is a toner seal mechanism for a bearing, wherein a recess is formed on the inner peripheral surface of the housing, and a convex portion that fits into the recess is formed on the outer peripheral surface of the housing seal portion of the toner seal member. In the first, second or third aspect of the present invention, a toner seal mechanism for a bearing, wherein the hardness of the toner seal member is 50 to 90 degrees in JISA hardness is a fourth aspect of the present invention.

As the thermoplastic elastomer, for example,
Urethane-based thermoplastic elastomers, polyester-based thermoplastic elastomers, and polyamide-based thermoplastic elastomers can be used.

According to the present invention configured as described above,
Because the shaft seal portion for preventing leakage of toner from between the bearing and the rotating shaft and the housing seal portion interposed in the gap between the housing of the device to which the bearing is fitted and the outer peripheral surface of the bearing are integrated. Since the toner seal member can be attached to the bearing only once and the number of parts can be reduced, the cost can be significantly reduced.

Further, since the toner seal member used in the present invention is integrated so as to cover the outer peripheral portion of the bearing and the side surface where the bearing contacts the toner, no special space for sealing is required. A compact design becomes possible. If the bearing member is made of a material such as an oil-impregnated sintered product, the oil contained in the bearing may ooze out and contaminate the toner in the conventional sealing mechanism. Is completely covered with the toner seal member, so that there is no fear of toner contamination. In addition, the elastic lip in contact with the rotating shaft prevents the toner from leaking from the sliding portion, and the convex portion formed on the outer peripheral surface of the housing seal portion of the toner seal member is formed in the concave portion formed on the inner peripheral surface of the housing. The fitting improves the airtightness of both, and prevents leakage of toner from between the bearing and the housing.

Furthermore, the toner seal member used in the present invention is separately molded and attached to the bearing. If the toner seal member is made of a thermoplastic elastomer, the toner seal member is injected after the bearing is installed in the mold cavity. Since so-called insert molding, which covers the bearing at the same time as the molding, can be performed, the cost of attaching the toner seal member to the bearing can be further reduced. Further, by using a thermoplastic resin such as nylon or polyacetal for the bearing member, the bearing member and the toner seal member can be formed by a two-color molding method at one time.

The hardness of the toner seal member is determined by JI
When the SA hardness is less than 50 °, it becomes difficult to obtain a necessary surface pressure with an elastic lip that seals the rotating shaft. on the other hand,
If the JISA hardness exceeds 90 °, the tightening force on the rotating shaft increases, causing an increase in the rotating torque,
If the hardness is too high, the fitting between the housing and the housing seal of the apparatus becomes tight, and it becomes difficult to attach the toner seal member. Therefore, it is preferable that the hardness of the toner seal member be between 50 and 90 degrees in JISA hardness.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 1 denotes a bearing, 2 denotes a toner seal member, 3 denotes a housing side plate of a device including a developing unit and a toner replenishing unit, and 4 denotes a rotating shaft partially buried in toner 5. Bearing 1 mounted on
Support the end of the rotating shaft 4. On the side where the housing side plate 3 contacts the toner seal member 2, a concave portion 3a that can be fitted with a convex portion 9a described later is formed.

The inner surface of the bearing 1 that comes into contact with the toner is hollowed out in a cylindrical shape to form a space.
As shown in detail in FIG. 2, a shaft seal portion 7 having an elastic lip 6 is disposed in a state of being in contact with the rotating shaft such that the lip tip faces the toner storage side. The toner seal member 2 includes a shaft seal portion 7, a side surface cover portion 8, and a housing seal portion 9. The toner seal member 2 is mounted so as to cover the contact surface of the bearing 1 with the toner, and the housing seal portion 9 has a projection 9 a. Is formed. And the housing seal part 9 is interposed in the gap between the housing side plate 3 and the outer periphery of the bearing 1,
The airtightness is ensured by fitting the convex portion 9a into the concave portion 3a of the housing side plate 3.

In the toner seal mechanism of the bearing configured as described above, when the rotating shaft 4 is rotating, the rotating shaft 4
The elastic lip 6 prevents the toner 5 from leaking from the sliding portion to the outside between the bearing and the bearing 1.
The leakage of the toner 5 is prevented between the bearing and the bearing 1 by the fitting of the projection 9a and the recess 3a.

Next, the present invention will be further described with specific numerical values. (Example) Commercially available polyurethane thermoplastic elastomer having a JISA hardness of 80 ° (Rezamine P880 manufactured by Dainichi Seika)
Was used to obtain a toner seal member having a sectional shape as shown in FIG. 2 (inner diameter = 5.6 mm, outer diameter = 14 mm,
Convex height = 0.2 mm). Then, the toner seal member was coated from the outer peripheral portion of the oil-impregnated sintered material bearing 1 to the contact side surface with the toner to obtain a bearing with a toner seal member having a shape as shown in FIG. As the polyurethane-based thermoplastic elastomer, an elastomer containing no plasticizer which affects the toner was selected.

Comparative Example 1 A commercially available oil seal (NTN)
(G inner diameter 6 mm, outer diameter 10 mm, thickness 2 mm) is press-fitted into the inner end of the oil-impregnated sintered material bearing 13 having a shape as shown in FIG. 3 to obtain a bearing with a toner seal member having a structure as shown in FIG. Was.

(Comparative Example 2) In the structure of FIG. 5, a commercially available O-ring (material NBR) is mounted in the groove 16a on the outer periphery of the bearing, and the commercially available oil seal used in Comparative Example 1 is mounted on the inner end of the bearing. By mounting, a bearing with a toner seal member having a structure as shown in FIG. 5 was obtained. The bearing material was an oil-impregnated sintered material.

The bearing with the toner seal member described above is mounted on a housing (not shown) of the toner storage device, and a rotary shaft (outer diameter: 6 mm, material: SUS) is fitted thereto, and the toner is charged into the toner storage device. The rotation shaft was continuously rotated at a rotation speed of 300 rpm for 100 hours, and the state of toner leakage was observed. The toner used was a two-component toner having an average particle diameter of 8 μm and an average particle diameter of 10 μm. The results are as shown in Table 1 below.

[0024]

[Table 1]

As shown in Table 1, it can be seen that the toner according to the embodiment of the present invention does not leak toner and has good sealing properties. On the other hand, in the case of Comparative Example 1, since the seal member was not provided between the bearing and the housing, the toner leaked from that portion. In this case, the toner particle diameter is 1
When it was increased to 0 μm, the amount of leakage was reduced, but toner still leaked.

In the case of Comparative Example 2, the toner did not leak, but there was a problem that the oil of the oil-impregnated sintered material used for the bearing solidified the toner and formed a toner mass.

[0027]

Since the present invention is configured as described above, the following effects can be obtained. With the double toner seal mechanism between the shaft rotating part and the bearing and the housing, the leakage of the toner can be effectively prevented. As a result, the toner does not fall or scatter in the image forming apparatus. Good images can be obtained. In addition, during inspection and repair work, the work can be efficiently performed without soiling the periphery. In addition, since the seal member of the shaft rotating portion and the seal member of the bearing and the housing are integrated, the number of parts and the number of assembling steps can be reduced, and the cost can be reduced. Further, since the structure is fitted to the outer periphery of the bearing, there is no need to provide a special space for sealing, and a compact design is possible.

If the seal member according to the present invention is made of a thermoplastic elastomer, it can be manufactured by injection molding. Therefore, if the bearing is molded as an insert, a bearing with a toner seal member can be obtained simultaneously with molding.

By fitting a convex portion formed on the outer periphery of the housing seal portion of the toner seal member into a concave portion formed on the inner peripheral surface of the housing, airtightness is improved, and leakage of toner is more reliably prevented. You.

By setting the hardness of the toner seal member to 50 to 90 degrees in JISA hardness, an appropriate sealing pressure is secured, and there is no trouble in mounting the toner seal member to the bearing.

[Brief description of the drawings]

FIG. 1 is a side sectional view of a toner seal mechanism of a bearing according to 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 a partially enlarged view of FIG. 3;

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.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Bearing 2 ... Toner seal member 3 ... Housing side plate 3a ... Concave part 4 ... Rotary shaft 5 ... Toner 6 ... Elastic lip 7 ... Shaft seal part 8 ... Side surface coating part 9 ... Housing seal part 9a ... Convex part

Claims (4)

[Claims] 1. A toner seal mechanism for a bearing having a toner seal member for preventing toner from leaking through a bearing supporting a rotary shaft mounted on a developing device and a toner storage device, wherein the toner seal member is a rotary shaft. A shaft seal portion having an elastic lip that comes into contact with the housing, a housing seal portion interposed in a gap between the housing of the device in which the bearing is fitted and the outer peripheral surface of the bearing, and a shaft seal portion that cuts off contact between the bearing and the toner. A toner seal mechanism for a bearing, comprising a side surface covering portion connected to and integrated with a housing seal portion. 2. The toner seal mechanism for a bearing according to claim 1, wherein the material of the toner seal member is a thermoplastic elastomer. 3. The housing according to claim 1, wherein a concave portion is formed on an inner peripheral surface of the housing, and a convex portion which fits into the concave portion is formed on an outer peripheral surface of the housing seal portion of the toner seal member. Bearing toner seal mechanism. 4. The toner sealing mechanism for a bearing according to claim 1, wherein the hardness of the toner seal member is 50 to 90 ° in JISA hardness.