JP2001294323A - Powder transfer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stator (an assembly with an outer diameter holding member) as an assembly having uniform thickness, and reduce wear deterioration of the stator caused by thin thickness with supplementing reduction in mechanical strength. SOLUTION: This powder transfer pump has the stator 11 in which a double pitch female screw spiral groove 20 is formed in the inner wall of a shaft hole of a cylindrical body 13 having the shaft hole 11a passing in the shaft direction; a rotor 12 rotatably inserted into the shaft hole 11a of the stator; and an outer diameter holding member 30 fitting to the female screw type stator and having a fitting hole for holding the outer circumferential surface of the stator. A double pitch female screw type spiral groove 21 having a locus along the female screw spiral groove in the inner wall of the shaft hole is formed on the outer circumferential surface of the cylindrical body of the stator, and an outer diameter holding member having a male screw-shaped spiral projection 32 for screwing with the female screw-shaped spiral groove of the stator is formed on the inner surface of the fitting hole of the outer diameter holding member.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a powder transfer pump, and more particularly to a powder transfer pump used for a toner collecting / transfer device provided in an electrophotographic image forming apparatus such as a copying machine, a printer and a facsimile. Regarding improvement.

[0002]

2. Description of the Related Art In an electrophotographic copying machine, printer, or facsimile employing a developing system using a one-component developer or a two-component developer, an electrostatic latent image on a photosensitive member is supplied from a developing device. An image is formed by transferring and fixing a toner image obtained by developing with a toner to be transferred onto transfer paper. Since the untransferred toner remains on the photoconductor after the transfer of the toner image, a cleaning device for removing the residual toner in preparation for the next image forming operation is provided. In addition, other than the photoreceptor, a cleaning device is disposed in a unit for supporting a toner image such as an intermediate transfer belt in order to remove residual toner after the transfer of the toner image. By the way, the toner removed and collected by the cleaning device has been discarded in a waste bottle or the like, but in order to satisfy various environmental problems in recent years and various demands for resource recycling, the collected residual toner is returned to the developing device again. Various toner recycling mechanisms for recycling as a developer have been proposed. In order to return the toner collected by the cleaning device to the developing device, the cleaning device and the developing device are connected by a tube,
It must be transported by the required transport means. The present applicant has proposed various techniques using a powder transfer pump (screw pump) as a means for transferring powder such as toner.

FIG. 4 is a sectional view showing an example of the structure of a conventional powder transfer pump. This powder transfer pump 1 is connected to a path 2 for collecting toner removed and collected by a cleaning device (not shown). It is connected to the connecting portion 3. A connecting pipe 5 internally provided with a conveying screw 4 is disposed between the connecting portion 3 and the powder transfer pump 1, and a shaft 4a of the conveying screw 4 is directly connected to a driving shaft 6 receiving a driving force from a motor. Have been. The powder pump 1 has a hollow cylindrical shape fixed between the case 10 fixed to the connecting pipe 5 and the like and a narrow space S between the inner wall of the case 10 and the inner wall of the case 10. It has a stator 11 and a rotor 12 that fits into a shaft hole 11a of the stator 11 and rotates. The other axial end 10a of the case 10 is connected to a transfer pipe connected to a developing device (not shown). An air supply source (not shown) is connected to the hole 10 b provided in the case 10 to send air into the case 10. One end of the rotor 12 is integrated with the shaft 4a. Stator 11
Has a cylindrical body 13 having a shaft hole 11a, a flange 14 provided on the outer periphery of one end in the axial direction of the cylindrical body 13, and a double-pitch female screw spiral groove provided on the inner wall of the shaft hole 11a. are doing. The outer shape of the rotor 12 is a male screw spiral shape that can be screwed into a double pitch female screw spiral groove of the stator 11 and relatively rotated. Therefore, when the drive shaft 6 is driven, the transport screw 4 integrated therewith rotates, and the rotor 12 integrated with the transport screw 4 rotates. Connecting part 3
The toner that has dropped into the connecting pipe 5 is sent to the powder transfer pump 1 by the rotation of the conveying screw 4, and the toner sent between the inner wall of the stator 11 and the outer peripheral surface of the rotor 12 is rotated when the rotor 12 rotates. It is sent out to the developing device side by a pump action generated between the inner wall of the shaft hole 11 a of the stator 11. At this time, the hole 10b is
Is mixed with the toner, and a mixture of the air and the toner is sent to the developing device.

[0004]

The stator used in such a conventional powder transfer pump has the following problems. That is, the stator 11 has the cylindrical body 13
The inner wall of the shaft hole 11a has a double-pitch spiral groove, so when the outer shape of the cylindrical body is straight, a thickness difference occurs between the outer diameter and the inner diameter of the cylindrical body, resulting in uneven wall thickness. Become. That is, the thickness of the spiral groove at the bottom and the outer surface is smaller than the thickness of the other portions. For this reason, molding defects such as sink marks are likely to occur on the outer and inner diameters during the molding process, and it has been difficult to ensure dimensional accuracy. In addition, the cylindrical body 1
Since the thickness of the stator 3 is not uniform throughout but is uneven, the frictional heat generated by the friction caused by the contact rotation with the rotor 13 is unevenly distributed between the thin portion and the stator 11 when the stator 11 is employed in the powder transfer pump. Compared to the thick portion, the heat transfer coefficient and heat dissipation of the uneven portion are reduced, so that a temperature deviation occurs within the inner diameter of the stator, the wear deterioration of the uneven portion becomes faster, and the durability of the parts is reduced. It was one of. That is, in order to improve the durability of the stator, it was necessary to reduce its thickness. However, since the stator has an uneven wall thickness, the resonance amount of the uneven wall portion due to rotation of the rotor is lower than the resonance amount of the thin wall portion. It was difficult to achieve a thinner wall. In other words, in order to reduce the wear on the inner wall of the stator due to the contact resistance with the rotor and to increase the durability, it is necessary to reduce the thickness of the stator. There is a trade-off problem that the wear deterioration of the steel increases. For this reason, it was difficult to reduce the thickness of the stator. SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has been achieved for the first time to realize a reduction in wear of an inner diameter due to resonance of a thin-walled portion while realizing a thinner stator to reduce wear deterioration. It is an object to provide a pump.

[0005]

In order to achieve the above object,
The invention according to claim 1 is a female screw type stator in which a double pitch female screw spiral groove is provided on the inner wall of the axial hole of a cylindrical body having an axial hole that penetrates in the axial direction, and a rotation inside the axial hole of the stator. A powder transfer pump comprising: a male screw rotor freely inserted and an outer diameter holding member having a fitting hole for holding the outer peripheral surface by fitting the female screw stator, The outer peripheral surface of the cylindrical body of the stator is provided with a double-pitch female screw-shaped spiral groove of a locus along the double-pitch female screw spiral groove of the shaft hole inner wall, and a fitting hole of the outer diameter holding member is provided. An outer diameter holding member having a male screw-shaped spiral ridge screwed into a double-pitch female screw-shaped spiral groove formed on the outer surface of the cylindrical body portion of the stator is provided on the inner surface. According to a second aspect of the present invention, a flange is provided at one axial end of the cylindrical body of the stator, and a press-fit recess is provided at an inner end surface of the flange, and the stator is fitted with the outer diameter holding member. A press-fit projection that fits into the press-fit recess is provided on the end face of the outer diameter holding member that abuts on the inner end face of the flange when fitted in the mating hole. A third aspect of the present invention is characterized in that the outer diameter holding member according to the first or second aspect is formed of a material having high heat conductivity and heat radiation such as aluminum.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. 1 (a) and 1 (b) show a powder transfer pump (screw pump) according to an embodiment of the present invention.
FIGS. 2A and 2B are an external perspective view of a stator provided and a conventional external perspective view of a stator. FIGS. 2A and 2B are external perspective views and an external diameter holding member of an outer diameter holding member according to an embodiment of the present invention. It is an external appearance perspective view in the state where the stator was fitted. Note that the stator of the present invention is an improvement of the structure of the stator used in the powder transfer pump shown in FIG.
The present invention will be described with reference to FIG. Therefore, the same parts as those in FIG. 4 are denoted by the same reference numerals, and duplicate description will be omitted. In the powder transfer pump 1 according to the present invention, the stator 11 is fixedly arranged at a predetermined space S in the case 10 as in the powder transfer pump 1 shown in FIG. The rotor 12 is rotatably supported. One characteristic configuration of the present invention is that the stator 11 is configured to be screwed and fixed in a fitting hole of a cylindrical outer diameter holding member. That is, the stator 11 is a female screw type stator in which a double pitch female screw spiral groove 20 is provided on the inner wall of the axial hole of the cylindrical body 13 having the axial hole 11a penetrating in the axial direction. A male screw rotor 12 is rotatably fitted into the shaft hole 11a. The outer peripheral surface of the female screw type stator 11 is held by an inner wall of a fitting hole 31 penetrating the center of an outer diameter holding member 30 made of iron or the like. The cylindrical body 1 of the stator 11
The double pitch female screw spiral groove 20 on the inner wall of the shaft hole 3 is
Two female screw spiral grooves are formed in parallel at a predetermined pitch. On the outer peripheral surface of the cylindrical body portion 13 of the stator 11, a double-pitch female screw having a locus along a groove bottom (minimum thickness portion of the stator) of each double-pitch female screw spiral groove 20 on the inner wall of the shaft hole 11a. A spiral groove 21 having a double-pitch female screw shape formed on the outer peripheral surface of the cylindrical body portion 13 of the stator is provided on the inner wall of the outer diameter holding member 30.
A male screw-shaped spiral ridge 32 to be screwed with 1 is formed. Accordingly, the stator 11 is rotated into the fitting hole 31 while the male screw-shaped spiral ridge 32 is fitted into the double-pitch female screw-shaped spiral groove 21 formed on the outer peripheral surface of the cylindrical body portion 13 of the stator 11. Fig. 2
(b) As shown in FIG.
Can be fixed to eliminate the problem caused by uneven thickness of the stator. Since the female screw-shaped spiral groove 21 is formed on the outer surface along the groove bottom of the female screw spiral groove 20 in the shaft hole 11a, the positional relationship in which the respective groove bottoms of the two spiral grooves 20 and 21 are aligned (opposing positional relationship) ), And the thickness of that portion is minimized. Therefore, the thickness of the stator is reduced as a whole, and the heat transfer coefficient and the heat radiation of the frictional heat generated by the friction during the contact rotation of the rotor are improved by the presence of the minimum thin portion, and the stator inside the inner diameter of the stator is reduced. The temperature deviation is reduced so that the wear deterioration of the uneven thickness portion is prevented, and the durability of the component is improved. That is, it is possible to satisfy one requirement of thinning necessary for improving the durability of the stator.

However, on the other hand, if the stator has a thin portion, the problem that the amount of resonance at the time of rotation of the rotor increases and the degree of wear deterioration of the stator inner diameter due to resonance increases for the thin portion still remains. In the present invention,
In order to solve such a problem, the outer diameter holding member 30 is tightly screwed and fitted to the outer surface of the stator 11 to reinforce the outer diameter holding member 30. A large-diameter flange 14 is integrated with one end of the stator 11 in the axial direction. When the outer diameter holding member 30 is fitted to the outer periphery of the stator 11 as shown in FIG. The holding member 30 is configured such that one end in the axial direction is seated on the inner end surface 14 a of the flange 14. Note that a spiral protrusion may be provided on the outer peripheral surface of the stator, and a spiral groove may be provided on the inner wall of the outer diameter holding member to be screwed thereto. Therefore, in the claims, the spiral groove 21 includes a case in which the spiral groove is a spiral protrusion, and the male screw-shaped spiral protrusion 32 includes a case in which the spiral groove is a spiral groove. As shown in FIG. 2 (b), a stator assembly in which the outer diameter holding member 30 is integrated with the outer periphery of the stator 11 is fixedly arranged inside the case 10 shown in FIG.
As a whole, the stator (assembly) is formed as a molded product having no uneven thickness, and wear deterioration due to thinner stator can be reduced. By reducing the thickness of the stator 11 itself by an amount corresponding to the attachment of the outer diameter holding member 30 to the outer periphery of the stator, an increase in the outer diameter of the entire assembly can be prevented. Further, the heat transfer coefficient and the heat radiation of the frictional heat generated by the friction due to the contact rotation between the stator 11 and the rotor 13 are better in the thin portion than in the uneven portion, and the wear deterioration is less, so the stator In order to improve the durability of the stator, it is necessary to reduce the thickness of the stator. However, according to the present embodiment, the female thread-shaped spiral groove provided in the shaft hole of the stator that causes the uneven thickness portion to be formed. Since the spiral groove 21 is formed on the outer surface of the cylindrical body corresponding to the groove bottom, the thinning is promoted by the facing structure of the groove bottoms. On the other hand, since the outer diameter holding member 30 having the spiral ridge 32 fitted into the spiral groove 21 provided on the outer surface of the cylindrical body portion 13 was fitted, the thin portion was provided at a position where the bottom grooves face each other. Can be compensated for the decrease in mechanical strength due to the formation of.

Next, FIG. 3A is a view showing another embodiment of the stator and the outer diameter holding member of the present invention, and FIG. In this embodiment, the stator 11
Press-fit recesses 26 are provided at a predetermined pitch in the circumferential direction on the inner end surface 14a of the
The press-fit projection 33 that fits into the press-fit recess 26 is provided on the end face of the outer diameter holding member that comes into contact with the inner end face of the flange portion 14 when fitted into the fitting hole 31. The formation position, formation pitch and shape of each press-fit recess 26 are determined by the stator 11
When the outer diameter holding member 30 is rotated clockwise while the spiral protrusion 32 is fitted into the double-pitch female screw-shaped spiral groove 21 on the outer peripheral surface of the outer peripheral surface, the fitting of the fitting hole 31 is completed.
Each press-fit projection 33 is set so as to fit in each press-fit recess 26 one-to-one. Therefore, the outer diameter holding member is securely fixed to the stator. Therefore, it is possible to prevent the two from being displaced by the resonance of the rotation of the rotor 12, and
The outer diameter of the stator is reliably maintained. As described above, by disposing the stator and the outer diameter holding member firmly fixed to each other by the fitting of the press-fitting recess 26 and the press-fitting protrusion 33 in the case 10, they may be displaced. The function as a stator can be exhibited without any trouble. Therefore, the transfer of the powder (toner) by the rotation of the rotor is facilitated. The material of the outer diameter holding member 30 is formed of a material having a high heat conductivity and heat radiation, such as aluminum, in addition to iron. Therefore, when the rotor 12 rotates, the stator 11
The heat conducted to the side is efficiently radiated to the outside via the outer diameter holding member 30.

[0009]

As described above, according to the present invention, it is possible to provide a stator (an assembly with an outer diameter holding member) as an assembly having no uneven thickness, and to make the stator thinner while compensating for a decrease in mechanical strength. It is possible to reduce wear deterioration due to the formation. That is, the invention according to claim 1 is characterized in that a female screw-shaped double-pitch spiral groove is provided on the outer periphery of a cylindrical body of a stator along the groove bottom of a spiral-shaped spiral groove having a double pitch of the inner diameter of the stator. Can be made thinner overall, and the conductivity and heat dissipation of the heat generated by the rotation of the rotor can be improved. Further, a double-pitch spiral protrusion of a male screw is disposed on the inner wall of a cylindrical outer diameter holding member made of iron or the like, and the outer diameter of the double-pitch spiral groove of the female screw on the outer periphery of the body of the stator is increased. By screwing the double-pitch helical projection of the male screw on the holding member side, the outer diameter of the stator is held, and wear deterioration due to thinning can be prevented. In claim 2, claim 1
A press-fit recess which can be press-fitted is provided on the inner end face of a flange provided at one axial end of the stator, and a press-fit projection is provided at one axial end of the outer diameter holding member. Then, when the double-pitch protrusion of the male screw having the inner diameter of the outer diameter holding member is rotated while being screwed along the double-pitch spiral groove of the female screw on the outer periphery of the trunk portion of the stator, the press-fit recess of the stator is formed. The press-fit projection of the outer diameter holding member is press-fitted to the outer diameter holding member, and the outer diameter holding member is securely fixed, thereby preventing the stator and the outer diameter holding member from being displaced due to resonance generated when the rotor rotates. As a result, the outer diameter of the stator is reliably maintained. In the third aspect, since the outer diameter holding member is made of a material having high thermal conductivity and heat dissipation such as aluminum, the efficiency of heat dissipation of the frictional heat of the stator can be improved.

[Brief description of the drawings]

1A and 1B are an external perspective view of a stator provided in a powder transfer pump (screw pump) according to an embodiment of the present invention and an external perspective view of a conventional stator.

FIGS. 2A and 2B are an external perspective view of an outer diameter holding member according to an embodiment of the present invention and an external perspective view of a state in which a stator is fitted into the outer diameter holding member.

FIGS. 3A and 3B are an external view and an enlarged view of a main part of a stator and an outer diameter holding member according to another embodiment.

FIG. 4 is a sectional view showing a configuration of an example of a conventional powder transfer pump.

[Explanation of symbols]

1 powder transfer pump, 2 path for collecting toner, 3
Connection part, 4 conveyance screw, 5 connection pipe, 6 drive shaft, 10 case, 11 stator, 11a shaft hole 12
Rotor, 13 cylindrical body, 14 flange, 20 female screw spiral groove, 21 female screw spiral groove, 26 press-fit recess, 3
0 outer diameter holding member, 31 fitting hole, 32 spiral protrusion, 3
3 Press-in projection.

Claims (3)

[Claims] 1. A female screw type stator having a double pitch female screw spiral groove formed on an inner wall of an axial hole of a cylindrical body having an axial hole penetrating in an axial direction, and rotatably provided in the axial hole of the stator. A powder transfer pump comprising: a male screw rotor to be inserted; and an outer diameter holding member having a fitting hole that fits the female screw stator and holds an outer peripheral surface of the stator. On the outer peripheral surface of the cylindrical trunk portion, there is provided a double-pitch female screw-shaped spiral groove having a locus along the double-pitch female screw spiral groove on the inner wall of the shaft hole, and on the inner surface of the fitting hole of the outer diameter holding member. A powder transfer pump having an outer diameter holding member having a male screw-shaped spiral ridge engaged with a double-pitch female screw-shaped spiral groove formed on the outer peripheral surface of the cylindrical body of the stator. . 2. A flange is provided at one axial end of the cylindrical body of the stator, and a press-fit recess is provided at an inner end face of the flange, and the stator is fitted into a fitting hole of the outer diameter holding member. 2. A powder transfer pump according to claim 1, wherein a press-fitting protrusion fitted to said press-fitting recess is provided on an end face of said outer diameter holding member which abuts on an inner end face of said flange when fitted to said flange. . 3. A powder transfer pump, wherein the outer diameter holding member according to claim 1 is formed of a material having high heat conductivity and heat radiation such as aluminum.