JP3512983B2 - Toner transfer pump - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a cylindrical stator made of an elastic material, and a rotor arranged inside the stator. The rotor and the stator are driven by rotating the rotor. The present invention relates to a toner transfer pump that sends out the toner sent between and to the outside.

[0002]

2. Description of the Related Art In an image forming apparatus configured as a copying machine, a printer, a facsimile, or a compound machine thereof, which visualizes an electrostatic latent image formed on a latent image carrier with powdery toner. Are used to transfer toner from one place to another for various purposes. A typical example thereof is to transfer the toner contained in the toner container of the toner supply device to the developing device, or transfer the transfer residual toner collected from the latent image carrier in the cleaning device to the waste toner container or the developing device.

It is already known to use a toner transfer pump of the type described at the beginning for transferring such toner (see, for example, JP-A-7-219329).
This pump is a screw pump known as a mono pump, and has a rotor made of a rigid body such as metal or resin, and a stator made of an elastic material arranged so as to enclose the rotor.

When a stator made of an elastic material is used, the stator portion pressed by the rotating rotor is elastically deformed, so that the external force applied to the transferred toner is reduced, and the toner particles are deformed or destroyed. Can be prevented. Moreover, since the stator made of an elastic material is elastically deformed when the rotor rotates, the heat generated by the friction between the two can be suppressed to a low level, which makes it possible to prevent the toner from agglomerating and form a toner image with the toner. By doing so, the image quality can be improved. Further, it is possible to prevent the toner from being melted and blocking, and the melted toner from being fixed to the rotor or the stator, so that the rotor can always be normally rotated.

As described above, when the stator of the screw pump is made of an elastic material, a toner transfer pump suitable for transferring toner in the image forming apparatus can be formed. However, the problem here is that when the rotor of the toner transfer pump rotates, a periodic abnormal noise called "Kyun Kyun" is generated. Such an abnormal sound is generally called "squealing". However, when such a squealing occurs, the environment of the office in which the image forming apparatus is installed may be harmed, which may cause a user discomfort.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a toner transfer pump which suppresses the above-mentioned abnormal noise, that is, squeaking.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a toner transfer pump of the type described at the beginning, where the rotor static torque is a and the rotor dynamic torque is b. A toner transfer pump characterized by satisfying /b≧0.03 is proposed (claim 1).

At this time, the main material of the stator is made of rubber, and the rubber and the inorganic filler mixed therein are 100
When the weight percentage is set, it is advantageous that the weight ratio of the inorganic filler is 20 wt% or less (claim 2).

Further, in the toner transfer pump according to claim 2, it is particularly advantageous that the rubber is ethylene propylene rubber (claim 3).

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

First, an application example of the toner transfer pump will be clarified. FIG. 1 is a schematic cross-sectional view showing a main part of an image forming apparatus having a toner transfer pump. The image forming apparatus shown here is a drum-shaped photoreceptor 1 which is an example of a latent image carrier.
And a toner supply device 3 for supplying powdery toner to the developing device 2 and the developing device 2 placed opposite thereto. The photoconductor 1 is rotatably supported by the frame of the main body of the image forming apparatus, and is rotationally driven clockwise in FIG.
At this time, the surface of the photoconductor is uniformly charged to a predetermined polarity by a charging device (not shown), and then the charged surface is imagewise exposed to form a predetermined electrostatic latent image on the surface of the photoconductor. . When the electrostatic latent image passes through the developing device 2, it is visualized by powdery toner.

The developer container 12 of the developing device 2 contains a powdery two-component developer D having a toner and a carrier. As the developer, a one-component developer containing no carrier is used. May be used. The developer D is agitated by the agitating members 8 and 9 which are rotationally driven, and at this time,
The toner and the carrier are triboelectrically charged with opposite polarities. The charged developer D is carried by the magnetic force on the peripheral surface of the developing sleeve 6 which is rotationally driven in the counterclockwise direction in FIG. 1 and is conveyed, and the conveying amount is regulated by the agent regulating blade 10, and then the sleeve 6 concerned. And is conveyed to the developing area between the photosensitive member 1 and the photosensitive member 1.

Toner of the developer conveyed to the developing area is electrostatically transferred to the electrostatic latent image formed on the photoconductor 1 as described above, and the latent image is visualized as a toner image. To be done. The toner image is transferred by the transfer device 13 onto a transfer material (not shown) fed to the photoconductor 1, and the transfer material is conveyed to a fixing device (not shown), where the toner on the transfer material is transferred. The image is fixed. On the other hand, after the transfer of the toner image, the toner remaining on the photoreceptor 1 is collected and removed from the surface of the photoreceptor by a cleaning device (not shown). The developing sleeve 6 by the agent regulating blade 10.
The developer scraped off from the developer falls under the developer container 12 while being guided by the separator 11.

While the above-described developing operation is being performed, the toner concentration of the developer D is lowered, and when this is detected by a toner concentration sensor (not shown), a toner replenishing case formed integrally with the developer container 12 is formed. 7 to developer container 1
Toner is replenished to 2. The toner supply case 7 is provided with a toner supply port 14 as shown in FIG. 2, and toner is supplied to the toner supply case 7 through the toner supply port 14 as described later. The supplied toner is conveyed by the toner conveying screw 7a shown in FIG. 1 and is replenished into the developer container 12 by the rotation of the toner replenishing roller 7b provided between the toner replenishing case 7 and the developer container 12. . An air vent hole 7d is formed in the upper plate 7c of the toner replenishing case 7, and an air filter 15 is arranged therein.

On the other hand, as shown in FIG. 3 in detail, the toner supply device 3 has a toner container 16 containing a powdery toner T formed by externally adding an auxiliary agent if necessary, and Toner is appropriately supplied into the toner container 16 from the upper opening 3a. At the time of supply, the lid 17 is opened. The upper opening of the toner guide duct 4 is connected to the lower opening 3b of the toner container 16, and the toner T in the toner container 16 is supplied to the toner guide duct 4. The motor 20 is supported by a motor mounting member 22 fixed to the toner container 16, and the output shaft of the motor 20 is connected to a screw shaft 21 having screw blades via a sleeve 23. The screw shaft 21 penetrates the toner guide duct 4 from the upper part to the lower part, and the toner supplied to the duct 4 is conveyed downward by the rotation of the screw shaft 21.

A toner transfer pump 5 is connected to the lower end of the toner guide duct 4. The toner transfer pump 5 shown here is a cylindrical stator 25 made of an elastic material, and a rotor 2 arranged inside the stator 25.
4 and. On the outer peripheral surface of the rotor 24, a single projecting strip 24A spirally extending along the axial direction is formed, and on the inner peripheral surface of the cylindrical stator 25, a spiral extending along the axial direction. A double groove 25A is formed. The stator 25 is fixedly arranged so as to surround the rotor 24, the rotor 24 is connected to the motor 20 via the screw shaft 21, and is driven to rotate about the axis of the rotor 24 by the operation of the motor 20. In this way, the rotor 24 arranged in the inner space of the tubular stator 25 is driven to rotate, and the outer peripheral surface of the rotor 24 comes into contact with and engages with the inner peripheral surface of the stator 25, and the inner peripheral surface of the stator 25 and the rotor 24.
The powdery toner sent into the space S formed between the outer peripheral surfaces of the toner is sent out to the outside. The rotor 24 is made of a material having higher rigidity than the stator 25, for example, a rigid body such as metal or hard resin.

As described above, the toner transfer pump 5 shown as an example in the drawing is constructed as a screw pump known as a mono pump, and is of a rotary displacement type and a pressure transfer type.

The stator 25 is held by an upper holder 26 and a lower holder 27, and the cylindrical upper holder 26 is fixed to the lower portion of the toner guide duct 4.
The stator 25 is fitted and fixed in a lower holder 27 formed in a tubular shape, and the upper portion of the lower holder 27 is detachably connected to the upper holder 26 to be integrated. A toner passage 30 is formed in a lower portion of the lower holder 27, and the toner passage 30 is provided with a toner transfer pipe 32.
It is connected to the toner supply port 14 of the toner supply case 7 shown in FIG. In FIG. 1, the toner transfer pipe 32 is shown in a simplified manner by the alternate long and short dash line.

When a toner remaining amount sensor (not shown) detects that the amount of toner in the toner replenishing case 7 is below a certain amount, the motor 20 starts to rotate by a command based on this, and the screw Shaft 21 and rotor 2
4 are rotationally driven together. In this way, the toner flowing down from the toner container 16 to the toner guide duct 4 is conveyed downward by the rotation of the screw shaft 21, and further the rotor 24 is conveyed downward by rotating around the axis thereof. In this way, the toner transfer pump 5 is
The powdery toner sent into the stator 25 is
It is transferred by the rotation of the rotor 24. The toner discharged from the toner transfer pump 5 is conveyed through the toner passage 30 of the lower holder 27 and the toner transfer pipe 32 to the toner supply port 14 of the toner replenishing case 7 shown in FIG. Is conveyed by the toner conveying screw 7a shown in FIG.

During the above-described toner conveying operation, the fan 28 arranged above the motor 20 shown in FIG. 3 is rotationally driven by the operation of the motor 20. As a result, the outside air is sucked through the air intake port 28a provided in the upper portion of the fan 28, the air is discharged through the air discharge ports 28b and 28c, and then the air supply port is passed through the pipe schematically shown by a chain line in FIG. It is introduced into the upper holder 26 and the lower holder 27 from 29 and 31. The air supply amount at this time is a small amount of, for example, about 0.5 to 2 liters / minute, and the air flow promotes fluidization of the toner, and the toner transfer pump 5 reliably transfers the toner. . This air contributes to the transfer of toner and then
And is discharged to the outside through the air filter 15 shown in FIG.

As described above, the powdery toner is conveyed to the developing device 2 by the toner transfer pump 5. By using the pump 5, it becomes possible to control the flow rate of the conveyed toner with high accuracy and high accuracy.

Here, the rotor 24 constituting the toner transfer pump 5 is made of a rigid body, while the stator 25 is made of an elastic material such as rubber. As a result, as described above, although the rotor 24 is made of a rigid body, when the toner particles pass between the rotor 24 and the stator 25, the stator portion pressed by the rotor 24 is elastically deformed. However, the external force applied to the toner particles is reduced, and the stress acting on the toner particles can be reduced. Therefore, it is possible to prevent the toner particles from being deformed or destroyed. Moreover, the rotor 2
Since the stator 25 is elastically deformed during the rotation of 4, the heat generated by the friction between the two can be suppressed to an extremely low level, and thus the aggregation of the toner can be prevented.
Since the toner image is formed on the photoconductor 1 by the toner, the image quality can be improved. Moreover, since it is possible to suppress the generation of frictional heat, it is possible to prevent the toner from melting and causing blocking, and also to prevent the melted toner from sticking to the outer peripheral surface of the rotor 24 or the inner peripheral surface of the stator 25. It is possible to rotate the rotor 24 in a normal state at all times.

By constructing the stator 25 with an elastic material as described above, a number of advantages are obtained. However, as described above, when the toner transfer pump 5 is operated to transfer the toner, the rotation of the rotor 24 causes a periodic noise called "squeaking". Therefore, the inventor conducted a number of experiments in order to elucidate the cause of such squeal. As a result, it became clear that the occurrence of this squeaking phenomenon was greatly related to the ratio of the static torque of the rotor 24 to its dynamic torque.

The static torque of the rotor of the toner transfer pump is the torque when the rotor is started to transfer toner, that is, when the rotor starts to rotate, and the dynamic torque of the rotor is the rotation of the rotor. After going up, this is the torque when rotating while transferring the powdery toner. For example, the torque of the rotor when the rotor rotates in a predetermined steady state to transfer toner is the dynamic torque. Here, when the static torque of the rotor 24 of the toner transfer pump 5 is a and the dynamic torque of the rotor 24 is b,
It has been clarified that the generation of squeal can be effectively reduced by setting each torque value so as to satisfy a / b ≧ 0.03.

The above facts will be clarified by introducing a part of the experiments conducted by the present inventor.

In this experiment, a stator was manufactured by using an outer die and a die having an aluminum stud pin fixedly arranged therein. A spiral ridge corresponding to the spiral groove on the inner peripheral surface of the stator is formed on the outer peripheral surface of the stud pin, and ethylene propylene rubber (EP21 manufactured by JSR) is used as a main material in the cavity between the stud pin and the outer mold. Then, the rubber composition was supplied to mold the stator 25.
Then, using the stud pins having different diameters, seven kinds of stators having different inner diameters were manufactured as shown in Table 1 to Table 1 below. The inner diameter of each stator shown here is the diameter of the minimum diameter portion measured using a pin gauge, and indicates the inner diameter of the stator in a free state before inserting the rotor.

A, B, C, shown in the column of "Compound" in Table 1,
D indicates the type of rubber compound used in manufacturing each of the stators, and the actual values of the respective compounds are as shown in the compounds A to D in Table 2 below. Here, the blending ratio is changed centering on the amounts of the softening agent (process oil) and the white filler (calcium carbonate),
The amount and type of vulcanizing agent are also slightly different. The values shown in the formulation table in Table 2 are parts by weight.

[0028]

[Table 1]

[0029]

[Table 2]

The seven types of stators manufactured as described above were respectively assembled to rotors of the same size obtained by cutting SUS material to form a toner transfer pump as shown in FIG. The outer diameter of the circle of the rotor cross section was 10.4 mm.

When the rotor of the toner transfer pump is rotated to transfer the powdery toner, the static torque a (N · m), the dynamic torque b (N · m) of the rotor, and the ratio a of the two. The result of the value of / b is shown in Table 1. Table 1
, And inner diameters 9.9 mm, 9.7 mm and 9.6
The dynamic torque of the rotor using the mm stator is a value when the rotor is rotated at 70 rpm and 200 rpm. Further, the dynamic torque of the rotor when the stators shown in Tables 1 to 3 are used are values when the rotor is rotated at 50 rpm, 100 rpm, and 200 rpm, respectively.

From the data in Tables 1 to 3, it can be seen that both the static torque and the dynamic torque of the rotor increase as the inner diameter of the stator decreases. This is because the outer diameter of the rotor is constant, so the smaller the inner diameter of the stator,
This is because the amount of elastic deformation of the stator increases and the load resistance of the rotor also increases. Further, the dynamic torque of the rotor tends to decrease as the number of rotations increases.

Here, the occurrence of squeaking of each toner transfer pump using the stators in Tables 1 to 3 was confirmed by ear, and the results were classified into levels and evaluated. The numerical value shown in each column of the static / dynamic torque ratio (a / b) in Table 1 shows the data of the value of a / b, and "x" added next to each data
The mark indicates that when the rotor was rotationally driven at the number of revolutions when the dynamic torque was measured, the rotor squeal was large, and the toner transfer pump could not be actually used.
The mark “◯” indicates that some noise was generated, but there was no problem even if the toner transfer pump was actually used. Furthermore, the mark “⊚” indicates that when the rotor was rotated under the same conditions, substantially no squeaking was observed, and the most preferable result was obtained.

From this evaluation, it can be understood that if the ratio of the static torque a to the dynamic torque b of the rotor is 0.03 or more, the toner transfer pump having the rotor can be used in the image forming apparatus without any trouble.

In Table 1, in the cases of and, when the number of rotations of the rotor is 70 rpm, a large squeal is generated, and the value of the ratio a / b of the static / dynamic torque of the rotor at this time is 0.027, 0.025 and 0.
029, both are smaller than 0.03. Similarly,
In ,, when the rotation speed of the rotor is 200 rpm,
In either case, there is no problem because only a slight squeal is detected. At this time, the value of the static / dynamic torque ratio a / b is
They are 0.03, 0.033, 0.036, respectively, and all of them are 0.03 or more. Similarly, in the cases of to, the value of the static / dynamic torque ratio a / b of the rotor is 0.03.
When the above is the case, squeaking does not occur or is very slight, and the toner transfer pump can be used without any problem. Especially when the value of a / b is 0.05 or more, no squeal is detected. On the other hand, when the a / b value becomes smaller than 0.03, the squealing becomes remarkable.

The factors that determine the operating state of the toner transfer pump are the static torque value and dynamic torque value of the rotor,
The values of the ratio of the two, the rotation speed of the rotor, the mixing ratio of the materials forming the stator, the elastic deformation amount of the stator, and the like can be mentioned. Among these factors, the value of a / b is
It can be well understood from Table 1 that it is a decisive factor that determines whether or not a loud squeal is generated.
By setting the value of a / b to 0.03 or more, preferably 0.05 or more, it is possible to effectively suppress the generation of squeaking or prevent the generation of squeaking.

It is clear from the data in Table 1 that the squealing is not significant when the rotor torque is high. As an extreme example, comparing the case of showing the highest static / dynamic torque value and the case of showing a smaller torque value, the dynamic torque of the rotor when the rotation speed of the rotor is 200 rpm is In the former case, the occurrence of squeal is smaller than in the latter case, but the former is smaller.

From the above description, the image forming apparatus provided with the toner transfer pump satisfying a / b ≧ 0.03 can be used without damaging the office environment due to abnormal noise. Moreover, since the generation of squeal can be suppressed by setting the value of a / b to 0.03 or more, the conditions for obtaining the toner discharge amount desired by the toner transfer pump, that is, the rotation speed of the rotor, the elastic deformation amount of the stator, etc. It can be set in a wide range and the degree of freedom in designing the toner transfer pump can be increased.

Further, it can be seen from the data in Table 1 that the difference in the compounding ratio of the materials constituting the stator is not directly related to the generation of squeal when the toner transfer pump is operated, but the present inventor further studied. When the main material of the stator is rubber, especially ethylene propylene rubber, it has been clarified that the compounding ratio of the rubber and the inorganic filler compounded therein has a significant influence on the generation of noise of the toner transfer pump. It was

Each numerical value in the rightmost column of the amount of filler in Table 1 is the inorganic filler, namely calcium carbonate, when EP21, calcium carbonate, zinc oxide and silica shown in Table 2 are 100% by weight. Shows the weight ratio of zinc oxide and silica. Here, the amount of this filler is 13.0%, but if the mixing ratio of the amount of filler is low and the value of the static / dynamic torque ratio a / b is 0.03 or more, the squealing sound is generated. Occurrence can be prevented more effectively. In Table 1, the rotor speed is 10
No squeaking occurred at 0 rpm and 200 rpm, and almost no squeaking occurred at 50 rpm.

Judging from the results of a large number of experiments conducted by the present inventor, the a / b ≧ 0.03 is satisfied as described above, and the main material of the stator is made of rubber, and the rubber and its combination are added. If the weight ratio of the inorganic filler is 20% by weight or less when the inorganic filler is 100% by weight, it is possible to effectively suppress squeaking when the toner transfer pump operates.

The image forming apparatus as shown in FIG. 1 has an element for generating ozone. Therefore, ozone exists in the main body of the image forming apparatus and the ozone may deteriorate the stator 25. . In addition, the stator 25
Is heated because the rotor 24 rotates inside it,
The heat may accelerate deterioration of the stator. Further, since the stator 25 is made of an elastic material, it is possible to prevent the toner from sticking to the inner peripheral surface of the stator 25. However, the toner may still stick to the inner peripheral surface of the stator 25 due to long-term use.

On the other hand, as shown in the above-mentioned experimental example, when ethylene propylene rubber is used as the rubber which constitutes the main material of the stator, it is excellent in ozone resistance and heat aging resistance, and moreover it is releasable from the toner. An excellent stator can be constructed.

The toner transfer pump according to the present invention can be widely used in image forming apparatuses other than those shown in FIGS.

[0045]

According to the toner transfer pump of the first aspect, it is possible to effectively suppress the generation of abnormal noise during its operation.

According to the toner transfer pump of the second aspect, it is possible to more effectively suppress the generation of abnormal noise during its operation.

According to the toner transfer pump of the third aspect, in addition to the above effects, the ozone resistance and the heat aging resistance of the stator can be enhanced, and the releasability from the toner can be enhanced.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an example of an image forming apparatus using a toner transfer pump.

FIG. 2 is an external perspective view of a toner supply case.

FIG. 3 is a vertical cross-sectional view of a toner supply device.

[Explanation of symbols]

5 Toner transfer pump 24 rotor 25 stator T toner

Claims (3)

(57) [Claims] 1. A cylindrical stator made of an elastic material, and a rotor arranged inside the stator,
In a toner transfer pump that sends the toner fed between the rotor and the stator to the outside by rotationally driving the rotor, when the static torque of the rotor is a and the dynamic torque of the rotor is b, a / b ≧
A toner transfer pump characterized by satisfying 0.03. 2. The main material of the stator is made of rubber, and the weight ratio of the inorganic filler is 20% by weight or less when the rubber and the inorganic filler mixed therein are 100% by weight. The toner transfer pump described in 1. 3. The toner transfer pump according to claim 2, wherein the rubber is ethylene propylene rubber.