JPH1148501A - Ink-jet recording apparatus and its air vent valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air vent valve for automatically discharging air inside an ink flow passage. SOLUTION: A valve for opening and closing an air discharge path 4C is constituted of a ball 1 and an O ring 2. When an air flow acts to the ball 1, the ball 1 falls by its own weight thereby turning the valve in an open state to permit the air to go out. When an ink flow acts to the ball 1, the ball 1 is pressed up thereby closing the valve to stop the ink not to flow out.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus and, more particularly, to an air vent valve in an ink circulation channel.

[0002]

2. Description of the Related Art An ink jet recording apparatus has a problem that its operation becomes unstable when air is mixed in an ink supply flow path to a nozzle. First, when air mixed into the ink supply flow path is ejected from a nozzle that ejects an ink beam, not only printing is disturbed but also the ink beam is deflected, and a nozzle head unit having the nozzle is provided. Ink is deposited on paper or printed matter or on a conveyor or the like that conveys printed matter, and becomes soiled. Secondly, in an apparatus that employs a method of managing the physical properties of ink by changing the amount of ink in the ink supply container, an error occurs in the amount of ink in the ink supply container if air remains in the ink supply passage. In addition, the physical properties of the ink change.

[0003] For this reason, a general ink jet recording apparatus bleeds air from an ink supply channel. This air bleeding is performed by circulating the ink by an ink supply pump into an ink circulation flow path including an ink supply flow path from the ink supply container to the nozzle head and an ink return flow path returning from the nozzle head to the ink supply container. The air is pushed out. However, since the upper part of the filter that is interposed in the ink supply flow path has a structure that makes it difficult for air to escape due to a dead end, a manually operated air vent valve is provided at the upper part of the filter to raise the ink level in the filter. A manual operation of closing the air vent valve is performed while visually observing the condition.

[0004] Some types of ink jet recording apparatuses are provided with structural means or control software so that there is no problem even if air cannot be completely exhausted.

[0005]

In the air bleeding operation in which the air bleed valve is manually closed while visually checking the rise of the ink level in the filter, there is a problem that ink leaks to the outside or air remains in the flow path. Occurs. Moreover, because the ink cannot be automatically filled in the ink flow path,
At least one worker is required.

Further, each of the structural and control software means for preventing any problem even if air remains in the ink flow path becomes complicated.

SUMMARY OF THE INVENTION The present invention has been made in view of such a background, and one object of the present invention is to make it possible to automatically and reliably perform an air bleeding operation when filling the ink supply flow path with ink. It is to make.

Another object of the present invention is to eliminate the need for a manual operator by automatically performing all operations for filling the ink into the ink supply flow path.

Still another object of the present invention is to stop the operation even if air enters the ink supply passage for some reason during the operation, and to start the operation when the next operation is started. To provide an air vent valve that can automatically discharge air.

Yet another object of the present invention is to provide an air vent valve which is structurally simple and inexpensive.

Still another object of the present invention is to provide an ink jet recording apparatus which can easily install an air vent valve in a small space.

Still another object of the present invention is to provide an ink jet recording apparatus which does not scatter the ink discharged from the air vent valve to the outside.

[0013]

SUMMARY OF THE INVENTION The present invention relates to an air vent valve provided in an ink flow path of an ink jet recording apparatus for discharging air from the ink flow path. When the air flow from inside the ink flow path is acting, the valve body is separated from the valve seat and opens the exhaust passage to allow the air to flow out of the ink flow path. When the ink flow from the passage acts, the ink moves by the force generated by the viscosity of the ink and comes into contact with the valve seat to close the exhaust passage so as to prevent the ink from flowing out. It automatically discharges air.

The air vent valve has a great effect when it is provided in a filter where air is most likely to remain in the ink flow path.

The valve body is formed into a ball or a column made of a material such as synthetic resin or stainless steel which is not affected by the ink. Then, the exhaust passage is opened, and when the ink flow acts, it is pushed up and comes into contact with the valve seat to close the exhaust passage.

The valve seat is preferably made of an elastic material such as rubber in consideration of the adhesion to the valve body, and among them, EPDM which is not affected by ink is preferable. Although the shape of the valve seat takes into consideration the close contact with the valve body, it is preferable to use an O-ring or the like. However, in consideration of the close contact with the moving valve element, it is desirable that the outer diameter of the O-ring is not fixed but has a degree of freedom so that the contact portion with the valve element is not distorted.

The inner diameter of the inner sleeve for accommodating the valve body and the valve seat is determined so as to form an appropriate clearance between the valve body and the inner sleeve. However, the degree of freedom is larger than the radial degree of freedom of the valve seat. Is applied to the valve body to improve the adhesion between the valve body and the valve seat.

The valve housing has a spherical contact portion with the valve mounting seat of the filter housing in order to prevent ink leakage from the coupling portion when mounted on the filter, and is tightened to the valve mounting seat with a mounting screw. The structure is such that the tightening force at the time of contact acts intensively on the circumference of the spherical contact portion and makes close contact with the valve mounting seat by contact stress.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a longitudinal sectional side view showing a state in which the air vent valve according to this embodiment is assembled to a filter, FIG. 2 is an exploded perspective view thereof, FIG. 3 is an enlarged view of the upper part of FIG. 2, and FIG. FIG. 5 is a longitudinal sectional side view of the disassembled state of FIG.
FIG. 6 is a partially enlarged view illustrating the operation of the air vent valve. FIG. 7 is a piping diagram of an ink jet recording apparatus provided with the air vent valve.

The air vent valve 20 in this embodiment is
From the lower part, the inner sleeve 3, the ball 1, the O-ring 2, the valve housing 4, and the screw cap 5 are configured to be incorporated in the filter 6.

The ball 1 functioning as a valve body is formed by using stainless steel SUS304 which is not eroded by an organic solvent such as methyl ethyl ketone used as an ink or a cleaning agent, or by using a synthetic resin such as POM. The O-ring 2 is formed by using EPDM which is also corrosion-resistant to an organic solvent. The dimensional relationship between ball 1 and O-ring 2 is
If the diameter of the ball 1 is too small or too large with respect to the diameter of the O-ring 2, the opening / closing operation and the sealing performance deteriorate. It is desirable that the center diameter d1 of the O-ring 2 and the diameter d2 of the ball 1 have the same dimensional relationship as shown in FIG.

The ball 1 and the O-ring 2 are sequentially inserted into the guide hole 3A of the inner sleeve 3 and the O-ring chamber 3B. The hole 3C formed with a smaller diameter than the guide hole 3A constitutes an inlet for air and ink and also constitutes a ball receiving portion for preventing the ball 1 from dropping. This ball 1 and O-ring 2
The important dimensional relationship between the guide hole 3A and the O-ring chamber 3B is
As shown in FIG. 5, the outer diameter of the O-ring 2 and the O-ring chamber 3B
The clearance b between the ball 1 and the guide hole 3A is to satisfy the relation of a <b with respect to the clearance a of the inner diameter of. If the relationship of a <b is not established, the center of the O-ring 2 and the ball 1 will not be aligned, and it may not be possible to obtain airtightness.

Next, the inner sleeve 3 into which the ball 1 and the O-ring 2 are inserted is pressed into the hole 4B of the valve housing 4. This press-fitting is carried out when the upper end surface of the inner sleeve 3 has the hole bottom 4
Repeat until it hits A. In this state, the O-ring 2
The O-ring chamber 3B will fit inside the ring chamber 3B.
It is important that the depth of the hole is larger than the diameter of the O-ring 2. If the hole is made shallow and a margin is given to the O-ring 2, the O-ring 2 will be distorted and the adhesion to the ball 1 will be poor, and the sealing performance will be poor. 4C is an exhaust passage.

The spherical portion 4 formed on the outer periphery of the valve housing 4
D is such that when it is mounted on the valve mounting seat 6D of the filter 6 with the screw cap 5, all of the tightening load is received by the contact portion between the spherical portion 4D and the tapered portion 6A of the valve mounting seat 6D. The leakage of ink is prevented by increasing the surface pressure.

The valve housing 4 incorporating the ball 1, the O-ring 2, and the inner sleeve 3 is fitted into the valve mounting hole 6C, and the screw cap 5 is mounted on the valve mounting seat 6D.
At this time, when the screw portion 5B of the screw cap 5 is engaged with the screw portion 6B of the valve mounting seat 6D and the screw cap 5 is tightened, the tapered portion 4E serves as a guide for the hole 5A, and the retaining 4F is caught. . The outer diameter of the retaining 4F is larger than the inner diameter of the hole 5A.
Is set to have a dimensional relationship that fits when tightened as it is. Then, when the screw cap 5 is tightened until it does not rotate, the hole 5A passes through the retaining 4F and rotatably engages with the small diameter engaging portion 4G.

Reference numeral 4H denotes a stopper when the exhaust pipe 7 is connected.

The filter 6 equipped with the air vent valve configured as described above is incorporated in an ink jet recording apparatus as shown in FIG. In FIG. 7, the ink 12 stored in the ink supply tank 11 is
After being pressurized by 3 and filtered by the filter 6, it is supplied to the nozzle head 15 via the ink supply pipe 14. In the nozzle head section 15, ink particles are ejected from the nozzles 15A to print on a printed matter, ink particles not used for printing are captured by a gutter 15B, and the ink supply tank 11 is discharged by an ink recovery pump 17 through an ink recovery pipe 16. To be collected.

When ink is filled in such an ink circulation flow path, the ink in the nozzle 15A is returned to the return pipe 19 by opening the ink return valve 18 to remove air. At this time, the air bleeding of the filter 6 is realized by the air bleeding valve 20 of the present invention as described above. The air discharged from the air release valve 20 is exhausted to the ink supply tank 11 by the exhaust pipe 7, so that the ink contained in the exhaust is prevented from scattering to the outside. In addition, it is possible to prevent scattering of ink flowing out due to operation delay or malfunction of the air release valve 20.

Next, the air bleeding operation of the air bleed valve 20 of the present invention will be described with reference to FIG.

FIG. 6A shows a state in which the fluid flowing through the air vent valve 20 is air. When filling the ink circulation flow path of the ink jet recording apparatus with the ink 12 from the ink supply container 11, the ink starts to accumulate in the filter 6 from the bottom first, and as the filling of the ink proceeds, the liquid level of the ink rises. come. At this time, the air in the filter 6 pushed out by the ink pushes up the ball 1 lightly and flows as shown by a broken line. When the air starts to flow, the force acting on the ball 1 to push it upwards is
This is a force generated by the viscosity of air, the clearance between the guide hole 3A, and the flow velocity of air. Considering a unit area on the ball 1 assuming that the viscosity coefficient of air is μ1, the velocity component of the air flow velocity upward is v1, and the distance to the guide hole 3A is y, the ball 1 is pushed upward. Force dF1
Is represented by the following equation (1).

DF1 = μ1 · dv1 / dy (1) The total pushing force F1 obtained by adding the pushing force per unit area dF1 expressed by the equation (1) over the entire surface of the ball 1 and the gravity mg of the ball 1 By setting the dimensional relationship and the flow rate of the ink supply pump 13 so that the relationship with F1 ≦ mg (2)
It does not move upward from the position shown in FIG. Therefore, the ball 1 and the O-ring 2 do not come into contact with each other to close the exhaust passage 4C and prevent the discharge of air.

Further, at the moment when the liquid level of the ink continues to rise and the air is completely exhausted and the fluid flowing into the air vent valve 20 becomes ink, as shown in FIG. It becomes the flow of ink. Assuming that the fluid is air, assuming that the viscosity coefficient of the ink is μ2, the velocity component of the ink flow velocity is v2, and the distance to the guide hole 3A is y, the ball 1 is pushed upward. The desired pushing force dF2 per unit area is expressed by the following equation (3).

DF 2 = μ 2 · dv 2 / dy (3) The total pushing force F 2 obtained by adding the pushing force dF 2 expressed by the equation (3) over the entire surface of the ball 1 and the gravity mg of the ball 1
If the dimensional relationship and the flow rate of the ink supply pump 13 are set such that the relationship with F2 ≧ mg (4) is satisfied, the ball 1 is pushed upward to come into contact with the O-ring 2, and the exhaust passage 4C is closed. Stop the ink spill. Then, although the ink flow total push-up force F2 becomes 0, the pressure in the filter 6 further increases because the ink supply pump 13 for supplying the ink continues to operate, and this pressure causes the pressure shown in FIG. As described above, the pressing force for pressing the ball 1 against the O-ring 2 increases, so that the ball 1 does not fall downward, and the ink does not flow out of the exhaust passage 4c.

Since the air vent valve 20 of the present invention operates in this manner, it is not necessary to manually close the air vent valve while observing the rise of the ink level in the filter 6 as in the prior art. Air in the ink supply flow path can be effectively eliminated. Further, since a delay occurs due to the stroke of the ball 1 from the moment when the ink flows into the air release valve 20 until the air release valve 20 is closed, the ink is initially released from the air release valve 2.
Although it is conceivable that the ink may flow out into the exhaust passage 4C, the exhaust passage 4C of the air vent valve 20 is connected to the ink supply container 11 by the exhaust pipe 7, so that the ink does not leak to the outside.

When the ink supply pump is stopped by stopping the operation of the apparatus,
Since the pressure in the ink supply channel is reduced, the ball 1 falls by its own weight and opens the exhaust passage 4C. Therefore, the air that has entered the ink supply flow path during operation can be discharged at the start of the next operation in the same manner as when the ink is filled. Such an air bleeding function can prevent a decrease in accuracy of ink physical property management based on the amount of ink in the ink supply container.

Regarding the stroke of the ball 1, when the air vent valve 20 is open, a large pressure loss is required to secure a flow path area that does not decrease the flow rate. In order to minimize the flow of the gas into the exhaust passage 4C, the design is made in consideration of not increasing the size unnecessarily.

As described above, when there is air in the filter 6, the air vent valve 20 is opened and the air is circulated and discharged, and the air is completely exhausted and the ink is filled and the ink circulates. As soon as it comes to a closed state.

It is important for the air vent valve 20 to set various dimensional relationships and the flow rate of the ink flow pump 13 so that the ball 1 moves and the valve opens and closes due to differences in the viscosity coefficient and flow rate of air and ink. It is.

It should be noted that an elastic sheet is used instead of the O-ring 2, a metal or a synthetic resin finished with high precision so as to obtain the close contact with the ball 1, or a ball 1 using SUS is used. Needless to say, a synthetic resin ball or a cylindrical valve may be used.

In the above-described embodiment, the air bleeding valve 20 is used for bleeding air from the filter 6. However, similar air bleeding can be performed even when the air bleeding valve 20 is installed in the remaining air portion of the ink flow path.

[0042]

According to the present invention, the following effects can be obtained.

(1) When the fluid acting on the valve element is air, the air vent valve is configured to open and exhaust the exhaust passage, and when the fluid is ink, the exhaust passage is closed to stop the outflow of the ink. Air bleeding in the flow path can be automatically and reliably performed.

(2) The air bleeding valve performs the air bleeding operation with the ink supplied by the ink supply pump, so that all the work of filling the ink supply flow path with the ink can be performed automatically, and Becomes unnecessary.

(3) If air enters the ink flow path during operation of the ink jet recording apparatus, the operation is stopped,
The next time the operation is started, the air vent valve can automatically discharge the mixed air, so that air accumulates in the ink flow path and an error occurs in the amount of ink in the ink supply container. Can be prevented. Therefore, it is possible to reduce a factor that causes an error in an apparatus that uses a method of managing physical properties of ink based on the amount of ink in an ink supply container.

(4) Since the air vent valve is attached to the filter and incorporated in the ink jet recording apparatus, it is possible to save space and to save labor in the attaching work.

(5) Since the air vent valve uses a ball serving as a valve body and an O-ring serving as a valve seat, the air vent valve can be structurally simplified and cost can be reduced.

(6) By arranging the exhaust passage of the air vent valve in the ink supply container, it is possible to prevent the ink contained in the exhaust from the exhaust passage and the ink flowing out due to the operation delay from scattering.

[Brief description of the drawings]

FIG. 1 is a vertical sectional side view showing a state where an air vent valve according to an embodiment of the present invention is assembled to a filter.

FIG. 2 is an exploded perspective view of the air vent valve shown in FIG.

FIG. 3 is an enlarged view of the upper part of FIG. 2;

FIG. 4 is a longitudinal sectional side view in a state where the air vent valve shown in FIG. 1 is disassembled.

FIG. 5 is an enlarged view of a part P in FIG. 1;

FIG. 6 is an explanatory diagram of an operation of the air vent valve according to the embodiment of the present invention.

FIG. 7 is a piping diagram of an ink jet recording apparatus provided with the air vent valve of the present invention.

[Explanation of symbols]

 1 ball 2 O-ring 3 inner sleeve 4 valve housing 5 screw cap 6 filter 6D valve mounting seat

Claims (10)

[Claims] 1. When air in an ink flow path is provided on a pipe system of an ink jet recording apparatus and is present on a lower surface side of a valve body, the air valve body and the valve are separated from a valve seat. When the ink is allowed to flow out from between the gaps of the seat and the valve body comes into contact with the ink, the ink is pushed up by the viscosity of the ink and comes into contact with the valve seat, and the gap is closed to prevent the ink from flowing out. An air vent valve for an ink jet recording apparatus. 2. The air vent valve according to claim 1, wherein the valve body is a ball, and an O-ring is used for a valve seat. 3. The air vent valve according to claim 2, wherein the ball is formed of stainless steel, and the O-ring is formed of EPDM. 4. An air vent valve for an ink jet recording apparatus according to claim 2, wherein said O-ring is movably installed in an arrangement space. 5. The ink jet printer according to claim 1, wherein the valve element falls under its own weight and separates from a valve seat while an air flow is acting. Vent valve for recording device. 6. The valve housing according to claim 1, wherein a contact portion of the valve housing that comes into contact with the valve mounting seat is formed in a spherical shape, and the valve housing is fastened to the valve mounting seat by a mounting screw. An air release valve for an ink jet recording apparatus, characterized in that the tightening force is brought into close contact with the valve mounting seat by a contact stress intensively acting on the circumference of the spherical contact portion. 7. An ink jet recording apparatus, wherein the air vent valve according to claim 1 is installed in an air remaining portion in an ink flow path. 8. An ink jet recording apparatus, wherein the air vent valve according to claim 1 is attached to a filter provided in an ink supply channel. 9. An ink jet recording apparatus in which ink in an ink supply container is pressurized by an ink supply pump and supplied to a nozzle head via an ink supply flow path. 7. An ink jet recording apparatus, comprising: the air vent valve according to any one of 6 to 6 described above; and an outlet of an exhaust passage of the air vent valve is piped to the ink supply container. 10. The ink jet recording apparatus according to claim 9, wherein a filter is provided in the ink supply channel, and the air vent valve is attached to the filter.