Title:
PULSATION GENERATING MECHANISM, CONNECTING FLOW CHANNEL TUBE, AND FLUID EJECTING APPARATUS
Kind Code:
A1


Abstract:
A fluid ejecting apparatus having a fluid chamber, an inlet flow channel, and a nozzle configured to eject fluid supplied from the inlet flow channel to the fluid chamber from the nozzle in a pulsed manner by changing the volume of the fluid chamber includes: a diaphragm; a wall surface provided so as to oppose the diaphragm; a spacer being provided between the diaphragm and the wall surface and having a cylindrical through hole; a piezoelectric element configured to displace the diaphragm; and a connecting flow channel tube communicated with the fluid chamber, wherein the nozzle is provided at an end of the connecting flow channel tube opposite to the fluid chamber, the fluid chamber is defined by the diaphragm, the wall surface, and an inner surface of the through hole of the spacer, and the inlet flow channel is defined by a groove provided on the wall surface and the spacer and is communicated with the fluid chamber.



Inventors:
Seto, Takeshi (Chofu-shi, JP)
Kawasumi, Kazuo (Chino-shi, JP)
Kojima, Hideki (Matsumoto-shi, JP)
Ono, Yasuhiro (Matsumoto-shi, JP)
Application Number:
12/548019
Publication Date:
03/04/2010
Filing Date:
08/26/2009
Assignee:
SEIKO EPSON CORPORATION (Tokyo, JP)
Primary Class:
Other Classes:
417/413.2
International Classes:
F04B43/04
View Patent Images:
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Primary Examiner:
PLAKKOOTTAM, DOMINICK L
Attorney, Agent or Firm:
OLIFF PLC (ALEXANDRIA, VA, US)
Claims:
What is claimed is:

1. A fluid ejecting apparatus comprising: a diaphragm; a wall surface provided so as to oppose the diaphragm; a spacer being provided between the diaphragm and the wall surface and having a cylindrical through hole; a piezoelectric element configured to displace the diaphragm; a fluid chamber defined by the diaphragm, the wall surface, and an inner surface of the through hole of the spacer; a connecting flow channel tube communicated with the fluid chamber; an inlet flow channel defined by a groove provided on the wall surface and the spacer, and in communication with the fluid chamber; and a nozzle provided at an end of the connecting flow channel tube opposite to the fluid chamber that is configured to eject fluid from the fluid chamber in a pulsed manner by changing the volume of the fluid chamber.

2. The fluid ejecting apparatus according to claim 1, the groove of the wall surface including: a first end portion provided with a hole through which the fluid is supplied into the groove of the wall surface, a first middle portion extending from the first end portion in an arcuate shape along the wall surface, a second middle portion extending from the first middle portion to the inner surface of the spacer along a direction of a line tangent to the inner surface of the spacer, and a second end portion extending from the second middle portion along an edge of the inner surface of the spacer.

3. The fluid ejecting apparatus according to claim 2, is the second end portion being formed into an inclined surface continuing from a bottom surface of the groove on the wall surface which defines the inlet flow channel to the wall surface.

4. The fluid ejecting apparatus according to claim 1, the fluid chamber being formed with a coating layer on an inner wall surface thereof.

5. The fluid ejecting apparatus according to claim 1, the fluid ejecting apparatus including a holding portion configured to hold a peripheral edge portion of the diaphragm, and the piezoelectric element being disposed in the interior of the holding portion and resin being filled in a space between the piezoelectric element and the holding portion.

6. The fluid ejecting apparatus according to claim 5, the resin having thermal conductivity.

7. The fluid ejecting apparatus according to claim 1, a connecting portion between the inner wall of the connecting flow channel tube and the inner wall of the fluid chamber having a substantially arcuate shape.

8. The fluid ejecting apparatus according to claim 1, the nozzle being inserted into the connecting flow channel tube and an adhesive groove being provided along a joint surface of the nozzle with respect to the connecting flow channel tube.

9. The fluid ejecting apparatus according to claim 1, the connecting flow channel tube being detachably attached.

10. A pulsation generating mechanism comprising: a diaphragm; a wall surface provided so as to oppose the diaphragm; a spacer being provided between the diaphragm and the wall surface and having a cylindrical through hole; a piezoelectric element configured to displace the diaphragm; a fluid chamber defined by the diaphragm, the wall surface, and an inner surface of the through hole of the spacer; and an inlet flow channel defined by a groove provided on the wall surface and the spacer that is in communication with the fluid chamber, the fluid ejecting apparatus being configured to discharge fluid supplied from the inlet flow channel to the fluid chamber in a pulsed manner from a flow channel that is in communication with the fluid chamber by changing the volume of the fluid chamber.

11. A connecting flow channel tube which is detachably attached to a pulsation generating mechanism configured to discharge fluid from an outlet flow channel in a pulsed manner by changing the volume of a fluid chamber that is in communication with the outlet flow channel, the connection flow channel tube comprising: a first end configured to be communicatable with the outlet flow channel; and a second end opposite to the first end and having a fluid ejecting opening with a smaller cross-sectional area in the vertical direction with respect to a direction of flow of the fluid than a cross-sectional area of the outlet flow channel.

12. A fluid ejecting apparatus comprising: a fluid chamber; an inlet flow channel that supplies fluid to the fluid chamber; and an outlet flow channel in communication with the fluid chamber, the outlet flow channel having an inertance less than an inertance of the inlet flow channel, the fluid ejecting apparatus ejecting the fluid supplied to the fluid chamber from the outlet flow channel by changing a volume of the fluid chamber.

13. The fluid ejecting apparatus according to claim 12, the inlet flow channel being formed to supply the fluid to the fluid chamber so as to create a whirling flow of the fluid within the fluid chamber.

14. The fluid ejecting apparatus according to claim 13, the inlet flow channel including: a first end portion provided with a hole through which the fluid is supplied to the inlet flow channel, a first middle portion extending from the first end portion in an arcuate shape around an outside of the fluid chamber, a second middle portion extending from the first middle portion to an inner surface of the fluid chamber along a direction of a line tangent to the inner surface of the fluid chamber, and a second end portion extending from the second middle portion along the inner surface of the fluid chamber.

15. The fluid ejecting apparatus according to claim 12, further comprising: an outlet flow channel tube including the outlet flow channel and an outlet connecting flow channel in communication with the outlet flow channel; and a nozzle in communication with the outlet flow channel tube, a fluid ejection opening of the nozzle having a diameter smaller than a diameter of the output flow channel.

16. A method for ejecting fluid comprising: supplying fluid from an inlet flow channel to a fluid chamber at a constant pressure; and changing a volume of the fluid chamber to eject the fluid from the fluid chamber and through an outlet flow channel having an inertance less than an inertance of the inlet flow channel.

17. The method for ejecting fluid according to claim 16, the fluid being supplied to the fluid chamber so as to create a whirling flow of the fluid within the fluid chamber.

Description:

This application claims priority to Japanese Application No. 2008-217671 filed in Japan on Aug. 27, 2008, the disclosure of which is hereby incorporated by reference in its entirety.

BACKGROUND

1. Technical Field

The present invention relates to a pulsation generating mechanism configured to discharge fluid with pulsation, a connecting flow channel tube to be inserted into the pulsation generating mechanism, and a fluid ejecting apparatus having the same and being configured to eject the fluid in a pulsed manner.

2. Related Art

Operation with ejected fluid enables incision of organ substances while maintaining vasculature such as blood vessels and, in addition, an incidental damage applied to anatomy other than the portion to be incised is small and hence a burden applied to a patient is small. Furthermore, since the amount of bleeding is small, visibility of an operation field is not hindered by blood, and hence quick operation is enabled, so that this technology is applied to many clinical surgeries specifically such as hepatic resection which causes medical personnel hardship due to the bleeding from small blood vessels.

As a fluid ejecting apparatus configured to incise or remove anatomy, a fluid ejecting apparatus including a pulsation generating mechanism configured to reduce the volume of a fluid chamber to discharge fluid and a connecting flow channel tube having a nozzle connected at one end thereof to an outlet flow channel of the pulsation generating mechanism and being reduced in diameter at the other end thereof to a diameter smaller than that of the outlet flow channel is known (for example, see JP-A-2005-152127).

According to a fluid ejecting apparatus disclosed in JP-A-2005-152127 described above, since a pumping action is performed by the fluid ejecting apparatus by itself, a priming action and an elimination of air bubbles in a pump chamber are needed at the time of activation from its driving characteristics.

The fluid (liquid) includes gas (air) although the quantity is not much. When the gas exists in the liquid, the gas gradually gets together to form air bubbles and stays therein. When the air bubbles stay in the fluid chamber, the internal pressure cannot rise sufficiently when the volume is reduced, so that a pulsation discharge might not be achieved.

SUMMARY

An advantage of some aspects of the invention is to solve at least a part of the problem mentioned above and the invention can be embodied in the following aspects or application examples.

APPLICATION EXAMPLE 1

Application example 1 is directed to a fluid ejecting apparatus having a fluid chamber, an inlet flow channel, and a nozzle configured to eject fluid supplied from the inlet flow channel to the fluid chamber from the nozzle in a pulsed manner by changing the volume of the fluid chamber including: a diaphragm; a wall surface provided so as to oppose the diaphragm; a spacer being provided between the diaphragm and the wall surface and having a cylindrical through hole; a piezoelectric element configured to displace the diaphragm; and a connecting flow channel tube communicated with the fluid chamber, in which the nozzle is provided at an end of the connecting flow channel tube opposite to the fluid chamber, the fluid chamber is defined by the diaphragm, the wall surface, and an inner surface of the through hole of the spacer, and the inlet flow channel is defined by a groove provided on the wall surface and the spacer and is communicated with the fluid chamber.

In this configuration, the inlet flow channel is formed with an arcuate shaped inlet flow channel on the wall surface which constitutes part of the fluid chamber. Therefore, an inertance on the inlet flow channel side of the fluid chamber may be set to a value sufficiently larger than an inertance on an outlet flow channel side of the fluid chamber from both facts that a long flow channel length of the inlet flow channel is secured, and that the cross-sectional area in the vertical direction with respect to the direction of flow of the fluid can be set to be small. In this configuration, a simple structure in which a check valve is not provided is realized.

Consequently, an operation to supply the fluid from the inlet flow channel into the fluid chamber at a constant pressure, and convert the same to a strong pulsation by changing the volume of the fluid chamber by the diaphragm is enabled. Therefore, a priming action is no longer necessary and, since an inflow of the fluid is continued even though air bubbles are generated, they are discharged in a certain time period and hence the normal operation may be restored.

APPLICATION EXAMPLE 2

Preferably, the groove on the wall surface includes a first end portion provided with a hole through which the fluid is supplied into the groove of the wall surface, is formed to extend from the first end portion in an arcuate shape along the wall surface, is formed to extend from the opposite side of the portion formed into the arcuate shape to the first end portion to the inner surface of the spacer along a direction of a tangent line of the inner surface of the spacer, and is formed from the opposite side of the portion formed along a direction of a tangent line of the inner surface of the spacer opposite to the arcuate portion along an edge of the inner surface of the spacer.

In this configuration, the fluid is caused to flow along the inner surface of the through hole of the spacer (that is, the inner peripheral surface of the fluid chamber), so that a whirling flow is generated in the fluid chamber.

By causing the fluid to whirl, the fluid is directed outward from the fluid chamber by a centrifugal force, and the air bubbles get together at the center portion and is discharged to the outside in association with discharge of the fluid through the connecting flow channel tube. Therefore, the air bubbles are prevented from staying in the fluid chamber, and the pressure in the interior of the fluid chamber may be increased sufficiently, so that a reliable pulsation discharge is achieved.

APPLICATION EXAMPLE 3

Preferably, a terminal end portion of the groove on the wall surface formed along the edge of the inner surface of the spacer is formed into an inclined surface continuing from a bottom surface of the groove on the wall surface which defines the inlet flow channel to the wall surface.

In this configuration, since the inlet flow channel is communicated with the fluid chamber continuously from the bottom surface of the groove which constitutes the inlet flow channel to the wall surface by the inclined surface, a fluid resistance at a connecting portion between the inlet flow channel and the wall surface is reduced, and also turbulence of the whirling flow and generation of the air bubbles due to a vortex flow generated by sudden change of the flow channel is restrained.

APPLICATION EXAMPLE 4

Preferably, the fluid chamber is formed with a coating layer on an inner wall surface thereof

Here, as the coating layer, for example, a membrane layer formed by plating may be employed.

Gas contained in liquid generates from the fluid when the pressure in the fluid chamber is reduced. The air bubbles get together to the center of the fluid chamber by the whirling flow. However, when small gaps or corners of components exist, the air bubbles might be adhered to these points and hence might not be discharged.

Therefore, by coating the small gaps or joint corners to form a continuous surface by forming the continuous coating layer in the interior of the fluid chamber, generation of the air bubbles is restrained.

APPLICATION EXAMPLE 5

Preferably, the fluid ejecting apparatus includes a holding portion configured to hold a peripheral edge portion of the diaphragm, and the piezoelectric element is disposed in the interior of the holding portion and resin is filled in a space between the piezoelectric element and the holding portion.

In this configuration, by coating the periphery of the piezoelectric element with the resin, inter-electrode short circuit due to attachment of water content to the piezoelectric element is prevented. Therefore, the resin to be filled preferably has low water absorbability.

APPLICATION EXAMPLE 6

Preferably, the resin has thermal conductivity.

When the fluid ejecting apparatus in this application example is driven continuously for a long time, heat is generated from the piezoelectric element. Therefore, by filling a material having a high coefficient of thermal conductivity by itself or resin mixed with a material having a high coefficient of thermal conductivity in a space between the piezoelectric element and the holding portion, the generated heat is dispersed to the outside via the holding portion, so that the piezoelectric element is effectively prevented from being deteriorated in performance due to the temperature rise.

APPLICATION EXAMPLE 7

Preferably, a connecting portion between the inner wall of the connecting flow channel tube and the inner wall of the fluid chamber is connected into a substantially arcuate shape.

In this configuration, the fluid resistance of a communicating portion between the fluid chamber and the connecting flow channel tube is reduced, and generation of the vortex flow at the joint portion is restrained, so that pressure waves generated when reducing the volume of the fluid chamber is transmitted to the nozzle without being attenuated.

APPLICATION EXAMPLE 8

Preferably, the nozzle is inserted into the connecting flow channel tube and the groove is provided along a joint surface of the nozzle with respect to the connecting flow channel tube.

The nozzle and the connecting flow channel tube are coupled by press-fitting and the joint portion between these members is reinforced by the adhesive agent, and the joint portion is hermetically sealed. In this case, it is difficult to apply the adhesive agent uniformly over the entire portion of the joint portion. Therefore, by forming the groove on the joint surface of the nozzle to provide an adhesive agent trap, reinforcement and hermeticity are ensured.

APPLICATION EXAMPLE 9

Preferably, the connecting flow channel tube is detachably attached.

Here, as a detachably attached structure, for example, a screwing structure may be employed.

In this configuration, easy replacement of the connecting flow channel tube as well as removal for cleaning in the unlikely event that the nozzle is clogged are achieved.

Also, there is also an effect that the shape of the connecting flow channel tube may be selected and attached as needed according to the object of usage by preparing a plurality of shapes of the connecting flow channel tube.

APPLICATION EXAMPLE 10

Application example 10 is directed to a pulsation generating mechanism having a fluid chamber and an inlet flow channel, and being configured to discharge fluid supplied from the inlet flow channel to the fluid chamber in a pulsed manner from a flow channel being in communication with the fluid chamber by changing the volume of the fluid chamber including: a diaphragm; a wall surface provided so as to oppose the diaphragm; a spacer being provided between the diaphragm and the wall surface and having a cylindrical through hole; and a piezoelectric element configured to displace the diaphragm, in which the fluid chamber is defined by the diaphragm, the wall surface, and an inner surface of the through hole of the spacer, and the inlet flow channel is defined by a groove provided on the wall surface and the spacer and is communicated with the fluid chamber.

According to the application example, an inertance of the inlet flow channel side of the fluid chamber may be set to a value sufficiently larger than that on the outlet flow channel side of the fluid chamber from both facts that a long flow channel length of the inlet flow channel is secured, and that the cross sectional area in the vertical direction with respect to the direction of flow of the fluid can be set to be small. Accordingly, the pulsation flow is achieved. Accordingly, a pulsation generating mechanism having a simple structure in which a check valve is not provided is realized.

APPLICATION EXAMPLE 11

Application example 11 is directed to a connecting flow channel tube which is detachably attached to a pulsation generating mechanism configured to discharge fluid from an outlet flow channel in a pulsed manner being in communication with the fluid chamber by changing the volume of the fluid chamber, being configured to be communicatable with the outlet flow channel and having a fluid ejecting opening having a smaller cross-sectional area in the vertical direction with respect to the direction of flow of the fluid than the cross-sectional area of the outlet flow channel at an end opposite to the side which communicates with the outlet flow channel.

In this configuration, since the fluid discharged from the pulsation generating mechanism in a pulsed manner is ejected from the fluid ejecting opening reduced in cross-sectional area than the outlet flow channel, so that the fluid is ejected as high-speed pulsed liquid drops having a high removing performance.

Also, there is an effect that the shape of the connecting flow channel tube may be selected and used as needed according to the object of usage by preparing a plurality of shapes of the connecting flow channel tube. In addition, by configuring the connecting flow channel tube to be detachably attached to the pulsation generating mechanism, the convenience may be further enhanced.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanying drawings where like numbers reference like elements;

FIG. 1 is an explanatory drawing showing a schematic configuration of a fluid ejecting system;

FIG. 2 is a cross-sectional view of a principal configuration of a pulsation generating mechanism according to a first embodiment taken along the direction of flow channel of liquid;

FIG. 3 is a side view of the pulsation generating mechanism viewed from the right side;

FIG. 4 is a side view of the pulsation generating mechanism viewed from the left side;

FIG. 5 is a cross-sectional view showing a joint portion between a first machine frame and a second machine frame according to the first embodiment in detail;

FIG. 6 is a plan view showing the first machine frame in a state of viewing from the side of a piezoelectric element according to the first embodiment;

FIG. 7 is a cross-sectional view showing an inlet port portion in an enlarged scale according to the first embodiment;

FIG. 8 is a cross-sectional view showing a joint structure between a nozzle and a connecting flow channel tube according to the first embodiment;

FIG. 9 is a cross-sectional view showing part of a fluid ejecting apparatus according to a second embodiment;

FIG. 10A is a cross-sectional view showing part of the fluid ejecting apparatus according to a third embodiment; and

FIG. 10B is a cross-sectional view taken along the line E-E in FIG. 10A.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Referring now to the drawings, embodiments of the invention will be described.

FIG. 1 shows a fluid ejecting system, FIGS. 2 to 8 show a fluid ejecting apparatus according to a first embodiment, FIG. 9 shows a second embodiment, and FIGS. 10A and 10B show a third embodiment.

Drawings referred to in the description given below are schematic drawings in which vertical and lateral reduction scales of members or portions are different from reality for the sake of convenience.

The fluid ejecting system and the fluid ejecting apparatus in the invention may be employed in various applications such as drawing using ink or the like, washing of precise substances or structures, surgical knife, and so on. In the embodiments described below, a fluid ejecting apparatus suitable for incising or removing anatomy is exemplified for description. Therefore, fluid used in the embodiments is liquid such as water or physiologic saline and the fluid is sometimes expressed as the liquid.

Fluid Ejecting System

FIG. 1 is an explanatory drawing showing a schematic configuration of the fluid ejecting system. In FIG. 1, a fluid ejecting system 1 includes a control device 20 having a liquid container configured to store the liquid and a pump (not shown) as a pressure generating unit as a basic configuration, a fluid ejecting apparatus 10 configured to eject the liquid supplied from the pump with pulsation, and a connecting tube 25 configured to communicate the fluid ejecting apparatus 10 with the pump.

The fluid ejecting apparatus 10 includes a pulsation generating mechanism 30 configured to discharge supplied liquid at a high pressure and a high frequency in a pulsed manner, a connecting flow channel tube 90 connected to the pulsation generating mechanism 30, and a nozzle 95 having a fluid ejection opening 97 reduced in cross-section of a flow channel is attached to a distal end of the connecting flow channel tube 90.

Subsequently, the flow of the liquid in the fluid ejecting system 1 will be described. The liquid stored in the liquid container provided in the control device 20 is supplied to the pulsation generating mechanism 30 via the connecting tube 25 at a constant pressure by the pump.

The pulsation generating mechanism 30 includes a fluid chamber 120 (see FIG. 2), and a volume changing device for the fluid chamber 120, and ejects the liquid from the fluid ejection opening 97 at a high speed in a pulsed manner by driving the volume changing device and generating pulses. Detailed description of the pulsation generating mechanism 30 will be described later in conjunction with FIG. 2 to FIG. 7.

The pressure generating unit is not limited to the pump, and a configuration in which an infusion solution bag as the liquid container is held at a position higher than the pulsation generating mechanism 30 by a stand or the like is also applicable. In this case, the pump is not necessary and hence the configuration is simplified, and in addition, sterilization of a liquid flow channel is easily achieved.

A discharge pressure of the pump is set to approximately three atmospheric pressure (0.3 MPa) or lower. When the infusion solution bag is used, the difference in height between the pulsation generating mechanism 30 and a liquid level of the infusion solution bag corresponds to the pressure, so that the height difference is preferably set to be approximately 0.1 to 0.15 pressure (0.01 to 0.015 MPa).

When performing a surgical operation using the fluid ejecting system 1, a principal portion where the personnel performing the surgical operation grips is the pulsation generating mechanism 30. Therefore, the connecting tube 25 to be connected to the pulsation generating mechanism 30 is preferably flexible as much as possible. In order to do so, a soft and thin tube is used, and the pressure of the liquid is preferably as low as possible within a range which allows delivery of the liquid to the pulsation generating mechanism 30.

Also, as in the case of a brain operation in particular, when the failure of the fluid ejecting system 1 might cause a critical accident, outburst of high-pressure fluid due to the breakage of the connecting tube 25 must be avoided. From this reason, keeping the liquid at a low pressure is required.

First Embodiment

Subsequently, the structure of the fluid ejecting apparatus 10 according to the first embodiment will be described.

FIG. 2 is a cross-sectional view showing a principal structure of a pulsation generating mechanism according to the first embodiment taken along the direction of the flow channel of the liquid, FIG. 3 is a side view showing the pulsation generating mechanism from the right side, and FIG. 4 is a side view showing the pulsation generating mechanism from the left side.

Referring now to FIG. 2 to FIG. 4, a schematic configuration of the fluid ejecting apparatus 10 will be described. The fluid ejecting apparatus 10 includes the pulsation generating mechanism 30 including a pulsation generating device which generates the pulsation of the liquid and the connecting flow channel tube 90 having an outlet connecting flow channel 92 and the nozzle 95 configured to discharge the liquid.

The pulsation generating mechanism 30 includes the fluid chamber 120 configured by tightly clamping a ring-shaped spacer 60 and a peripheral edge of a diaphragm 70 formed of a disk-shaped metallic thin plate by opposed surfaces of a first machine frame 80 and a second machine frame 50 as a machine frame and being surrounded by a wall surface 82 on the second machine frame 50 side of the first machine frame 80, the diaphragm 70, and an inner peripheral wall surface of the spacer 60.

A tube connecting pipe 81 is formed on an outer side surface of the first machine frame 80 so as to project therefrom, and an inflow connecting flow channel 84 is opened in the tube connecting pipe 81. A connecting flow channel 85 which communicates with the fluid chamber 120 is connected to the inflow connecting flow channel 84, and is in communication with an inlet flow channel 83 formed on the wall surface 82. The inlet flow channel 83 will be described in detail in conjunction with FIGS. 5 and 6.

The connecting tube 25 is fitted to the tube connecting pipe 81, and the connecting tube 25 is connected to the pump provided in the interior of the control device 20 (see FIG. 1), so that the liquid is supplied to the fluid chamber 120 via the inlet flow channel 83.

The connecting flow channel tube 90 is inserted into the first machine frame 80 at the substantially center of the wall surface 82 thereof substantially vertically with respect to the diaphragm 70 (that is, the wall surface 82). The connecting flow channel tube 90 includes an outlet flow channel 91 in communication with the fluid chamber 120 and the outlet connecting flow channel 92 in communication with the outlet flow channel 91, and the nozzle 95 is fitted to an end opposite to the outlet flow channel 91.

The nozzle 95 includes a nozzle flow channel 96 in communication with the outlet connecting flow channel 92 and the fluid ejection opening 97.

Here, the outlet connecting flow channel 92 and the nozzle flow channel 96 have the same cross-sectional area, and this cross-sectional area is larger than the cross-sectional area of the outlet flow channel 91. Then, the cross-sectional area of the fluid ejection opening 97 is reduced to be smaller than the cross-sectional area of the outlet connecting flow channel 92.

The above-described cross-sectional area means the cross-sectional area of the flow channel when it is cut vertically with respect to the direction of flow of the liquid.

The second machine frame 50 is a cylindrical member having an outer flange portion 56 and a cylindrical portion 51, and the outer shapes of the outer flange portion 56 and the cylindrical portion 51 are both square. Then, a cylindrical hole 51a penetrating through the second machine frame 50 is formed.

An opening of the hole 51a on the opposite side to the first machine frame 80 is sealed by a lower panel 100. A piezoelectric element 40 as a drive source is provided inside the hole 51a. The piezoelectric element 40 is a laminated piezoelectric element and constitutes a column shaped actuator.

One end of the piezoelectric element 40 is secured to the diaphragm 70 via an upper panel 110 and the other end thereof is secured to the inner surface of the lower panel 100.

Opposing side surfaces of the piezoelectric element 40 are each provided with a drive electrode (not shown) and connecting leads 151 and 152 provided with insulating coatings thereon are connected to these drive electrodes. The connecting leads 151 and 152 are respectively drawn to the outside through lead insertion holes 54 and 55 formed on the side surfaces of the cylindrical portion 51 of the second machine frame 50, and are connected to a drive circuit unit (not shown) of the control device 20 (see FIG. 1).

The first machine frame 80 and the second machine frame 50 are fixed to each other at four corners with fixing screws 161 in a state in which the peripheral portion of the diaphragm 70 and the spacer 60 clamped therebetween, and are brought into tight contact with each other (see FIG. 4).

In contrast, the second machine frame 50 and the lower panel 100 are fixed at four corners with the fixing screws 160 after dimensions are adjusted so as to prevent the diaphragm 70 to be deformed by the piezoelectric element 40 in an assembled state (see FIG. 3).

In this manner, in a state in which the first machine frame 80, the second machine frame 50, and the lower panel 100 are fixed to each other, resin 140 is filled in a space defined between the cylindrical portion 51 of the second machine frame 50 and the piezoelectric element 40. The filling range includes the interior of the lead insertion holes 54 and 55 in which the connecting leads 151 and 152 are inserted.

The resin 140 to be filled is preferably a material having a low water absorbability (or a material having water repellency). Also, materials having a high coefficient of thermal conductivity by itself, or resin mixed with a material having a high coefficient of thermal conductivity are preferable, and inorganic ceramics powder, carbon powder, and the like having a high coefficient of thermal conductivity are applicable as the material to be mixed. Materials which satisfy both conditions of a low water absorbability and a high coefficient of thermal conductivity are further preferable.

Furthermore, the resin, being filled to coat the periphery of the piezoelectric element 40, has flexibility to an extent which does not hinder the drive of the piezoelectric element 40.

Referring now to FIG. 5, a joint portion between the first machine frame 80 and the second machine frame 50 will be described.

FIG. 5 is a cross-sectional view showing the joint portion between the first machine frame and the second machine frame. Therefore, description is given with the same reference numerals as those in FIG. 2.

The first machine frame 80 includes a ring-shaped recess 86 around the wall surface 82, and the second machine frame 50 is formed with a ring-shaped projection 53 opposing the ring-shaped recess 86. By inserting the ring-shaped projection 53 into the ring-shaped recess 86, an accurate positional restraint between the first machine frame 80 and the second machine frame 50 is achieved.

In this case, the diaphragm 70 and the spacer 60 are interposed between the wall surface 82 at the center portion of the first machine frame 80 and an inner periphery flange portion 52 provided inside the ring-shaped projection 53 of the second machine frame 50 in a compressed state.

Diameters of an inner peripheral wall 61 of the spacer 60 and the inner periphery flange portion 52 of the second machine frame 50 are set to be substantially the same, and the supporting positions with respect to displacement of the diaphragm 70 are the same.

A packing 130 as a sealing member is interposed between a bottom portion of the ring-shaped recess 86 of the first machine frame 80 and the distal end portion of the ring-shaped projection 53 of the second machine frame 50. The packing 130 is deformed by being pressed in a state in which the diaphragm 70 and the spacer 60 are interposed in the compressed state, so that the movement of the liquid between the outside and the fluid chamber 120 is restrained.

The connecting flow channel tube 90 is press-fitted into the first machine frame 80 to a position where the end portion reaches the fluid chamber 120, and the outlet flow channel 91 is in communication with the fluid chamber 120. The end surface of the connecting flow channel tube 90 is machined so as to be flush with the surface of the wall surface 82 in the fluid chamber 120. In addition, a connecting portion (communicating portion) of the outlet flow channel 91 with respect to the fluid chamber 120 is smoothly connected into a substantially arcuate shape.

The machining as described above is realized by press-fitting the connecting flow channel tube 90 from the wall surface 82 so as to project slightly into the fluid chamber 120, then grinding the connecting flow channel tube 90 to be flush with the surface of the wall surface 82, and then by grinding inner corner of the outlet flow channel 91.

The inlet flow channel 83 is configured by a groove formed on the wall surface 82 of the first machine frame 80 and the spacer 60 which seals the opening of the groove.

Referring now to FIGS. 6 and 7, the inlet flow channel 83 will be described.

FIG. 6 is a plan view showing the first machine frame in a state of viewing from the side of the piezoelectric element. The inlet flow channel 83 is formed as the groove on the wall surface 82 of the first machine frame 80, and is formed into a substantially arcuate shape extending from the connecting portion with respect to the connecting flow channel 85 as a proximal end and to an inlet port portion 83a as a distal end which communicates with the fluid chamber 120.

This groove extends from the connecting portion with respect to the connecting flow channel 85 to a position A in the drawing as a concentric circle having the outlet flow channel 91 as the center, and extends in the direction of a tangent line of the inner peripheral wall 61 of the spacer 60 (that is, in the direction of the tangent line of the side wall of the fluid chamber 120) in a range from the positions B to C in the drawing. In addition, in the range from the positions C to D, the groove extends along the inner peripheral wall 61 of the spacer 60.

The range from the positions A to B is connected as a small arc which changes the direction of flow of the liquid smoothly.

A most part of an opening of the groove formed in this manner (upper side in the drawing) is sealed by the ring-shaped spacer 60 to define the inlet flow channel 83, and the inlet port portion 83a is in communication with the fluid chamber 120.

By forming the inlet flow channel 83 in this manner, the liquid flowing from the connecting tube 25 at a constant pressure assumes a whirling flow along the inner peripheral wall 61 of the spacer 60.

The inlet port portion 83a of the inlet flow channel 83 into the fluid chamber 120 is continued by an inclined surface 83d from the bottom surface to the wall surface 82.

FIG. 7 is a cross-sectional view showing the inlet port portion in an enlarged scale. The inlet port portion 83a is continued to the wall surface 82 via the inclined surface 83d from a groove bottom surface 83b substantially within a range from the positions C to D (see also FIG. 6) of the inlet flow channel 83.

Referring now to the drawings, a joint structure between the nozzle and the connecting flow channel tube in this embodiment will be described.

FIG. 8 is a cross-sectional view showing the joint structure between the nozzle and the connecting flow channel tube. The nozzle 95 includes a distal end flange portion 98 and an insertion portion 99, and includes the nozzle flow channel 96 which communicates with the outlet connecting flow channel 92 of the connecting flow channel tube 90 and the fluid ejection opening 97. A groove 99a is formed on a midsection in terms of the longitudinal direction on the outer peripheral surface of the insertion portion 99, and a smaller-diameter tube portion 99b having a smaller outer diameter is formed at the distal end portion on the insertion side.

A nozzle insertion hole 90f is formed at the end portion of the connecting flow channel tube 90. The nozzle 95 is press-fitted into the nozzle insertion hole 90f. In this case, an end surface 99c of the nozzle 95 is brought into tight contact with a bottom surface 94 of the nozzle insertion hole 90f.

The nozzle 95 is press-fitted into the connecting flow channel tube 90 after an adhesive agent is applied on the outer peripheral side surface of the insertion portion 99 for reinforcement of the press-fitting strength. At the time of the press-fitting, the adhesive agent is accumulated in the groove 99a. Therefore, the groove 99a in this embodiment corresponds to the adhesive agent trap, and has a function to enhance the adhesive strength and a function to prevent liquid leakage or entry of air at the joint portion between the nozzle 95 and the connecting flow channel tube 90.

The smaller-diameter tube portion 99b serves to stop the adhesive agent within the range of the smaller-diameter tube portion 99b and prevent the adhesive agent from entering the interior of the outlet connecting flow channel 92 or the nozzle flow channel 96.

Referring now to FIGS. 5 and 6, the operation of the fluid ejecting apparatus 10 in this embodiment will be described. The liquid discharge of the pulsation generating mechanism 30 in this embodiment is performed by the difference between an inertance L1 on the inlet flow channel side (also referred to as synthetic inertance L1) and an inertance L2 on the outlet flow channel side (also referred to as synthetic inertance L2).

First of all, an inertance will be described.

An inertance L is expressed by L=ρ×h/S, where 92 is a density of the liquid, S is the cross-sectional area of the flow channel, and h is the length of the flow channel. A relation; ΔP=L×dQ/dt is delivered by deforming a dynamic equation in the flow channel using the inertance L, where ΔP is a pressure difference in the flow channel, Q is a flow rate of the liquid flowing in the flow channel, and t is time.

In other words, the inertance L shows a degree of influence applied to the change of flow rate with time and, the larger the inertance L, the smaller the change of flow rate with time is, and the smaller the inertance L, the larger the change of flow rate with time is.

Since the cross-sectional areas of the inflow connecting flow channel 84 and the connecting flow channel 85 are set to be sufficiently larger than the cross-sectional area of the inlet flow channel 83, the synthetic inertance L1 is calculated within the range of the inlet flow channel 83. In this case, since the connecting tube 25 has flexibility, it may be eliminated from the calculation of the synthetic inertance L1.

Since the connecting flow channel tube 90 has a sufficient rigidity for propagating pressure waves of the liquid, the synthetic inertance L2 may be considered to be sum of the outlet flow channel 91 and the outlet connecting flow channel 92.

Then, the flow channel length and the cross-sectional area of the inlet flow channel 83, the flow channel length and the cross-sectional area of the outlet flow channel 91 and the outlet connecting flow channel 92 are set so that the synthetic inertance L1 is larger than the synthetic inertance L2 in this embodiment.

Subsequently, the operation of the pulsation generating mechanism 30 will be described.

The liquid at an always constant pressure is supplied to the inlet flow channel 83 by the pump. Consequently, when the piezoelectric element 40 is not operated, the liquid flows into the fluid chamber 120 due to the difference between the discharge pressure of the pump and a fluid resistance value of the entire inlet flow channel side.

Here, assuming that a drive signal is inputted to the piezoelectric element 40, and the piezoelectric element 40 is expanded abruptly, the pressure in the fluid chamber 120 rises quickly to several tens atmospheric pressure if the synthetic inertances L1 and L2 on the inlet flow channel side and the outlet flow channel side have a sufficient magnitude. Since this pressure is larger than the pressure by the pump applied to the inlet flow channel 83 by far, inflow of the liquid from the inlet flow channel 83 into the fluid chamber 120 is reduced by the pressure, and outflow of the liquid from the outlet flow channel 91 is increased.

However, the synthetic inertance L1 on the inlet flow channel side is larger than the synthetic inertance L2 on the outlet flow channel side, the amount of increase of the liquid discharged from the outlet flow channel 91 is larger than the amount of decrease of the flow rate of the liquid flowing into the fluid chamber 120 from the inlet flow channel 83. Therefore, a fluid discharge in a pulsed manner, that is, a pulsation flow is generated in the outlet flow channel 91.

Pressure variations at the time of discharge propagate in the interior of the connecting flow channel tube 90, and the liquid is ejected from the fluid ejection opening 97 of the nozzle 95 at the distal end (see FIG. 2 for both). Since the diameter of the fluid ejection opening 97 is smaller than the diameter of the outlet flow channel 91, the liquid is ejected as further high-pressure and high-speed pulsed liquid drops.

In contrast, the interior of the fluid chamber 120 is brought into a vacuum state immediately after the pressure rise because of the mutual action of the reduction of an amount of inflow liquid from the inlet flow channel 83 and the increase of the amount of liquid outflow from the outlet flow channel 91. Consequently, the liquid in the inlet flow channel 83 is restored to flow toward the fluid chamber 120 at a speed similar to that before the operation of the piezoelectric element 40 after having elapsed a certain period of time by the pressure from the pump and the vacuum state in the fluid chamber 120. If the expansion of the piezoelectric element 40 occurs after having restored the flow of the liquid in the inlet flow channel 83, the liquid from the nozzle 95 may be continuously ejected in a pulsed manner.

This embodiment has a structure to form the inlet flow channel 83 on the wall surface 82 of the first machine frame 80 as a groove and seal the opening by the spacer 60. Accordingly, the synthetic inertance L1 on the inlet flow channel side may be set to a value sufficiently larger than the synthetic inertance L2 on the outlet flow channel side from both facts that a long flow channel length of the inlet flow channel 83 is secured, and that the cross sectional area in the vertical direction with respect to the direction of flow of the liquid can be set to be small. Therefore, a simple structure in which a check valve is not provided is realized.

Consequently, an operation to supply the liquid from the inlet flow channel 83 into the fluid chamber 120 at a constant pressure, and convert the same to a strong pulsation by the pulsation generating mechanism 30 is enabled. Therefore, a priming action is no longer necessary and, since the inflow of the liquid is continued even though air bubbles are generated, they are discharged in a certain time period and hence the normal operation may be restored.

Also, the inlet flow channel 83 extends along an arcuate portion extending from the connecting portion (proximal end) with respect to the connecting flow channel 85, in the direction of the tangent line of an inner peripheral wall 93 of the spacer 60 from the arcuate portion, and along the inner peripheral wall 93, and finally communicates with the fluid chamber 120 from the inlet port portion 83a. Therefore, the whirling flow is generated in the fluid chamber 120.

By the generation of the whirling flow, the liquid is directed outward from the fluid chamber 120 by a centrifugal force, and the air bubbles get together at the center portion and are discharged to the outside in association with discharge of the liquid from the outlet flow channel 91. Therefore, the air bubbles are prevented from staying in the fluid chamber 120, and the pressure in the interior of the fluid chamber 120 may be raised sufficiently, so that a high-pressure pulsation discharge is achieved.

Also, at the inlet port portion 83a where the inlet flow channel 83 is connected to the fluid chamber 120, the groove bottom surface 83b which defines the inlet flow channel 83 is continued to the wall surface 82 via the inclined surface 83d, the fluid resistance at the connecting portion between the inlet port portion 83a and the fluid chamber 120 is reduced, and the turbulence of the whirling flow due to a vortex flow generated by the sudden change of the flow channel is restrained.

The space in the cylindrical portion 51 of the second machine frame 50 in which the piezoelectric element 40 is disposed is filled with the resin 140. Since the resin 140 has a low absorbability, entry of the water content into the space is prevented, so that inter-electrode short circuit due to attachment of the water content to the piezoelectric element 40 is prevented.

Since the resin 140 is filled in the lead insertion holes 54 and 55 (see FIG. 2) which allow insertion of the connecting leads 151 and 152, reinforcement of the connecting portion with respect to the piezoelectric element 40 and the connecting leads 151 and 152 in the second machine frame 50 is achieved.

In addition, by employing a material having a high coefficient of thermal conductivity as the resin 140, heat generated from the piezoelectric element 40 by continuous driving for a long time is diverged to the outside via the second machine frame 50, the piezoelectric element 40 is effectively prevented from being deteriorated in performance due to the temperature rise.

Also, since the joint portion with respect to the wall surface 82 of the outlet flow channel 91 is connected by a substantially arcuate shape and rounded smoothly, reduction of the fluid resistance at the joint portion between the fluid chamber 120 and the outlet flow channel 91 is achieved and, in addition, generation of the vortex flow at the joint portion is restrained, and the pressure waves generated when reducing the volume of the fluid chamber 120 is propagated to the nozzle 95 without being attenuated.

Also, the groove 99a as the adhesive agent trap is formed on the joint surface between the nozzle 95 and the connecting flow channel tube 90. The nozzle 95 and the connecting flow channel tube 90 are coupled by press-fitting and the coupled portion between these members is reinforced by the adhesive agent. In this case, with the provision of the adhesive agent trap, the reinforcement of the strength and the hermeticity are secured.

Second Embodiment

Subsequently, referring to the drawings, the second embodiment will be described. The second embodiment is different from the first embodiment in that the outlet flow channel is provided on the first machine frame, and the outlet connecting flow channel provided in the connecting flow channel tube is in communication with the outlet flow channel. Therefore, the points different from the first embodiment will mainly be described.

FIG. 9 is a cross-sectional view showing part of the fluid ejecting apparatus according to the second embodiment. In FIG. 9, an outlet flow channel 88 in communication with the fluid chamber 120 is formed on the first machine frame 80, and a connecting flow channel insertion portion 80a is formed on the opposite side to the fluid chamber 120 so as to project therefrom, and the center portion is formed with an insertion hole 80c.

Then, the connecting flow channel tube 90 is fitted to the connecting flow channel insertion portion 80a. The outlet connecting flow channel 92 is formed in the connecting flow channel tube 90, so that the outlet flow channel 88 and the outlet connecting flow channel 92 are communicated.

The flow channel lengths and the cross-sectional areas (diameters) of the outlet flow channel 88 and the outlet connecting flow channel 92 are set to similar values as those in the first embodiment.

The connecting flow channel tube 90 is press-fitted until a distal end portion 90g comes into tight contact with a bottom portion 80b of the insertion hole 80c.

Also a groove portion 90d is provided at a midsection of a range of the connecting flow channel tube 90 which is joined with the insertion hole 80c and a smaller-diameter tube portion 90e having a smaller outer diameter is provided at a distal end portion thereof.

The connecting flow channel tube 90 is press-fitted into the insertion hole 80c after the adhesive agent is applied on the outer peripheral surface for reinforcement of the press-fitting strength. At the time of the press-fitting of the connecting flow channel tube 90, the adhesive agent is accumulated in the groove portion 90d. Therefore, the groove portion 90d in this embodiment corresponds to the adhesive agent trap, and has a function to enhance the adhesive strength and a function to prevent liquid leakage or entry of air at the joint portion between the connecting flow channel tube 90 and the first machine frame 80.

The smaller-diameter tube portion 90e serves to stop the adhesive agent within the range of the smaller-diameter tube portion 90e and prevent the adhesive agent from entering the interior of the outlet flow channel 88 or the outlet connection flow channel 92.

In this configuration, the outlet flow channel 88 is formed in the first machine frame 80. Therefore, since the outlet flow channel 88 continues with the same surface of the wall surface 82 which constitutes part of the fluid chamber 120, the joint portion between the connecting flow channel tube 90 and the wall surface 82 is not formed in the fluid chamber 120, so that generation of the air bubbles caused by the existence of a joint surface is restrained.

Third Embodiment

Referring now to the drawings, the fluid ejecting apparatus according to the third embodiment will be described. While the connecting flow channel tube 90 is press-fitted into and fixed to the pulsation generating mechanism 30 (first machine frame 80) in the first and second embodiment, the connecting flow channel tube 90 is detachable with respect to the pulsation generating mechanism 30 in the third embodiment. Therefore, the different points from the above-described first and second embodiments will mainly be described.

FIGS. 10A and 10B show the fluid ejecting apparatus according to the third embodiment. FIG. 10A is a cross-sectional view showing part of the fluid ejecting apparatus, and FIG. 10B is a cross-sectional view showing a cross section taken along the line E-E in FIG. 10A. In FIGS. 10A and 10B, the fluid ejecting apparatus 10 is configured in such a manner that the connecting flow channel tube 90 is fixedly screwed to the pulsation generating mechanism 30 with screw portions of the partner members.

More specifically, the connecting flow channel insertion portion 80a is provided on the first machine frame 80 which constitutes the pulsation generating mechanism 30 opposite to the fluid chamber 120 so as to project therefrom, and the outlet flow channel 88 and a connecting flow channel 89 which are in communication with the fluid chamber 120 are formed in the connecting flow channel insertion portion 80a. In addition, a female screw 80d is formed in the range from the distal end portion of the connecting flow channel insertion portion 80a to the connecting flow channel 89.

The outlet connecting flow channel 92 is formed in the connecting flow channel tube 90, and a male screw 90a is formed on the outer periphery of the distal end portion. By screwing these screw portions, the connecting flow channel tube 90 is fixed to the pulsation generating mechanism 30. Therefore, the connecting flow channel tube 90 has a configuration which is detachable with respect to the pulsation generating mechanism 30 (that is, the first machine frame 80).

The connecting flow channel tube 90 is screwed in until the distal end portion 90g comes into tight contact with the bottom portion 80b of the female screw 80d.

The diameters of the connecting flow channel 89 and the outlet connecting flow channel 92 are the same, and the flow channel length and the cross-sectional area (diameter) of the outlet flow channel 88, the connecting flow channel 89, and the outlet connecting flow channel 92, that is, the synthetic inertance L2 on the outlet flow channel side is set in the same manner as in the first embodiment 1.

A cut portion 90b is formed on the outer peripheral portion at a midsection of the connecting flow channel tube 90 in terms of the longitudinal direction. As shown in FIG. 10B, the cut portion 90b is formed by cutting the outer periphery of the connecting flow channel tube 90 into plane surfaces opposing to each other. The cut portion 90b is used for mounting to and demounting from the pulsation generating mechanism 30 of the connecting flow channel tube 90 by rotating the same by a jig or the like.

Therefore, in this configuration, easy replacement of the connecting flow channel tube 90 as well as removal for cleaning or sterilization of the connecting flow channel tube 90 in the unlikely event that the nozzle 95 is clogged is achieved.

Also, there is also an effect that the shape of the connecting flow channel tube 90 may be selected and attached as needed according to the object of usage by preparing a plurality of shapes of connecting flow channel tube 90.

Fourth Embodiment

Subsequently, a fourth embodiment will be described. The fourth embodiment is characterized in that a coating layer is formed on an inner wall surface of the fluid chamber. Although not shown, description will be given on the basis of FIG. 5.

The fluid chamber 120 is defined by a space surrounded by the wall surface 82 of the first machine frame 80, the inner peripheral wall 61 of the spacer 60, and the diaphragm 70. In this case, a joint portion and corners of the first machine frame 80 and the wall surface 82, a joint portion and corners of the inner peripheral wall 61 of the spacer 60 and the diaphragm 70, and a joint portion between the connecting flow channel tube 90 and the wall surface 82 are formed.

Small gaps might be formed at these joint portions due to the machining reasons, and the inner angle of the corners is 90 degrees.

The coating layer is formed over the entire periphery of the inner wall surface of the fluid chamber 120. As an example of the coating layer, a metal plated layer may be employed. Although the material of the plated layer is not specifically limited, a material having a resistance against the liquid to be used is selected.

Formation of the plated layer is achieved by inserting the connecting flow channel tube 90 into the pulsation generating mechanism 30 and then immersing the same in plating solution, and by forcing the plating solution to flow from the inflow connecting flow channel 84 through the inlet flow channel 83 to the outlet connecting flow channel 92, the plating solution is circulated to minute portions in the respective flow channels, so that the plated layer may be formed over the entire flow channels.

The coating layer is also formed at the corners formed between the bottom portion and the side walls of the groove of the inlet flow channel 83 and the corners of the joint portion between the groove and the spacer 60 which seals the groove. The coating layer is formed also at the joint portions between the nozzle 95 and the connecting flow channel tube 90.

Therefore, the continuous thin coating layer is formed over the entire flow channel for the liquid.

As described above, the gas contained in the flowing liquid gets together to small gaps or corners at the joint portions of the components gradually to generate air bubbles. If the air bubbles exist in the fluid chamber 120, the internal pressure might not rise sufficiently when reducing the volume of the fluid chamber 120 by the diaphragm 70.

Therefore, by embedding the small gap at the joint portions of the respective components by forming the continuous thin coating layer over the entire flow channel for the liquid including the fluid chamber 120 and rounding the corners with the coating layer, generation of the air bubbles caused by the existence of the small gaps or corners is restrained, so that the internal pressure in the fluid chamber 120 may be raised to a predetermined level.

Although this embodiment has been described on the basis of the first embodiment described above, it may also be applied to the second and third embodiments.