JP2003307163A - Liquid jetting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid jetting device capable of quickly exhausting bubbles existing or generated in the liquid to be jetted and of jetting the liquid upon being atomized at the requested timing. <P>SOLUTION: The liquid jetting device 10 is equipped with a jetting device 15 and a solenoid-operated opening/closing jetting valve 14 to discharge the pressurized fuel to the jetting device. The discharge hole of the valve is connected with a sealed space in a cylindrical shape, which is connected with a liquid discharge nozzle through a liquid injection hole in the jetting device, a liquid supply passage, and a chamber. The valve discharges the pressurized fuel at an inclined angle to the axis of the sealed space so as to generate a fuel flow in a wide part of the sealed space, and thereby prevents generation of large bubbles in the sealed space. The jetting device gives the liquid a vibratory energy based upon a change of the chamber capacity due to a piezoelectric/ electrostrictive element and atomize the liquid to be injected. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid ejecting apparatus which atomizes and ejects liquid into a liquid ejecting space.

[0002]

2. Description of the Related Art A fuel injection device for an internal combustion engine is known as a liquid injection device of this type. A fuel injection device for an internal combustion engine is a so-called electrically controlled fuel injection device including a pressurizing pump for pressurizing a liquid and an electromagnetic injection valve, and is widely put into practical use. However, in the electrically controlled fuel injection device, the fuel pressurized by the pressure pump is injected from the injection port of the electromagnetic injection valve, and thus the size of the injected fuel droplets is generally The size is relatively large, at least about 100 μm, and the size is not uniform. Such non-uniformity in the size and size of the fuel droplets increases the amount of unburned fuel during combustion, which in turn leads to an increase in harmful exhaust gas.

On the other hand, conventionally, there has been proposed a droplet discharge device which pressurizes the liquid in the liquid supply passage by the operation of the piezo electrostrictive element and discharges the liquid as fine droplets from the discharge port. (For example, refer to Patent Document 1). Such a device
By applying the principle of a conventional inkjet ejection device (for example, refer to Patent Document 2), ejection droplets (droplets of fuel to be ejected) are smaller and more uniform than those of the electrically controlled fuel ejection device. Therefore, it can be said that the device is excellent in terms of atomizing the fuel.

[0004]

[Patent Document 1] JP-A-54-90416 (second
(Page, Fig. 5)

[Patent Document 2] Japanese Patent Application Laid-Open No. 6-40030 (pages 2 to 3, FIG. 1)

[0005]

By the way, the ink jet discharge device has little fluctuation in temperature, pressure and the like and is in a relatively constant ambient environment (for example, in an office, a school, etc.).
When used in, the desired performance of ejecting a liquid as fine particles can be exhibited. However, it is generally difficult to sufficiently exhibit the performance of atomizing the fuel when it is used in an environment such as an internal combustion engine that is subject to drastic fluctuations due to fluctuations in operating conditions and the like. Therefore,
A device that applies the principle of an inkjet discharge device, and is a liquid (fuel) that can sufficiently inject liquid into a mechanical device such as an internal combustion engine whose surrounding environment changes drastically after being sufficiently atomized. The present situation is that the injection device has not been provided yet.

Further, when such a liquid ejecting apparatus is applied to a mechanical device such as an internal combustion engine, the injection amount of liquid required by the mechanical device can be reliably and stably supplied, and the injection required by the mechanical device can be performed. It is required to eject the liquid without delaying the timing. However, since the liquid ejecting apparatus performs ejection by increasing / decreasing the pressure of the liquid, bubbles are likely to be generated in the liquid, and the pressure of the liquid does not increase as expected when the bubbles are not discharged before they grow large. Therefore, the requirements regarding the injection amount and the injection timing cannot be satisfied.

Therefore, an object of the present invention is to provide a liquid ejecting apparatus capable of ejecting a liquid, in which liquid droplets to be ejected are small and uniform, and atomization of the liquid is stably achieved. Especially. Further, another object of the present invention is to
It is an object of the present invention to provide a liquid ejecting apparatus having a structure capable of ejecting a liquid stably even under a condition where the usage environment of the liquid ejecting apparatus such as the liquid ejecting space changes violently and suddenly. Further, another object of the present invention is to provide a liquid ejecting apparatus capable of ejecting a desired amount of liquid at a desired ejection timing by making it difficult for bubbles to be generated in the liquid in the liquid ejecting apparatus. is there.

[0008]

SUMMARY OF THE INVENTION A liquid ejecting apparatus according to the present invention has a liquid ejecting nozzle, one end of which is exposed in a liquid ejecting space, a piezoelectric / electrostrictive element, and the liquid ejecting nozzle whose volume is changed by the operation of the piezoelectric / electrostrictive element. An injection device including a chamber connected to the other end of the nozzle for liquid, a liquid supply passage connected to the chamber, and a hollow cylindrical liquid injection port communicating the liquid supply passage with the outside, The electromagnetic on-off valve is provided with a pressurizing means for pressurizing, a liquid pressurized by the pressurizing means, and an electromagnetic on-off valve and a discharge hole opened and closed by the electromagnetic on-off valve. An electromagnetic open / close type discharge valve that discharges the pressurized liquid through the discharge hole when opened, and the same liquid between the discharge hole of the electromagnetic open / close type discharge valve and the liquid injection port of the injection device. Practically with the inlet A closed space forming member forming a hollow cylindrical closed space having a diameter, the liquid discharged from the electromagnetic open / close type discharge valve is atomized by the volume change of the chamber, and the liquid discharge nozzle ejects the liquid. A liquid ejecting apparatus for ejecting liquid droplets into a space, wherein the electromagnetic on-off type discharge valve is configured such that a distance of a liquid discharged from the discharge hole from a central axis of the hollow cylindrical closed space is from the discharge hole. It is characterized in that the liquid is ejected in a direction having a predetermined angle with respect to the central axis so as to increase with an increase in the distance toward the liquid injection port.

According to this, the liquid pressurized by the pressurizing means is ejected from the electromagnetic opening-and-closing type ejection valve to the ejection device and ejected from the liquid ejection nozzle, and the volume of the chamber of the ejection device changes. It is made into fine particles.

In this case, the size of the atomized droplets depends on the pressure applied to the liquid, the amplitude / frequency of the vibration of the piezoelectric / electrostrictive element, the shape of the flow path, the size of the flow path, and the viscosity of the liquid. -Although it varies depending on physical properties such as surface tension, the cycle of vibration applied to the liquid is near the end of the nozzle (opening exposed to the liquid ejection space) in the liquid ejection nozzle. If it is smaller than the time required to move by a length corresponding to the diameter of, the size of the ejected liquid droplets will be approximately equal to or smaller than the diameter of the end portion of the liquid ejection nozzle. Therefore, for example, if the diameter of the end (opening) exposed in the liquid ejecting space of the liquid ejecting nozzle is designed to be several tens of μm or less, the liquid ejecting apparatus ejects extremely finely divided droplets. When used as a fuel injection device for an internal combustion engine, for example, the fuel to be injected can be atomized into droplets having an appropriate diameter, so that the fuel efficiency of the internal combustion engine is improved and harmful exhaust gas is reduced. be able to.

Further, according to the above configuration, since the pressure required for ejecting the liquid is generated by the pressurizing means, the environment (for example, the pressure) of the liquid ejecting space may change due to fluctuations in the operating conditions of the applied machine. The liquid can be stably jetted and supplied as desired fine particles even if the temperature and temperature) fluctuate drastically.

Further, the conventional carburetor (carburetor) is
The fuel (liquid) flow rate is determined according to the air flow velocity in the space inside the intake pipe that is the droplet discharge space, and the degree of atomization also changes depending on the air flow velocity. For example, it is possible to discharge the required amount of fuel (liquid) maintaining a good atomization state regardless of the air flow velocity. in addition,
According to the liquid injection device of the present invention, a compressor for supplying assist air is not always required, as in a device for promoting atomization of fuel by supplying assist air to the nozzle portion of a conventional fuel injection injector. Therefore, the device can be made inexpensive.

Further, according to the above construction, the closed space forming member substantially forms a hollow cylindrical liquid injection port between the discharge hole of the electromagnetic on-off type discharge valve and the liquid injection port of the injection device. A hollow cylindrical closed space of the same diameter is formed in the hollow cylinder, and the liquid discharged from the discharge hole has the same hollow cylinder as the distance from the discharge hole to the liquid injection port increases. Is discharged in a direction having a predetermined angle with respect to the central axis so that the distance from the central axis of the circular closed space increases.

As a result, a flow of the liquid to be discharged is generated in a wide portion of the hollow cylindrical closed space. Therefore, in particular, a corner portion near the discharge hole of the electromagnetic open / close type discharge valve in the hollow cylindrical closed space. The bubbles are unlikely to stay in the chamber, or the bubbles are easily discharged quickly before the bubbles formed in the same corner become large. Therefore, in the liquid ejecting apparatus, since the increase in the pressure of the liquid is not easily blocked by the bubbles, the pressure of the liquid can be increased as expected, and the liquid droplets can be ejected at the ejection amount and the ejection timing required by the mechanical device. It will be possible.

In this case, the angle formed by the discharge streamline of the liquid droplets discharged from the discharge port with respect to the axis of the hollow cylindrical closed space, that is, the predetermined angle θ is 5 ° or more and 30 It is preferable that the angle is less than or equal to °.

That is, if the predetermined angle θ is smaller than 5 °, the fluid is likely to stay in the corner portion near the discharge hole of the electromagnetic open / close type discharge valve in the hollow cylindrical hermetically sealed space, so that bubbles are generated in the same portion. If the predetermined angle θ is larger than 30 °, the moving distance until the liquid ejected from the ejection hole reaches the liquid supply passage becomes substantially long, so that the liquid pressure in the liquid supply passage is increased. This is because the rise is delayed, and as a result, it becomes difficult to eject droplets from the ejection nozzle at a desired ejection timing.

Further, in any one of the liquid ejecting apparatuses described above, at least one flow of the liquid ejected from the electromagnetic opening-and-closing type ejection valve is ejected from the ejection nozzle into the liquid ejection space. Suitably, it is constructed so that it can be bent at a substantially right angle.

With such a configuration, for example, the liquid injection port and the liquid supply passage are arranged such that the flow direction of the liquid passing through the liquid injection port and the flow direction of the liquid passing through the liquid supply passage are orthogonal to each other. Is arranged and configured, the liquid that passes through the liquid supply passage is arranged and configured so that the liquid is introduced into the chamber by being bent at a substantially right angle, and the liquid that passes through the chamber. Can be obtained by arranging and configuring the same chamber and the same discharge nozzle so that they are bent at a substantially right angle and flow into the discharge nozzle.

According to this structure, since the flow of the liquid discharged from the electromagnetic on-off type discharge valve is bent at least once at a substantially right angle, it is generated when the electromagnetic on-off type discharge valve is opened. Since the pulsation of the liquid pressure in the ejection device is reduced and / or the liquid pressure distribution is uniform,
It becomes possible to stably eject the droplets. In particular, when the ejection device has a plurality of chambers connected to a common liquid supply passage, if the flow of the liquid discharged from the electromagnetic on-off type discharge valve is bent at a substantially right angle by the liquid inlet and the liquid supply passage, Since the pressure of the liquid in the liquid supply passage is stable, the pressure of the liquid in each chamber is also stable, and as a result, the size of the droplets ejected from the ejection nozzles connected to each chamber is made uniform. can do.

Further, in any one of the above liquid ejecting apparatuses, the liquid supply passage includes a flat surface portion that faces a virtual plane formed by a portion communicating with the liquid injection port and is parallel to the virtual plane. In the electromagnetic on-off type discharge valve, a discharge streamline of the liquid discharged from the discharge hole has a side wall of the hollow cylindrical closed space formed by the closed space forming member and the side wall of the liquid supply passage. It is preferable that the liquid supply passage is arranged so as to intersect with the plane portion of the liquid supply passage without intersecting with the side wall that virtually extends to the plane portion.

According to this, the liquid discharged from the electromagnetic opening-and-closing type discharge valve reaches the flat surface portion of the liquid supply passage while maintaining the kinetic energy (flow velocity) thereof at a high state. At, the liquid is strongly reflected toward the vicinity of the ejection hole in the hollow cylindrical closed space of the liquid inlet and the closed space forming member. As a result, the flow of the reflected liquid makes it possible to discharge the air bubbles staying at the corners in the vicinity of the discharge holes of the hollow cylindrical closed space, so that the amount of air bubbles existing in the liquid can be reduced. As a result, the liquid ejecting apparatus is
The increase in the pressure of the liquid becomes more difficult to be blocked by the bubbles, and the pressure of the liquid can be increased as expected. Therefore, it is possible to eject the liquid droplets at the ejection amount and the ejection timing required by the mechanical device.

Further, in any one of the liquid ejecting apparatus described above, the liquid discharge device for the electromagnetic open / close type discharge valve is provided with respect to the discharge amount (discharge flow rate) Q (cc / min) of the liquid discharged from the electromagnetic open / close type discharge valve. The ratio of the volume V (cc) of the liquid flow path formed up to the tip of the liquid ejection nozzle of the ejection device (V / cc)
It is preferable that Q) is configured to be 0.03 or less.

Here, the volume of the liquid flow path formed from the electromagnetic on-off type discharge valve (that is, from the end surface of the electromagnetic on-off type discharge valve on the ejection device side) to the tip of the ejection nozzle of the ejection device. Is the sum of the volumes of the closed space of the closed space forming member, the liquid injection port, the liquid supply passage, the chamber, and the liquid discharge nozzle (in the case where the liquid supply passage and the chamber are connected by the liquid introduction hole, It is the volume including the volume of the liquid introduction hole).

As described above, the magnitude of the ratio (V / Q) is set so that when the ratio (V / Q) becomes larger than 0.03, the volume V (cc) becomes the discharge flow rate Q (cc / min). However, the time from the start of liquid discharge from the electromagnetic opening / closing discharge valve until the pressure of the liquid in the discharge nozzle of the injection device rises becomes longer, and droplets are discharged at the desired timing. Because it will be difficult.

Further, in any one of the above liquid ejecting apparatus, the ejecting device is provided with a plurality of the liquid ejecting nozzles, and the ejection directions of the liquid droplets ejected from the respective liquid ejecting nozzles are parallel to each other. It is preferable that the

According to this, the liquid droplets ejected from the respective ejection nozzles into the liquid ejecting space do not substantially intersect with each other, and therefore it is possible to prevent the liquid droplets from colliding with each other to form a large liquid droplet. Therefore, the atomized state of the ejected droplets can be maintained in a good condition.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a liquid ejecting apparatus (liquid spraying apparatus, liquid supplying apparatus, liquid droplet ejecting apparatus) according to the present invention will be described below with reference to the drawings. FIG. 1 schematically shows the configuration of the present liquid injection device applied to an internal combustion engine as a mechanical device that requires a liquid that has been made into fine particles.

The liquid injection device 10 has a fuel injection space 21 formed by an intake pipe (or intake port) 20 of an internal combustion engine, and a finely divided liquid (toward a back surface of an intake valve 22 of the internal combustion engine). Liquid fuel, for example gasoline, below,
Sometimes referred to simply as "fuel". ) Is injected, and a pressurizing pump (fuel pump) 11 as a pressurizing means, a liquid supply pipe (fuel pipe) 12 through which the pressurizing pump is interposed, and the pressurization of the liquid supply pipe 12 A pressure regulator 13, which is provided on the discharge side of the pump, an electromagnetic on-off type discharge valve 14, a chamber in which a piezoelectric / electrostrictive element is formed on at least the wall surface of the liquid in order to atomize the liquid injected into the fuel injection space 21, and for discharge An injection unit (spray unit) 15 including a nozzle, and a valve opening drive signal as a drive signal and a chamber volume change (piezoelectric / electrostrictive element actuation) for the electromagnetic opening / closing type discharge valve 14 and the injection unit 15. An electric control device 30 is provided for supplying the drive voltage signal and the drive voltage signal, respectively.

The pressurizing pump 11 is connected to the bottom of a liquid storage tank (fuel tank) 23, and an inlet 11 a to which fuel is supplied from the liquid storage tank 23 and a discharge part connected to the liquid supply pipe 12. 11b and. The pressurizing pump 11 introduces the fuel in the liquid storage tank 23 from the introducing portion 11a, and the fuel is supplied to the pressure regulator 13, the electromagnetic on-off type discharge valve 14, and the injection unit 1.
5 (even if the piezoelectric / electrostrictive element of the ejection unit 15 is not activated) through the liquid ejection space 2
1 is pressurized up to a pressure that can be injected (this pressure is referred to as "pressurizing pump discharge pressure"), and the pressurized fuel is discharged from the discharge portion 11b into the liquid supply pipe 12. ing.

The pressure regulator 13 is provided with pressure in the intake pipe 21 by a pipe (not shown), and reduces (or regulates) the pressure of the fuel pressurized by the pressure pump 11 based on this pressure. , A liquid supply pipe 1 between the pressure regulator 13 and the electromagnetic on-off type discharge valve 14
The pressure of the fuel in 2 is adjusted so as to be a pressure higher than the pressure in the intake pipe 21 by a predetermined (constant) pressure (this pressure is referred to as “adjustment pressure”). As a result, when the electromagnetic open / close type discharge valve 14 is opened for a predetermined time, a fuel having a fuel amount substantially proportional to the predetermined time is supplied to the intake pipe 2.
The fuel is injected into the intake pipe 21 regardless of the pressure inside 1.

The electromagnetic open / close type discharge valve 14 is a well-known fuel injector (electromagnetic open / close type injection valve) which has been widely adopted in the electric control type fuel injection device of the internal combustion engine. FIG. 2 is a front view of the electromagnetic on-off type discharge valve 14, and shows a tip side portion of the electromagnetic on-off type discharge valve 14 with a cross section taken along a plane including the center line of the electromagnetic on-off type discharge valve 14. The injection unit 15 fixed to 14 is shown in a cross section cut along the same plane as the above plane. Further, FIG. 3 shows the electromagnetic on-off type discharge valve 14 and the injection unit 1 near the tip of the electromagnetic on-off type discharge valve 14 shown in FIG.
5 is an enlarged sectional view of FIG.

As shown in FIG. 2, this electromagnetic opening / closing type discharge valve 14 has a liquid introduction port 14 to which a liquid supply pipe 12 is connected.
a, an outer cylinder portion 14c forming a fuel passage 14b communicating with the liquid introduction port 14a, a needle valve 14d that operates as an electromagnetic on-off valve, and an electromagnetic mechanism (not shown) that drives the needle valve 14d. There is. As shown in FIG. 3, a conical valve seat portion 14c-1 having substantially the same shape as the distal end portion of the needle valve 14d is provided at the center of the distal end of the outer cylinder portion 14c, and the valve seat portion 14c-1 is provided. Top (tip)
Near the inside of the outer cylinder part 14c (that is, the fuel passage 14b)
There are provided a plurality of discharge holes (through holes) 14c-2 that communicate with the outside of the outer cylinder portion 14c. This discharge hole 14c-
No. 2 is inclined by an angle θ with respect to the axis line CL of the needle valve 14d (electromagnetic on-off type discharge valve 14). Although not shown, when the outer cylinder portion 14c is viewed from the direction along the axis CL, the plurality of discharge holes 14c-2 are provided at equal intervals on the same circumference.

With the above construction, the electromagnetic opening / closing type discharge valve 14
In the above, when the needle valve 14d is driven by the electromagnetic mechanism to open / close the discharge hole 14c-2 and the discharge hole 14c-2 is opened, the fuel in the fuel passage 14b is discharged from the discharge hole 1c.
4c-2 is discharged (jetted). Since the discharge hole 14-2c is inclined with respect to the axis line CL of the needle valve 14d, the fuel discharged in this manner spreads along the side surface of the cone whose center line is the coaxial line CL (cone. Be ejected.

As shown in FIG. 2, the injection unit 15 includes an injection device 15A and an injection device fixing plate 15B.
And a holding unit 15C for holding the injection device fixing plate 15B, and a sleeve 15D for fixing the tip of the electromagnetic on-off type discharge valve 14.

As shown in FIG. 4, which is a plan view of the injection device 15A, and FIG. 5, which is a cross-sectional view of the injection device 15A taken along a plane along line 1-1 of FIG.
A plurality of ceramic thin plates (hereinafter referred to as "ceramic sheets") 15a to 15f each having a substantially rectangular parallelepiped shape extending in parallel with X, Y, and Z axes whose sides are orthogonal to each other and sequentially laminated and pressure bonded. And a plurality of piezoelectric / electrostrictive elements 15g fixed to the outer surface of the ceramic sheet 15f (a plane along the XY plane in the positive Z-axis direction). This ejection device 15A has a liquid supply passage 15-1 inside.
, And a plurality of independent ones (7 in each column, total 1
4) chambers 15-2 and each chamber 15-2
And a plurality of liquid introduction holes 15-3 communicating with the liquid supply passage 15-1, each chamber 15-2 and the ejection device 15
One end of each of the liquid ejecting spaces 2 communicates with the outside of A.
1. A plurality of liquid ejection nozzles 15 which are substantially exposed to
-4 and a liquid injection port 15-5.

The liquid supply passage 15-1 is formed in the ceramic sheet 15c and has a side wall surface of an oval notch having a major axis and a minor axis along the X-axis direction and the Y-axis direction, and a plane surface of the ceramic sheet 15b. It is a space defined by an upper surface and a lower surface which is a flat surface of the ceramic sheet 15d.

Each of the plurality of chambers 15-2 is formed in the ceramic sheet 15e, and the side wall surface of the oval notch portion whose major axis and minor axis are along the Y-axis direction and the X-axis direction, and the ceramic sheet 15d, respectively. It is a long space (a liquid flow path having a longitudinal direction) defined by the upper surface and the lower surface of the ceramic sheet 15f. Each chamber 15-2
One end in the Y-axis direction extends to the upper part of the liquid supply passage 15-1, and each chamber 15-2 has a diameter d provided in the ceramic sheet 15d at this one end. The hollow cylindrical liquid introducing hole 15-3 communicates with the liquid supply passage 15-1. In the following,
The diameter d is also simply referred to as “introduction hole diameter d”. The other end of each chamber 15-2 in the Y-axis direction is connected to the other end of the liquid ejection nozzle 15-4.
With the above configuration, the chamber 15-2 (flow path portion)
From the liquid introduction hole 15-3 to the liquid discharge nozzle 15-
The liquid is made to flow toward 4 (that is, in the Y-axis direction).

Each of the plurality of liquid ejecting nozzles 15-4 is a hollow cylindrical through hole provided in the ceramic sheet 15a and having a diameter of D, and is substantially exposed to the liquid ejecting space 21 at one end ( Liquid ejection port, opening exposed to liquid ejection space) 15-4a, and ceramic sheets 15b to 15d whose sizes (diameters) gradually increase from the liquid ejection port 15-4a toward the chamber 15-2. And the hollow cylindrical communication holes 15-4b to 15-4d. The axis of each liquid ejection nozzle 15-4 is parallel to the Z axis. In the following, the diameter D is also simply referred to as "nozzle diameter D".

The liquid injection port 15-5 is the injection device 15
The liquid supply passage 1 is a space formed by side walls of cylindrical through holes provided in the ceramic sheets 15d to 15f at the X axis positive direction end portion of A and substantially in the Y axis direction central portion.
5-1 and the outside of the ejection device 15A communicate with each other. The liquid inlet 15-5 is the ceramic sheet 1
It is connected to the upper part of the liquid supply passage 15-1 by an imaginary plane hp lying in the boundary plane with the 5d and 15c. A portion of the liquid supply passage 15-1 facing the virtual plane hp, that is, the upper surface of the ceramic sheet 15b is a flat surface portion sp parallel to the virtual plane hp.

Here, the shape and size of each chamber 15-2 will be additionally described.
-2 is a plane (X-) that is orthogonal to the liquid flowing direction in the central portion (flow passage portion) of each longitudinal direction (Y-axis direction).
The cross-sectional shape of the same flow path section cut along the (Z plane) is substantially rectangular. In addition, the long axis L of the flow path portion having a long shape
(Length along Y-axis) and short axis W (length along X-axis and length of one side of the rectangle) are 3.5.
mm and 0.35 mm, and the height T thereof (the length along the Z-axis and the length of the side orthogonal to one side of the rectangle)
Is 0.15 mm. That is, in a rectangle which is the cross-sectional shape of the flow path portion, the ratio of the length (height T) of the side orthogonal to the same side to the length of one side (short axis W) provided with the piezoelectric / electrostrictive element ( T / W) is 0.15 / 0.35 = 0.4
3, and this ratio (T / W) is preferably larger than 0 and smaller than 1. Thus, by selecting the ratio (T / W), the vibration energy of the piezoelectric / electrostrictive element 15g can be efficiently transmitted to the fuel in the chamber 15-2.

In addition, the end portion 15-4a of the liquid discharge nozzle
And the diameter d of the liquid introduction hole 15-3 were 0.031 mm and 0.025 mm, respectively. In this case, the cross-sectional area S1 of the channel of the chamber 15-2 (= W ×
T) is the cross-sectional area S of the end portion 15-4a of the liquid ejection nozzle.
It is desirable that it is larger than 2 (= π · (D / 2) ² ) and larger than the cross-sectional area S3 (= π · (d / 2) ² ) of the liquid introduction hole 15-3. Further, in order to make the liquid into fine particles, it is desirable that the cross-sectional area S2 is larger than the cross-sectional area S3.

Each piezoelectric / electrostrictive element 15g is (Z
It is slightly smaller than each chamber 15-2 (when viewed from the positive axis direction), and is arranged on the upper surface of the ceramic sheet 15f (the flow path portion of the chamber 15-2) so as to be disposed inside the chamber 15-2 in the same plan view. The driving voltage signal generating means (circuit) of the electric control device 30 is fixed between the electrodes (not shown) provided on the upper surface and the lower surface of each piezoelectric / electrostrictive element 15g, which are fixed to the wall surface including one side of a quadrangle, which is the cross section of ) Is operated (driven) based on the drive voltage signal DV given by
The upper wall) of the chamber 15-2.
The volume of is changed by ΔV.

The above-mentioned ceramic sheets 15a to 15f,
The following method was adopted as the method for forming the laminate. 1; A ceramic green sheet is formed using zirconia powder having a particle size of 0.1 to several μm. 2; This ceramic green sheet is punched using a die punch and a die, and cutouts (chamber 15-2, liquid introduction hole 15-3) corresponding to the ceramic sheets 15a to 15e shown in FIG. , Liquid supply passage 1
5-1, liquid discharge nozzle 15-4, liquid injection port 15-
5 (see FIG. 4)). 3; Laminate each ceramic green sheet, heat press bond,
Firing is performed at 1550 ° C. for 2 hours to be integrated.

The piezoelectric / electrostrictive element 15g sandwiched by the electrodes is formed on the upper surface of the portion corresponding to the chamber portion of the laminated body of ceramic sheets thus formed. By the above, the ejection device 15A is manufactured. When the ejection device 15A is integrally formed of zirconia ceramics in this manner, the characteristics of the zirconia ceramics make it possible to maintain high durability against frequent deformation of the wall surface 15f by the piezoelectric / electrostrictive element 15g, and a plurality of A liquid ejecting device having the liquid ejecting nozzles 15-4, 15-4, ... Can be realized with a small total length of several cm or less, and can be easily manufactured at low cost.

The jetting device 15A is fixed to the jetting device fixing plate 15B as shown in FIGS. The ejection device fixing plate 15B has a rectangular shape that is slightly larger than the ejection device 15A in a plan view, and each liquid ejection port 15 of the ejection device 15A in a state where the ejection device 15A is fixed.
-4a is provided with a through hole (not shown) at a position facing each other, and each liquid ejection port 15-4a is exposed to the outside through the through hole. In addition, the injection device fixing plate 15
B is fixed to the holding unit 15C at its peripheral portion.
Is held.

The holding unit 15C has the same outer shape in plan view as the ejection device fixing plate 15B,
As shown in FIG. 1, the peripheral portion thereof is fixed to the intake pipe 20 of the internal combustion engine by a bolt (not shown). As shown in FIG. 2, the holding unit 15C has an outer cylinder portion 14 of the electromagnetic on-off type discharge valve 14 at the center thereof.
The through hole has a diameter slightly larger than the diameter of c, and the outer cylinder portion 14c is inserted into the through hole.

The sleeve (closed space forming member) 15D is
As shown in FIGS. 2 and 3, it has a cylindrical shape whose inner diameter is equal to the outer diameter of the outer cylinder portion 14c of the electromagnetic on-off type discharge valve 14, and whose outer diameter is equal to the inner diameter of the through hole of the holding unit 15C. is doing. One end of the sleeve 15D is closed and the other end is open. As shown in FIG. 3, the liquid injection port 15 of the ejection device 15A is located at the center of the closed end.
An opening 15D-1 having the same diameter as -5 (approximately the same diameter) is provided. An O-ring groove 15D-1a is formed on the inner peripheral side wall surface forming the opening 15D-1 and outside the closed end.

The outer cylinder portion 1 of the electromagnetic on-off type discharge valve 14
4c is the sleeve 15D from the open end side of the sleeve 15D.
It is press-fitted until it contacts the inside of the closed end of D, and the sleeve 1
5D is press-fitted into the through hole of the holding unit 15C. At this time, the O-ring 16 inserted in the O-ring groove 15D-1a is brought into contact with the ceramic sheet 15f of the ejection device 15A.

As described above, the electromagnetic open / close type discharge valve 14 and the injection unit 15 are integrally assembled, and the discharge hole 14c-2 of the electromagnetic open / close type discharge valve 14 (the electromagnetic open / close type injection in which the discharge hole 14c-2 is formed). The closed end surface of the outer cylinder portion 14c of the valve 14 (outside of the closed end surface), or the portion of the cylindrical outer cylinder portion 14c that can be referred to as the outside of the discharge hole 14c-2 forming surface) and the liquid injection port 15 of the injection device 15A. A closed space having a hollow cylindrical shape is formed between it and -5. Also, in this state,
Opening of sleeve 15D (hollow cylindrical closed space) 15D-
The central axis of 1 is the liquid injection port 15 of the ejection device 15A.
It is made to coincide with the central axis line of −5 and is made to coincide with the central axis line CL of the needle valve. As described above, the sleeve 15D includes the electromagnetic open / close type discharge valve 14
Between the discharge hole 14c-2 and the liquid injection port (liquid injection part) 15-5 of the injection device 15A, and the discharge hole 14c-2 (that is, the outer cylinder part 1 of the electromagnetic on-off type discharge valve 14).
4c between the end surface gp on the ejection device 15A side and the liquid injection port 15-5, the liquid injection port 15-5 has substantially the same diameter, and the liquid injection port 15-5 and the needle valve 14d (electromagnetic). A hollow cylindrical hermetically sealed space whose central axis coincides with each central axis CL of the on-off type discharge valve 14) is formed.

Further, as described above, the discharge hole 14c
-2 is inclined by an angle θ with respect to the axis CL of the needle valve 14d (hence, the axis of the hollow cylindrical closed space) CL, the fuel discharged from the electromagnetic on-off valve 14 is the opening 15D- of the sleeve 15D- In the inside of 1 (that is, the closed space of the hollow cylinder), as it approaches the injection device 15A, it spreads at an angle θ with respect to the axis CL. In other words, the distance of the droplet-shaped fuel discharged from the discharge hole 14c-2 from the central axis CL of the hollow cylindrical closed space is the discharge hole 14c-2 (that is, the outer cylinder of the electromagnetic on-off valve 14). It increases with an increase in the distance from the end face gp on the ejection device 15A side of the portion 14c toward the liquid injection port 15-5.

Further, in the present embodiment, the fuel discharged in this way is the opening 15D-1 of the sleeve 15D.
(In other words, the inner peripheral wall surface (excluding the inner peripheral wall surface of the O-ring groove 15D-1a) forming the hollow cylindrical closed space) and the inner peripheral wall surface of the flat surface portion (ceramic) of the liquid supply passage 15-1. Before reaching the wall surface WP (indicated by the phantom line of the two-dot chain line in FIG. 3) that is virtually extended to the upper surface sp of the sheet 15b) sp, the same plane portion sp of the liquid supply passage 15-1 is reached. The angle θ is determined so that

In other words, the electromagnetic on-off type discharge valve 14
Indicates that the discharge streamline of the liquid discharged from the discharge hole 14c-2 (shown by the one-dot chain line DL in FIG. 3) is the sleeve 15
The side wall of the hollow cylinder (opening 15D-
1) and the side wall 15D-1 directly with the flat surface sp of the liquid supply passage 15-1 without intersecting the side wall WP that virtually extends to the flat surface sp of the liquid supply passage 15-1. It is arranged so as to intersect.

With the above structure, the electromagnetic opening / closing type discharge valve 14
The fuel discharged and supplied from the discharge hole 14c-2 of the above to the liquid supply passage 15-1 through the liquid injection port 15-5 is introduced into each chamber 15-2 through each liquid introduction hole 15-3. It Then, the vibration energy is given to the fuel in each chamber 15-2, and the fuel discharge nozzle 15
From the liquid ejection port 15-4a through the through hole of the ejection device fixing plate 15B.
The droplets are ejected into the intake pipe 20.

As shown in FIG. 1, the electric control unit 30 is connected to an engine rotation speed sensor 31 and an intake pipe pressure sensor 32, and inputs the engine rotation speed N and the intake pipe pressure P from these sensors. Then, the amount of fuel required for the internal combustion engine is determined, and a high level signal (valve opening signal) is sent as the valve opening drive signal INJ for a time corresponding to the amount of fuel. As a result, the needle valve 14d of the electromagnetic on-off type discharge valve 14 opens the discharge hole 14c-2 in response to the high level signal and can be moved so as to discharge fuel from the discharge hole 14c-2. Has become.

Further, the electric control unit 30 has a built-in drive signal generation circuit for applying a drive voltage signal DV having a frequency f (cycle T) between electrodes (not shown) of the piezoelectric / electrostrictive element 15g. In this case, the driving frequency f is a portion that causes the structure of the chamber 15-2, the structure of the liquid ejection nozzle 15-4, the nozzle diameter D, the introduction hole diameter d, and the deformation of the ceramic sheet 15f of the piezoelectric / electrostrictive element 15g. Is set to a frequency equal to the resonance frequency (natural frequency) of the ejection device 15A determined by the shape, the type of liquid, and the like, for example, in the vicinity of 50 kHz.

Here, the time relationship between the valve opening drive signal INJ and the drive voltage signal DV will be described with reference to FIG. The electric control device 30 sets the drive voltage signal DV to the same time t1 as the time t1 when the drive signal INJ for opening the valve to the electromagnetic on-off type discharge valve 14 rises (changes from a low level signal to a high level signal), Alternatively, application of the piezoelectric / electrostrictive element 15g is started from time t0 immediately before time t1, and the trailing edge of the valve opening drive signal INJ to the electromagnetic open / close type discharge valve 14 (changes from a high level signal to a low level signal).
Time t4, which is a time later than the time t3 by a predetermined time, and at which the pressure of the liquid in the liquid supply passage 15-1 decreases to a steady pressure when the electromagnetic on-off type discharge valve 14 is closed. Up to the piezoelectric / electrostrictive element 15 of the drive voltage signal DV
The application to the drive voltage signal DV is continued at the same time point t4.
Is terminated.

Next, the operation of the liquid ejecting apparatus constructed as described above will be explained. The electric control unit 30 operates the valve opening drive signal INJ based on the engine operating conditions such as the engine speed N and the intake pipe pressure P. (The length of the high level signal) is determined, and the timing (time t1 in FIG. 6) at which the valve opening drive signal INJ is output is determined. Then, the electric control device 30 starts to apply the driving voltage signal DV of the frequency f between the electrodes of the piezoelectric / electrostrictive element 15g at time t0, which is a predetermined time before the time t1, and opens the valve at time t1. The drive signal INJ is applied to the electromagnetic on-off type discharge valve 14.

At time t2 which is slightly delayed from time t1 (that is, when the ineffective injection time of the electromagnetic on-off type discharge valve 14 elapses), the needle valve 14d is moved to open the discharge hole 14c-2, The fuel in the fuel passage 14b is discharged from the discharge hole 14c-2 into the liquid supply passage 15-1 of the injection device 15A through the hollow cylindrical closed space of the sleeve 15D and the liquid injection port 15-5 of the injection device 15A.・ Begin to be supplied. As a result, the liquid supply passage 15-
The pressure of the liquid in 1 starts rising as shown in FIG. 6 (B).

Then, after the time t2, when the pressure of the fuel in the chamber 15-2 rises to a sufficient pressure, the fuel is the liquid injection port 15-4a as shown in FIG.
Is ejected (injected) from the end face of the liquid ejection space 21 into the liquid ejection space 21 in the intake pipe 20. At this time, the vibration energy due to the operation of the piezoelectric / electrostrictive element 15g is generated in the chamber-15.
Since it is added to the fuel within −2, a constricted portion is generated in the fuel, and the fuel is detached from the constricted portion at the tip portion thereof so as to be torn off. As a result, uniform and finely divided fuel is injected into the intake pipe 21.

In this case, the discharge amount (discharge flow rate) of the liquid discharged from the electromagnetic opening / closing discharge valve 14 per unit time is Q
(Cc / min), and the discharge nozzle 1 of the injection device 15A from the electromagnetic open / close type discharge valve 14 (that is, the end surface gp of the outer cylinder portion 14c of the electromagnetic open / close type discharge valve 14 on the injection device 15A side).
When the volume of the liquid flow path formed up to the tip of 5-4 (that is, the end surface of the liquid ejection port 15-4a) is V (cc), the ratio (V / Q) is 0.03 or less. It is configured so that

Here, the volume V is the hollow cylindrical closed space formed by the sleeve 15D, the liquid injection port 15-5, the liquid supply passage 15-1, the chamber 15-2, the liquid introduction hole 15-3, and the liquid. This is the total volume of the discharge nozzles 15-4.

Further, in this embodiment, as shown in FIG. 6, the time when the valve opening drive signal INJ is the high level signal is limited to the time when the intake valve 22 of the internal combustion engine is opened. It was set so that In other words, when the fuel injected by the liquid injection device reaches the intake valve 22, the intake valve 22 is opened, and the fuel is injected into the intake valve 2.
It was designed to be directly sucked into the cylinder without adhering to the back surface of No.2. As a result, the fuel that is atomized and injected is directly sucked into the cylinder, so that it does not adhere to the wall surfaces of the intake valve 22 and the intake pipe 20. It was possible to reduce the amount of fuel gas.

The speed of the atomized fuel (droplets, spray droplets) ejected from the liquid ejection nozzle 15-4 is
It is preferable to change it according to the lift amount of the intake valve 22 and / or the intake flow velocity (wind speed) in the intake pipe. According to this, the fuel atomized and injected can be directly sucked into the cylinder without further adhering to the wall surface. The speed of the atomized fuel injected from the liquid ejection nozzle 15-4 is determined by the waveform of the drive voltage signal DV (particularly, the rising speed of the signal DV or the maximum voltage) with respect to the piezoelectric / electrostrictive element 15g. It can be changed by changing or by changing the pressure (fuel pressure) of the fuel supplied to the electromagnetic on-off type discharge valve 14. Further, the fuel pressure is changed by changing the adjustment pressure of the pressure regulator 13, or the pressure regulator 1
In the case where 3 is not provided, it can be changed by changing the discharge pressure of the pressurizing pump.

As described above, according to the liquid ejecting apparatus according to the embodiment of the present invention, the fuel is pressurized by the pressure pump 11, and the pressure of the fuel causes the fuel to enter the liquid ejecting space 21 in the intake pipe 20. Since the fuel is injected, it is possible to stably inject a desired amount of fuel even when the pressure (intake pressure) in the liquid injection space 21 changes.

Further, vibration energy is applied to the fuel by the volume change of the chamber 15-2 of the injection device 15A, and the fuel is atomized into the liquid discharge nozzle 1 while being atomized.
It is injected from 5-4a. As a result, the present liquid ejecting apparatus was able to eject extremely finely divided droplets. Further, since the injection device 15A includes the plurality of chambers 15-2 and the plurality of discharge nozzles 15-4, even if bubbles are generated in the fuel, the bubbles are likely to be finely divided, and as a result, It was possible to avoid large fluctuations in the injection amount due to the presence of bubbles.

The discharge hole 14 of the electromagnetic on-off type discharge valve 14
As the distance from c-2 to the liquid supply passage 15-1 increases, the distance of the fuel discharged from the discharge hole 14c-2 from the central axis CL of the hollow cylindrical closed space increases. Since the direction of fuel discharge from the discharge hole 14c-2 is determined, the flow of fuel discharged occurs in a wide portion of the hollow cylindrical closed space formed by the sleeve 15D. As a result, in particular, it is difficult for bubbles to occur in the corner portion (the portion indicated by the black triangle mark in FIG. 3) near the discharge hole 14c-2 of the electromagnetic open / close type discharge valve 14 in the closed space, or the same. The performance of discharging bubbles generated at the corners is improved. Therefore, in this liquid injection device, the increase in the fuel pressure is not easily obstructed by the bubbles, so that the pressure of the fuel can be increased as expected, and the liquid injection of the fuel can be performed at the injection amount and the injection timing required by the mechanical device such as the internal combustion engine. It became possible to eject drops.

In the liquid ejecting apparatus, the liquid ejected from the electromagnetic on-off type ejection valve 14 is ejected from the ejection nozzle 1
The flow of the liquid is at least once (4 in this example) between the time 5-4 and the time when the liquid is injected into the liquid injection space 21.
It is configured so that it can be bent at a substantially right angle.

That is, in the present liquid ejecting apparatus, the flow of the liquid discharged from the electromagnetic on-off type discharge valve 14 is such that the liquid injection port 15-5 and the liquid supply passage 15-1 are orthogonal to each other. The liquid inlet 15-5 and the liquid supply passage 15
It is bent at a right angle at the connection with -1. Next, since the major axis direction of the liquid supply passage 15-1 is parallel to the X axis and the central axis of the liquid introduction hole 15-3 is parallel to the Z axis, the liquid supply passage 15-1 and the liquid introduction hole 15 are arranged. At the -3 connection, the liquid flow is bent at a right angle.

Further, since the major axis of the chamber 15-2 is parallel to the Y axis and the central axis of the liquid introducing hole 15-3 is parallel to the Z axis, the chamber 15-2 and the liquid introducing hole 15-3 are arranged.
At the connection, the liquid flow is bent at a right angle. Further, since the major axis of the chamber 15-2 is parallel to the Y axis and the axis of the liquid ejecting nozzle 15-4 is parallel to the Z axis, the connecting portion between the chamber 15-2 and the liquid ejecting nozzle 15-4. Even at, the liquid flow is bent at a right angle.

According to this structure, since the flow of the liquid discharged from the electromagnetic on-off type discharge valve 14 is bent at least once at a substantially right angle, the liquid pressure accompanying the opening of the electromagnetic on-off type discharge valve 14 is increased. Pulsation is reduced, and stable droplet ejection can be performed. In other words, the dynamic pressure of the liquid that accompanies the opening of the electromagnetic on-off valve 14 becomes a static pressure, and the fuel is injected under the static pressure. As a result, it has become possible to stably inject the fuel from each discharge nozzle.

In particular, the present liquid ejecting apparatus has the ejecting device 1
5A has a plurality of chambers 15-2, 15-2, ... Connected to a common liquid supply passage 15-1, and the flow of the liquid discharged from the electromagnetic on-off type discharge valve 14 is the liquid injection port 15-. 5 is bent at a substantially right angle at the connecting portion between the liquid supply passage 15-1 and the liquid supply passage 15-1, the pressure of the liquid in the liquid supply passage 15-1 becomes stable. Therefore, each chamber 15-2, 15-2
Since the liquid pressure inside is static and stable,
The droplets discharged from the discharge nozzles 15-4, 15-4, ... Connected to the chambers 15-2, 15-2, ... Can be made uniform.

Further, in the electromagnetic on-off type discharge valve 14, the discharge streamline of the liquid (fuel) discharged from the discharge hole 14c-2 (shown by the one-dot chain line DL in FIG. 3) is the sleeve 15
The side wall 15D-1 and the side wall 15D-1 which form the hollow cylindrical closed space of D intersect with the side wall WP which is virtually extended to the plane portion (the upper surface of the ceramic sheet 15b) sp of the liquid supply passage 15-1. Without liquid supply passage 15
It is arranged so as to directly intersect the plane portion sp of -1.

As a result, the liquid discharged from the electromagnetic on-off type discharge valve 14 reaches the flat portion sp of the liquid supply passage 15-1 while maintaining its kinetic energy (flow velocity) at a high level. The plane portion sp strongly reflects toward the ejection hole 14c-2 side of the hollow cylindrical closed space. As a result, the flow of the reflected liquid discharges the air bubbles staying at the corners (portions indicated by black triangles in FIG. 3) near the discharge holes 14c-2 in the hollow cylindrical closed space. , The amount of bubbles present in the liquid is reduced. As a result, in the liquid ejecting apparatus, the increase in the pressure of the liquid is less likely to be hindered by the bubbles, and the pressure of the liquid can be increased as expected. It became possible to do.

The discharge amount (discharge flow rate) Q (cc / cc) of the liquid discharged from the electromagnetic open / close type discharge valve 14 per unit time
Min), and the injection device 15A from the electromagnetic on-off type discharge valve 14
Since the ratio (V / Q) of the volume V (cc) of the liquid flow path formed up to the tip of the discharge nozzle 15-4 is 0.03 or less, the volume V is Since it does not become excessive with respect to the discharge flow rate Q, the time from the start of discharge of the liquid by the electromagnetic open / close type discharge valve 14 to the rise of the pressure of the liquid in the discharge nozzle 15-4 of the injection device 15A is shortened. It was possible to eject the liquid droplets at a desired timing.

Further, in the liquid ejecting apparatus, the generation of the drive voltage signal DV is made earlier than the generation of the valve opening drive signal INJ, and the drive voltage signal DV is made to disappear rather than the valve open drive signal INJ is made to disappear. I'm late. As a result, since vibrational energy is always given to the injected fuel, the fuel can be surely atomized and injected at the start and end of the injection, and the drive voltage signal DV is generated only when necessary. As a result, the power consumption can be reduced.

That is, the droplet jetting device according to the present invention is
A liquid ejection nozzle whose one end is exposed to the liquid ejection space, a piezoelectric / electrostrictive element that is operated by a drive voltage signal, and the volume is changed by the operation of the piezoelectric / electrostrictive element, and the other end of the liquid ejection nozzle An ejection device including a connected chamber, a liquid supply passage connected to the chamber, and a liquid injection port that communicates the liquid supply passage with the outside, a pressurizing unit for pressurizing the liquid, and the pressurizing unit. Is provided with a liquid pressurized by the electromagnetic opening / closing valve driven by a valve opening drive signal and a discharge hole opened / closed by the electromagnetic opening / closing valve, and the electromagnetic opening / closing valve is driven. And a drive voltage signal generating means for generating the drive voltage signal, and an electromagnetic on-off type discharge valve for discharging the pressurized liquid to the liquid injection port of the ejection device through the discharge hole. An electric control device including a valve-opening drive signal generating means for generating a valve-driving signal, wherein the liquid discharged from the electromagnetic on-off type discharge valve is atomized by the volume change of the chamber to discharge the liquid. A liquid ejecting apparatus that ejects liquid droplets from a nozzle into the liquid ejecting space, wherein the electrical control device is configured to start increasing the pressure of the liquid in the liquid supply passage due to the generation of the valve opening drive signal. It can also be said that it is configured to start generating the drive voltage signal from the previous time point.

According to this, at the time when the pressure of the liquid in the liquid supply passage starts to rise due to the generation of the valve opening drive signal, that is, the ejection of droplets from the ejection nozzle of the ejection device is started. At a time when there is a possibility, the piezoelectric / electrostrictive element has already been driven by the drive voltage signal and vibration energy has been applied to the liquid, so it is possible to reliably eject finely divided droplets from the beginning of the ejection of the liquid. .

Similarly, the liquid droplet ejecting apparatus according to the present invention is a liquid ejecting nozzle, one end of which is exposed in the liquid ejecting space,
A piezoelectric / electrostrictive element operated by a drive voltage signal, a chamber whose volume is changed by the operation of the piezoelectric / electrostrictive element and which is connected to the other end of the liquid ejection nozzle, and a liquid supply connected to the chamber An injection device including a passage and a liquid injection port that communicates the liquid supply passage with the outside, a pressurizing unit that pressurizes the liquid, and the liquid pressurized by the pressurizing unit is supplied and opened. An electromagnetic opening / closing valve driven by a valve drive signal and a discharge hole opened / closed by the electromagnetic opening / closing valve, and discharges the pressurized liquid when the electromagnetic opening / closing valve is driven. An electromagnetic opening-and-closing type discharge valve for discharging to a liquid injection port of the injection device through a hole, a drive voltage signal generating means for generating the drive voltage signal, and a valve opening drive signal generating means for generating the valve opening drive signal. Comprising an electric control device comprising,
A liquid ejecting apparatus which atomizes the liquid ejected from the electromagnetic open / close type ejection valve by the volume change of the chamber and ejects the liquid into the liquid ejecting space from the liquid ejecting nozzle, wherein the electrical control device includes the valve opening valve. It can be said that the liquid ejecting apparatus is configured to continue the generation of the drive voltage signal until a time point after the extinction of the drive signal.

According to this, even after the valve-opening drive signal disappears, the pressure of the liquid in the liquid supply passage is higher than the pressure required for ejection, so that the droplets are ejected from the ejection nozzle of the ejection device. At the time when the ejection is performed, the piezoelectric / electrostrictive element is still driven by the drive voltage signal, and vibration energy is applied to the liquid. Therefore, even after the valve opening drive signal disappears (until the liquid is no longer ejected), the liquid can be reliably atomized and ejected.

Furthermore, since the axis of each liquid discharge nozzle 15-4 is parallel to the Z axis, each discharge nozzle 15-
Since the liquid droplets ejected from the liquid ejecting space 21 from 4 do not substantially intersect with each other during flight, the fuel liquid droplets do not collide with each other in the liquid ejecting space 21 and become large liquid droplets. As a result, it was possible to form a uniform and atomized fuel spray.

In the above embodiment, the intensity of vibration applied to the fuel depends on the potential difference (that is, the driving voltage signal DV of the driving voltage signal DV) applied between the electrodes (not shown) provided on the upper surface and the lower surface of the piezoelectric / electrostrictive element 15g. It varies depending on the maximum voltage, the strength of the electric field applied to the piezoelectric / electrostrictive 15g, the thickness of the ceramic sheet 15f (upper wall of the chamber 15-2), and the like. In this example, the ceramic sheet 15f is deformed by the operation of the piezoelectric / electrostrictive element 15g, and the volume change amount ΔV of the chamber 15-2 obtained by this is the chamber 15-
When expressed as a ratio V / ΔV (that is, chamber volume / volume change amount) related to the volume V of 2, the same ratio V / ΔV was set to 1500. It should be noted that this ratio V / ΔV is 30 when 2 or more.
A value of 00 or less, particularly a value of 2 or more and 1500 or less is preferable.

This is because when the ratio (chamber volume / volume change amount) exceeds 3000, the amount of vibration energy transmitted to the liquid in the chamber 15-2 becomes small, and sufficient atomization of the liquid cannot be realized. When the same ratio (chamber volume / volume change amount) becomes smaller than 2, the pressure of the liquid in the chamber 15-2 fluctuates greatly, and the discharge amount (jet flow rate) becomes unstable, and
This is because when the liquid is volatile like gasoline fuel, a large amount of bubbles are generated inside the liquid, and stable injection may not be possible, which is feared.

The droplet size of gasoline injected under the above conditions was uniform at 30 μm, and as a result, it was possible to improve fuel efficiency and reduce harmful exhaust gas.

Further, in the liquid ejecting apparatus of the above embodiment, an experiment for investigating the relationship between the nozzle diameter D and the introduction hole diameter d of the ejecting unit 15 (ejection device 15A) and the ejection condition of the liquid droplets is conducted. It was In this experiment, the length L of the long axis of the chamber 15-2 is 3.5.
mm, the length W of one side of the cross section of the chamber 15-2, and the height T were 0.35 mm and 0.15 mm, respectively, and the injection device 15A was used, and gasoline was used as the discharge liquid. Further, at the time of ejection (during ejection), the liquid pressure in the chamber 15-2 is increased to 0.1 MPa, and the driving frequency f is set to 4 in the piezoelectric / electrostrictive element 15g.
A drive voltage signal DV having a frequency of 5 kHz and a maximum voltage value V0 of the signal of 20 V was applied. The experimental results are shown in Table 1. In this experiment, it is assumed that the size of the droplet is smaller than the nozzle diameter D at a position 5 mm away from the end of the liquid ejection port 15-4a toward the ejection space and the ejection is performed stably. The ejection status was considered good (indicated by “◯” in Table 1), and the other cases were inferior (indicated by “x” in Table 1).

[0085]

[Table 1]

As can be seen from Table 1, the introduction hole diameter d
When the ratio (D / d) of the nozzle diameter D with respect to 6 was larger than 6.200, stable ejection was not performed (see Sample 1). This is because when the diameter d of the introduction hole becomes excessively small with respect to the diameter D of the nozzle, the flow resistance in the liquid introduction hole 15-3 becomes excessively large, so that the amount of liquid flowing into the chamber 15-2 becomes insufficient. Is considered to be.
Therefore, it is desirable that the ratio D / d is less than 6.200 (preferably 5.000 or less, and more preferably 4.429 or less (see Sample 2)).

As can be seen from Table 1, when the ratio D / d was smaller than 1.000, stable ejection was not performed (see Sample 5). This is because the diameter d of the introduction hole is excessively larger than the diameter D of the nozzle, so that the vibration (vibration energy) of the piezoelectric / electrostrictive element 15g applied to the liquid is passed through the liquid introduction hole 15-3 and the liquid supply passage 15 is formed.
It is considered that the same vibration (vibration energy) was not sufficiently applied to the liquid ejected from the chamber 15-2 through the ejection nozzle 15-4 by being absorbed on the -1 side.

Therefore, the piezoelectric / electrostrictive element 1 is applied to the liquid to be ejected.
In order to transmit the vibration of 5g sufficiently, the ratio D /
d is greater than 1.000 (preferably 1.240)
That is, the sectional area at one end of the liquid ejection nozzle 15-4, which is determined by the nozzle diameter D, exposed in the liquid ejection space (the sectional area of the liquid ejection port 15-4a) is
It is preferable that it is configured to be larger than the cross-sectional area of the liquid introduction hole 15-3 determined by the introduction hole diameter d.

According to this, the vibration energy of the piezoelectric / electrostrictive element 15g added to the liquid in the chamber 15-2 is less likely to be attenuated in the liquid supply passage 15-1 via the liquid introduction hole 15-3, and the same. Vibration energy is discharged from the nozzle 15
Since the liquid is efficiently transmitted to the liquid discharged from one end of -4, atomization of the liquid is reliably achieved.

Further, when a similar experiment was conducted with the nozzle diameter D set to various values, the nozzle diameter D was 0.1 mm.
The following is preferable, and further 0.02 to 0.0
It has been found that 4 mm is more desirable. This is because when the nozzle diameter D is larger than 0.1 mm, it becomes difficult to atomize the ejected droplets, and when the nozzle diameter D is smaller than 0.02 mm, dust contained in the liquid (fuel or the like) is discharged into the liquid jet port 15. This is because the -4a is likely to be clogged and the practicality is impaired.

Further, in the liquid ejecting apparatus of the above embodiment, a sinusoidal potential difference of frequency f (driving voltage signal of driving frequency f = 1 / T, period T) is applied between the electrodes of the piezoelectric / electrostrictive element 15g, Piezoelectric / electrostrictive element 15g in that case
Maximum displacement (Z of piezoelectric / electrostrictive element 15g in FIG. 5)
The maximum amount of displacement in the axial direction) was examined. The result of the experiment is shown in FIG. The vertical axis of FIG. 8, to the maximum displacement amount D ₀ of the piezoelectric / electrostrictive elements 15g when the drive frequency f was 5 kHz, the maximum displacement amount D _f of the piezoelectric / electrostrictive elements 15g at each driving frequency f Ratio (D _f / D ₀ ).

As shown in FIG. 8, the ratio (D _f / D ₀ ) became maximum when the driving frequency f was in the vicinity of 50 kHz. The frequency near 50 kHz is
2 structure, the structure of the liquid ejection nozzle 15-4, the nozzle diameter D, the introduction hole diameter d, the shape of the portion of the piezoelectric / electrostrictive element 15g that causes deformation of the ceramic sheet 15f, the type of liquid, and the like. Is equal to the resonance frequency (natural frequency) of the injection device 15A. That is, the drive voltage signal D
By matching the drive frequency f of V with the frequency near the resonance frequency of the ejection device 15A (ejection unit 15), even if the amplitude of the drive voltage signal DV is the same, a large vibration is generated in the piezoelectric / electrostrictive element 15g. It has been found that the pressure of the liquid can be greatly oscillated with smaller energy. As described above, in the liquid ejecting apparatus according to the present invention, the driving frequency f of the piezoelectric / electrostrictive element 15g is a frequency in the vicinity of the resonance frequency of the ejecting device 15A (a frequency of 0.7 to 1.3 times the resonance frequency). That is, it is preferably within ± 30% of the resonance frequency). By doing so, since the wall surface of the ejection device (ejection unit) can be greatly vibrated with a small amount of energy, the power consumption of the liquid ejection device is reduced. It turned out that it can be made smaller.

As described above, according to the liquid ejecting apparatus of the present invention, the fuel as the liquid can be finely atomized into a fine size and ejected into the liquid ejecting space. The present invention is not limited to the above-mentioned embodiment, and various modifications can be adopted within the scope of the present invention. For example, in the above embodiment,
It is configured such that the flow of the liquid discharged from the electromagnetic open / close type discharge valve 14 is bent at a substantially right angle four times before the liquid is discharged from the discharge nozzle 15-4 into the liquid spray space 21. However, as shown in FIG. 9, the flow of the liquid may be bent only once at a substantially right angle.
As shown in, the flow of the liquid may be bent twice substantially at right angles. Further, the liquid ejecting apparatus according to the above-mentioned embodiment,
Although it was applied to the internal combustion engine, it can also be applied to other mechanical devices or the like that form a material with droplets of a liquid raw material that has been atomized.

Further, although the liquid ejecting apparatus of the above-mentioned embodiment is applied to the gasoline internal combustion engine of the type in which fuel is injected into the intake pipe (intake port), the liquid droplet ejecting apparatus according to the present invention is applied to the inside of the cylinder. It is also effective to apply to a so-called "direct injection gasoline internal combustion engine" that directly injects fuel. That is, when the fuel is directly injected into the cylinder by the electric control type fuel injection device using the conventional fuel injector, the fuel may accumulate in the gap (clevis) between the cylinder and the piston, and unburned HC (hydrocarbon) ) In some cases, when the fuel is directly injected into the cylinder using the liquid injection device according to the present invention, the fuel is injected into the cylinder in a finely divided state. The amount of fuel adhering to the inner wall surface can be reduced, or the amount of fuel entering the gap between the cylinder and piston can be reduced.
The emission amount of C can be reduced.

Furthermore, it is also effective to use the liquid droplet ejecting apparatus according to the present invention as a direct injection injector for a diesel engine. That is, the conventional injector has a problem that it is impossible to inject the atomized fuel because the fuel pressure is low especially when the engine load is low. In this case, if the common rail type injection device is used, the fuel pressure can be increased to some extent even when the engine is running at low speed, so that the atomization of the injected fuel can be promoted.
Since the fuel pressure is lower than when the engine is running at high speed, the fuel cannot be sufficiently fine particles. On the other hand, the liquid ejecting apparatus according to the present invention atomizes the fuel by operating the piezoelectric / electrostrictive element 15g regardless of the load of the engine (that is, even when the engine has a low load). It is possible to inject sufficiently atomized fuel.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a liquid ejecting apparatus according to an embodiment of the present invention applied to an internal combustion engine.

FIG. 2 is a view showing an electromagnetic opening / closing type discharge valve and an injection unit shown in FIG.

FIG. 3 is an enlarged cross-sectional view of the electromagnetic on-off type discharge valve and the injection unit near the tip of the electromagnetic on-off type discharge valve shown in FIG.

FIG. 4 is a plan view of the ejection device shown in FIG.

5 is a cross-sectional view of the injection device cut along a plane along line 1-1 of FIG.

6 (A) is an opening / closing valve drive signal applied to an electromagnetic opening / closing type discharge valve, FIG. 6 (B) is a liquid pressure in a liquid supply passage, and FIG. 6 (C) is a piezoelectric / electrostrictive element. FIG. 6D is a time chart showing the opening timing of the intake valve, and the drive voltage signal applied to the element.

7 is a diagram showing a state of liquid ejected from the liquid ejecting apparatus according to the present invention shown in FIG.

FIG. 8 is a graph showing changes in the amount of displacement of the piezoelectric / electrostrictive element when the frequency of the drive voltage signal applied to the piezoelectric / electrostrictive element is changed.

9 is a conceptual diagram showing the flow of liquid in a modification of the liquid ejecting apparatus shown in FIG.

10 is a conceptual diagram showing the flow of liquid in another modification of the liquid ejecting apparatus shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Liquid injection device, 11 ... Pressurizing pump, 11a ... Introduction part, 11b ... Discharge part, 12 ... Liquid supply pipe, 14 ... Electromagnetic opening-and-closing type discharge valve, 14c ... Outer cylinder part, 14c-2 ... Discharge hole, 1
4d ... Needle valve, 15 ... Injection unit, 15A ... Injection device, 15B ... Injection device fixing plate, 15C ... Holding unit, 15a-15f ... Ceramic sheet, 15g
... Piezoelectric / electrostrictive element, 15-1 ... Liquid supply passage, 15-2
... Chamber, 15-3 ... Liquid introduction hole, 15-4 ... Liquid ejection nozzle, 15-4a ... Liquid injection port, 15-5 ... Liquid injection port, 20 ... Intake pipe, 21 ... Fuel injection space, 30 ...
Electric control device.

Claims (6)

[Claims] 1. A liquid ejection nozzle, one end of which is exposed in a liquid ejection space, a piezoelectric / electrostrictive element, the volume of which is changed by the operation of the piezoelectric / electrostrictive element, and which is connected to the other end of the liquid ejection nozzle. A chamber, a liquid supply passage connected to the chamber, and a hollow cylindrical liquid injection port that communicates the liquid supply passage with the outside; a pressurizing unit for pressurizing the liquid; It is provided with a liquid pressurized by a pressure means, and is provided with an electromagnetic opening / closing valve and a discharge hole opened / closed by the electromagnetic opening / closing valve, and the discharge hole is opened when the electromagnetic opening / closing valve is opened. An electromagnetic open / close type discharge valve for discharging the pressurized liquid via a liquid, and a diameter substantially the same as the liquid inlet between the discharge hole of the electromagnetic open / close type discharge valve and the liquid inlet of the injection device. The hollow cylindrical closed space of A liquid ejecting liquid ejected from the electromagnetic on-off type ejection valve into fine particles by changing the volume of the chamber and ejecting the liquid ejecting nozzles into the liquid ejecting space as droplets. In the device, the electromagnetic on-off type discharge valve has a distance from a central axis of the hollow cylindrical closed space of the liquid discharged from the discharge hole,
A liquid ejecting apparatus configured to eject the liquid in a direction having a predetermined angle with respect to the central axis so as to increase with an increase in a distance from the ejection hole toward the liquid injection port. 2. The liquid ejecting apparatus according to claim 1, wherein the predetermined angle is 5 ° or more and 30 ° or less. 3. The liquid ejecting apparatus according to claim 1, wherein the liquid ejected from the electromagnetic opening / closing ejection valve is ejected from the ejection nozzle into the liquid ejection space. A liquid ejecting apparatus configured such that the flow of the liquid is bent at least once at a substantially right angle. 4. The liquid ejecting apparatus according to claim 1, wherein the liquid supply passage faces a virtual plane formed by a portion communicating with the liquid injection port. And the electromagnetic open / close type discharge valve, wherein the discharge streamline of the liquid discharged from the discharge hole is the hollow cylindrical shape formed by the closed space forming member. The liquid ejecting apparatus is configured to intersect the flat surface portion of the liquid supply passage without intersecting the side wall of the closed space and the side wall that virtually extends the side wall to the flat portion of the liquid supply passage. 5. The liquid ejecting apparatus according to claim 1, wherein a discharge amount Q (cc / min) of the liquid discharged from the electromagnetic opening / closing discharge valve per unit time. ), The ratio (V / Q) of the volume V (cc) of the liquid flow path formed from the electromagnetic open / close type discharge valve to the tip of the discharge nozzle of the injection device is 0.03.
The following liquid ejecting apparatus. 6. The liquid ejecting apparatus according to any one of claims 1 to 5, wherein the ejecting device includes a plurality of the liquid ejecting nozzles, and ejects from each of the liquid ejecting nozzles. A liquid ejecting apparatus configured such that droplets are ejected in parallel to each other.