JPH03286177A - Fuel injection valve - Google Patents

Abstract

PURPOSE:To control a fuel injection amount from a very low flow rate to a high flow rate with high accuracy by interposing a piezoelectric element between a housing having a fuel injection port and a valve seat and a valve body having a valve portion at the valve seat, and providing an elastic body for energizing the valve portion of the valve body in the closing direction of the fuel injection port. CONSTITUTION:With application of a pulse voltage of, for example, 0-100V, a piezoelectric element 13 is extended by a piezoelectric function to instantly move a valve body 11 in such a direction that the valve portion 11a of the valve body 11 is separated from a valve seat 9, whereby a fuel injection port 8 is opened so that fuel is injected. with application of a high voltage having the same frequency as a resonance frequency determined by a spring constant of a spring 15 and a weight of the valve body 11 to the piezoelectric element 13, the valve body 11 is elevated by a displacement amount several times larger than that of the piezoelectric element 13. Therefore, a fuel injection amount can be changed arbitrarily according to magnitude, frequency and application time of the pulse voltage applied to the piezoelectric element 13, and the fuel injection amount can be controlled from a very low flow rate to a high flow rate with high accuracy.

Description

[Detailed description of the invention] [Purpose of the invention]

(Industrial Application Field) The present invention relates to a fuel injection valve that is used to perform fuel injection by opening and closing a fuel injection port by reciprocating a valve body using a piezoelectric element. (Prior Art) Conventionally, a fuel injection valve that injects fuel by opening and closing a fuel injection port by reciprocating a valve body using a piezoelectric element has been used, for example, as shown in FIG. Publication) and as shown in FIG. 5 (Utility Model Application Publication No. 126555/1983). Among these, the fuel injection valve 51 shown in FIG. 4 includes two disk-shaped piezoelectric elements 53a on the male threaded portion 52a of the horn 52, which has a male threaded portion 52a, a flange portion 52b, a fuel passage 52C, and a vibration amplifying portion 52d. 53b and electrode plate 54
a, 54b are inserted through the insulating vibrator 55, and the piezoelectric elements 53a, 53b are fixed between the horn 52 and the flange portion 52b by screwing the nut 7157 into the male threaded portion 52a through the washer 56. A valve seat 59 having a fuel outlet 58 is fixed to the vibration amplifying portion 52d, and a valve body 61 is provided with a valve portion 61a for opening and closing the fuel outlet 58. A spring 63 is provided between the provided spring receiving portion 62 and the valve seat 59 to bias the valve portion 61a in a direction to close the fuel outlet 58. In the fuel injection valve 51 having such a structure, by applying a high frequency voltage to the piezoelectric elements 53a, 53b via the electrode plates 54a, 54b, the piezoelectric elements 53a,
53b expands and contracts, thereby causing the entire fuel injection valve 51 to vibrate, thereby applying a predetermined excitation force to the spring 63, the valve portion 61a moves away from the fuel outlet 58 and opens the valve, thereby causing the fuel to be injected. It is atomized and sprayed. Further, the fuel injection valve 71 shown in FIG.
A spherical valve 73 for opening and closing the fuel injection hole 72a is provided inside the valve casing 72 having a valve seat 72b and a valve seat 72b.
A guide member 75 is provided at the other end of the piezoelectric element 74 and provided with a fuel passage 75a, and is screwed into an internal threaded portion 72c formed inside the valve casing 72. Spring adjuster 76 having a male threaded portion 76a and a fuel introduction hole 76b
It has a structure in which a coil spring 77 is provided between the guide member 75 and the guide member 75. In the fuel injection valve 71 having such a structure, when a negative voltage is applied to the piezoelectric element 74 via the lead wires 78a and 78b, the spherical valve 73 is separated from the valve seat 72b due to instantaneous contraction of the piezoelectric element 74. , fuel injection lower 2
A is opened so that fuel can be injected. (Problems to be Solved by the Invention) However, in the conventional fuel injection valve 51.71 described above, the former fuel injection valve 51 disclosed in FIG. 53a
, 53b is used to excite the entire fuel injection valve 51, and since the excitation is caused by longitudinal vibration, excessive power is required from the point of view of injecting fuel, and furthermore, it is difficult to miniaturize the injector. The problem was that it was difficult. Further, when fixing the fuel injection valve 51, there is a problem that it is difficult to attach the fuel injection valve 51 because if the nodes of vibration are not fixed, unnecessary parts (for example, the fuel supply pipe) will also vibrate. On the other hand, in the fuel injection valve 71 disclosed in the latter figure 'S5 (Japanese Utility Model Publication No. 63-126555), the piezoelectric element 74 contracts rapidly, causing the spherical valve 73 to close to the valve seat 72b.
Since the fuel injection hole 72a is configured to open further away, the amount of lift of the spherical valve 73 is determined by the amount of contraction of the piezoelectric element 74 and the downward pressing force of the coil spring 77. There is a problem that fuel cannot be injected, and it has been a challenge to solve these problems. (Purpose of the Invention) This invention was made in view of such conventional problems, and it is possible to control the amount of fuel injection with high precision from a minute flow rate to a large flow rate, and it is possible to control the amount of fuel injection with high precision, and also to It is an object of the present invention to provide a fuel injection valve that does not require much power and can be fixed relatively easily.

[Structure of the invention]

(Means for Solving the Problems) A fuel injection valve according to the present invention includes a housing having a fuel injection port and a valve seat, and a valve body having a valve portion that contacts the valve seat in a spaced manner to open and close the fuel injection port. A piezoelectric element is provided between the holes, and an elastic body is provided that biases the valve portion of the valve body in the direction of closing the fuel injection port.
An embodiment characterized in that Lrj is configured to open the fuel injection port by separating the valve portion of the valve body from the valve seat against the biasing force of the elastic body by stretching the piezoelectric element. A piezoelectric sensor is provided between the housing and the elastic body, and the piezoelectric element is drive-controlled by detecting the operating state of the valve body via the elastic body based on a signal from the piezoelectric sensor. The structure of the fuel injection valve is a means for solving the above-mentioned conventional problems. (Function of the Invention) Since the fuel injection valve according to the present invention has the above-described configuration, when the piezoelectric element is energized, the piezoelectric element expands to cause the valve body to move against the urging force of the elastic body. Since the valve part is separated from the valve seat and the fuel injection port opens, the amount of fuel injected can be controlled with high precision from a minute flow rate to a large flow rate by controlling the energization of the piezoelectric element. As a result, a large amount of power is not required for fuel injection. (Embodiment) FIG. 1 shows an embodiment of a fuel injection valve according to the present invention. The fuel injection valve 1 shown in FIG. 1 has a housing 2 that is a combination of an upper housing 2a and a lower housing 2b.
It is caulked and fixed airtightly via a ring 3. The upper housing 2a has a lead terminal 4, a fuel inlet 5. A fuel outlet 6 is provided and an adjusting screw 7 is screwed in. Further, the lower housing 2b is provided with a fuel injection port 8, a valve seat 9, and an annular protrusion 10. Inside the housing 2, a valve portion 11a that opens and closes the fuel injection port 8 by contacting the valve seat 9 at a distance, a shaft portion 11b, a protruding portion 11c, a shaft portion lid, and a large diameter portion 11 are provided.
A valve body 11 is provided, and a fuel reservoir 12 is provided between the shaft portion 11b of the valve body 11 and the lower housing 2b. Further, a piezoelectric element 13 is provided between the bottom side of the flange portion 11f of the valve body 11 and the inner diameter side of the annular protrusion 1o provided on the lower housing 2b, and the Riet wire f3a, ? 3b is connected to the lead terminal 4. This piezoelectric element 13 is made of a piezoelectric material such as lead zirconate titanate (PZT) or barium titanate (BaTi03), and is preferably made into a cylindrical shape by a laminate or molded body. The lower end of the piezoelectric element 13 is fixed to the upper end surface of the lower housing 2b with adhesive or the like, and the upper end is fixed to the flange portion 1 of the valve body 11.
It is brought into contact with the bottom surface of 1f. Further, a spring 15, which is an elastic body, is provided between the inner diameter side of the annular protrusion 11g provided on the upper surface of the flange portion 11f of the valve body 11 and the adjustment screw 7. It has a structure that biases the fuel injection port 8 in the direction of closing it,
A protrusion 11c provided on the valve body 11 holds the valve body 11 slidably within a fuel passage 16 provided in the lower housing 2b. When injecting fuel with the fuel injection valve 1 having such a structure, the lead terminal 4 and the lead wire 13a are
, 13b, a pulse voltage of, for example, 0 to 1 oov is applied to the piezoelectric element 13. By applying this pulse voltage, the piezoelectric element 13 expands due to its piezoelectric action, thereby moving the valve body 11 to its valve portion 1.
1a is instantly moved in the direction away from the valve seat 9, the fuel injection port 8 is opened, and fuel is injected. At this time, the valve body 11 moves at a speed given by the displacement of the piezoelectric element 13 and the spring 15.
After rising by a predetermined amount determined by the spring constant of
By coming into contact with the fuel injection port 8, the fuel injection port 8 is closed again. By the way, in such a state, if a high voltage with the same frequency as the resonance frequency determined by the spring constant of the spring 15 and the weight of the valve body 11 is applied to the piezoelectric element 13, the piezoelectric element 13
The valve body 11 rises with an amount of displacement several times larger than the amount of displacement. Therefore, the fuel injection amount can be arbitrarily changed by changing the magnitude, frequency, and application time of the pulse voltage applied to the piezoelectric element 13, and the fuel injection amount can be controlled with high precision from a minute flow rate to a large flow rate. FIG. 2 shows the main parts of another embodiment of the fuel injection valve 1 according to the present invention. In the fuel injection valve 1 of this embodiment, a piezoelectric sensor 18 is provided between the spring 15 and the adjusting screw 7, and the piezoelectric sensor 18 detects the resonance state between the valve body 11 and the spring 15, and applies the detected resonance to the piezoelectric element 13. This enables feedback control of the voltage applied. With the fuel injection valve 1 having such a configuration, by detecting changes in the resonant frequency due to changes in ambient temperature or changes over time and performing feedback control, the fuel injection amount can be kept constant regardless of changes in the ambient temperature or changes over time. It will be possible to control it with high precision to achieve the desired results. Figure NIJ3 shows a case in which the fuel injection valve 1 according to the present invention is directly incorporated into a fuel supply pipe, taking advantage of its small size and simple structure. The fuel pipe 21 shown in Figure 83 is a straight pipe,
The fuel pipe 22 is processed into a shape that allows the fuel injection valve 1 to be incorporated therein, and forms a part of the housing 2 shown in FIG. 1. Further, filters 23 and 24 are provided on both left and right sides of the fuel pipe 22, and the fuel pipe 21 and the fuel pipe 22 are connected by caulking and fixing via O-rings 25 and 26, and the piezoelectric element 13 ．． Valve body 11. The spring 15 is attached to the lower housing 2
b and the upper housing 2a with the same structure as shown in FIG. 1.

【Effect of the invention】

The fuel injection valve according to the present invention includes a piezoelectric element provided between a housing having a fuel injection port and a valve seat and a valve body having a valve portion that contacts the valve seat in a spaced manner to open and close the fuel injection port. An elastic body is provided that biases the valve portion of the valve body in the direction of closing the fuel injection port, and when the piezoelectric element is energized, the piezoelectric element is expanded to cause the valve body to resist the biasing force of the elastic body. Since the valve part is separated from the valve seat to open the fuel injection port, it is possible to control the injection amount of fuel with high precision from a minute flow rate to a large flow rate, and it is possible to control the injection amount of fuel from a very small amount to a large amount when injecting 5 fuels. It has the remarkable advantages of being able to perform efficient fuel injection without requiring power, and also being able to downsize the fuel injection valve and making it relatively easy to fix. effect is brought about.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional explanatory diagram showing one embodiment of the fuel injection valve according to the present invention, FIG. 2 is a partial cross-sectional explanatory diagram showing another embodiment of the fuel injector according to the present invention, and FIG. A cross-sectional explanatory diagram showing an example in which an injection valve is provided in a fuel pipe,
FIG. 4 and FIG. 5 are cross-sectional explanatory views each illustrating a conventional fuel injection valve. DESCRIPTION OF SYMBOLS 1... Fuel injection valve, 2... Housing, 8... Fuel injection port, 9... Valve seat, 11... Valve body, lla...
- Valve part of valve body, 13... piezoelectric element, 15... elastic body (spring), 18... piezoelectric sensor.

Claims (2)

[Claims] (1) A piezoelectric element is provided between a housing having a fuel injection port and a valve seat and a valve body having a valve portion that opens and closes the fuel injection port by contacting the valve seat at a distance, and a valve portion of the valve body. is provided with an elastic body that biases the valve in the direction of closing the fuel injection port, and when the piezoelectric element is energized, the piezoelectric element expands to move the valve portion of the valve body toward the valve seat against the biasing force of the elastic body. A fuel injection valve characterized in that the fuel injection port is opened at a distance from the fuel injection port. (2) A piezoelectric sensor is provided between the housing and the elastic body,
The fuel injection valve according to claim 1, wherein the piezoelectric element is drive-controlled by detecting the operating state of the valve body via the elastic body based on a signal from the piezoelectric sensor.