JP2009127534A - Fuel injection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To materialize a fuel spray state corresponding to an engine operation state over heavy load from light load of the engine. <P>SOLUTION: A plasma generation element 7 is formed in a cylindrical shape. Its cylindrical inner wall forms a fuel injection hole 3. A plasma generation element 7 is provided with an inductive body 101 and an insulating layer 102. The inductive body 101 comprises ceramic element, and the insulating layer 102 comprises sheet material using polyimide. A pair of electrodes are disposed at a front surface side and a back surface side of the inductive body 101 to put the inductive body 101 therebetween. The plasma generation element 7 is disposed to make fluid flow at the inductive body 101 side. Flow of fluid in a direction reverse to a flow direction of fuel is generated in the injection hole 3 by applying voltage to the plasma generation element 7 to form separation in flow of fuel. Spray is dispersed by generation of separation in the flow of the fuel. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel injection device.

  The engine fuel injection device has been devised in various ways to achieve efficient combustion in the combustion chamber, and such proposals have been made from various viewpoints. For example, Patent Document 1 proposes a fuel injection device that can change the form of fuel spray while reliably reforming fuel with a simple structure. Here, the form of fuel spray includes the shape and penetration force of fuel spray. The specific configuration of this fuel injection device is as follows. That is, the fuel injection device includes a cylindrical body and an in-cylinder direct injection type fuel injection valve accommodated in the internal space of the cylindrical body, and an annular discharge gas passage between the cylindrical body and the fuel injection valve. Is formed. The cylindrical body and the casing of the fuel injection valve act as a pair of discharge electrodes. In such a fuel injection device, when fuel is injected from the fuel injection port of the fuel injection valve, the fuel is reformed by discharging the discharge gas while circulating the discharge gas around the fuel injection port. When a narrow and high penetrating fuel spray is to be obtained, the amount of discharge gas flowing around the fuel nozzle is increased, and when a wide and low penetrating fuel spray is to be obtained, the discharge gas amount is decreased.

JP 2006-257896 A

  As shown in the example above, there are a wide variety of proposals for fuel injection devices aimed at improving combustion efficiency. Here, factors for improving the combustion efficiency include atomization of the spray, separation of the fuel, and adjustment of the penetration force. In some cases, the occurrence of smoke or the like may be a problem. However, these elements have different requirements depending on the load state of the engine, and it has been difficult for conventional proposals to adapt to the requirements over a wide range during engine operation.

Therefore, an object of the present invention is to realize a fuel spray state corresponding to the operating state of the engine from a low load to a high load of the engine.

  In order to solve such a problem, a fuel injection device of the present invention includes a plasma generating element mounted on an inner hole of a nozzle body formed in a nozzle body of a fuel injection valve or connected to the nozzle hole, and And a power supply device for applying a voltage to the plasma generating element (claim 1). By setting it as such a structure, the state of the fuel injected from the nozzle hole of a fuel injection valve can be controlled. In such a fuel injection device, the plasma generating element may be mounted in a direction to generate a fluid flow in a direction that is in a direction reverse to the direction of flow of the fuel injected from the injection hole. ). By adopting such a configuration, it is possible to cause separation in the flow of fuel injected from the injection hole. Spray dispersion can be promoted by promoting peeling. As the plasma generating element, a device in which a dielectric and an insulating layer are provided and electrodes are arranged on the front and back of the dielectric can be adopted. The voltage applied to such a plasma generating element is preferably an alternating voltage. By using an alternating voltage, continuous plasma generation can be realized. Plasma is generated by applying a voltage to a plasma generating element mounted on the inner wall of the nozzle body connected to the nozzle hole or connected to the nozzle hole. At this time, momentum is transmitted to the fluid in the nozzle body by an electric field. Thereby, a flow can be created intentionally and the separation of the flow of fuel injected from the injection hole can be promoted.

  In such a fuel injection device, the power supply device may include a control unit that controls a voltage applied to the plasma generating element in accordance with a load state of the engine. The power supply apparatus may include a control unit that controls a voltage applied to the plasma generating element based on at least one of a fuel injection pressure and a fuel injection amount in the fuel injection valve. By providing such a control unit, it is possible to perform fuel injection to obtain a combustion state that matches the operating state of the engine.

  In such a fuel injection device, the control unit may be configured to correct a voltage applied to the plasma generating element with reference to a coolant temperature. In a diesel engine, when the temperature of the cooling water is low, the spray injected from the nozzle hole has a small penetration force, and the combustion can be reduced when the fuel is not diffused so much. Therefore, it is desirable to correct the applied voltage with reference to the cooling water temperature.

  Furthermore, the power supply device in such a fuel injection device can include a battery and an inverter. The voltage applied to the plasma generating element is preferably an alternating voltage, but when a battery mounted on a vehicle is used as a power source, direct current electricity can be converted into alternating current using an inverter and supplied to the plasma generating element. By controlling the switching in the inverter, a desired voltage can be applied to the plasma generating element.

  According to the present invention, the plasma generating element is mounted in the nozzle hole formed in the nozzle body of the fuel injection valve or on the inner wall of the nozzle body connected to the nozzle hole, and the flow acting on the injected fuel is intentionally Since it is created, fuel can be injected according to the operating state of the engine to improve combustion.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 1 is an explanatory diagram showing a schematic configuration of a fuel injection device 1 according to an embodiment of the present invention. The fuel injection device 1 is used for a diesel engine, and is used in combination with a common rail (not shown). The fuel injection device 1 includes a plasma generating element 7 combined with a nozzle body 2 and a holder 4 of a fuel injection valve. FIG. 2 is an explanatory view showing a state in which the holder 4 and the plasma generating element 7 are removed from the nozzle body 2. Further, FIG. 3 is an explanatory view showing the plasma generating element 7 combined with the holder 4 in cross section and enlarged. The nozzle body 2 is provided with a mounting hole 2 a for the plasma generating element 7. A stopper 2a1 is formed at the end of the nozzle body outer peripheral surface of the mounting hole 2a. Further, a lead wire lead-out passage 2b communicating with the mounting hole 2a is provided.

  The plasma generating element 7 is formed in a cylindrical shape. The cylindrical inner wall forms a fuel injection hole 3. The plasma generating element 7 includes a dielectric 101 and an insulating layer 102. The dielectric 101 is made of a ceramic material, and the insulating layer 102 is made of a sheet material using polyimide. A pair of electrodes are mounted on the front surface side and the back surface side of the dielectric 101 so as to sandwich the dielectric 101 therebetween. The plasma generating element 7 is mounted so that fluid flows through the dielectric 101 side. In the present embodiment, the plus electrode 103 is attached to the front surface side of the dielectric 101, that is, the surface side of the plasma generating element 7, and the minus electrode 104 is attached to the back surface side. The lead wire 5 is connected to the positive electrode 103, and the lead wire 6 is connected to the negative electrode 104. The plus electrode 103 is located on the downstream side of the fuel flow, that is, the outside of the nozzle body 2, and the minus electrode 104 is located on the upstream side of the fuel flow, that is, the inside of the nozzle body 2. In this way, by shifting the electrode in the fuel flow direction, the fluid flow generated along with the generation of plasma can be set in a direction reverse to the fuel flow direction injected from the nozzle hole 3.

  Such a plasma generating element 7 is combined with a cylindrical holder 4. A stopper 4 a is formed on one end side of the holder 4. Such a plasma generating element 7 and the holder 4 are fitted into a mounting hole 2 a formed in the nozzle body 2. At this time, the stopper 4a of the holder 4 and the stopper 2a1 of the mounting hole 2a are engaged with each other. The holder 4 and the plasma generating element 7 fitted in the mounting hole 2 a form a part of the nozzle body 2. The lead wires 5 and 6 attached to the plasma generating element 7 are drawn out of the nozzle body 2 through the lead wire drawing passage 2b. Lead wires 5 and 6 led out of the nozzle body 2 are connected to an inverter 8. The inverter 8 is electrically connected to a battery 9 and an ECU (Electronic control unit) 10. The ECU 10 corresponds to a control unit in the present invention, and performs control when the direct current supplied from the battery 9 is converted into an alternating current and an alternating voltage is applied to the plasma generating element 7. The ECU 10 is connected to a sensor group 11 including a water temperature sensor and a pressure sensor mounted on a common rail, and acquires various measurement values. Moreover, ECU10 acquires the information regarding an engine speed and an engine load from such a sensor group 11, and determines fuel injection amount. The ECU 10 controls energization of the plasma generating element 7 based on these measured values and calculated values. The battery 9, the inverter 8, and the ECU 10 constitute a power supply device according to the present invention.

  The control of the fuel injection amount 1 configured as described above will be described with reference to the flowchart shown in FIG. First, in step S1, the ECU 10 determines whether or not the engine is in a low load state. If NO is determined in step S1, that is, if it is determined that the engine is in a high load state, no voltage is applied to the plasma generating element 7, and the process returns. As a result, when the engine is heavily loaded, the fuel flow is not separated and a high penetration force is maintained. On the other hand, if YES is determined in step S1, the process proceeds to step S2. When YES is determined in step S1, voltage application control to the plasma generating element 7 is performed. In step S2, a calculation is performed to estimate the fuel flow velocity in the vicinity of the injection hole 3 from the value of the fuel injection pressure acquired from the pressure sensor included in the sensor group 11 and the value of the fuel injection amount calculated by the ECU 10 itself.

  ECU10 performs the process of step S3 following the process in step S2. In step S3, a required applied voltage for generating a fluid flow capable of causing separation is calculated for the fuel having the flow velocity estimated in step S2. That is, the specification of the voltage applied to the plasma generating element 7 is determined. Specifically, the specifications of the applied AC voltage are determined with reference to a map relating to the correspondence between the fuel flow velocity and the applied AC voltage. The numerical value of the applied voltage to be controlled is a voltage value and a frequency, and is controlled in a range of 5 to 10 kv and a range of 1 to 10 kHz, respectively. The higher the frequency, the faster the generated fluid flow. The frequency can be controlled to a desired value by the timing of switching from direct current to alternating current in the inverter 8.

  ECU10 performs the process of step S4 following the process of step S3. In step S4, the voltage specifications calculated in step S3 are corrected based on information from the water temperature sensors included in the sensor group 11. When the water temperature is low, the correction is made to increase the effect of fuel flow separation. That is, the penetration force is reduced by increasing the peeling effect, and the spray is prevented from diffusing as much as possible. Thereby, generation | occurrence | production of HC at the time of low water temperature can be suppressed.

  In step S5, the ECU 10 issues a voltage application command according to the specification of the applied voltage calculated in step S3 and corrected in step S4. As a result, a fluid flow that reverses in the direction of fuel flow occurs in the nozzle hole 3, causing separation of the fuel flow. The spray is dispersed by the separation of the fuel flow.

  By performing the control as described above, fuel can be injected according to the state of the engine.

  Next, a second embodiment of the present invention will be described. The second embodiment differs from the first embodiment in the following points. That is, in Example 1, the plasma generating element 7 formed in a cylindrical shape and arranged in the nozzle hole is provided, whereas in Example 2, the plasma generating element is formed on the inner wall of the nozzle body 2 connected to the nozzle hole 3. 17. FIG. 5 is an explanatory view showing a position where the plasma generating element can be mounted. The plasma generating element can be mounted in the nozzle hole indicated by reference symbol A or the inner wall of the nozzle body indicated by reference symbol B in FIG.

  FIG. 6 is an explanatory diagram showing a schematic configuration of the fuel injection device 50 according to the second embodiment. Unlike the plasma generating element 7 in the first embodiment, the plasma generating element 17 has a flat plate shape and is embedded in the inner wall of the nozzle body 2 connected to the nozzle hole 3. At this time, the plasma generating element 17 is installed so that the plus electrode 103 is located on the side close to the nozzle hole 3. As a result, a fluid flow reverse to the direction of the fuel flow is generated, and the fuel flow is easily separated. Even with such a configuration, the fuel flow injected from the nozzle hole 3 can be separated. Such energization control to the plasma generating element 17 can be performed in the same manner as in the first embodiment. Such a flat plasma generating element may be mounted in the nozzle hole. In addition, in Example 2, the same reference number is attached | subjected about the component which is common in Example 1, and the detailed description is abbreviate | omitted.

  The above-described embodiments are merely examples for carrying out the present invention, and the present invention is not limited to them. Various modifications of these embodiments are within the scope of the present invention. It is apparent from the above description that various other embodiments are possible within the scope. For example, the material of the plasma generating element 7 can be changed as appropriate. The fuel injection device can also be used for an exhaust addition injector. In this case, a highly dispersed spray is desirable. Therefore, the voltage and frequency applied to the plasma generating element 7 are set as large as possible. Furthermore, it is possible to perform control with reference to engine rotation fluctuation. For example, if foreign matter that has entered exhaust gas accumulates in the fuel injection valve, injection variation occurs. When it is determined that there is an injection variation from fluctuations in the engine speed, it is possible to perform control to increase the applied voltage and increase the separation until the injection variation is eliminated.

It is explanatory drawing which showed schematic structure of the fuel-injection apparatus of Example 1. FIG. It is explanatory drawing which shows the state which removed the holder and the plasma generation element from the nozzle body. It is explanatory drawing which shows the structure of a plasma generation element. It is a flowchart which shows an example of the control in a fuel-injection apparatus. It is explanatory drawing which shows the position which can mount a plasma generating element. It is explanatory drawing which showed schematic structure of the fuel-injection apparatus of Example 2. FIG. It is explanatory drawing which shows the structure of the plasma generation element of Example 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 50 Fuel injection apparatus 2 Nozzle body 2a Mounting hole 2b Lead wire extraction path 3 Injection hole 4 Holder 5, 6 Lead wire 7 Plasma generating element 8 Inverter 9 Battery 10 ECU
101 Dielectric 102 Insulating layer 103 Positive electrode 104 Negative electrode

Claims (6)

A plasma generating element mounted in an injection hole formed in a nozzle body of a fuel injection valve or an inner wall of the nozzle body connected to the injection hole;
A power supply device for applying a voltage to the plasma generating element;
A fuel injection device comprising: The fuel injection device according to claim 1, wherein
The fuel injection device according to claim 1, wherein the power supply device includes a control unit that controls a voltage applied to the plasma generating element in accordance with a load state of the engine. In the fuel injection device according to claim 1,
The power supply apparatus includes a control unit that controls a voltage applied to the plasma generating element based on at least one of a fuel injection pressure and a fuel injection amount in the fuel injection valve. The fuel injection device according to claim 2 or 3,
The said control part correct | amends the voltage applied to the said plasma generation element with reference to cooling water temperature, The fuel-injection apparatus characterized by the above-mentioned. The fuel injection device according to claim 1, wherein
The fuel injection device according to claim 1, wherein the plasma generating element is mounted in a direction to generate a fluid flow in a direction reverse to a flow direction of fuel injected from the nozzle hole. The fuel injection device according to claim 1, wherein
The power injection device includes a battery and an inverter.

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