DEVICE FOR THE IGNITION OF A FUEL MIXTURE IN INTERNAL COMBUSTION ENGINES

Abstract

 An ignition plug for internal combustion engines fitted with a piezo-ceramic acoustic duct is described. As a result of this, the instantaneous power produced at the moment of ignition of the fuel mixture is increased.

Description

Technology field:

[0001] This invention relates to the field of engine construction, and more specifically to the ignition system of internal combustion engines (ICEs).

Prior art:

[0002] There is a known device for the ignition of fuel mixture in an internal combustion engine (USSR Authorship Certificate No. 1464274, and also Ross Tveg, Ignition Systems for Cars, Moscow, "Za rulyom" Publishing House, 1998, p. 39), including an ignition plug containing a metal body and a ceramic insulator, inside which is a central electrode.

[0003] The problem with the known ignition plugs (spark plugs) is the relatively low instantaneous power, due to the collapse of the front profile of the ignition pulse.

[0004] To amplify the low instantaneous power, there is a device for the ignition of fuel mixture in an internal combustion engine (Russian Federation Patent Application No. 9610357/06 dated 22.06.96), comprising an ignition plug consisting of a steel body and a ceramic insulator, inside which is a central electrode coated with a piezo-ceramic layer. The piezo-ceramic layer on the central electrode, due to the formation of an acoustic wave in the piezo-ceramic, makes it possible to increase somewhat the steepness of the front profile of the ignition pulse; however, due to the electrical and mechanical contact between the piezo-ceramic and the central electrode over the entire surface, the increase in instantaneous power is negligible.

Substance of the invention:

[0005] There remains the urgent problem of raising the instantaneous power of ICE ignition plugs produced at the moment of ignition of the fuel mixture.

[0006] This problem is solved in the present invention due to the fact that the device for ignition of fuel mixture in internal combustion engines, including an ignition plug having a metal body and a ceramic insulator, inside which is a central electrode, is provided with a piezo-ceramic acoustic duct with three electrodes, one of which is connected to a power supply, the second to the body of the ignition plug or to an engine, and the third to the central electrode of the ignition plug.

[0007] The piezo-ceramic acoustic duct may be in the form of a piezo-electric voltage transformer or a piezo-electric current transformer, or a parallel-wired piezo-electric voltage transformer and piezo-electric current transformer.

[0008] It is advisable that the magnitude of the capacitance of the central electrode of the ignition plug relative to that of its body should decrease uniformly, and the magnitude of the active resistance should increase uniformly towards the discharge gap.

[0009] From the design point of view, it is advisable that there should be a cavity in the ceramic insulator of the ignition plug, and that the said piezo-ceramic acoustic duct should be located in this cavity.

Brief description of the drawings:

[0010] 

FIGURE 1 shows the design of an ignition plug made in accordance with the present invention;

FIGURE 2 shows graphs of the instantaneous output power for a conventional plug and for a plug in accordance with the present invention;

FIGURE 3 shows a piezo-electric voltage transformer; and

FIGURE 4 shows a piezo-electric current transformer.

Example of implementation of the invention:

[0011] The device is made and works as follows.

[0012] The piezo-ceramic acoustic duct (5) (Fig. 1) is connected by one electrode (6) to a power supply (not shown), by a second electrode (7) to the body (2) of the ignition plug or to an engine, and by a third electrode (4) to the central electrode (3) of the plug, located inside the ceramic insulator (1) of the ignition plug.

[0013] When a pulse signal is supplied to the electrode (6) (Fig. 1) of the piezo-ceramic acoustic duct (5) for the ignition of the fuel mixture from the power supply, due to the different rate of propagation of the harmonic components of the input signal in the piezo-ceramic acoustic duct, a shock profile is formed, as a result of which the instantaneous energy transmitted through the third electrode (4) of the acoustic duct (5) to the central electrode (3) and given off in the combustion chamber increases in proportion to the change in the steepness of the pulse profile.

[0014] As is apparent from Fig. 2, which shows the graphs of the instantaneous output power for a conventional device (curve 1) and for the use of a piezo-ceramic acoustic duct in accordance with the present invention (curve 2), the steepness of the profile of the ignition pulse, and consequently the instantaneous power, increases with the use of a piezo-ceramic acoustic duct.

[0015] The piezo-ceramic acoustic duct (5) may be made in the form of a piezo-electric voltage transformer (Fig. 3) on the basis of a piezo-ceramic plate (8), on which the first (9), second (10) and third (11) electrodes are mounted. In this case, when the pulse ignition signal is supplied to the first electrode (9), enhanced voltage relative to the second electrode (10) forms on the third electrode (11) of the piezo-electric voltage transformer, and the steepness of the profile of the ignition signal increases.

[0016] The piezo-ceramic acoustic duct (5) may also be made in the form of a piezo-electric current transformer on the basis of a piezo-ceramic plate (12) (Fig. 4), on which the first (13), second (14) and third (15) electrodes are mounted. In this case, when the pulse ignition signal is supplied to the first electrode (13), an enhanced current relative to the second electrode (14) is formed on the third electrode (15) of the piezo-electric current transformer, and the steepness of the profile of the ignition signal again increases.

[0017] This effect is also maintained in the case of the piezo-ceramic acoustic duct being made in the form of parallel-wired piezo-electric voltage and current transformers.

[0018] The magnitude of the capacitance of the central electrode (3) of the ignition plug relative to its body (2) can decrease uniformly towards the discharge gap, and the magnitude of the active resistance can increase uniformly. In this case, as a result of a specially created change in the capacitance and active resistance along the ignition plug, a sector of non-homogeneous co-axial line forms between the central electrode (3) and the body (2). As a result of interference processes in this non-homogeneous co-axial line, an increase in the steepness of the profile of the pulse transmitted through the central electrode (3) of the ignition plug takes place, as a result of which there is an increase in the instantaneous energy given off in the combustion chamber (in the discharge gap).

[0019] The physical implementation of the change in the capacitance and active resistance of the central electrode (3) relative to the body (2) can be obtained, for example, by gradually altering the dielectric permeability and resistance of the losses of the ceramic insulator (1) of the ignition plug along the central line of the ignition plug, or by altering the shape of the ceramic insulator.

EXAMPLE 1

[0020] The ignition plug contained a piezo-electric voltage transformer of standard piezo-ceramic PZT-11, dimensions 11.5 × 5 × 2 mm. In this case, the instantaneous power in the internal combustion engine increases by 18%.

EXAMPLE 2

[0021] The ignition plug contained a piezo-electric current transformer of standard piezo-ceramic PZT-11, dimensions 11 × 5 × 4 mm. In this case, the instantaneous power in the internal combustion engine increases by 19%.

Claims

1. A device for ignition of fuel mixture in internal combustion engines, comprising an ignition plug having a metal body and a ceramic insulator, inside which is a central electrode, which is distinguished in that the ignition plug has a piezo-ceramic acoustic duct with three electrodes, one of which is connected to a power supply, the second to the body of the ignition plug or to an engine, and the third to the central electrode of the ignition plug.

2. A device as claimed in claim 1, characterised in that the piezo-ceramic acoustic duct is in the form of a piezo-electric voltage transformer.

3. A device as claimed in claim 1, characterised in that the piezo-ceramic acoustic duct is in the form of a piezo-electric current transformer.

4. A device as claimed in claim 1, characterised in that the piezo-electric acoustic duct is in the form of parallel-wired piezo-electric voltage and current transformers.

5. A device as claimed in any one of claims 1 to 4, characterised in that the central electrode of the ignition plug has a capacitance whose magnitude relative to a capacitance of the body decreases uniformly towards a discharge gap, and wherein the central electrode has an active resistance whose magnitude increases uniformly towards the discharge gap.

6. A device as claimed in any one of claims 1 to 5, characterised in that the ceramic insulator of the ignition plug has a cavity formed therein, and wherein the piezo-ceramic acoustic duct is located in the cavity.

Drawing