JPH0451664B2 - - Google Patents

Description

Detailed Description of the Invention (a) Technical Field The present invention relates to a device for injecting fuel into a combustion chamber, and more particularly to a combustion chamber equipped with an injection nozzle and a heating element disposed on the side of the combustion chamber of the injection nozzle. In particular, it relates to a device for injecting fuel into the combustion chamber of a diesel engine.

B. Prior Art Conventional equipment of this type incorporates a heater plug to aid in starting. These components provide the injection region with favorable conditions for heating, vaporization and ignition of a portion of the fuel, which subsequently ignites the entire injected fuel. Such heater plugs and heater pins are special components, and their incorporation into the combustion chamber will affect sensitive flow characteristics. Considering that alcohol and vegetable oil are increasingly being substituted for fuel as energy becomes increasingly scarce, forming and igniting a mixture becomes even more difficult when fuel is injected.

Furthermore, devices are known in which a mixing chamber with an ignition device is provided after the injection nozzle (eg DE 27 15 943). In this device, the walls of the combustion chamber are heated, and combustion begins there. The mixing chamber is designed as a bushing screwed into the combustion wall, in which the injection nozzle is supported. However, such devices have the disadvantage that they are very expensive and must be carefully adapted to the fuel used and the characteristics of the engine.

On the other hand, there is known a device that allows the fuel injected from an injection nozzle to pass through without changing its direction or making any changes and without coming into contact with a heating element. In such a heating element, the ignitability of the fuel is improved by making the temperature of the air in the passage higher than that of the combustion chamber at the beginning of injection. In this case, due to the ignition injection effect, additional air is drawn from the combustion chamber into the passage of the heating element and heated there. The swirling of the heated air mixes it with the fuel, promoting ignition. This is particularly important in drive ranges where atomization deteriorates when the injection pressure is low, such as during startup, high rotation, or low rotation speed. In any case, the atomized fuel required for ignition must be formed beforehand in the area surrounding the injected fuel. However, the conventional method has a drawback in that the function of the heating element cannot reduce smoke during startup or high rotation.

C. Purpose Therefore, the present invention has been made in order to eliminate these conventional drawbacks, and requires only slight deformation of a normal injection nozzle, and can be relatively easily adapted to engine and fuel conditions. The purpose of the present invention is to provide a device for injecting fuel into a combustion chamber.

In order to achieve such an object, the present invention includes an injection nozzle and a heating element disposed behind the injection nozzle on the combustion chamber side of the injection nozzle,
The heating element is formed with a passage surrounded by a heating wall through which the injected fuel flow passes and partially vaporizes the injected fuel flow.
In a device for injecting fuel into a combustion chamber, particularly a combustion chamber of a diesel engine, the shape and position of the inner wall of the heating element surrounding the passage with respect to the nozzle axis;
The parameter that determines the cone angle or injection angle of the fuel flow coming out of the injection nozzle is set so that at least a part of the injected fuel flow hits the inner wall of the heating element of the heating element in a predetermined driving region of the internal combustion engine and is vaporized. A configuration was adopted in which the heating element is made of ceramics and supports a heating element formed by a metal film laminated on the surface of the ceramics.

D. Examples The present invention will be described in detail below according to examples shown in the drawings.

FIG. 1 shows an injection nozzle with a nozzle body 10. In FIG. A valve needle 12 that opens against the flow of fuel is slidably attached to the nozzle body 10. This valve needle is the valve seat 14
A cylindrical injection opening 16 follows from this valve seat, into which a throttle axis needle 18 formed in the valve needle 12 fits. This throttle shaft needle 18 is followed by an injection shaft needle 20, by means of which the fuel is injected in a conical shape 22 at an angle a, as shown. The nozzle body 10 is fixed to a nozzle holder (not shown) by a nut 24, and a unit constituted by these parts is attached to an engine casing (not shown).

Ceramic heating element 30 downstream of the injection nozzle
is placed. This heating element has a passage 32 inside it.
, through which the fuel exiting the injection opening 16 is injected and guided into the combustion chamber. The heating element 30 partially overlaps a step portion 34 having a different diameter from the nozzle body 10, and is pressed against a shoulder portion 36 of the nozzle body 10 by being tightened by a nut 24 via an intermediate member to be described later. A cylindrical cylindrical portion 38 of the passage 32 is provided inside the heating element 30 downstream of the stepped portion 34 of the nozzle body.
A conical portion 40 that expands into a conical shape is formed.

A heating element 42 configured as a metal layer formed by film formation or vapor deposition is attached to the inner wall of the conical portion 40 of the passage 32. The ends 44 and 46 of the heating element 42, which is formed as strips, extend upwardly along the radially opposite wall surface of the cylindrical inner wall of the heating element 30 and are guided to a surface 48. Surface 4 of heating element 30
8 includes two metal contact layers 5 in an annular sector shape.
0 and 52 are formed, which are connected to respective ends 44 and 46 of heating element 42, respectively. Contact layer 5
Between the opposing ends of the heating element 30, two radially opposing ridges 54 are formed, the height of which corresponds to the thickness of the contact plates 56, 58. These ridges 54 serve to separate and insulate contact layers 50, 52 from each other.

Similarly, contact plates 56 and 58 in the form of annular sectors are superposed on the contact layers 50 and 52, and these contact plates are fixed to one side of an insulating plate 60 in the form of an annular ring. Note that the raised portion 54 has an annular sector-shaped contact plate 56,
Similarly, the contact plates 56 and 58 have the function of separating and insulating each other and positioning them, and by providing such a raised portion, it is easy to accurately position and attach the contact plates 56 and 58 to the contact layers 50 and 52. become. The insulating plate 60 has two metal sleeves 62, 64, which are connected to the contact plate 5.
6 and 58 as well as connecting wires 66 and 68 which are insulated from the nozzle body 10. A disk-shaped spring 70 is disposed between the insulating plate 60 and the shoulder 36 of the nozzle body 10, and this spring 70 limits the tightening force applied to the heating element 30 by the nut 24 to a predetermined value. This prevents the heating element 30 from being destroyed. At the same time, this spring also ensures a secure contact and ensures that current is supplied to the heating element 42.

The conical portion 40 of the passage 32 has a cone angle b, which angle is chosen to be smaller than the cone angle a of the injected fuel stream 22. The conical part 40 is arranged opposite to the injection end face of the nozzle body 10 when viewed in the axial direction, and the injected fuel flow 22 impinges on the heat-generating wall of the conical part 40 in all drive regions of the internal combustion engine and is swirled there. Some of it evaporates or vaporizes. During this process, the combustion air also reaches the vaporized fuel, as indicated by the arrows in FIG. In this way, a mixture of fuel and air is obtained from the heating element 30, which is heated to a considerable temperature and vaporized in almost all areas, and is rapidly and completely ignited and combusted in the combustion chamber.

By mutually setting the injection angle or cone angle a of the injected fuel stream 22 and the shape and dimensions of the heating element 30, the magnitude of the temperature of the heating element 30 as well as the spatial distribution of the temperature can be set, as the case may be. This makes it possible to optimally inject fuel according to each fuel and engine.

In the embodiment shown in FIG. 2, a so-called perforated nozzle is used as the injection nozzle. By means of an inwardly opening valve needle 72, the fuel is then led into a bottom bore 74 and from there into an injection opening 76.
The conical part 80 of the heating element 82 made of ceramic is injected as an injected fuel stream 78 through the conical part 80.
It reaches the point where it hits the wall which generates heat. Since the injection angle c of each injected fuel stream 78 is made larger than half the cone angle b of the cone section 80, an effect similar to that of the embodiment of FIG. 1 is obtained.

In the embodiment of FIG. 3, the cone angle b of the cone 80 is greater than twice the injection angle c of each injected fuel stream 78. Particularly in this embodiment, the cone 80 is offset outwardly in its axial extension with respect to the discharge surface of the injection opening 76, so that the injected fuel flow 7
8 is the inlet region 84 of the heated wall of the conical section 80;
It will hit. The fuel is then redirected outward by the Coanda effect and is injected approximately parallel to the wall of the conical portion 80.

In the embodiment of FIG. 4, the injection openings 76 emerge tangentially from the central bottom hole 86, so that a swirl occurs in each injected fuel stream 78, thereby causing the fuel to reach the heating surface of the heating element. The desirable effect is that most of the fuel components are evenly distributed and vaporized and mixed well with the air.

The invention thus provides the advantage that it requires less modification to the housing of a conventional injection nozzle and can be relatively easily adapted to different engine conditions and fuels. A heating element is fixed to or formed integrally with the injection nozzle. The heating element can also be fixed between the injection nozzle and the shoulder of the cylinder head or directly on the cylinder head.

Furthermore, in the present invention, the fuel flow in all drive regions of the internal combustion engine is further improved in that not only the peripheral region of the injection but also a large part of the entire fuel flow impinges on the wall surface and is vaporized there. This makes it possible to significantly reduce the generation of smoke even in drive ranges such as during startup and high rotation, and at the same time allows the heating element to ignite the fuel under all drive conditions.

The embodiments of the invention also use the so-called Coanda effect, whereby the injected fuel flow is guided into the end region of the cone of the heating element.

Further, the present invention can be applied to a shaft needle type nozzle, a perforated type nozzle, and a nozzle having a valve needle that opens outward.

Further, in an embodiment of the present invention, a hole is formed in the injection nozzle so that a swirl occurs in the fuel flow discharged by the injection nozzle, thereby further increasing the vortex state of the injected fuel flow. It is possible to achieve good vaporization.

Further, in the present invention, the heating element is made of ceramic, and the heating element is preferably laminated as a layered conductor path on the inner or outer surface of the heating element. This conductor path can generate heat by controlling the current. It is also possible to provide a plurality of heating circuits in the ceramic body. This makes it possible to heat each region of the heating element separately from the other regions, thereby generating different heating conditions and optimizing the injection fuel flow and ignition characteristics to the operating point of the respective internal combustion engine. It becomes possible to adjust to.

Furthermore, in the present invention, favorable results are obtained because the heating element is attached to the conically expanding inner surface of the heating element.

Effects As explained above, in the present invention, the shape and position of the inner wall of the heating element with respect to the nozzle axis and the parameter that determines the cone angle or injection angle of the injected fuel flow are mutually adjusted so that the fuel is injected from the injection nozzle. The flow hits the inner wall of the heating element and becomes vaporized. In addition, since the heating element is made of ceramics, it has high heat resistance and the inner wall of the heating element can be easily shaped into various shapes, allowing the fuel flow injected from the injection nozzle to be adjusted to suit the engine and fuel conditions. It can be efficiently vaporized by applying it to the inner wall of the heating element. In addition, since the heating element carried by the heating element is formed by a metal film laminated on the ceramic surface, it is easy to set the thickness, shape, and position of this metal film to various values.
By doing so, it is possible to obtain arbitrary heat generation characteristics,
Various effects are obtained, such as the ability to optimally adjust the injected fuel flow as well as the ignition characteristics to the operating point of the respective internal combustion engine.

[Brief explanation of the drawing]

FIG. 1 is an enlarged sectional view showing a first embodiment of the present invention, FIGS. 2 and 3 are sectional views showing other different embodiments of the present invention, and FIG. 4 is an enlarged sectional view showing a first embodiment of the present invention. It is an explanatory view showing the state of the flow formed in the cross section of the nozzle showing the modification of the example. 10... Nozzle body, 12... Valve needle, 16
... Injection opening, 22 ... Injected fuel, 24 ... Nut, 30 ... Heating element, 32 ... Passage, 38 ...
Cylindrical part, 40...Cone part, 42...Heating wire, 5
0,52...Contact layer, 56,58...Contact plate, 6
0... Insulating plate, 66, 68... Connection wire, 70...
Disc spring.

Claims (1)

[Claims] 1. Comprising an injection nozzle and a heating element disposed behind the injection nozzle and on the combustion chamber side of the injection nozzle,
The heating element is formed with a passage surrounded by a heating wall through which the injected fuel flow passes and partially vaporizes the injected fuel flow.
In an apparatus for injecting fuel into a combustion chamber, in particular a combustion chamber of a diesel engine, the shape and position of the inner walls of the heating elements 30, 82 surrounding the passage with respect to the nozzle axis, and the fuel flow 22, 78 emerging from the injection nozzle.
The parameters that determine the cone angle a or the injection angle c are set such that at least a part of the injected fuel flow 22, 78 hits the inner wall of the heating element 30, 82 in a predetermined drive region of the internal combustion engine and is vaporized, The apparatus for injecting fuel into a combustion chamber is characterized in that the heating elements 30 and 82 are made of ceramics and support a heating element 42 forming a metal film laminated on the surface of the ceramics. 2. The heating elements 30, 82 have conically expanding passages 40, 80 at the ends on the side of the combustion chamber, and at least a portion of the fuel flows 22, 78 pass through the conically expanding passages in the driving region. 2. A device for injecting fuel into a combustion chamber according to claim 1, characterized in that the parameters are selected such that the fuel injects into the combustion chamber so as to hit the wall surfaces of the sections 40, 80. 3 The injection nozzle has a valve needle with an injection axis needle passing through the injection opening, the fuel flow injected through this injection axis needle has a conical shape, the cone angle of the fuel flow is equal to the cone of the heating element 30. The passage section 4 expands into
A device for injecting fuel into a combustion chamber according to claim 2, characterized in that the cone angle b is greater than zero. 4. The injection nozzle has at least one injection opening 76 having a predetermined angle with respect to the nozzle axis, and the injection angle c of the injection opening with respect to the nozzle axis corresponds to the conical passage portion 80 of the heating element 82 that expands conically. 3. Device for injecting fuel into a combustion chamber according to claim 2, characterized in that the angle b is greater than half of the angle b. 5 The injection nozzle has at least one injection opening having a predetermined angle with respect to the nozzle axis, and the injection angle c of the injection opening with respect to the nozzle axis is less than half of the cone angle b of the conical passage portion 80 of the heating element. is also slightly smaller and this conical passage 80 is offset outwardly in its axial extent with respect to the injection opening 76 so that the injected fuel flow is directed to the inlet area 8 of the conical passage 80.
4. The device for injecting fuel into a combustion chamber according to claim 2, wherein the fuel injects into the combustion chamber. 6. The device for injecting fuel into a combustion chamber according to claim 4 or 5, wherein the injection nozzle is formed with an injection hole 76 through which the injected fuel flow swirls. 7. The combustion chamber according to any one of claims 1 to 6, wherein the heating element 42 is formed on the wall surface of the conical passage portion 40, 80 of the heating element 30, 82. A device that injects fuel into 8 The end of the metal coating layer forming the heating element 42 extends to the heating element surface 48 facing the nozzle body 10, and the heating element 30 is connected to the contact plates 56, 58 and the insulating plate 6.
0. Claim 7, characterized in that it is attached to the nozzle body 10 via a dish-shaped spring 70.
A device for injecting fuel into the combustion chamber described in paragraph 1. 9. Claims characterized in that the contact plates 58, 58 are fixed to an insulating plate 60 and connected to connecting wires 66, 68, and the connecting wires are guided to the outside via the insulating plate 60 and the nozzle body 10. A device for injecting fuel into the combustion chamber according to item 8. 10 The insulating plate 60 is an annular sector-shaped contact plate 5
6, 58, and two radially opposing ridges 54 are formed on the surface of the heating element 30, and the height of the ridges corresponds to the thickness of the contact plates 56, 58. An apparatus for injecting fuel into a combustion chamber according to claim 9.