JPS6032927A - Sub-combustion chamber type diesel engine - Google Patents

Abstract

PURPOSE:To prevent the catalyst performance from being deteriorated even during a long operation by depositing a catalyst metal on an oxide layer formed on at least part of the inner wall surface of a sub-combustion chamber or the surface of a glow plug then forming an oxide layer on the layer. CONSTITUTION:An intermediate layer 7 made of an Ni-Cr-Al alloy is formed on the inner wall surface of a sub-combustion chamber 3 or the surface of a glow plug 1, and a composite oxidized layer 8 with composition of ZrO2-CaO is formed on the layer 7. Furthermore, it is immersed in a solution of dinitrodiamino platinum and rhodium chloride than is taken out, a catalyst metal (Pt, Rh) is deposited, next, it is immersed in an alumina slurry liquid then is taken out to form an alumina layer 9. Accordingly, stable ignition performance and startability can be maintained without deteriorating the catalyst performance.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention provides a catalyst and further improves the durability of the catalyst. The present invention relates to a diesel engine having an auxiliary combustion chamber.

(Prior Art) In order to improve the ignitability and startability of a diesel engine, a catalyst layer is formed on the wall surface of the sub-combustion chamber and on the surface of the knobby plug in the sub-combustion chamber. For example, nickel is applied to the wall surface of the sub-combustion chamber and the glow plug surface.
Forms a metal intermediate layer consisting of chromium, aluminum, etc.
A heat-resistant inorganic material layer such as an oxide such as zirconium oxide or a composite oxide of zirconium oxide and an oxide of a metal of subgroup 1 [a or l [a] of the periodic table is formed on the surface of the intermediate layer. It has been known that catalyst metals such as platinum and rhodium are supported on an inorganic material layer.

However, calcium (Ca) and phosphorus (P), which are contained as additives in engine oil and gasoline,
, lead (PB), and other compounds are decomposed by combustion and deposited on the catalyst surface in the form of fine particles, which close the pores on the surface and allow fuel gas to diffuse inside. The performance of conventional catalytic sub-combustion chamber type diesel engines deteriorated in a short period of time because the catalyst was poisoned by interfering with i or reacting with the catalyst metal to reduce its activity.

(Object of the Invention) The present invention is intended to solve the problems in the prior art described above. The purpose is to provide a catalytically controlled sub-combustion chamber type diesel engine in which the catalyst performance does not deteriorate even when the engine is operated linearly for a long time.

(Structure of the Invention) That is, in the sub-combustion chamber type diesel engine of the present invention, an oxide layer is formed on at least a part of the wall surface of the sub-combustion chamber or the surface of the glow plug, and after a catalyst metal is supported on the oxide layer, It is characterized in that an oxide layer such as alumina is further formed on the layer.

The oxide layer that is formed on top of the catalytic layer by supporting the catalytic metal acts as a protective layer that protects the underlying catalytic layer from poisonous substances, or as a conditioning layer that adjusts the diffusion of fuel gas, etc. Therefore, its properties are important and the type of oxide.

It is necessary to optimally select the average particle size (specific surface area), particle size distribution, thickness, etc.

Oxides that can be used in the present invention include various crystalline alumina (At20.), '-/Rica (8i 0x)
Besides, for example, magnesia (MgO), calcia (Ca
b), Ittoria (ytos) e Titania (T'O*
) tzirconia (monocompositional metal oxides such as zroJ, and e.g. zro, -YtOm e Zr□,
- Complex oxides such as CaO, i.e. CaT103, L
Perovskite type compounds such as aAt03, or Mg
A40+ t Fe (NIFe) 04# Zn (TIZ
n) spinel type compounds such as 04, or MgtSI0
Examples include sinterable inorganic oxides such as silicates such as 4s Hato S 10H. Moreover, you may use these in combination.

Preferred oxides include those that do not reduce the activity of the catalytic metal, such as oxides of Si, and metals that increase the activity, such as LB and Ce.

Examples include oxides containing Fe, Ni, etc.

The specific surface area of the oxide is preferably 2 aorrr/l or less, preferably 10 to 1 oorrr/l.

A narrower particle size distribution is more convenient for forming a uniform layer.

The thickness of the oxide layer is determined in consideration of the type of oxide and the specific surface area, but for example, when alumina is used, the thickness is 5 to 200 μm, preferably 60 to 100 μm.

In addition, for example, if two or more alumina layers with different specific surface areas are stacked, and the upper layer is made of alumina with a small specific surface area (large average particle size), clogging of pores on the surface can be effectively prevented. Can be done.

In the above, oxides other than alumina can of course be used in the same manner, and different types of oxides may be optimally combined. The thickness of each layer can also be optimally selected.

Other materials or methods used to convert the auxiliary combustion chamber type diesel engine 11 of the present invention.

Materials and methods commonly used in this field can be used.

(Example) Examples of the present invention will be described in detail below. Note that the present invention is not limited to the following examples.

Example 1: FIG. 1 represents a cross-sectional view of the sub-combustion chamber of a catalyzed diesel engine of the present invention. In the diagram, 1 is a glow plug, 2
6 represents a fuel injection valve, 6 represents an auxiliary combustion chamber, 4 represents an intake valve, and 5 represents a piston.

Nickel (N+)-chromium (C
r) - An intermediate layer of aluminum (At) alloy is formed to a thickness of 50 μm, and 95% Zr02-5% by weight is applied thereon.
A composite oxide layer having a composition of CaO was formed to a thickness of 50 μm by thermal spraying in a nitrogen atmosphere, and then immersed in dinitrodiaminoplatinum and rhodium chloride solution, taken out, dried, and fired to form a catalyst metal (Pi, R11). was carried. Next, convert this to the specific surface m20rr? /f was immersed in an alumina slurry solution, taken out, dried, and fired to form an alumina layer with a thickness of 50 μm.

FIG. 2 shows an enlarged cross-sectional view of the surface portion (2) of the glow plug 1 shown in FIG. 1 surrounded by a broken line. 6 in the figure is the glow plug base material,
7 is N1-Cr-At intermediate layer, 8 is zro, -CaO
(P t + Rh) layer, 9 indicates an alumina layer.

Example 2: By the same method as in Example 1, but after forming the Nl-Cr-At intermediate layer 7 on the surface of the glow plug 1, a silicon dioxide (SIOT) intermediate layer was thermally sprayed thereon. A catalyzed glow plug was obtained by forming it to a thickness of 50 μm by the method.

FIG. 5 is a partially enlarged sectional view of the surface portion of the glow plug of this embodiment. 10 in the figure is Sin.

represents the middle layer, and the others have the same meaning as shown in FIG.

S10. By forming the intermediate layer, the strength against peeling becomes even stronger.

Example 5: The inner wall surface of the auxiliary combustion chamber 6 shown in FIG. 1 was catalyzed by the same method as in Example 1 to obtain a diesel engine of the present invention.

Example 4: By the same method as in Example 1, except that ZrO2-CaO
After forming the (Pt, Rh) layer 8, a small alumina layer with a specific surface area of 1 ooy/f and a thickness of 25 μm is formed thereon, and a layer of alumina with a large particle size and a specific surface area of 10 mm is further formed on top of the layer 8. The layer was formed to a thickness of 25 μm.

FIG. 4 is a partially enlarged sectional view of the surface portion of the glow plug of this embodiment. In the figure, 11 is an alumina layer with small particle size, 1
2 represents an alumina layer with a large particle size, and the others have the same meanings as shown in FIG.

By providing an alumina layer with a large particle size on the surface, the pores are less likely to be clogged by poisonous substances.

Example 5: By the same method as in Example 1, but using ZrO.

- ZrO2 with a specific surface area of 1 awr/y on which no catalytic metal is supported after forming the CaO (Pi, Rh) layer 8
A -CaO layer was formed to a thickness of 50 μm.

FIG. 5 is a partially enlarged sectional view of the surface portion of the glow plug of this embodiment. In the figure, 16 represents the Zr02-'CaO layer, and the others have the same meanings as shown in FIG.

If the oxide layer provided on the surface is the same as the oxide layer supporting the catalyst metal, they will firmly adhere to each other and will be difficult to peel off.

Example 6: By the same method as in Example 1, but using ZrO.

- Zr02 with a specific surface area of 10 m'/7 on which no catalyst metal is supported after forming the Cab (Pt, Rh) layer 8 -
A CaO layer was formed to a thickness of 25 μm, and an alumina layer with a large grain size of 25 μm with a specific surface of [100 d/f] was formed on top of the CaO layer to a thickness of 25 μm.
It was formed to a thickness of .

FIG. 6 is a partially enlarged sectional view of the surface portion of the glow plug of this embodiment. In the figure, 12 and 13 have the same meanings as shown in FIGS. 4 and 5, respectively, and the others have the same meanings as shown in FIG. 2.

This example has the features of Example 4 and Example 5,
It is difficult to peel off and blockage of pores on the surface is also difficult.

Comparative Example: A glow plug of a comparative example was obtained in the same manner as in Example 1 except that an alumina layer was not provided on the oxide layer supporting the catalyst metal.

Actual durability test: Using test engine 2L-T, rotation speed 640°rpm
A continuous high-speed durability test was conducted for 30 hours under full load.

Ignition performance evaluation test: Diesel engine auxiliary combustion chamber samples equipped with catalyzed glow plugs produced in Example 1 and Comparative Example were maintained at a predetermined temperature, and JIS-2 diesel oil was heated to a certain level (1
μt), and the amount of carbon dioxide (CO,) generated is ≠
It was quantified by Cass chromatography. The results are shown in Figure 7.
I'm jealous.

As is clear from the figure, conventional products that do not have an oxide layer on one surface have high initial ignition performance, whereas the performance deteriorates significantly after the durability test.

The product of the present invention, which has an oxide layer on its surface, shows no change in performance at the initial stage or after durability.

Furthermore, after durability, the ignition performance significantly exceeds that of conventional products.

(Effects of the Invention) As described above, in the diesel engine of the present invention, after the catalytic metal is supported on the oxide layer, an appropriate oxide layer is further supported on the layer to the optimum thickness. This protects the lower catalyst layer from stolen substances such as calcium, #, and lead in the exhaust gas, and the catalyst performance does not deteriorate even after long-term use, maintaining stable ignition performance and startability. This has a great effect on stabilizing engine performance.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a catalyzed diesel engine sub-combustion chamber according to an embodiment of the present invention, and FIG. 2 is an enlarged cross-sectional view of the surface portion (2) of the glow plug in FIG. 1 surrounded by a broken line. Figures 3 to 6 are enlarged cross-sectional views of glow plug surfaces of other embodiments of the present invention, and Figure 7 is a comparison of glow plug surfaces in initial and durable paper between an embodiment of the present invention and a comparative example. It is a graph showing the relationship between temperature and carbon dioxide generation curtain. In the diagram, 1--Glow plug, 2--Fuel injection valve% 3--
・Sub-combustion chamber, 4... Air supply valve, 5... Piston, 6.
- Glow plug base material, 7... Nl-Cr-Al intermediate layer, 8... Zr0l-CaO(Pt*Rh
) Layer% 9-...Alumina layer, 1゜...SiO, intermediate layer, 11-...Alumina layer with small particle size, 12-...Alumina layer with large particle size, 13...Zr02-CaO layer Patent Applicant: Toyota Motor Corporation Fang 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 3jP7 Glow plug surface temperature ('C)

Claims (1)

[Claims] An oxide layer is formed on a small part of the wall surface of the sub-combustion chamber or the surface of the glow plug, and after supporting the catalytic metal on the oxide layer, an oxide layer such as alumina is further formed on the layer. This is a sub-combustion chamber type diesel engine.