U.S. patent application number 17/609523 was filed with the patent office on 2022-07-21 for fuel composition for lean burn engine.
This patent application is currently assigned to ENEOS Corporation. The applicant listed for this patent is ENEOS Corporation. Invention is credited to Taketora NAIKI, Ken OBATA.
Application Number | 20220228078 17/609523 |
Document ID | / |
Family ID | 1000006301070 |
Filed Date | 2022-07-21 |
United States Patent
Application |
20220228078 |
Kind Code |
A1 |
OBATA; Ken ; et al. |
July 21, 2022 |
FUEL COMPOSITION FOR LEAN BURN ENGINE
Abstract
A fuel composition for a lean burn engine comprising
hydrocarbons having 4 to 6 carbon atoms as main component, with an
aromatic content of 25 vol % or less.
Inventors: |
OBATA; Ken; (Tokyo, JP)
; NAIKI; Taketora; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ENEOS Corporation |
Tokyo |
|
JP |
|
|
Assignee: |
ENEOS Corporation
Tokyo
JP
|
Family ID: |
1000006301070 |
Appl. No.: |
17/609523 |
Filed: |
July 17, 2020 |
PCT Filed: |
July 17, 2020 |
PCT NO: |
PCT/JP2020/027879 |
371 Date: |
November 8, 2021 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C10L 1/06 20130101 |
International
Class: |
C10L 1/06 20060101
C10L001/06 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 31, 2019 |
JP |
2019-140862 |
Claims
1. A fuel composition for a lean burn engine comprising
hydrocarbons having 4 to 6 carbon atoms as main component, with an
aromatic content of 25 vol % or less.
2. The fuel composition for a lean burn engine according to claim
1, wherein the content of olefins having 4 to 6 carbon atoms is 20
to 60 vol % relative to the total amount of hydrocarbons having 4
to 6 carbon atoms.
3. The fuel composition for a lean burn engine according to claim
1, wherein the content of normal paraffins having 4 to 6 carbon
atoms is 20 vol % or less relative to the total amount of
hydrocarbons having 4 to 6 carbon atoms.
4. The fuel composition for a lean burn engine according to claim
1, wherein the content of hydrocarbons having 4 to 6 carbon atoms
is 85 vol % or more.
Description
TECHNICAL FIELD
[0001] The present invention relates to a fuel composition for a
lean burn engine.
BACKGROUND ART
[0002] Conventionally, a lean burn engine that burns fuel in an
air-fuel mixture leaner than the theoretical air-fuel ratio has
been known. As a fuel for the lean burn engine, for example, in
Patent Literature 1, a fuel composition for a lean burn engine
including one or more types of gasoline selected from the group
consisting of alkylate gasoline, catalytically reformed gasoline,
light catalytic cracking gasoline, and coker light gasoline is
disclosed.
CITATION LIST
Patent Literature
[0003] Patent Literature 1: Japanese Unexamined Patent Publication
No. 2007-182579
SUMMARY OF INVENTION
Technical Problem
[0004] In a lean burn engine, the upper limit of operable air-fuel
ratio (air/fuel) is referred to as lean limit, and through
expansion of the lean limit, improvement in fuel efficiency and
stabilization of combustion are expected.
[0005] An object of the present invention is to provide a fuel
composition for a lean burn engine capable of expanding the lean
limit of a lean burn engine.
Solution to Problem
[0006] One aspect of the present invention relates to a fuel
composition for a lean burn engine, which comprises hydrocarbons
having 4 to 6 carbon atoms as main component, with an aromatic
content of 25 vol % or less.
[0007] In an aspect, the content of olefins having 4 to 6 carbon
atoms may be 20 to 60 vol % relative to the total amount of
hydrocarbons having 4 to 6 carbon atoms.
[0008] In an aspect, the content of normal paraffins having 4 to 6
carbon atoms may be 20 vol % or less relative to the total amount
of hydrocarbons having 4 to 6 carbon atoms.
[0009] In an aspect, the content of hydrocarbons having 4 to 6
carbon atoms may be 85 vol % or more.
Advantageous Effect of Invention
[0010] According to the present invention, a fuel composition for a
lean burn engine capable of expanding the lean limit of a lean burn
engine is provided.
DESCRIPTION OF EMBODIMENT
[0011] A preferred embodiment of the present invention will be
described in detail below.
[0012] The fuel composition of the present embodiment is a fuel
composition that comprises hydrocarbons having 4 to 6 carbon atoms
as main component (for example, 50 vol % or more, preferably 60 vol
% or more, more preferably 70 vol % or more, still more preferably
80 vol % or more, and further preferably 85 vol % or more).
[0013] In the present embodiment, the aromatic content in the fuel
composition is 25 vol % or less, preferably 20 vol % or less, more
preferably 15 vol % or less, still more preferably 10 vol % or
less, further preferably 5 vol % or less, furthermore preferably 3
vol % or less, and particularly preferably 2 vol % or less.
[0014] The fuel composition of the present embodiment comprises
hydrocarbons having 4 to 6 carbon atoms as main component with an
aromatic content equal to or less than a specific value to expand
the lean limit of a lean burn engine, being suitable for use as a
fuel composition for a lean burn engine (in particular, for use in
ultra-lean burn with a lean limit of 2 or more).
[0015] In the present specification, the content of each component
in the fuel composition is a value measured by the method described
in JIS K 2536-2 "Liquid petroleum products-testing method of
components, Part 2: Determination of total components by gas
chromatography".
[0016] The aromatic content of the fuel composition may be, for
example, 0.1 vol % or more, or may be 0.5 vol % or more. By
containing a slight amount of aromatic compound, the effect of
further increasing the heating value per volume while suppressing
knocking can be obtained.
[0017] More specifically, the aromatic content of the fuel
composition may be 0.1 to 25 vol %, 0.1 to 20 vol %, 0.1 to 15 vol
%, 0.1 to 10 vol %, 0.1 to 5 vol %, 0.1 to 3 vol %, 0.1 to 2 vol %,
0.5 to 25 vol %, 0.5 to 20 vol %, 0.5 to 15 vol %, 0.5 to 10 vol %,
0.5 to 5 vol %, 0.5 to 3 vol %, or 0.5 to 2 vol %.
[0018] In the hydrocarbons having 4 to 6 carbon atoms, for example,
normal paraffins having 4 to 6 carbon atoms, isoparaffins having 4
to 6 carbon atoms, olefins having 4 to 6 carbon atoms, and an
aromatic compound having 6 carbon atoms (benzene) may be
included.
[0019] In the fuel composition of the present embodiment, the
content of normal paraffins having 4 to 6 carbon atoms may be, for
example, 30 vol % or less, preferably 20 vol % or less, and more
preferably 15 vol % or less, relative to the total amount of
hydrocarbons having 4 to 6 carbon atoms. Thereby, the effect
described above tends to be obtained more remarkably.
[0020] The content of normal paraffins having 4 to 6 carbon atoms
may be, for example, 0.5 vol % or more, or may be 1 vol % or more,
preferably 5 vol % or more, and still more preferably 10 vol % or
more, relative to the total amount of hydrocarbons having 4 to 6
carbon atoms. Thereby, the effect described above tends to be
obtained more remarkably.
[0021] More specifically, the content of normal paraffins having 4
to 6 carbon atoms may be 0.5 to 30 vol %, 0.5 to 20 vol %, 0.5 to
15 vol %, 1 to 30 vol %, 1 to 20 vol %, 1 to 15 vol %, 5 to 30 vol
%, 5 to 20 vol %, 5 to 15 vol %, 10 to 30 vol %, 10 to 20 vol %, or
10 to 15 vol %, relative to the total amount of hydrocarbons having
4 to 6 carbon atoms.
[0022] In the fuel composition of the present embodiment, the
content of isoparaffins having 4 to 6 carbon atoms may be, for
example, 20 vol % or more, preferably 25 vol % or more, more
preferably 30 vol % or more, and still more preferably 35 vol % or
more, relative to the total amount of hydrocarbons having 4 to 6
carbon atoms. Thereby, the effect described above tends to be
obtained more remarkably.
[0023] Also, the content of isoparaffins having 4 to 6 carbon atoms
may be, for example, 80 vol % or less, preferably 75 vol % or less,
and more preferably 70 vol % or less, relative to the total amount
of hydrocarbons having 4 to 6 carbon atoms. The content of
isoparaffins having 4 to 6 carbon atoms may be 60 vol % or less, 50
vol % or less, or 45 vol % or less, relative to the total amount of
hydrocarbons having 4 to 6 carbon atoms. Thereby, the effect
described above tends to be obtained more remarkably.
[0024] More specifically, the content of isoparaffins having 4 to 6
carbon atoms may be 20 to 80 vol %, 20 to 75 vol %, 20 to 70 vol %,
20 to 60 vol %, 20 to 50 vol %, 20 to 45 vol %, 25 to 80 vol %, 25
to 75 vol %, 25 to 70 vol %, 25 to 60 vol %, 25 to 50 vol %, 25 to
45 vol %, 30 to 80 vol %, 30 to 75 vol %, 30 to 70 vol %, 30 to 60
vol %, 30 to 50 vol %, 30 to 45 vol %, 35 to 80 vol %, 35 to 75 vol
%, 35 to 70 vol %, 35 to 60 vol %, 35 to 50 vol %, or 35 to 45 vol
%, relative to the total amount of hydrocarbons having 4 to 6
carbon atoms.
[0025] In the fuel composition of the present embodiment, the
content of olefins having 4 to 6 carbon atoms may be, for example,
5 vol % or more, preferably 10 vol % or more, more preferably 20
vol % or more, and still more preferably 25 vol % or more, relative
to the total amount of hydrocarbons having 4 to 6 carbon atoms.
Also, the content of olefins having 4 to 6 carbon atoms may be 30
vol % or more, 35 vol % or more, or 40 vol % or more, relative to
the total amount of hydrocarbons having 4 to 6 carbon atoms.
Thereby, the effect described above tends to be obtained more
remarkably.
[0026] Also, the content of olefins having 4 to 6 carbon atoms may
be, for example, 70 vol % or less, preferably 65 vol % or less,
more preferably 60 vol % or less, still more preferably 55 vol % or
less, further preferably 50 vol % or less, and furthermore
preferably 45 vol % or less, relative to the total amount of
hydrocarbons having 4 to 6 carbon atoms. Thereby, the effect
described above tends to be obtained more remarkably.
[0027] More specifically, the content of olefins having 4 to 6
carbon atoms may be 5 to 70 vol %, 5 to 65 vol %, 5 to 60 vol %, 5
to 55 vol %, 5 to 50 vol %, 5 to 45 vol %, 10 to 70 vol %, 10 to 65
vol %, 10 to 60 vol %, 10 to 55 vol %, 10 to 50 vol %, 10 to 45 vol
%, 20 to 70 vol %, 20 to 65 vol %, 20 to 60 vol %, 20 to 55 vol %,
20 to 50 vol %, 20 to 45 vol %, 25 to 70 vol %, 25 to 65 vol %, 25
to 60 vol %, 25 to 55 vol %, 25 to 50 vol %, 25 to 45 vol %, 30 to
70 vol %, 30 to 65 vol %, 30 to 60 vol %, 30 to 55 vol %, 30 to 50
vol %, 30 to 45 vol %, 35 to 70 vol %, 35 to 65 vol %, 35 to 60 vol
%, 35 to 55 vol %, 35 to 50 vol %, 35 to 45 vol %, 40 to 70 vol %,
40 to 65 vol %, 40 to 60 vol %, 40 to 55 vol %, 40 to 50 vol %, or
40 to 45 vol %, relative to the total amount of hydrocarbons having
4 to 6 carbon atoms.
[0028] In the fuel composition of the present embodiment, the total
amount of normal paraffins having 4 to 6 carbon atoms, isoparaffins
having 4 to 6 carbon atoms and olefins having 4 to 6 carbon atoms
is, for example, 50 vol % or more, preferably 70 vol % or more,
more preferably 80 vol % or more, still more preferably 90 vol % or
more, and further preferably 93 vol % or more, relative to the
total amount of hydrocarbons having 4 to 6 carbon atoms. Thereby,
the effect described above tends to be obtained more
remarkably.
[0029] The fuel composition of the present embodiment may contain
hydrocarbons having more than 6 carbon atoms. The hydrocarbons
having more than 6 carbon atoms may be, for example, hydrocarbons
having 7 to 15 carbon atoms, or may be hydrocarbons having 7 to 10
carbon atoms.
[0030] In the fuel composition of the present embodiment, the
content of hydrocarbons having more than 6 carbon atoms may be, for
example, less than 50 vol %, preferably 40 vol % or less, more
preferably 30 vol % or less, still more preferably 20 vol % or
less, and further preferably 15 vol % or less, relative to the
total amount of the fuel composition.
[0031] In the fuel composition of the present embodiment, the ratio
of hydrocarbons having 4 to 6 carbon atoms relative to the total
amount of hydrocarbons is, for example, 50 vol % or more,
preferably 60 vol % or more, more preferably 70 vol % or more,
still more preferably 80 vol % or more, further preferably 85 vol %
or more, and furthermore preferably 90 mass % or more. Also, the
ratio of hydrocarbons having 4 to 6 carbon atoms relative to the
total amount of hydrocarbons may be 100 vol % or less, 98 vol % or
less, or 95 vol % or less.
[0032] More specifically, the ratio of hydrocarbons having 4 to 6
carbon atoms relative to the total amount of hydrocarbons may be 50
to 100 vol %, 50 to 98 vol %, 50 to 95 vol %, 60 to 100 vol %, 60
to 98 vol %, 60 to 95 vol %, 70 to 100 vol %, 70 to 98 vol %, 70 to
95 vol %, 80 to 100 vol %, 80 to 98 vol %, 80 to 95 vol %, 85 to
100 vol %, 85 to 98 vol %, 85 to 95 vol %, 90 to 100 vol %, 90 to
98 vol %, or 90 to 95 vol %.
[0033] The fuel composition of the present embodiment may further
contain oxygen-containing compounds.
[0034] The oxygen-containing compounds are organic compounds
containing oxygen as a constituent element. Examples of the
oxygen-containing compounds include oxygen-containing heterocyclic
compounds, oxygen-containing aromatic compounds, and
oxygen-containing aliphatic compounds. One of the oxygen-containing
compounds may be used alone, or two or more thereof may be used in
combination.
[0035] The oxygen-containing heterocyclic compounds are compounds
having an oxygen-containing heterocycle. Examples of the
oxygen-containing heterocyclic compounds include compounds having
an oxygen-containing heterocycle such as a furan ring, a
tetrahydrofuran ring, an ethylene oxide ring, a propylene oxide
ring, a pyran ring, a tetrahydropyran ring, a benzofuran ring, and
a benzopyran ring. As the oxygen-containing heterocyclic compounds,
compounds having a furan ring are preferred from the viewpoint of
obtaining the effect described above more remarkably. Examples of
the compounds having a furan ring include furan, 2-methylfuran and
2,5-dimethylfuran. As the compounds having a furan ring, furan and
2-methylfuran are particularly preferred.
[0036] Oxygen-containing aromatic compounds are compounds that
contain oxygen as a constituent element and have an aromatic ring.
Examples of the oxygen-containing aromatic compounds include
aromatic compounds having an oxygen atom directly bonded to an
aromatic ring (for example, alkoxybenzene, phenols). Examples of
alkoxybenzene include anisole, phenetol, and propyloxybenzene. As
alkoxybenzene, anisole and phenetol are preferred from the
viewpoint of the range of boiling point.
[0037] Examples of the oxygen-containing aliphatic compounds
include alcohols, ethers (for example, ethyl alcohol, isobutyl
alcohol, ETBE (ethyl-tert-butyl ether)).
[0038] In the fuel composition of the present embodiment, the
content of the oxygen-containing compound may be, for example, less
than 50 vol %, preferably 40 vol % or less, more preferably 30 vol
% or less, and still more preferably 25 vol % or less relative to
the total amount of the fuel composition.
[0039] In the case where the fuel composition of the present
embodiment contains an oxygen-containing compound, the content
thereof may be, for example, 1 vol % or more, 3 vol % or more, 5
vol % or more, or 10 vol % or more, relative to the total amount of
the fuel composition.
[0040] More specifically, the content of the oxygen-containing
compound relative to the total amount of the fuel composition may
be 0 vol % or more and less than 50 vol %, 0 to 40 vol %, 0 to 30
vol %, 0 to 25 vol %, 1 vol % or more and less than 50 vol %, 1 to
40 vol %, 1 to 30 vol %, 1 to 25 vol %, 3 vol % or more and less
than 50 vol %, 3 to 40 vol %, 3 to 30 vol %, 3 to 25 vol %, 5 vol %
or more and less than 50 vol %, 5 to 40 vol %, 5 to 30 vol %, 5 to
25 vol %, 10 vol % or more and less than 50 vol %, 10 to 40 vol %,
10 to 30 vol %, or 10 to 25 vol %.
[0041] The fuel composition of the present embodiment may further
contain components other than the above. Examples of the other
components include a cleaning dispersant, an antioxidant, a metal
deactivator, a surface ignition inhibitor, an antifreeze agent, a
combustion improver, an antistatic agent, a colorant, a rust
inhibitor, a drainage agent, a fuel marker, an odorant, and a
friction modifier. The total content of these other components may
be, for example, 1 vol % or less, preferably 0.5 vol % or less, and
more preferably 0.1 vol % or less, relative to the total amount of
the fuel composition. Also, the total content of the other
components may be, for example, 0.001 vol % or more, or 0.002 vol %
or more, relative to the total amount of the fuel composition.
[0042] More specifically, the total content of the other components
described above may be 0 to 1 vol %, 0 to 0.5 vol %, 0 to 0.1 vol
%, 0.001 to 1 vol %, 0.001 to 0.5 vol %, 0.001 to 0.1 vol %, 0.002
to 1 vol %, 0.002 to 0.5 vol %, or 0.002 to 0.1 vol %.
[0043] As the cleaning dispersant, a commonly used cleaning
dispersant may be used, and, for example, a compound known as a
cleaning dispersant for gasoline such as succinimide,
polyalkylamine, or polyetheramine may be used. Examples of the
antioxidant include N,N'-diisopropyl-p-phenylenediamine,
N,N'-diisobutyl-p-phenylenediamine, 2,6-di-t-butyl-4-methylphenol,
and hindered phenols. Examples of the metal deactivator include an
amine-carbonyl condensation compound such as
N,N'-disalicylidene-1,2-diaminopropane. Examples of the surface
ignition inhibitor include an organic phosphorus compound. Examples
of the antifreeze agent include a polyhydric alcohol or an ether
thereof. Examples of the combustion improver include an alkali
metal salt or alkaline earth metal salt of organic acid, and a
higher alcohol sulfate ester. Examples of the antistatic agent
include an anionic surfactant, a cationic surfactant, and an
amphoteric surfactant. Examples of the colorant include an azo dye.
Examples of the rust inhibitor include an organic carboxylic acid
and a derivative thereof, and an alkenyl succinic acid ester.
Examples of the drainage agent include sorbitan esters. Examples of
the fuel marker include kilyzanine and coumarin. Examples of the
odorant include a natural essential oil and a synthetic fragrance.
Examples of the friction modifier include a mixture of a higher
carboxylic acid monoglyceride and a higher carboxylic acid amide
compound.
[0044] A preferred embodiment of the present invention has been
described above, though the present invention is not limited
thereto.
EXAMPLES
[0045] The present invention will be described in more detail with
reference to Examples as follows, though the present invention is
not limited thereto.
Example 1
[0046] As the fuel composition, a fuel composition having a
composition shown in the following Table 1 was prepared. The
composition of the fuel composition is based on the values measured
by the method described in JIS K 2536-2 "Liquid petroleum
products-Testing method of components, Part 2: Determination of
total components by gas chromatography". Using the prepared fuel
composition, the lean limit was measured by the following method.
The results are shown in Table 1.
[0047] <Measurement of Lean Limit>
[0048] With use of the following test engine, the lean limit was
measured by changing the excess air ratio under conditions with a
rotation speed of 2000 rpm, an indicated mean effective pressure of
800 kPa, and a minimum spark advance for best torque (MBT). The
excess air ratio at a point where the fluctuation rate of the
indicated mean effective pressure exceeds 3% was presumed as the
lean limit. The excess air ratio is the air-fuel ratio of the
air-fuel mixture during testing divided by the theoretical air-fuel
ratio of the fuel composition, which is the reciprocal of
equivalence ratio .PHI..
[0049] (Test Engine)
[0050] Engine: single cylinder
[0051] Displacement: 563 cc
[0052] Injection method: port injection
Examples 2 to 10, and Comparative Examples 1 to 3
[0053] The composition of the fuel composition was changed to the
composition shown in Table 1, Table 2 or Table 3, and the lean
limit was measured in the same manner as in Example 1. The results
are shown in Table 1, Table 2 or Table 3. In Example 9, ethanol was
used as the oxygen-containing compound, and in Example 10,
2-methylfuran was used as the oxygen-containing compound. Further,
Comparative Example 1 is an example with use of high-octane
gasoline, and the oxygen content in Comparative Example 1 indicates
the content of the oxygen-containing compound contained in
high-octane gasoline.
[0054] In the tables, "Saturated content" indicates the content
(vol %) of saturated hydrocarbons, "Unsaturated content" indicates
the content (vol %) of unsaturated hydrocarbons (excluding aromatic
compounds), "Aromatic content" indicates the content (vol %) of
aromatic compounds, "Oxygenates content" indicates the content (vol
%) of oxygen-containing compounds, and "Total" indicates the total
content (vol %) of saturated hydrocarbons, unsaturated
hydrocarbons, aromatic compounds and oxygen-containing
compounds.
[0055] Further, in the tables, "C4 to C6 hydrocarbon" indicates the
content (vol %) of hydrocarbons having 4 to 6 carbon atoms in the
fuel composition, "n-Paraffin" indicates the content (vol %) of
normal paraffins having 4 to 6 carbon atoms relative to the total
amount of hydrocarbons having 4 to 6 carbon atoms, "Isoparaffin"
indicates the content of isoparaffins having 4 to 6 carbon atoms
relative to the total amount of hydrocarbons having 4 to 6 carbon
atoms, "Olefin" indicates the content (vol %) of olefins having 4
to 6 carbon atoms relative to the total amount of hydrocarbons
having 4 to 6 carbon atoms, and "Subtotal" indicates the total
content (vol %) of normal paraffins having 4 to 6 carbon atoms,
isoparaffins having 4 to 6 carbon atoms, and olefins having 4 to 6
carbon atoms relative to the total amount of hydrocarbons having 4
to 6 carbon atoms.
TABLE-US-00001 TABLE 1 Example 1 Example 2 Example 3 Example 4
Example 5 Saturated content 72.2 45.4 44.3 49.8 55.4 Unsaturated
content 8.0 33.7 54.1 48.7 43.3 Aromatic content 20.1 21.0 1.9 1.8
1.5 Oxygenates content -- -- -- -- -- C4 TO C6 50.3 68.7 87.5 88.5
90.0 HYDROCARBON n-Paraffin 34.8 5.2 5.2 10.6 4.0 Isoparaffin 60.7
32.4 32.4 33.3 47.4 Olefin 2.7 56.7 56.7 50.5 44.1 Subtotal 98.2
94.3 94.3 94.3 95.6 Lean limit 2.17 2.20 2.23 2.25 2.30
TABLE-US-00002 TABLE 2 Example 6 Example 7 Example 8 Example 9
Example 10 Saturated content 72.1 55.0 57.6 39.8 35.4 Unsaturated
content 27.1 43.8 41.3 48.7 43.3 Aromatic content 1.0 1.6 1.5 1.7
1.5 Oxygenates content -- -- -- 10.0 20.0 C4 TO C6 93.7 90.1 90.8
78.7 70.0 HYDROCARBON n-Paraffin 2.4 11.8 13.4 5.2 5.2 Isoparaffin
68.5 38.7 40.3 32.4 32.4 Olefin 26.5 44.6 41.7 56.7 56.7 Subtotal
97.4 95.1 95.4 94.3 94.3 Lean limit 2.32 2.35 2.40 2.26 2.38
TABLE-US-00003 TABLE 3 Comparative Comparative Comparative Example
1 Example 2 Example 3 Saturated content 40.1 46.6 71.4 Unsaturated
content 19.1 13.3 6.7 Aromatic content 37.8 40.0 21.3 Oxygenates
content 2.9 -- -- C4 TO C6 49.9 0.0 11.7 HYDROCARBON n-Paraffin 9.8
0.0 56.0 Isoparaffin 45.5 0.0 43.8 Olefin 33.5 0.0 0.2 Subtotal
88.8 0.0 100.0 Lean limit 1.99 2.01 1.99
* * * * *