EP0326975B1 - Lubricant for traction drive with continuously variable transmission - Google Patents

Abstract

The present invention relates to a lubricant for traction drives with infinitely adjustable power transmission. It is particularly suitable for traction chain drives.

Description

The present invention relates to a lubricant for transmissions with continuously variable power transmission. It is particularly suitable for pull chain transmissions.

It is known to the person skilled in the art that transmissions with continuously variable transmission (CVT transmission, Continuously Variable Transmission) are gaining importance, since motor vehicles with such transmissions have very good efficiency, low noise and low fuel consumption. As with conventional automatic transmissions, shifting is not necessary.

A distinction is made between push chain drives and pull chain drives.

A well-known push chain transmission is, for example, the CVT transmission with Van Doorne push link belt. (Drive technology 26, (1987) No. 8, page 47-52).

The lubricant is of great importance for pull and push chain gearboxes. It should not only have a good lubricating effect in order to keep the wear on the chains low, but it must also have a certain coefficient of friction in order to enable the power transmission. The coefficient of friction must be higher than with conventional lubricating oils, but not as high as with so-called traction fluids.

definiert.In the latter, the highest possible coefficient of friction is desirable, since the task of lubricating chain links at the same time is eliminated. Rather, discs or rollers run on each other, the "slip" of which should be as small as possible. If the rotational speed of one body is V1 and that of the other V2, the slip value is as $$\frac{\text{V1 - V2}}{\text{V1}}$$

Are defined.

Lubricants for pull chain transmissions have already been described in the literature.

For example, DE-OS 3127970 discloses a lubricant which consists of a hydrocarbon oil which contains 19-30 hydrocarbon atoms and 3 six-membered carbocyclic rings.

DE-A-3321773 describes a lubricant which contains decalin rings connected by carbon bridges.

DE-A-3337503 discloses a lubricant from the same applicant which also contains hydrogenated condensed aromatics.

Phosphetane derivatives as an additive to conventional lubricants are disclosed in DE-A-2715529.

in einer Menge von 3 × 10⁻⁶ Mol bis 1 × 10⁻² Mol, bevorzugt 1,5 × 10⁻⁵ bis 5 × 10⁻³ Mol und besonders bevorzugt 3 × 10⁻⁵  - 3 × 10⁻³ Mol bezogen auf 100 g Schmiermittel, wobei R₁, R₂, R₃ und R₄, H, lineare, verzweigte und ringförmige gesättigte C₁-C₄-Kohlenwasserstoffreste sein können,

X₁, X₂ und X₃

unabhängig voneinander O oder S bedeuten

n

falls X₁ O ist, 1 und falls X₁ S ist, 1-2 bedeutet,

Z

eine ein- oder mehrwertige stickstoffhaltige öllösliche organische Base ist,

m

1-2 ist und

p

1-2 bedeutet.

The applicant has now surprisingly found that a lubricant which is excellently suitable for transmissions with continuously variable power transmission, in particular pull chain transmissions, is characterized in that it contains 10 to 80% by weight of naphthenic hydrocarbons, 80 to 10% by weight of polyisobutene with a degree of polymerization of mol% 200 to 10,000, preferably moles by weight, 300 to 6000 and an additive of at least one phosphetane derivative of the general formula

in an amount of 3 × 10⁻⁶ mol to 1 × 10⁻² mol, preferably 1.5 × 10⁻⁵ to 5 × 10⁻³ mol and particularly preferably 3 × 10⁻⁵ - 3 × 10⁻³ mol based on 100 g of lubricant, where R₁, R₂, R₃ and R₄, H, can be linear, branched and ring-shaped saturated C₁-C₄ hydrocarbon radicals,

X₁, X₂ and X₃

independently represent O or S.

n

if X₁ is O, 1 and if X₁ is S, means 1-2,

Z

is a mono- or polyvalent nitrogen-containing oil-soluble organic base,

m

Is 1-2 and

p

1-2 means.

X₁

S

n

1-2

X₂ und X₃

O und

Z

ein primäres, sekundäres oder tertiäres Amin der Formel N R₅ R₆ R₇, worin R₅ und R₆ unabhängig voneinander Wasserstoff oder einen aliphatischen oder aromatischen Rest und R₇ einen aliphatischen oder aromatischen Rest bedeuten.

Preferably means

X₁

S

n

1-2

X₂ and X₃

O and

Z

a primary, secondary or tertiary amine of the formula N R₅ R₆ R₇, wherein R₅ and R₆ independently of one another are hydrogen or an aliphatic or aromatic radical and R₇ is an aliphatic or aromatic radical.

X₁

S

n

1

X₂ und X₃

O und

Z

ein primäres Amin der Formel H₂ N R₈, worin R₈ einen aliphatischen Rest bedeutet und

m

= 1

Means particularly preferred

X₁

S

n

1

X₂ and X₃

O and

Z

a primary amine of the formula H₂ N R₈, wherein R₈ is an aliphatic radical and

m

= 1

The naphthenic component is a highly refined or fully hydrated product. Such products are available on the market. Of course, they can also be produced by refining in our own plants.

Likewise, the polyisobutene component can be found on the market available product.

The naphthenic component is contained in the lubricant in a concentration of 10 to 80% by weight, preferably 15 to 50% by weight.

The polyisobutene component is present in the lubricant in a concentration of 10 to 80% by weight, preferably 40 to 70% by weight.

X₁, X₂ und X₃

unabhängig voneinander O oder S bedeuten

n

falls X₁ O ist, 1 und falls X₁ S ist, 1-6 bedeutet,

Z

eine ein- oder mehrwertige stickstoffhaltige öllösliche organische Base ist,

m

1-2 ist und

p

1-2 bedeutet.

The groups on the four-membered ring R₁, R₂, R₃ and R₄ of the phosphetane derivative can be the same or different. They are preferably H, but can also be C₁-C₄ hydrocarbon radicals, which can be branched, ring-shaped and straight-chain, wherein

X₁, X₂ and X₃

independently represent O or S.

n

if X₁ is O, 1 and if X₁ is S, means 1-6,

Z

is a mono- or polyvalent nitrogen-containing oil-soluble organic base,

m

Is 1-2 and

p

1-2 means.

X₁

S

n

1-2

X₂ und X₃

O und

Z

ein primäres, sekundäres oder tertiäres Amin der Formel N R₅ R₆ R₇, worin R₅ und R₆ unabhängig voneinander Wasserstoff oder einen aliphatischen oder aromatischen Rest und R₇ einen aliphatischen oder aromatischen Rest bedeuten.

Preferably means

X₁

S

n

1-2

X₂ and X₃

O and

Z

a primary, secondary or tertiary amine of the formula N R₅ R₆ R₇, wherein R₅ and R₆ independently of one another are hydrogen or an aliphatic or aromatic radical and R₇ is an aliphatic or aromatic radical.

X₁

S

n

1

X₂ und X₃

O und

Z

ein primäres Amin der Formel H₂ N R₃ ist, worin R₃ einen aliphatischen Rest bedeutet und

m

= 1

Mean particularly preferred

X₁

S

n

1

X₂ and X₃

O and

Z

is a primary amine of the formula H₂N R₃, wherein R₃ is an aliphatic radical and

m

= 1

In principle, any mono- or divalent organic nitrogen base can be used as the base for salt formation with the 1,3-thiaphosphetanes. For practical reasons, only oil-soluble nitrogen bases are suitable for use in lubricants, and in particular those with a total C number of 6-40 C atoms.

Monovalent compounds are preferably used as the oil-soluble organic nitrogen bases, and in particular primary, secondary or tertiary amines of the formula R₅ R₆NR₇, where R₅ and R₆ independently of one another are hydrogen or an aliphatic or aromatic radical, and R₇ is an aliphatic or aromatic radical.

If R₅, R₆ and R₇ are an aliphatic radical, it may be branched or straight-chain alkyl which may be interrupted with O and / or S, such as methyl, ethyl, n-propyl, isopropyl, t-butyl, amyl, hexyl, 1-methylpentyl , t-octyl, 2-ethyl-hexyl, n-decyl, 2-ethyl-decyl, n-tetradecyl, n-octadecyl, n-eicosyl, 2,7,8-trimethyl-decyl, 4-isobutyl-2,5 -dimethyl-heptyl, octacosoyl, dotriacontyl, hexatriacontyl or tetracontyl. However, R₅, R₆ and R₇ can also be an aliphatic radical which may be interrupted with O or S, branched or straight-chain alkenyl such as allyl, vinyl, 2-butenyl, 2-hexenyl, 2-dodecenyl or 2-hexatriacontenyl. The total C number of the radicals R₅, R₆ and R₇ should be 6 to 40.

The amino group can optionally also be ethoxylated, the degree of ethoxylation having to be matched to the desired oil solubility of the product.

If R₅, R₆ and R₇ represent an aromatic radical, this is a phenyl group which is optionally substituted by alkyl groups each having 1 to 12 carbon atoms, such as methyl, ethyl, propyl, butyl, hexyl, oxyl, decyl or dodecyl.

Among the organic nitrogen bases of the formula R₅ R₆NR₇ to be used are those in which R₅ and R₆ independently of one another are hydrogen or an aliphatic radical, and R₇ is a phenyl group which is optionally substituted by alkyl groups.

However, primary organic nitrogen bases of the formula H₂NR₈ are particularly preferably used, in which R₈ is optionally interrupted by O or S, branched or straight-chain alkyl or alkenyl each having 6 to 40, and in particular each having 8 to 24, carbon atoms.

In practice, mixtures of different nitrogen bases are often used, e.g. Primene 81-R (mixture of primary C₁₂-C₁₅ t-alkylamines, from Rohm and Haas, USA). However, the salts which have a uniform nitrogen component are equally suitable.

Examples of such amines are:
Methylamine, ethylamine, propylamine, butylamine, t-butylamine, hexylamine, octylamine, (2-ethylhexyl) amine, t-octylamine, decylamine, t-dodecylamine, tetradecylamine, octadecylamine, phenylamine, benzylamine, (nonylphenyl) amine, cyclohexylamine, pyridine Piperidine, dimethylamine, methyloctylamine, didodecylamine, methyloctadecylamine, methylcyclohexylamine, phenyloctylamine, trimethylamine, dimethylcyclohexylamine, methyloctyldecylamine, (octoxyethyl) amine, (octylthioethyl) amine, (t-dodecylthioethyl) amine Dodecyldimethylamine, hexadecyldimethylamine, decyldimethylamine, didodecylmethylamine, methylbutyldodecylamine, dimethylpropylamine, trioctylamine, dioctylmethylamine, dodecylbenzylmethylamine, nonylphenyldimethylamine, phenyl methyl-amine, phenyl-dimethyl-amine, phenyl-dimethyl-amine, allyl-dibutyl-amine, methyl-dodecyl-amine, heptadecyl-dimethyl-amine, dioctyl-methyl-amine, methyl-α-naphthyl-phenyl-amine, Cyclohexyl-dimethyl-amine, nonyl-dimethyl-amine, tris (n-tridecyl) amine, tris (n-dodecyl) amine, tris (isooctyl) amine, methylbutylhexadecyl amine, tri-ethyl amine, 3,5-dimethyl -pyridine, 2- (ethylhexyl) -methyl-dodecyl-amine, (methylethyl) -didecyl-amine, methyl-butyl-dodecyl-amine, dimethyl-dodecyl-amine, hexadecyl-dimethyl-amine, tris (i-dodecyl) - amine, dimethylbenzylamine, dimethyl- (tert-octylphenyl) amine, (N-methyl) -1-imidazoline (N-methyl) -1-pyrrazoline, oxazoline, quinoline, pyrrolidine, N-ethyl-pyrrolidine, N-methyl-piperidine, N-butyl-piperidine, N-butyl-piperidine, thiazole, N-methyl-phenothia min.

Examples of phosphetane compounds according to the invention are:
Dodecylammonium salt of 3-hydroxy-3-oxo-1,3-thiaphosphetane
Di-n-butylammonium salt of 3-mercapto-3-thio-1,3-thiaphosphetane
Tri-n-octylammonium salt of 3-hydroxy-3-oxo-1,3-thiaphosphetane
(2,6-di-tert-butyl-phenyl) ammonium salt of 3-mercapto-3-oxo-1,3-oxaphosphetane
(2,6-diethyl-phenyl) -diethylammonium salt of 3-hydroxy-3-oxo-1,3-thiaphosphetane
Tri-n-nonyl ammonium salt of 3-hydroxy-3-oxo-1,3-oxaphosphetane
Di- (2-ethyl-hexyl) ammonium salt of 3-hydroxy-3-oxo-1,3-thiaphosphetane.

A specific one or several of the mentioned phophetane derivatives can be used.

The investigations by the applicant have surprisingly shown that the wear on the chains is reduced very greatly by the phosphetane derivatives according to the invention, so that a lubricant is obtained which gives both the desired coefficient of friction and low chain wear.

The lubricant according to the invention has been carefully tested in numerous tests both in the CVT transmission test bench and in the vehicle.

The test gear was filled with approx. 5 L test oil before each start of the test.

Between the tests, thorough cleaning followed by rinsing with approx. 1.5 L of the new test lubricating oil.

After every 3000 KWh (corresponding to 12,000 km test run), 50 ml of lubricant were removed for testing and the same amount of fresh oil was added.

Each start-up cycle lasted almost 1 minute, corresponding to a distance of 1 km.

Tests were carried out with distances of 12,000, 24,000 and 38,000 km.

The start-up cycle was chosen so that the chain and tapered pulleys were subjected to the highest possible load through constant adjustment, standstill adjustment and correspondingly high sliding components.

Transferred to a vehicle, the clutch was started at medium engine speed and medium engine torque and quickly accelerated to a driving speed of approx. 120 km / h. Then the brakes were applied fully and the converter ratio was reset to the starting gear at the same time.

The evaluation criteria for the quality of the lubricant used were the closure on the weighing pressure pieces used, the formation of gray spots on the conical disks and the coefficient of friction.

nämlich Viskositätsverbesserer wie z.B. Polymethacrylate, Antischaummittel, Korrosionsschutzmittel und Antioxidantien z.B. des Phenol- und/oder Amintyps.A typical lubricant formulation contained the following components:

namely viscosity improvers such as, for example, polymethacrylates, anti-foaming agents, anti-corrosion agents and antioxidants, for example of the phenol and / or amine type.

It is also advantageous to use wear protection additives e.g. phosphorus and / or sulfur based.

However, other products available on the market can also be used as additives.

eingesetzt.When was phosphetane

used.

The following results were obtained:

The table shows that with an optimal coefficient of friction there is a surprising reduction in wear in the case of the pattern III according to the invention.
Without the addition of the phosphetane, however, the pattern IV corresponding to the formulation of pattern III neither gives a usable wear number nor a usable cleaning number.

Appearance of the conical disks: no gray spots. Viscosity behavior

a,

13.000 km

b,

25.000 km

und

c,

38.000 km

untersucht.

There were 3 samples with mileage from

a,

13,000 km

b,

25,000 km

and

c,

38,000 km

examined.

The results show that the lubricant according to the invention has excellent shear stability. The neutralization number and saponification number also show that oil aging can also be regarded as very low.

From Table 3 it can be seen for samples ac that the very low levels of Cu and Fe and the negligible increases in these metals, the additives ensure excellent wear protection. Oil change intervals can therefore be easily extended to over 40,000 km.

In addition, the levels of Pb, Si, Mn, Mo, Ca, Zn, Ni, Al, Cr, B, P, Mg, Ba and Sn were checked.

No changes were found in these elements compared to the reserve sample (original sample).

The composition of the lubricant was varied within the limits specified, with numerous phosphetane derivatives being added in the disclosed amount ranges, which were prepared according to DE-A-2715529 and the literature cited therein. Similar good test results were obtained.

Only some of the lubricant mixtures examined are summarized in Table 4.

Claims (13)

1. Lubricant, characterized in that it contains 10-80 weight-% of naphthenic hydrocarbons, 80-10 weight-% of polyisobutene with a degree of polymerization of molar weight of 200 to 10,000, and that it contains an additive of at least one of the phosphetane derivatives of the general formula

in a quantity of 3 × 10⁻⁶ moles to 1 × 10⁻² moles based on 100 g of lubricant, whereby R₁, R₂, R₃ and R₄ are H and/or linear and/or branched and/or cyclic saturated C₁-C₄ hydrocarbon groups,

X₁, X₂ and X₃   are independent of each other O (oxygen) or S (sufur),

n   is 1, if X₁ is O (oxygen) and 1-6, if X₁ is S (sulfur)

Z   is a mono- or polyvalent, nitrogen containing, oil soluble,organic base

m   is 1 or 2 and

P   is 1 or 2;

preferably

X₁   is S

n   is 1 or 2

X₂ and X₃   are O

Z   is a primary, secondary or tertiary amine of the formula NR₅R₆R₇,wherein R₅ and R₆ are independant of each other H, an aliphatic or aromatic group and R₇ is an aliphatic or aromatic group; and...

particularly preferable

X₁   is S

n   is 1

X₂ and X₃   are O

Z   is a primary amine of the formula H₂NR₈, wherein R₈ is an aliphatic group and

m   is 1

2. Lubricant according to claim 1, characterized in that R₁, R₂, R₃ and R₄ are H.

3. Lubricant according to claims 1 and 2, characterized in that the naphthenic oil is hydrogenated.

4. Lubricant according to claims 1-3, characterized in that the degree of polymerization of the polyisobutene corresponds to a molar weight of 300 to 6000.

5. Lubricant according to claims 1-4, characterized in that the concentration of the naphthenic oil is 15-50 weight-%.

6. Lubricant according to claims 1-5, characterized in that the concentration of the polyisobutene is 40-70 weight-%.

7. Lubricant according to claims 1-6, characterized in that the concentration of the phosphetane derivative(s) is 1.5 × 10⁻⁵ to 5 × 10⁻³ moles and particularly preferable 3 × 10⁻⁵ to 3 × 10⁻³ moles based on 100 g of lubricant.

8. Lubricant according to claims 1-7, characterized in that it contains in addition a viscosity improver.

9. Lubricant according to claims 1-8, characterized in that it contains in addition an anti-foaming agent.

10. Lubricant according to claims 1-9, characterized in that it contains in addition an anti-corrosion agent.

11. Lubricant according to claims 1-10, characterized in that it contains in addition an anti-wear agent.

12. A transmission fluid composition for continuously variable mechanical transmissions, which comprises the lubricant according to claims 1-11.

13. A transmission fluid composition for pulling chain transmissions, which comprises the lubricant according to claims 1-11.