Additive Releasing Oil Filter

Abstract

An oil filter for dispensing additive into oil used in an engine, comprises: a canister; a filter within said canister, said filter having an outside and an inside and defining a space between the filter outside and the canister; a chamber within the canister and defined by a member having an opening therethrough; at least one additive disposed in said chamber; and a gate accruable between open and closed positions, said gate being disposed so as to occlude said opening when in the closed position and being disposed so as to allow fluid flow through said opening when in the open position. The additive may be in a solid form and may contact the oil when said gate is in the open position. The gate may be temperature- or pressure-actuated.

Description

RELATED CASES

This case claims priority to U.S. Application Ser. No. 60/943,959, filed Jun. 14, 2007, which is incorporated herein by reference.

FIELD OF INVENTION

The present invention relates to improved apparatus and methods for lubrication of internal combustion engines. More particularly, this invention relates to an oil filter that releases performance enhancing additives into the oil over time, thereby prolonging the life of the oil and improving engine performance.

BACKGROUND OF THE INVENTION

Internal combustion engines are typically lubricated using oil compositions that have been formulated for that purpose. During operation of an internal combustion engine, hydrocarbon fuel and oxygen burn in the presence of nitrogen. The combustion produces mostly carbon dioxide and water, but also results in the formation of contaminants that include organic, sulfur and nitrogen-based acids as well as soot formed from incomplete combustion. These contaminants often enter the lubricating fluid, where they cause undesirable engine wear, corrosion, increased oil viscosity and unwanted deposits, all of which are undesirable.

To minimize the undesirable effects of these contaminants, lubricant additives such as detergents and dispersants are typically included in the lubricating fluid. Detergents are effective for controlling piston deposits, dispersants are effective for controlling viscosity increase due to soot and sludge formation, and both detergents and dispersants are effective for neutralizing combustion acid.

However, as set out in U.S. Application Serial No. 20060260874, which is incorporated herein by reference, there are upper limits on the amounts of these additives that can be included in an oil formulation. First, some detergents and dispersants have solubility limits in the oil. If the upper solubility limits are reached, some of these additives may precipitate, adhere to pistons, and form deposits. Thus, increasing detergent concentration above a certain level has diminishing returns. Second, high dispersant concentrations increase the viscosity of the lubricant, especially at low temperature, and high viscosities decrease lubricant and engine efficiency. Still further, dispersants typically are more expensive than detergents. Thus, viscosity and economics limit how much dispersant can be added to a lubricant. Third, both detergents and dispersants are stoichiometric additives. Unlike a catalytically active material, each molecule or detergent or dispersant performs its function only once and must then be replaced.

In addition, certain components in the lubricant additives can foul exhaust after-treatment systems. The components, such as sulfated ash, phosphorus and sulfur (SAPS), are introduced into these systems through the combustion of the lubricant. Because exhaust after-treatment mechanisms are required in order to meet national emission limits, limits on SAPS in commercial lubricants have been set by organizations that establish lubricant standards.

Because additives are gradually consumed, but cannot be initially provided at concentrations above certain limits, these additives must be replenished or replaced intermittently in order to maintain optimum lubricant functionality. Often, the only way to accomplish this is to decrease the interval between oil replacements. However, reducing the interval between oil changes is economically and environmentally undesirable. Since lubricant additive levels, in general, determine the oil drain interval, therefore, it has heretofore been desirable to formulate oils having initial additive concentrations that are at the upper limits of their possible concentration ranges.

In light of the foregoing, there remains a need for an engine lubrication system that significantly prolongs oil life without negatively affecting engine performance and without requiring undesirably high concentrations of additives in the lubricant.

U.S. Pat. No. 6,843,916 discloses a canister that fits between the engine block and the oil filter. The canister contains additive-containing particles that gradually dissolve in above ambient temperature oil. Because the device disclosed in the '916 patent releases additive whenever it is exposed to above ambient temperature oil, there is a possibility that the rate of additive addition may exceed the rate of additive use, with the result that the excess additives will precipitate out elsewhere in the engine. Hence, there is a need for an additive addition system that will increase additive concentration in the oil only during periods when the engine is not running, thereby limiting the amount of additive that will be added and extending the period of additive addition.

SUMMARY OF THE INVENTION

The present invention provides a lubrication system that significantly prolongs oil life without negatively affecting engine performance. The present system increases the additive concentration in the oil only during periods when the engine is not running.

According to preferred embodiments of the invention, an automotive engine spin-on filter uses a pressure- or temperature-responsive gate to expose the lubricating fluid (oil) to solid additive(s) during limited time periods that are determined by operation of the engine.

In certain embodiments, a filter in accordance with the invention includes a temperature-responsive gate that opens when the engine is cold and closes when the engine is hot. In other embodiments, a filter includes a pressure-responsive gate that opens when the engine is turned off and closes when the engine is turned on. In each embodiment, opening the gate exposes the lubricating fluid to additional additive(s), which may be provided in solid, pellet, felt or other suitable form. Because the lubricating fluid is exposed to the additive only when the engine is cold, or is not operating, the uptake of solid additives, e.g. antioxidants and dispersants, into the oil stream is limited. This intermittent introduction of additional additives into the oil extends the life of the oil.

BRIEF DESCRIPTION OF THE DRAWINGS

Advantages of the present invention will become apparent to those skilled in the art with the benefit of the following detailed description of embodiments and upon reference to the accompanying drawings, in which:

FIG. 1 is a schematic cross-section of an oil filter constructed in accordance with a preferred embodiment of the present invention, with the gate in a closed position;

FIG. 2 is a schematic cross-section of the oil filter of FIG. 1, with the gate in an open position;

FIG. 3 is a schematic cross-section of an oil filter constructed in accordance with a preferred embodiment of the present invention, with the gate in a closed position; and

FIG. 4 is a schematic cross-section of the oil filter of FIG. 3, with the gate in an open position.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood that the drawings and detailed description thereto are not intended to limit the invention to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the present invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring initially to FIG. 1, an oil filter 10 comprises an outer canister 12 and an inner filter 14. An annular space 16 is defined between filter 14 and canister 12. When the engine is operating, dirty oil flows into annular space 16, as indicated by arrows 17. The dirty oil flows through filter 14, which removes various particulate contaminants, and the flows out of the center of the filter, as indicated by arrows 19. In accordance with certain embodiments of the invention, an additional chamber 20 is defined within canister 12. Chamber 20 may be at the closed end of filter 10, as shown, or may alternatively be provided elsewhere in filter 10.

Chamber 20 is isolated from space 16 by an inner wall 22 having an opening 24 therein. Opening 24 can be closed with a gate 26, which may be actuable in response to changes in temperature or pressure. In a pressure-actuated embodiment, gate 26 comprises a reed valve, which opens when the pressure in space 16 drops below a predetermined value that is greater than the pressure in the filter when the engine is off, as shown in FIG. 2. Conversely, when the pressure in space 16 rises above the predetermined pressure, such as occurs when the engine is switched on and the oil pump is operating, gate 26 closes again.

In a temperature-actuated embodiment, shown in FIGS. 3 and 4, gate 26 comprises a thermally responsive element that opens when the temperature of the oil in the filter drops below a predetermined value. In preferred embodiments, the predetermined temperature value will be set below the operating temperature of the oil and above the ambient temperature, so that the valve will be open when the engine is “cold.” In alternative embodiments, gate 26 may be configured so as to be closed when the engine is “cold” and open at operating temperatures.

Various desired additives may be provided within chamber 20. When gate 26 is open, the volume of oil that is present in filter 10 will be exposed to the additives in chamber 20. However, because gate 26 is configured to be generally closed during operation of the engine, oil does not generally circulate through filter 10 while gate 26 is open. Providing additional additives in this manner ensures that the solid additives dissolve only into the volume of engine oil that is trapped in the filter during shut down. This in turn ensures, that additives are added to the oil slowly to the, and that their addition is partly a function of the number of engine starts.

When the gate opens, which preferably occurs when the engine is turned off, the additives in chamber 20 are in contact with the volume of oil that is contained in filter 10. So long as additives remain in chamber 20, a portion of those additives will dissolve into the fixed volume of oil, up to their respective solubility limits. Put another way, additives are dissolved in the dirty side of the oil outside the filter media. The dissolved additives pass through filter 14 and circulate with the clean oil when the engine is re-started. Because gate 26 is preferably normally closed during engine operation, additional additives are not added until the next engine shut down.

The additives in chamber 20 can be provided in solid, gel, pellet, fiber, or any other suitable configuration, such as are known in the art.

If the additives are provided in a oil-soluble carrier, which may be polymeric. The carrier selection will depend on the system in which it is used and on operating temperatures of the engine. The carrier is preferably a thermoplastic solid, a solid mass, or gel and has a desired rate of dissolution in oil at the temperatures of oil contact. For example, the additive(s) may be provided in crystalline granules that packed into chamber 20.

Suitable carriers include but are not limited to: ethylene-propylene copolymers ranging in molecular weight from 200,000 to 300,000; ethylene-ethylacrylate polymers ranging in molecular weight from 200,000 to 300,000; polypropylene oxide having a molecular weight of about 500,000; and ethylene-vinyl acetate copolymer ranging in molecular weight from 200,000 to 300,000. Particularly preferred is polyisobutylene ranging in molecular weight from approximately 60,000 to 135,000. Also preferred are copolymers obtained by polymerizing a C_10-20 alkyl methacrylate with a vinylpyridene. Suitable copolymers range in molecular weight from 200,000 to about 800,000. Also preferred is polystyrene ranging in molecular weight from 30,000 to 50,000 and copolymers obtained by polymerizing propylene with a C_10-24 monoolefin and ranging in molecular weight from 81,000 to 135,000. Any other polymer having a low rate of dissolution in the oil may also be suitable.

Any detergent, antioxidant, anti-wear agent, and/or other additive that is known for use in lubricating oils may be included in chamber 20. In particular, anti-wear agents tend to be depleted relatively quickly, so it is preferred that the additives in chamber 20 contain at least an anti-wear agent. Suitable anti-wear agents are known in the art, and include but are not limited to zinc, phosphorus, molybdenum disulfide (MoD), and zinc dialkyldiacylphosphate (ZDDP). Although both ash-containing, metal-based detergents and ashless detergents are useful in such solid particles-containing suspensions, ashless detergents are preferred. There are many examples of ash-containing, metal-based detergents which are suitable in such solid particles-containing suspensions. The ashless detergents preferred for use are compounds which comprise an oil-solubilizing tail and a polar detergent head. Many ashless detergents fitting this general description are known to the art and are commercially available. Suitable antioxidant agents are known in the art.

The present invention provides a novel filter that provides controlled placement and release of additives into oil in the filter, thereby ensuring effective replacement of additives into the oil, and providing for optimum additive replenishment over the service life of the oil.

It is to be understood that the forms of the invention shown and described herein may be taken as the presently preferred embodiments. Elements and materials may be substituted for those illustrated and described herein, parts and processes may be reversed, and certain features of the invention may be utilized independently, all as would be apparent to one skilled in the art after having the benefit of this description to the invention. Changes may be made in the elements described herein without departing from the scope of the invention as described in the following claims. In addition, it is to be understood that features described herein independently may, in certain embodiments, be combined.

Claims

1. An oil filter for dispensing additive into oil used in an engine, comprising:

a canister;

a filter within said canister;

a chamber within the canister and defined by a member having an opening therethrough;

at least one additive disposed in said chamber; and

a gate actuable between open and closed positions, said gate being disposed so as to occlude said opening when in the closed position and being disposed so as to allow fluid flow through said opening when in the open position.

2. The oil filter according to claim 1 wherein said additive is in a solid form and contacts the oil when said gate is in the open position.

3. The oil filter according to claim 1 wherein said gate is temperature-actuated.

4. The oil filter according to claim 3 wherein said gate closes at a predetermined temperature that is between the operating temperature of the engine and an ambient temperature.

5. The oil filter according to claim 4 wherein said gate is closed at temperatures above the predetermined temperature.

6. The oil filter according to claim 4 wherein said gate is closed at temperatures below the predetermined temperature.

7. The oil filter according to claim 1 wherein said gate is pressure-actuated.

8. The oil filter according to claim 7 wherein said gate closes at a predetermined oil pressure that is below the operating oil pressure.

9. The oil filter according to claim 8 wherein said gate is closed at pressures above the predetermined pressure.

10. The oil filter according to claim 8 wherein said gate is closed at pressures below the predetermined pressure.