NL2035801B1 - Lubrication system for an internal combustion engine - Google Patents

Abstract

TITLE: lubrication system for an internal combustion engine In one aspect, it is aimed to provide a lubrication system for an internal combustion engine, comprising a pressure less lubricant collection chamber; a lubricant pump having a pump inlet fluidly coupled to the collection chamber; and a pump outlet fluidly coupled to a lubricant filter module; said filter module provided between the pump outlet and a lubricant gallery that comprises a manifold being fluidly connected to selective engine components to be lubricated; said pump outlet and said pilot pressure line in fluid connection with the lubricant gallery via a regulating valve, that controls a pressurized lubricant flow from the gallery to the pilot pressure control line; wherein a second overpressure valve is provided between the pump outlet and the pilot pressure line that in case of overpressure provides a lubricant flow from the pump outlet to the pilot pressure line additional to the pressurized lubricant flow from the regulating valve, to provide a maximum flow rate through the second overpressure valve that is higher than a pressurized lubricant flow from the gallery to the pilot pressure control line. FIG. 3

Description

P135026NL00

TITLE: LUBRICATION SYSTEM FOR AN INTERNAL COMBUSTION

ENGINE

DESCRIPTION Field of invention

The invention relates to a lubrication system for an internal combustion engine.

Description of the prior art

In heavy duty vehicles, especially vehicles heaving an internal combustion engine a conventional way of providing lubricant to selective engine components is via an oil/lubricant gallery, which is pressurized. The lubricant is pumped into the pressurized gallery via an oil filter module, which conditions the oil, e.g. filters it and may heats/cool it additionally. The lubricant gallery is fluidly connected to selective engine parts to be lubricated via a manifold or like. A typical pressure generator for such lubrication systems is a vane pump or like, due to its convenient pump pressure control behaviour which is substantially decoupled from engine speed (which drives the pump) by a pilot pressure control line, controlling the pump between a maximum outlet pressure at low pilot pressure and a minimum outlet pressure at high pilot pressure. This provides a natural balance, if the pilot pressure is low, the pump output is increased, and if the pilot pressure is high, the pump output is diminished.

The lubricant is provided from a typically pressure less lubricant collection chamber or sump; the lubricant pump has a pump inlet fluidly coupled to the collection chamber; and a pump outlet fluidly coupled to a lubricant filter module. The filter module is provided between the pump outlet and lubricant gallery that fluidly connects to selective engine components to be lubricated.

The pilot pressure line is in fluid connection with the pressurized lubricant gallery via a regulating valve, that controls a pressurized lubricant flow from the gallery to the pilot pressure control line. In this way the pressure of the lubricant gallery can be maintained at a designated pressure.

These lubricant systems have lubricant pumps with a return line in fluid connection with the collection chamber e.g. to capture lubricant leakage in the pump.

A potential drawback of this type of pump control lies typically in startup or malfunction phase, when the pump is operated via the pilot pressure control line and the filter module causes a substantial pressure drop, e.g. due to clogging or cold viscous oil. Typically, as a failsafe measure, the return line fluidly connects the pump outlet via a first overpressure valve for directing overpressure to the collection chamber. This overpressure valve is capable of diverting lubricant pressure when the lubricant cannot flow to the pressure gallery or engine components, e.g. due to clogging or a malfunction in the pump actuation.

However, the type of pump control having a maximum outlet pressure at low pilot pressure may, when the pilot pressure does not increase continue to run at maximum pump capacity despite the overpressure valve which may cause damage to the pump. EP3102830B1 discloses a pump arrangement wherein in case of malfunction the regulating valve continues to pressurize the control line by an overpressure arrangement, which provides pressure to the control chamber when the pilot pressure is absent due to malfunction of the regulating valve. However, this overpressure arrangement is complex in that at the same time it provides pressure to the control line, it shuts off pressure from the control line to be able to substantially pressurize the control line.

The invention aims to provide an improved lubrication system having a simple concept of providing pressure to the control line, e.g. without a need for additional shut off functionality of the overpressure valve.

Summary of the invention

In one aspect, it is aimed to provide a lubrication system according to the features of claim 1. In another aspect, the lubrication system according to the present invention is characterized by wherein a second overpressure valve is provided between the pump outlet and the pilot pressure line that in case of overpressure provides a lubricant flow from the pump outlet to the pilot pressure line additional to the pressurized lubricant flow from the regulating valve, to provide a maximum flow rate through the second overpressure valve that is higher than a pump leakage flow rate.. In this way, the pump flow can be tempered in conditions the pump outlet pressure is too high and there is no malfunction of the regulating valve. The failing pilot pressure from regulating valve is conveniently boosted by the second overpressure valve, which adds to the pilot pressure and reduces the pump flow away from a maximum pump pressure, thereby sparing the pump from sustained extreme loads in case the oil module has a substantial pressure drop. Usually, this condition resolves when the oil gets warmer and the pump resume running normal. However, in the transient condition it 1s prevented from running at maximum capacity, which could result in higher bending stress of vanes in the pump the pump or rotor breakage. While the system 1s especially convenient with vane pumps, other pump types having a similar control of the pump via a failing pilot pressure could similarly benefit from this arrangement.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be further elucidated in the figures:

Figure 1 shows a conventional setup for a lubricant pump having an input, output, pilot pressure control line and return line;

Figure 2 shows an exemplary embodiment of such a conventional setup;

Figure 3 shows a lubricant system according to an aspect of the present invention.

DETAILED DESCRIPTION

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs as read in the context of the description and drawings. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. In some instances, detailed descriptions of well-known devices and methods may be omitted so as not to obscure the description of the present systems and methods.

Terminology used for describing particular embodiments is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. The term "and/or" includes any and all combinations of one or more of the associated listed items. It will be further understood that the terms "comprises" and/or "comprising" specify the presence of stated features but do not preclude the presence or addition of one or more other features.

While example embodiments are shown for systems and methods, also alternative ways may be envisaged by those skilled in the art having 5 the benefit of the present disclosure for achieving a similar function and result. E.g. some components may be combined or split up into one or more alternative components. Finally, these embodiments are intended to be merely illustrative of the present system and should not be construed as limiting the appended claims to any particular embodiment or group of embodiments. Thus, while the present system has been described in particular detail with reference to specific exemplary embodiments thereof, it should also be appreciated that numerous modifications and alternative embodiments may be devised by those having ordinary skill in the art without departing from the scope of the present systems as set forth in the claims that follow. The specification and drawings are accordingly to be regarded in an illustrative manner and are not intended to limit the scope of the appended claims.

Any reference signs in the claims do not limit their scope; several "means" may be represented by the same or different item(s) or implemented structure or function; any of the disclosed devices or portions thereof may be combined together or separated into further portions unless specifically stated otherwise. The mere fact that certain measures are recited in mutually different claims does not indicate that a combination of these measures cannot be used to advantage.

Turning now to Figure 1, schematically a pump 100 is illustrated having an inlet I, an outlet O, a controllable pilot pressure line C and a return line R. The pilot pressure control line C controls the pump 100 between a maximum outlet pressure at low pilot pressure and a minimum outlet pressure at high pilot pressure. The return line may be in fluid connection with an oil sump, which functions as a collection chamber and returns lubricant from the pump to the collection chamber, e.g. to capture lubricant leakage in the pump.

The pilot pressure control line typically converts the pilot pressure in a desired output pressure, which is typically inverse to the pilot pressure, that 1s, when a pilot pressure 1s low, the pump outlet is increased, so that the pilot pressure increases until an equilibrium is attained.

Figure 2 shows an exemplary embodiment of such a conventional pump, in this case a vane pump. In the embodiment, the return line C is fluidly connected with an overpressure valve 101. Typically, as a failsafe measure, the return line R fluidly connects to the pump outlet O via a first overpressure 201 valve for directing overpressure to the collection chamber to thereby spare the pump in case of overpressure. The overpressure valve 201 is capable of diverting lubricant pressure when the lubricant cannot flow out of the pump outlet O, e.g. to the pressure gallery or engine components, e.g. due to clogging or a malfunction in the pump actuation.

Figure 2 further shows a displaceable pump rotor R, wherein the pump rotor eccentricity relative to the pump housing is controlled by pilot pressure control line via a displacement actuator 102 that is controlled, preferably hydraulically, by the pilot pressure of control terminal C. The pump rotor displacement is such that at minimum pilot pressure the pump has maximum eccentricity which maximizes flow through the rotating vanes

V, which in the displayed embodiment adapt the vane heights in the eccentric rotation. However, when a pump pressure goes above its pressure limit, pilot pressure control in a pump control chamber (fluidly provided between the pilot pressure control terminal C and the actuator 102 1s not sufficient to regulate the pump, which may be caused by a pressure drop between engine system and solenoid. This will result in pump 100 running at maximum eccentricity with extended vanes. Higher pressure in the pump 200 may cause higher bending stress on vanes V which may result in breakage of the rotor R and/or vanes V.

Figure 3 shows a schematic setup of a lubricant system 3000 according to an embodiment of the invention. A pump 300 is provided with a second overpressure valve 1V, in addition to a safety relief valve in return section R which fluidly connects the pump outlet O to the collection chamber

S. Unpressured lubricant is supplied from the collection chamber S at reference numeral 9 to pump inlet I at reference numeral 1, and pumped out of outlet O at reference numeral 2. Filter module M conditions and filters the oil which may result in a pressure drop at reference numeral 4, relative to pump output pressure X at reference numeral 3. In normal conditions, overpressure valve 1V is closed, but opens at a certain pressure threshold X at pump outlet O.

Scenario 1: Working below one way valve opening pressure X:

Regulation is provided by solenoid valve SV in a normal fashion, which may direct pressure from the main oil gallery via a three way valve either to the oil pump regulating chamber C or to collection chamber S. Pressure level in the pump outlet O is not too much to cause a problem on rotor.

Scenario 2: Working equal to/above one way valve opening pressure X:

Regulation is provided by one way valve to protect oil pump 300 in high level pressure. Pressure drop over one way valve 1V is lower (negligible) and pressure is sufficient enough to regulate the pump 300. Solenoid channel SV may not feed the regulation chamber C in this condition (no enough pressure for mechanical valve). Electronic regulation of the solenoid valve can continue to work.

The second overpressure valve 1V is provided between the pump outlet O and the pilot pressure line C via solenoid valve SV. The overpressure valve 1V, when opened, has a small pressure drop Y2 in comparison with the pressure drop Y1 over the solenoid valve SV, resulting in a higher pilot pressure T2 in control chamber C in comparison with the pilot pressure provided by the solenoid valve SV. The over pressure valve 1V is preferably of a one way type to prevent that unfiltered oil of pump outlet

O enters the regulating valve SV at reference numeral 7. Regulating valve

SV may be a pulse width modulated controlled solenoid, that transfers a portion of the gallery pressure at reference numeral 5 to the pilot pressure control line C, dependent on a pressure drop Z of the pump due to leakage.

Lubricant gallery G comprises a manifold fluidly connected to selective engine parts EP to be lubricated, such as bearings, valve trains, piston cooling jets and turbo-charger. Overpressure valve 1V is constructed so that additional to the pressurized lubricant flow from the regulating valve SV, a maximum flow rate with higher pressure is provided through the second overpressure valve 1V that is higher than a pressurized lubricant flow from the gallery G to the pilot pressure control line in case of overpressure at reference numeral 3, e.g. due to a failing gallery pressure. The flow rate is higher than an internal leakage flow resulting in a pressure drop Z in control chamber C. In an example, the overpressure valve 1V is constructed to provide a ratio of a maximum flow rate through said valve, relative to a pump leakage rate, of about 2-5, whereas suitable rates may be in the order of 1-3 min for a pump leakage rate, and 5-10 I/'min provided through the over pressure valve IV. Typical gauge pressure for the overpressure valve 1V can be in the order of 0.5-2 barG.

The overpressure valve 1V may be passive, so that it will open when a certain output pressure threshold is exceeded. Advantageously, the output flow of over pressure valve 1V is such, that it is sufficient to counter a leak flow to the sump, so that the control chamber C remains pressurized, even when regulating valve SV is malfunctioning. Overpressure valve 1V may also be an active valve, e.g. controlled by active valve control (not illustrated). Accordingly, a higher pressure in the control chamber C from the pump 300 will able to regulate the pump 300 to a lower pump output.

Claims (7)

CONCLUSIONS 1. A lubrication system for an internal combustion engine, comprising a pressureless lubricant collection chamber; a lubricant pump having a pump inlet fluidly connected to the collection chamber; and a pump outlet fluidly connected to a lubricant filter module; the filter module being disposed between the pump outlet and a lubricant gallery fluidly connected to engine parts to be selectively lubricated; — the lubricant pump further comprising a return line and a pilot pressure line; the return line being in fluid communication with the collection chamber; the pilot pressure line controlling the pump between a maximum outlet pressure at low pilot pressure and a minimum outlet pressure at high pilot pressure; — the pilot pressure line being in fluid communication with the lubricant gallery via a control valve controlling a pressurized lubricant flow from the gallery to the pilot pressure line; — the return line fluidly communicates the pump outlet with a first pressure relief valve to direct excess pressure to the collection chamber; — wherein a second pressure relief valve is provided between the pump outlet and the control pressure line and in the event of overpressure provides a flow of lubricant from the pump outlet to the control pressure line in addition to the pressurised lubricant flow from the control valve, so as to provide a maximum flow rate through the second pressure relief valve greater than a leakage flow rate from the pump. 2. The lubrication system of claim 1, wherein the second pressure relief valve is constructed to provide a maximum flow rate greater than a pressurized lubricant flow from the gallery to the control pressure line. 3. The lubrication system according to any one of the preceding claims, wherein the second pressure relief valve is actively controlled. 4. The lubrication system according to any one of the preceding claims, wherein the second pressure relief valve is passive. 5. The lubrication system of any preceding claim, wherein the second pressure relief valve is constructed to provide a ratio of maximum flow rate through the valve to pump leakage rate of about 2-5. 6. The lubrication system according to any of the preceding claims, wherein the lubricant pump is driven by the combustion engine. 7. The lubrication system of any preceding claim, wherein the lubricant pump comprises a movable pump rotor, the pump rotor displacement being controlled by the control pressure line via a hydraulic displacement actuator.