Lubricant quantitative supply device for gaseous fuel engine

Abstract

A lubricant dosing device (10) for a gaseous fuel delivery system of an internal combustion engine, in particular a hydrogen engine, comprises a body (12) having therein a pumping bore (20) extending along a pumping axis (A) and defining at an end a pumping chamber (24), the volume of which is varied by a piston (22) reciprocating in the pumping bore. An inlet valve assembly (26) is disposed in the inlet section. The outlet section (18) includes an outlet valve assembly (28) to control discharge of pressurized lubricant fluid from the pumping chamber. The outlet valve assembly is configured as a check valve having an outlet valve seat (48) and an outlet valve member (49) downstream thereof. The outlet valve member (49) includes a sealing surface adapted to mate with the outlet valve seat (48), the sealing surface being formed of or coated with an elastomeric polymer.

Description

Technical Field

[0001] The present invention relates generally to internal combustion engines and, more particularly, to gaseous fuel delivery systems for gaseous fuel engines, particularly hydrogen engines. Background Art

[0002] Currently, more than 20% of the global energy demand is related to the transport sector, which is largely dominated by internal combustion engines that can operate using a wide range of fuels. Over the past few decades, the focus on gaseous fuels (such as compressed natural gas) has increased significantly. But recently the demand for alternative fuels has continued to grow. This is not only related to the dwindling fossil fuel resources, but also to the growing concern for the natural environment and the fight against global warming.

[0003] In this context, hydrogen, which results in a cleaner combustion process, is foreseen as a practical alternative to gasoline or diesel.

[0004] However, hydrogen, and compressed or liquefied gases in general, are relatively dry fuels that lack lubricating compounds compared to gasoline or diesel. As a result, the service life and operating reliability of fuel injectors using gaseous fuels are limited. The lack of lubrication is even more problematic for fuel injectors installed for direct fuel injection, as they face higher temperatures, resulting in excessive wear, primarily at the pintle / seat interface of the injector nozzle.

[0005] To solve this problem, US2019 / 0211720A1 proposes injecting lubricant into the gas fuel supply line upstream of the fuel injector. The lubricant is stored in a dedicated tank connected to the fuel supply pipeline through a metering valve. The control unit operates the metering valve to adjust the amount of lubricant injected into the gas fuel based on the engine operating conditions.

[0006] While the patent document provides a solution for lubricating dry fuel gas (such as CNG), it is silent on the details of the implementation. One of the challenges in designing a lubricating device for a hydrogen engine is the need to inject a small amount (about 2mm per injection) of 3 ) is injected into a 50 bar H2 environment. Therefore, it is desirable to keep the actuation energy as low as possible and be able to ensure that the injection has occurred.

[0007] Purpose of the Invention

[0008] It is therefore an object of the present invention to provide an improved lubricant dosing device for a gaseous fuel delivery system which does not have the above-mentioned disadvantages. Summary of the invention

[0009] The present invention relates to a lubricant quantitative supply device for an internal combustion engine, in particular a gas fuel delivery system of a hydrogen engine. The lubricant quantitative supply device comprises:

[0010] a body having a pumping bore therein, the pumping bore extending along a pumping axis (A) and defining a pumping chamber at an end, the pumping chamber being varied by a piston reciprocating in the pumping bore;

[0011] an inlet section in the body through which lubricant fluid is supplied to the pumping chamber (24), wherein an inlet valve assembly is preferably arranged in the inlet section;

[0012] an outlet section in the body, wherein an outlet valve assembly is arranged to control discharge of pressurized lubricant fluid from the pressure chamber, the outlet valve assembly being configured as a check valve having an outlet valve seat and an outlet valve member downstream thereof;

[0013] The outlet valve component comprises a sealing surface adapted to cooperate with the outlet valve seat, wherein the sealing surface is formed of an elastic polymer or coated with an elastic polymer.

[0014] The invention provides a lubricant dosing device which allows the introduction of lubricant into the gaseous fuel flow in order to ensure the presence of a certain level of lubricant in the fuel reaching the injector. The invention allows avoiding the problems of missing lubrication and risk of wear at the fuel delivery system components, in particular at the fuel injectors.

[0015] The outlet valve member is made of an elastic polymer; or made of another material (e.g. metal / steel), the sealing surface of the outlet valve member being coated with an elastic polymer. An elastic polymer is an elastic and compressible polymer that can be compressed when an external force is applied and can recover its original shape when the external force is removed. The polymer is advantageously selected to be compatible with oil and gaseous fuels such as hydrogen. Elastomers are particularly preferred, especially from the FKM family.

[0016] The use of such an elastic polymer / elastomer provides a dynamic seal at the outlet valve, which allows for enhanced compression forces to be achieved.

[0017] Although specifically designed for use with hydrogen engines, the present invention is applicable to any type of gaseous fuel, natural or synthetically produced, such as natural gas, methane, synthetic methane, etc. In some cases, the gaseous fuel may be stored in a partially liquid form in a fuel tank.

[0018] The lubricant metering device may be arranged at any suitable position in the gaseous fuel delivery system, for example, it may be arranged immediately upstream in the circuit, close to the fuel tank, or before or after the fuel rail. If desired, more than one lubricant metering device may be arranged in the fuel delivery system at the previously mentioned positions, or, for example, one lubricant metering device may be arranged per fuel injector.

[0019] In practice, the lubricant dosing device may be housed in a support member that includes fuel and oil passages and / or connections. Alternatively, the lubricant dosing device may be designed to include connectors / fittings that are connected or assembled to the oil supply and fuel supply lines.

[0020] The outlet valve member may take any suitable form or shape, in particular a ball, pivot or plate. As previously mentioned, the outlet valve member is a polymer / elastomeric member or a metal member coated with a polymer / elastomeric at least on the sealing surface to cooperate with the outlet valve seat.

[0021] In an embodiment, the outlet valve member is biased toward the outlet valve seat in a closing direction by a first spring supported by a spring seat member; the outlet valve member is installed in a cup-shaped guide element; the first spring is supported by the spring seat member at one end and abuts against the guide element at its opposite end; the spring seat member is fixed in the outlet section.

[0022] The spring seat member may include a base having a peripheral wall and a cylindrical protrusion extending from the base toward the guide element, the first spring end engaging on the cylindrical protrusion.

[0023] In an embodiment, the cup-shaped guiding element (which may be made of metal / steel) comprises an end wall and an annular wall extending therefrom, which defines a recess in which the valve member is received. The annular wall defines an annular abutment surface around the protruding portion of the valve member, the abutment surface being configured to abut against the outlet valve seat when the valve member reaches a predetermined compression state. Thus, when the polymer valve member or the polymer coating reaches a certain degree of compression, the abutment surface will contact the valve seat, thereby preventing further compression and thus preventing potential damage to the outlet valve member.

[0024] The outlet valve assembly is configured to have a predetermined opening pressure. The term "opening pressure" defines the pressure reached in the pumping chamber that causes the outlet valve member to lift. The device is designed so that the opening pressure is at least 50 bar, for example up to 60 bar, 70 bar or 80 bar.

[0025] The purpose of the device is to deliver relatively small volumes of oil into a gaseous fuel stream. The lubricant metering device of the invention is advantageously configured so that the discharge volume is between 1 and 3 mm 3 , particularly at a pressure of at least 50 bar.

[0026] Lubricant fluid (oil) is supplied to the lubricant dosing device of the present invention through an inlet section. The supply may be gravity fed (ie the oil may flow or be pumped through the inlet section) or the supplied oil may be pressurized (engine oil or an independent source).

[0027] In an embodiment, the inlet valve assembly may be arranged in the inlet section, but this is not required.

[0028] Such an inlet valve assembly can be configured as a non-return valve having an inlet valve seat and an inlet valve member located downstream of the inlet valve seat. The inlet valve member is biased in a closing direction toward the inlet valve seat by a second spring supported by a control pin protruding in the pumping chamber toward the valve seat. One end of the spring engages on the control pin and its opposite end abuts against the inlet valve member. An end face of the control pin is at a predetermined distance from the guide element in the closed position to form a lifting stop.

[0029] In an embodiment, a pressure sensitive switch device is arranged to detect a predetermined pressure threshold in the pumping chamber, the switch device having a reciprocatingly arranged sensing pin having a tip exposed to the pressure in the pumping chamber. The pressure sensitive switch device is typically configured to detect a predetermined pressure greater than the opening pressure of the outlet valve.

[0030] Preferably, the head of the sensing pin is biased towards the pumping chamber by a spring in a rest position; and the spring has a predetermined force which, when overcome by pressure in the pumping chamber, causes the sensing pin to close an electrical detection circuit.

[0031] The sensing device may include: a hollow housing fixed in a passage of the housing leading to the pumping chamber; a cylindrical insulating guide arranged at an open front end of the hollow housing, wherein the sensing pin is slidably accommodated in the cylindrical insulating guide. The detection element is arranged in the housing backward relative to the sensing pin and is insulated from the housing.

[0032] The sensing element is at a predetermined voltage in use whereby, when the spring force is overcome by the pressure, the sensing pin moves rearwardly and abuts the sensing element, thereby connecting the sensing element to ground via the spring and the housing.

[0033] The detection element can be a pin element axially aligned with the sensing pin and surrounded by an annular control screw engaged with the threaded rear section in the housing. A spring is engaged on the front end of the detection element, one end abutting against the control screw and the other end abutting against the head of the sensing pin.

[0034] Conveniently, actuation of the lubricant dosing device may be performed by means of an electrically controllable actuator having an actuation rod configured to selectively apply an actuation force to the piston to compress the fuel in the pumping chamber.

[0035] According to another aspect, the present invention relates to a gaseous fuel delivery system for an internal combustion engine, comprising a fuel tank, a gaseous fuel filter and a device providing one or more functions selected from shut-off, pressure regulation and pressure relief, and at least one lubricant dosing device disclosed herein. The gaseous fuel may in particular be one of natural gas, methane, synthetic methane or hydrogen, but this should not be construed as limiting. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The present invention will now be described by way of example with reference to the accompanying drawings, in which

[0037] Figure 1 is a longitudinal cross-sectional view through an embodiment of the present lubricant metering device; and

[0038] Figure 2 It passes through Figure 1 A transverse cross-sectional view of a lubricant metering supply device. DETAILED DESCRIPTION

[0039] exist Figure 1 and Figure 2 An embodiment of the present lubricant dosing device 10 is shown in FIG. The pressure regulator device 10 has been developed for use in hydrogen internal combustion engines, although it can be used with other gaseous fuels (e.g. CNG or fuel cell gas). In the following, for ease of description, the terms fluid lubricant and oil are used as synonyms.

[0040] In this embodiment, the lubricant dosing device 10 is designed as a unit or module integrated / received in a support that can be arranged at any suitable position in the fuel delivery system, in particular upstream or downstream of the fuel rail. Such a support can be built on a metal block (partially shown) with a cylindrical recess in which the lubricant dosing device is received.

[0041] The lubricant dosing device 10 is designed to allow a predetermined amount of lubricant to be selectively introduced (or injected) into the gaseous fuel flow. For the purpose of injector nozzle lubrication, any suitable lubricant can be used, in particular oil, for example similar to standard engine oil already present in the engine (depending on the engine type and size).

[0042] The device 10 comprises a housing or body 12 having a gas passage 14 extending between an inlet section 16 (or inlet passage) for receiving a lubricant fluid and an outlet section 18 (or outlet passage) through which the lubricant fluid is discharged. The inlet 14 is in communication with an oil reservoir (not shown); the pressurized oil / lubricant is discharged through the outlet section 18 at a pressure of up to 20 to 40 bar into a gaseous fuel stream which is further directed to the fuel injector. The oil reaches the inlet section 16 through a channel provided in a support block (not shown). On the outlet side, the oil is discharged directly into a pipe, tube or channel (not shown) containing the pressurized gaseous fuel stream.

[0043] The lubricant (liquid oil) may be stored in a lubricant reservoir at atmospheric pressure, and the lubricant dosing device 10 allows the oil to be pressurized to a level above the pressure in the fuel conduit / passageway into which it is injected. Although the lubricant is pressurized to a pressure above the fuel pressure in the supply line, the pressure level can still be adjusted depending on the application and the required gas flow rate.

[0044] The body 12 is made of metal, such as stainless steel, and has a generally cylindrical shape extending along an axis A, whereby the body 12 has a first end 12.1, a second end 12.2 and a side 12.3. In this embodiment, the inlet section 16 is located transversely on the side 123, while the outlet is located at the first end 121 of the body 12.

[0045] The body 12 is provided with a pumping bore 20 extending along a pumping axis, which is here coaxial with the axis A. The pumping bore 20 opens into the passage 14. In the pumping bore 20, a piston 22 (or plunger) is guided to perform a reciprocating displacement, thereby varying the volume of a pumping chamber 24 defined by the passage portion between the inlet valve and the outlet valve and the corresponding portion of the pumping bore 20 delimited by the piston 22. The sealing at the piston 22 can be achieved with a close clearance and / or using a piston rod seal.

[0046] As can be seen, inlet section 16 opens into pumping chamber 24 and is controlled by inlet valve assembly 26 (or inlet valve for short). Flow out of pumping chamber 24 occurs through outlet section 18 and is controlled by outlet valve assembly 28 (or outlet valve for short).

[0047] Typically, the plunger 22 is actuated via the open end of the plunger bore 20 based on input from an electric actuator (not shown), which can be selectively actuated. The actuator can be a solenoid actuator. Energizing the actuator will cause outward movement of its actuating rod, which will apply an actuating force to the piston 22 in the direction of arrow 30 (i.e., in a compressive direction). A spring 32 biases the piston 22 in the opposite direction toward the rest position. It can be noted that in Figure 1, the piston 22 is in its innermost position, ie at the end of the compression stroke (it cannot move further to the left).

[0048] The inlet valve 26 is configured to allow oil arriving from the oil reservoir through the inlet section 16 to enter the pumping chamber 24. The inlet valve 26 is configured as a check valve (one-way flow) that allows oil to enter the pressure chamber 24 and will be closed during the compression stroke to allow pressure to accumulate. The inlet valve 26 includes a valve seat 34 at the interface between the inlet section 16 and the pressure chamber 24. The valve seat 34 surrounds the passage 14 and includes an annular sealing surface 36 around the flow orifice 35 toward the pressure chamber 24. The sealing surface 36 is arranged on the side of the pressure chamber 24 (i.e., the downstream seat 34). The spherical valve member 38 is arranged to cooperate with the seat 34. The valve member 38 can move between a closed position and an open position, in which the valve member 38 rests on the annular sealing surface 36 and closes the flow hole 35, and in the open position, the valve member 38 is spaced apart from the inlet valve seat 34 and allows oil to enter the pressure chamber 24. The valve member 38 is biased to the closed position by a second spring 40. As will be appreciated, during the compression phase, the valve member 38 is additionally urged towards the closed position by hydraulic pressure.

[0049] The valve member 38 may be a metal ball, in particular made of wear-resistant steel, eg 100Cr6 or the like.

[0050] The portion 37 of the channel 14 located directly downstream of the valve seat 34 has a cross section D 37 , the cross section is suitable to provide some axial guidance for the valve member, yet have an appropriate annular clearance to allow oil flow.

[0051] For example, the channel portion 37 may have a diameter D between 1.2 and 1.8 times the diameter of the ball 38. 37 , preferably 1.4 to 1.6 times.

[0052] Reference numeral 42 denotes a control pin for holding the spring 40 and controlling the lift of the valve member 38. The control pin 42 is arranged in a passage 44 (or port) through the body 12, which opens in the pumping chamber 24. The control pin 42 includes a base 42.1 supporting a pin portion 42.2 of narrower diameter. The base 42.1 is screwed into the passage 44 and abuts against the shoulder 46, thereby providing a fluid seal of the pumping chamber 24. The pin portion 42.2 protrudes in the pumping chamber 24 and extends toward the inlet valve assembly 26. The spring 40 is assembled around the pin portion 422 at one end and supported on the valve member 42 at the other end. Figure 1The axis B in FIG. 4 shows the lift direction of the valve member 38. In the present design, this direction is transverse, in particular perpendicular to the axis A, and the channel 44 also extends along the axis B, as does the control pin 42, the end face 42.3 of its pin portion 42.2 facing the valve member 38. As will be understood, the length of the pin portion 42.2 will determine the gap between its end face and the valve member 38, and thus act as an end stop for the valve member 38 when lifted from the valve seat 34. Therefore, the control pin 42 defines the lift of the inlet valve 26. In the closed position, the distance between the end face 42.3 and the valve member 38 is preferably between 0.5 and 1 times the diameter of the ball 38.

[0053] The outlet valve assembly 28 in turn allows the pressurized lubricant fluid to be discharged from the pumping chamber 24 into the hydrogen flow. The outlet valve 28 is also designed as a check valve, i.e., only one-way flow is allowed. Reference numeral 48 denotes a second valve seat cooperating with an outlet valve member 49 at the interface between the pressure chamber 24 and the outlet section 18. The second valve seat 48 includes an annular sealing surface 50, which surrounds an outlet flow orifice 52 leading from the pressure chamber 24 to the outlet section 18. The annular sealing surface 50 is located on the downstream side, and the valve member 49 is therefore movably arranged downstream of the seat 48. The valve member 49 is elastically biased by a third spring 54 to a closed position, in which the valve member 49 rests on the seat 48 and closes the flow orifice 52 in a fluid-tight manner. The surface of the valve member 49 that contacts the valve seat 48 is called a sealing surface (not shown).

[0054] In the embodiment shown, the valve member 49 takes the form of a ball which is received in a cup-shaped guide element 56, from which the valve member 49 protrudes at least 20%, 25% or 30%. The guide element 56 is received in a guide section 58 of the passage 16 having an adapted cross section configured to maintain the alignment of the guide 56 and the ball 49 relative to the seat 48 while having a peripheral clearance to allow the flow of oil.

[0055] The valve member 49 may be a ball made of a polymer material, in particular, the ball 49 may include or consist of an elastomer (eg an elastomer of the FKM family).

[0056] Alternatively, the valve member may be a metal (steel) ball, or other shape (eg, a pivot) with a polymer / elastomer coating over the entire surface of the ball / member or at least on the surface corresponding to the sealing surface.

[0057] When a ball member made integrally from or fully coated with a polymer / elastomer is used, any portion of the elastomer may form the sealing surface.

[0058] The use of elastic / compressible materials for or on the valve member allows some compression of the valve member 49 on the outlet valve seat 48, as a strong contact pressure is required to ensure a good seal for hydrogen. Elastomers are generally preferred due to their elasticity / resilience. The polymer should also be compatible with use in hydrogen and oil environments. Elastomers from the FKM family may be used, but this should not be considered restrictive.

[0059] Referring more specifically to the guide element 56, it comprises a bottom wall 56.1 and an annular wall 56.2 defining a recess in which the valve member 49 is arranged. The free end of the annular wall 562 defines an annular abutment surface 563 surrounding the portion of the valve member 49 protruding from the guide element 56. This abutment surface 56.3, in particular its axial position relative to the front of the valve member 49, is configured to abut against the outlet valve seat 48 in the event of a pressure peak or excessive spring force, in order to avoid over-compression / damage to the elastomer of the valve member 49.

[0060] The guide section 58 leads to the outlet section 18, which has a relatively wide cross section. Reference numeral 60 denotes a spring seat member fixed by screwing into the outlet section 18. The spring seat member 60 is formed as a blind sleeve having a plate 62 with an annular peripheral wall 64. The plate member 62 includes a central cylindrical protrusion 66 receiving one end of the spring 54, the opposite end of which rests on an annular shoulder 68 surrounding the guide element 56.

[0061] One or more through holes 70 are arranged in the plate 62 to allow oil to flow out of the outlet section 18. The spring seat member 60 with the protrusion 66 also controls the lift of the valve member 49.

[0062] Again, the cylindrical protrusion 66 can advantageously be used to limit the lift / stroke of the guide member 56 / valve member 49, thereby limiting the leakage of hydrogen. Preferably, in the closed position of the outlet valve, the axial distance between the front side of the cylindrical protrusion 66 and the facing side of the bottom 56.1 of the guide element 56 is less than 250 μm, preferably less than 150 μm or even less than 100 or 80 μm.

[0063] In an embodiment, the device 10 can be designed so that the volume is 1, 2, 3 mm 3 of oil or may be up to 5 or 10 mm 3 The oil can be discharged through the outlet valve 28 at a pressure of at least 50 bar.

[0064] In embodiments, the pumping chamber may have a width of up to 20 mm. 3 volume.

[0065] Depending on the embodiment, the outlet valve assembly 28 with the third spring 54 may be configured to have an opening pressure between 50 and 100 bar.

[0066] Figure 2 A cross section of the lubricant dosing device 10 in a plane containing the axis B and perpendicular to the axis A is shown.

[0067] Reference numeral 72 denotes a sensor assembly, referred to as a pressure sensitive switch device, which is arranged to detect an injection event, ie when the pressure in the pumping chamber will rise to a predetermined pressure greater than the opening pressure of the outlet valve 28 .

[0068] The pressure sensitive switch device 72 is arranged in a passage 74 (or port) in the body 12 leading to the pumping chamber 24. The passage 74 extends along the axis C and is for example transverse to the axis A, in particular perpendicular thereto.

[0069] The pressure sensitive switch device 72 includes a detection pin 76 , a sensing pin 78 , an insulating guide 80 , a spring 82 , and a control screw 84 , which are arranged in a housing formed by a hollow screw 86 .

[0070] The hollow screw 86 is arranged in the channel 74 and abuts against the shoulder 90 to provide a seal with the pumping chamber 24. The sensing pin 78 is arranged at the inner open end of the hollow screw 74 so that the end of the sensing pin is exposed to the pressure in the pumping chamber. The sensing pin 78 is insulated from the body 12 by a hollow cylindrical (electrically) insulating guide 80, wherein the sensing pin 78 can move along the axis C with a small gap. The sensing pin 78 has a head, on which one end of a fourth spring 82 rests, which biases the sensing pin 78 toward the pumping chamber 24. At its other end, the spring 82 rests on a control screw 84. The control screw 84 is formed as a sleeve with an external thread that cooperates with the inlet threaded section in the hollow screw 86. The detection pin 76 is received in the control screw 84 and has an electrically insulating coating 91.

[0071] In use, the detection pin 76 is set at a predetermined voltage (via wires / terminals) and connected to a controller or ECU, while the hollow screw 84 is at ground potential.

[0072] In summary, the pressure sensitive switch device 10 relies on the principle of using a small piston (sensing pin 78) insulated from the body 12 and subjected to the pressure in the pumping chamber 24. Once the pressure rises above a given set value defined by the spring 82, the sensing pin 78 moves (retracts) to make electrical contact with the detection pin 76. Electrical contact is then established between the body (ground) through the spring 82, the sensing pin 78 and the detection pin 76 insulated from the surrounding components. Thus, an electrical link is created towards the controller / ECU detection driver to sense the ground event.

[0073] In practice, the switch device 72 is configured so that the set value for triggering the electrical contact is a pressure that is higher than the fuel / H2 pressure downstream of the outlet section 18 and lower than the maximum pumping chamber pressure. In particular, the set value is higher than the opening pressure of the outlet valve assembly.

[0074] Preferably, the sensing pin 78 has a low clearance relative to the insulating guide 80 to avoid pumping losses. Preferably, the volume inside the switch device 72 is kept small enough that its effect on the pumping efficiency is negligible.

[0075] The spring 82 can be provided with a specific screw 84, but the screw 84 can alternatively be replaced by a pressing part at the desired position, thereby ensuring the specific force required. The required force can be measured during the setting operation. The spring 82 can be set to an outlet pressure level suitable for a system with the same components.

[0076] The position of the sensing pin 76 is advantageously adjusted to minimize sensing pin displacement. This can be achieved by having a mating thread or pressure at a given position. The sensing pin travel can be measured during the setting operation.

[0077] The lubricant metering device of the present invention operates on the general principle of a pumping system using inlet and outlet valves fed from a source of lubricating oil at low pressure.

[0078] The driving force is achieved by an axial solenoid actuator with sufficient force and travel using a battery voltage source. However, it should be noted that the design according to the present invention allows the device 10 to be driven with a solenoid force of approximately 45N, which is easily achievable using existing low-cost actuator technology.

[0079] The present lubricant dosing device 10 can be controlled directly or indirectly by an engine control unit (ECU-not shown). The ECU is typically operably connected to a plurality of sensors and actuators for controlling and monitoring engine operation, as known in the art. The ECU can be a conventional microcomputer, including: a microprocessor unit, input / output ports, read-only memory, random access memory, and a conventional data bus. The ECU is conveniently configured to receive various signals from sensors connected to the internal combustion engine and to send command signals to actuators in components in the vehicle, such as a throttle (not shown), a fuel injector, etc. In addition, the ECU is also configured to receive a pedal position (PP) from a pedal position sensor connected to a pedal actuated by an operator.

[0080] The ECU may also be configured to control the lubricant dosing device 10 by adjusting the amount of lubricant discharged into the gaseous fuel flow via the outlet section 18 based on one or more engine operating conditions. Typically, the ECU commands various actuators to achieve desired engine performance, which depends on user demand and is reflected by parameters such as engine speed and / or load. The gaseous fuel flow may also be speed / load dependent and regulated by the ECU.

[0081] In this case, it can therefore be noted that the gas fuel flow (flow rate or pressure) can be used as the primary input for the amount of lubricant required in order to achieve the target oil concentration / ratio.

Claims

1. A lubricant metering supply device (10), the lubricant metering supply device being used in a gas fuel delivery system of an internal combustion engine, in particular a hydrogen engine, the lubricant metering supply device comprising: a body (12) having a pumping bore (20) therein, the pumping bore extending along a pumping axis (A) and defining a pumping chamber (24) at an end, the volume of the pumping chamber being varied by a piston (22) reciprocating in the pumping bore; an inlet section (16) in the body through which lubricant fluid is supplied to the pumping chamber (24), wherein an inlet valve assembly (26) is preferably arranged in the inlet section; an outlet section (18) in the body, wherein an outlet valve assembly (28) is arranged to control discharge of pressurized lubricant fluid, the outlet valve assembly being configured as a check valve having an outlet valve seat (48) and an outlet valve member (49) downstream of the outlet valve seat; The outlet valve member (49) comprises a sealing surface adapted to cooperate with the outlet valve seat (48), wherein the sealing surface is formed of an elastic polymer or coated with an elastic polymer.

2. The lubricant quantitative supply device according to claim 1, wherein: The outlet valve member (49) is biased in a closing direction toward the outlet valve seat (48) by a first spring (54) supported by a spring seat member (60); The outlet valve member (49) is mounted in a cup-shaped guide element (56); The first spring (54) is supported at one end by the spring seat member (60) and abuts against the guide element at an opposite end thereof; The spring seat member is fixed in the outlet section (18).

3. The lubricant quantitative supply device according to claim 2, wherein: The spring seat member (60) includes a base (62) having a peripheral wall (64) and a cylindrical protrusion (66) extending from the base toward the guide element (56), the first spring end engaging on the cylindrical protrusion.

4. The lubricant quantitative supply device according to claim 2 or 3, wherein The cup-shaped guide element (56) comprises an end wall (56.1) and an annular wall (56.2) extending from the end wall, the end wall and the annular wall defining a recess for receiving the valve member; The annular wall (56.2) defines an annular abutment surface (56.3) surrounding a protruding portion of the valve member (49), the abutment surface being configured to abut against the outlet valve seat when a predetermined compressed state of the valve member is reached.

5. A lubricant metering device according to any one of the preceding claims, wherein: The outlet valve (28) has an opening pressure of at least 50 bar.

6. A lubricant metering device according to any one of the preceding claims, wherein: The outlet valve member (49) is spherical and made of a polymer; or the outlet valve member is a metal ball coated with a polymer.

7. A lubricant metering device according to any one of the preceding claims, wherein: The elastomeric polymer is an elastomer, in particular an elastomer of the FKM family.

8. A lubricant metering device according to any one of the preceding claims, wherein: The lubricant metering device is configured so that the discharge volume can be 3 and 3mm 3 Changes between.

9. A lubricant metering device according to any one of the preceding claims, wherein: The inlet valve assembly (26) is configured as a check valve having an inlet valve seat (34) and an inlet valve member (38) downstream of the inlet valve seat; The inlet valve member is biased in a closing direction towards the inlet valve seat by a second spring (40), the second spring being supported by a control pin (42.2) protruding in the pumping chamber towards the valve seat; The spring engages the control pin at one end and abuts the inlet valve member (38) at an opposite end thereof; The end surface of the control pin is at a predetermined distance from the inlet valve member (38) in the closed position to form a lifting stop.

10. A lubricant metering device according to any one of the preceding claims, wherein: A pressure sensitive switch device (72) is arranged to detect a predetermined pressure threshold in the pumping chamber (24), the switch device having a reciprocatingly arranged sensing pin (78) having a distal end exposed to the pressure in the pumping chamber.

11. The lubricant quantitative supply device according to claim 10, wherein: The head of the sensing pin is biased toward the pumping chamber by a spring (82) in a rest position; The spring has a predetermined force, which, when overcome by the pressure in the pumping chamber, causes the sensing pin to close an electrical detection circuit.

12. The lubricant quantitative supply device according to claim 11, wherein: The sensing device comprises: a hollow housing (86) secured in a passage (74) of the housing leading to the pumping chamber; a cylindrical insulating guide (80) arranged at the open front end of the hollow shell, wherein the sensing pin is slidably accommodated in the cylindrical insulating guide; A detection element (76) is arranged in the housing rearwardly relative to the sensing pin and is insulated from the housing; Wherein the detection element is at a predetermined voltage in use, whereby when the spring force is overcome by the pressure, the sensing pin moves backwards and abuts against the detection element, thereby grounding the detection through the spring and the housing.

13. The lubricant quantitative supply device according to claim 12, wherein: The detection element (76) is a pin element axially aligned with the sensing pin (78) and surrounded by an annular control screw (84) that engages a threaded rear section in the housing (86); The spring engages on the front end of the detection element with one end resting against the control screw and the other end on the head of the sensing pin.

14. A lubricant dosing device according to any one of the preceding claims, comprising an electrically controllable actuator having an actuation rod configured to selectively apply an actuation force to the piston to compress the lubricant fluid in the pumping chamber.

15. A gaseous fuel delivery system for an internal combustion engine, the gaseous fuel delivery system comprising a fuel tank, a gaseous fuel filter and means for providing one or more functions selected from shut-off, pressure regulation and pressure relief, and at least one lubricant dosing device according to any one of the preceding claims.

16. The system of claim 15, wherein: The gas fuel is one of natural gas, methane, synthetic methane and hydrogen.

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