Crankcase ventilation / lubrication system for an internal combustion engine, especially for a vehicle with a passenger saddle

Abstract

A lubrication system (100) for an internal combustion engine, in particular for a vehicle with a riding saddle, comprising a crankcase (110) in which at least one connecting rod is accommodated, and a basin or pan (120) for collecting lubricating liquid (LL), the crankcase (110) and the collecting basin or pan (120) being arranged in communication with each other by a first opening (111) provided in the crankcase (110), and the flow of the lubricating liquid (LL) through the first opening (111) from the crankcase (110) to the basin (120) being regulated by a first adjusting element (112) adapted to be switched to an open position to allow the lubricating liquid (LL) to be discharged from the crankcase (110) to the collecting basin or pan (120) at a predetermined switching gas pressure value in the crankcase (110).

Description

[Technical Field]

[0001] The invention relates to the field of manufacturing internal combustion engines, for example with poppet valves, both multi-cylinder and single-cylinder, in particular for vehicles with a riding saddle, a term generally intended to mean motorcycles or automobiles with two, three or four wheels, primarily intended for the transportation of people. In particular, the invention relates to the field of manufacturing engines of the aforementioned type, equipped with a ventilation and / or lubrication system for lubricating the linkages and / or gears (in particular rotating ones) housed in the crankcase and actuated by the movement of one or more pistons. [Background technology]

[0002] As is known, an internal combustion engine, for example for a vehicle with a passenger saddle, comprises a drive shaft, the rotation of which is caused by the movement of pistons in the combustion chambers of the respective cylinders, and the conversion of the reciprocating translational movement of one or more pistons is obtained in particular by a linkage, such as a connecting rod, interposed between the pistons and the drive shaft, said linkage being housed in the crankcase.

[0003] Therefore, a need has been felt to adequately lubricate said linkage within the crankcase, and various solutions have been implemented in the past for that purpose, such as the so-called "wet crankcase" and "dry crankcase".

[0004] In particular, in known types of "wet crankcase" solutions, lubricating oil is drawn from a collection and accumulation pan and introduced into the crankcase or crankcase via a hydraulic circuit (including a pump, valves, etc.), with the oil accumulated in the crankcase periodically drained into the pan. For this purpose, the crankcase and the pan are placed in communication with each other by a flexible reed valve, which is adapted to switch to an open position upon receiving an appropriate pressure. This pressure is generated, in particular, by both the oil accumulated in the chamber and the introduction of gas, e.g., blow-by gas, into the crankcase. Thus, an increase in the gas pressure in the crankcase up to a predetermined value (a function of the reed's flexibility) triggers the reed to switch to its open position, thereby causing the oil accumulated in the crankcase to be discharged into the pan.

[0005] Although the known solutions of the type "wet crankcase" summarized above may be evaluated from various points of view, such as reliability and efficiency of lubrication, simplicity of construction and / or implementation, and overall low production costs, they are not entirely without problems and / or drawbacks, which the Applicant intends to overcome or at least mitigate by means of the present invention.

[0006] The first drawback of known solutions of the "wet crankcase" type is the low frequency with which the oil accumulated in the crankcase is drained to the pan. This draining frequency corresponds to the frequency with which the reed is switched open and is inversely proportional to the free volume in the crankcase, i.e., the volume not occupied by the lubricated linkage. The greater the free volume, the longer it takes for the gas pressure in the crankcase to reach the "switching" value at which the reed is switched open, and therefore the lower the draining frequency. Obviously, a low oil draining frequency further leads to the accumulation of excess oil in the crankcase, which risks interfering with the drive shaft due to the accumulated oil. Furthermore, there is a risk that the accumulated oil will be exposed to drift phenomena during vehicle operation, especially when cornering, and therefore even impair stability (due to the influence of the center of gravity movement).

[0007] Prior art solutions of the "wet crankcase" type are known from US Pat. No. 5,623,299, US Pat. No. 5,623,299 and US Pat. No. 5,623,299. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] European Patent No. 2305973 [Patent Document 2] European Patent No. 2492461 [Patent Document 3] European Patent No. 2690275 Summary of the Invention [Problem to be solved by the invention]

[0009] The main object of the present invention is to provide a crankcase ventilation and / or lubrication system, in particular for internal combustion engines, for example of the multi-cylinder type with poppet valves, as well as of the single-cylinder type, in particular for vehicles with a passenger saddle, which makes it possible to overcome or at least minimize the drawbacks indicated above and which affect known systems, in particular of the "wet crankcase" type. Within this object, a first object of the present invention is therefore to convert a system of the "wet crankcase" type into a system of the "dry crankcase" type, or at least to provide a system whose functionality is as similar as possible to the functionality of a system of the "dry crankcase" type.

[0010] Furthermore, a second object of the present invention is to provide a system in which the solution ensuring the desired advantages summarized above is easily manufactured and / or implemented at competitive costs. [Means for solving the problem]

[0011] The present invention arises from the general consideration that the above-summarized objectives may be effectively achieved by introducing additional air volume into the crankcase (e.g., in addition to blow-by air) to avoid a vacuum in the crankcase during the compression step that would degrade engine performance. Furthermore, this additional air volume in the crankcase reduces the time required for the pressure in the crankcase to reach the minimum switching value required to switch the drain reed from a closed to an open position, thereby increasing the reed switching frequency and therefore increasing the drain frequency of the lubricant.

[0012] The present invention arises from the further consideration that the above-summarized objectives may also be achieved by reducing the free internal volume of the crankcase, where the term free internal volume means the internal volume of the crankcase that is not occupied by gears dedicated to rotating the linkage and / or drive shaft.

[0013] In fact, by reducing the free internal volume of the crankcase, the time required for the pressure in the crankcase to reach the minimum switching value required to switch the reed from the closed position to the open position is reduced, thereby increasing the reed switching frequency and therefore the lubricant drain frequency.

[0014] Based on the above considerations, in order to overcome the drawbacks affecting known types of lubrication devices and / or to achieve the further objectives summarized above, the present invention relates to an internal combustion engine for a vehicle, in particular with a riding saddle, according to one of claims 1 to 7, and to a vehicle according to claim 8.

[0015] The present application further describes a lubrication system for an internal combustion engine, in particular for a vehicle equipped with a riding saddle, comprising a crankcase in which at least one connecting rod is accommodated, and a basin or pan for collecting lubricating liquid, the crankcase and the collecting basin or pan being arranged in communication with each other by a first opening provided in the crankcase, the flow of lubricating liquid from the crankcase to the basin through the first opening being regulated by a first adjusting element adapted to be switched to an open position to allow the lubricating liquid to be discharged from the crankcase to the collecting basin or pan at a predetermined switching gas pressure value in the crankcase, the system comprising a fixed insert accommodated in the crankcase, the first predetermined switching gas pressure value in the crankcase being achieved in the presence of a volume of lubricating liquid that is less than the volume of lubricating liquid that would be present when the predetermined pressure value is achieved in the absence of the fixed insert.

[0016] According to the disclosed embodiment, the difference between the volume of lubricating liquid present when the predetermined pressure value is achieved in the absence of the fixed insert and the volume of lubricating liquid present when the predetermined pressure value is actually achieved is substantially equal to the difference between the free internal volume of the crankcase and the volume of the fixed insert.

[0017] According to a disclosed embodiment, the crankcase is shaped to define a collection and drain sump for the lubricating liquid, and the first opening is provided at a bottom of the collection and drain sump.

[0018] According to the disclosed embodiment, the fixed insert is disposed in the collection and drain sump at least partially in the protruding portion of the first opening.

[0019] According to a disclosed embodiment, the stationary insert is positioned and shaped to define a transfer channel for transferring the lubricating liquid to the collection and drain sump.

[0020] According to the disclosed embodiment, the volume of the fixed insert is 20% to 70%, preferably 35% to 55% of the free internal volume of the crankcase.

[0021] According to a disclosed embodiment, the first switching element comprises a first flexible lead that is switchable by bending to the open position.

[0022] According to a disclosed embodiment, the crankcase is placed in communication with the outside through a second opening provided in the crankcase, and the system includes a second adjustment element switchable to an open position that allows the introduction of pressurized gas into the crankcase through the second opening.

[0023] According to a disclosed embodiment, the second switching element comprises a second flexible lead that is switchable by bending to the open position when exposed to a gas pressure having a predetermined value.

[0024] According to a disclosed embodiment, the second opening is provided in a compartment, in which an introduction channel communicating with the outside of the compartment leads for introducing the pressurized gas into the compartment.

[0025] According to a disclosed embodiment, the introduction channel is adapted to be placed in communication with an HPC (High Pressure Cooling) system for generating the pressurized gas.

[0026] According to a disclosed embodiment, the second opening and the introduction channel are disposed in communication with the second flexible lead in the open position.

[0027] Further disclosed in the present application is an internal combustion engine for a motor vehicle having a passenger seat, comprising a drive shaft and at least one connecting rod adapted to convert combustion energy into rotation of the drive shaft, the engine comprising a lubrication system according to one of the embodiments of the present invention, and the at least one connecting rod of the engine being housed within a crankcase of the lubrication system.

[0028] The present application also covers a vehicle equipped with a riding saddle including an engine according to the above embodiment.

[0029] The present invention will be further clarified below by a detailed description of the embodiments illustrated in the drawings. However, the present invention is not limited to the embodiments described below and illustrated in the drawings; on the contrary, all variations of the embodiments described below and illustrated in the accompanying drawings that will be apparent to those skilled in the art are included within the scope of the present invention. [Brief explanation of the drawings]

[0030] [Figure 1] 1a and 1b show schematic cross-sectional views of a system according to an embodiment of the present invention in two different operating situations. [Figure 2] FIG. 2 shows a perspective view and partial cross-section of a system according to one embodiment of the present invention. [Figure 3] FIG. 3 shows a perspective view and partial cross-section of a system according to one embodiment of the present invention. [Figure 4] 1 shows a perspective view, possibly partial cross-section, of a system according to one embodiment of the present invention; [Figure 5] 1 shows a perspective view, possibly partial cross-section, of a system according to one embodiment of the present invention; [Figure 6] 1 shows a perspective view, possibly partial cross-section, of a system according to one embodiment of the present invention; [Figure 7] 1 shows a perspective view, possibly partial cross-section, of a system according to one embodiment of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0031] The invention finds particularly advantageous application when implemented in internal combustion engines, both multi-cylinder and single-cylinder, for example with poppet valves, in particular for vehicles equipped with a passenger saddle, the reasons for which will be explained below, where possible, with particular reference to engines of the aforementioned type.

[0032] However, the possible applications of the invention are not limited to engines of the aforementioned type only; on the contrary, the invention is suitable for use and implementation in all cases where effective and reliable lubrication of linkages is required, such as, for example, in the case of air compressors.

[0033] The system 100 shown according to the embodiment of Figures 1 to 3 comprises a crankcase 110, a basin or pan 120 for collecting a lubricating liquid (e.g. oil) LL, the crankcase 110 communicating with a cylinder in which a piston P is housed, the reciprocating translational movement of which, generated by the combustion of fuel, is converted into a rotational movement of a drive shaft by means of linkages (not shown in the figures) housed in the crankcase 110 (which are not shown in the figures both because they vary depending on the type of engine and because they are not essential for the purposes of the present invention); by way of example and for the sake of completeness of the description, said linkages may comprise one or more connecting rods or similar components.

[0034] The crankcase 110 and the pan or basin 120 are arranged in communication with each other by means of an opening 111 provided in the bottom of the chamber 110, in particular in the lowest part of the bottom of the chamber 110, in particular in the bottom 114 of an accumulation sump 113. Furthermore, an adjustment element (related to the flow of lubricating liquid from the chamber 110 to the pan 120, see below) is arranged in the opening 111, in fact a reed valve (with a flexible reed) 112 adapted to be switched between a closed position (not shown) in which it closes the opening 111, thereby preventing the flow of lubricating liquid LL from the chamber 110 to the pan 120, and an open position of FIG. 1 in which the flow of lubricating liquid LL from the chamber 110 to the pan 120 may instead be possible. In fact, the operating mode of the system 100 of FIGS. 1-3, which partially corresponds to the operating mode of systems according to the prior art, can be summarized as follows:

[0035] Lubricating oil LL is drawn from a collection and accumulation pan 120 and introduced into the crankcase or crankcase 110 through a hydraulic circuit (not shown, including pumps, valves, etc.). Furthermore, the reciprocating translational movement of the piston P is converted into the introduction of pressurized gas into the chamber 110, preventing the chamber 110 itself from dropping in pressure during the upward movement of the piston P. The lubricating oil LL repeatedly (substantially continuously) introduced into the chamber 110 accumulates at the bottom of the chamber 110, particularly at least partially in an accumulation sump 113, and is periodically discharged through the opening 111 into the pan 120. Indeed, as the pressure in the chamber 110 increases, the flexible reed (e.g., made of PVC) 112 is subjected to increasing pressure until it bends (switches from the closed position in FIG. 1a to the open position in FIG. 1b) at a predetermined pressure value (inversely proportional to the flexibility of the reed 112), thereby opening the opening 111 and allowing the oil LL and gas to be discharged from the chamber 110 to the pan 120. However, as mentioned above, the system 100 according to the invention comprises features aimed at increasing the frequency with which the mixture of lubricating oil LL and gas in the chamber 110 is discharged into the pan 120. Indeed, the numeral 140 in the drawings identifies a further opening in the outer wall of the crankcase 110, which, like the opening 111, is provided with a reed valve (with a flexible reed) 141 adapted to be switched by bending between a closed position (FIG. 1b, in which the reed valve closes the opening 140) and an open position (FIG. 1a) in which the reed valve opens the opening 140, thereby allowing the introduction of pressurized gas into the crankcase 110. Obviously, the introduction of pressurized gas (e.g., air) into chamber 110 in addition to blow-by gas or that derived from another source reduces the time required to reach the switching pressure of reed valve 112 in chamber 110, thereby reducing the time between two successive switching operations of reed 112 (both in the open position), increasing the switching frequency of reed 112 and reducing the amount of lubricating liquid LL that can accumulate in chamber 110 between two successive switching operations of reed 112.

[0036] The interior of the crankcase 110 is placed in communication with further zones of said internal combustion engine, in particular with an air source inside the engine, for example the HPC (High Pressure Cooling) system, by a circuit leading to an opening 140 .

[0037] Depending on the source of the air, or more generally the pressurized gas, amounts of gas (eg, air) that are an order of magnitude greater than the amount of blow-by gas may be introduced into the crankcase 110 over a period of time.

[0038] In the embodiment of Figures 3 to 7, the second lead 141 is housed in a compartment 150 (closed by a removable cover 160), in which an inlet channel 151 communicates with the exterior of said compartment 150 for introducing said pressurized gas into said compartment 150 and leads to a second channel 170, the latter defining an opening 140, the interior of the compartment 150 being arranged in communication with the interior of the crankcase 110 by means of the channel 170.

[0039] In the embodiment shown in Figures 6 and 7, the interior of compartment 150 is arranged in communication with the engine's chain compartment and / or flywheel cover compartment 500 by channel 151, said chain compartment and / or flywheel cover compartment in turn being in communication with the oil pan 120, so that a closed recirculation of air is created from the pan 120 to the crankcase 110 without the need to draw air or gas from the outside; in fact, the air flow created by said moving chain and / or flywheel compartment is introduced into compartment 150, and in the closed position, reed 141 divides compartment 150 into a first half-compartment communicated by channel 151 and a second half-compartment communicated by channel 170.

[0040] The closed recirculation of air generated from the pan 120 into the crankcase 110 and the chain and / or flywheel compartment can limit the flow of air emitted from the blow-by valve, thus limiting the emission of oily vapors and fumes, thereby reducing oil consumption.

[0041] In fact, attention has been paid to the method of drawing in air from outside the engine and then releasing that volume of air through the blow-by valve. It has been discovered that drawing in fresh air from outside increases the released air flow by approximately four times compared to internal recirculation. This increased outlet flow rate results in increased smoke and vapors, which are oily vapors containing oil from crankcase cleaning. The release of these vapors also increases oil consumption.

[0042] In the above solution, the channel 151 creates a closed recirculation of air, where air is drawn from the chain and / or flywheel compartment into the interior. This creates an air exchange between two closed interior volumes. Thus, the air is recirculated from the interior, rather than coming from the exterior.

[0043] This solution, as mentioned above, makes it possible to obtain an effective cleaning of the crankcase, thus reducing the temperature of the oil remaining in the crankcase in a short time, and the overpressure obtained by the introduction of air causes the oil to be expelled more frequently by the reed 141. This is because the average pressure in the crankcase increases, which accelerates the disposal of the oil and thus prevents the spalling action that causes power losses and high temperatures.

[0044] Furthermore, such a solution allows for a limited flow of air discharged to the outside by the blow-by valve, thus correspondingly reducing smoke and steam, as well as oil consumption. Because this is an internal air recirculation, the flow discharged to the outside is less than the amount of air introduced from the outside, which reduces smoke and steam and correspondingly reduces oil consumption.

[0045] Next, when reed 141 is switched to the open position, particularly when the air pressure in compartment 150 reaches the switching value of reed 141, channels 151 and 170 communicate with each other, thus introducing air into crankcase 110 from the HPC system and / or from the chain compartment and / or from the flywheel compartment, with the effects described above for increasing the switching frequency of reed 112.

[0046] Further features of the system according to the invention are described below with reference to FIGS.

[0047] As shown, a fixed insert 130 is accommodated in the chamber 110 in order to reduce the free internal volume (not occupied by the moving linkage) of the crankcase 110. Said insert 130 has a trapezoidal cross section (according to a plane parallel to the plane in which the connecting rod moves and therefore perpendicular to the axis of rotation of the drive shaft) and is located in the sump 113 at a predetermined distance from its bottom 114 (so as not to interfere with the accumulation of oil LL in the sump 113), in particular at least partially in the protruding part (shown in dashed lines) of the opening 111, thus defining a conveying channel 115 for conveying said lubricating liquid LL to said collection and discharge sump 113.

[0048] By virtue of the insert 110, the predetermined gas pressure value (hereinafter also defined as the switching pressure value) at which the reed 112 switches by bending from the closed position to the open position is achieved in the crankcase 110 in the presence of a volume of lubricating liquid LL that is smaller than the volume of lubricating liquid LL that would be present when the predetermined gas pressure value would be achieved in the absence of the fixed insert 130; obviously, the reduction in the amount of oil required to reach the switching gas pressure results in a greater switching frequency of the reed 112 (or in other words, an increased switching frequency), and therefore a reduced amount of liquid LL that accumulates between two successive switching operations of the flexible reed 112 (both from the closed position to the open position); and the difference between the volume of lubricating liquid LL that would be present when the predetermined switching pressure value would be achieved in the absence of the fixed insert 130 and the volume of lubricating liquid LL that is present when the predetermined switching pressure value is actually reached is substantially equal (by virtue of the insert 130) to the difference between the free internal volume of the crankcase 110 and the volume of the fixed insert 130.

[0049] As mentioned above, the reduction in the amount of lubricating liquid LL that can accumulate in the chamber 110 between two successive switching operations of the reed 112 results in a further reduction in the risk of interference with the drive shaft with the accumulated oil and of the accumulated oil being subject to the phenomenon of drift when the vehicle is moving, especially in corners, and thereby even compromising its stability (due to the effect of shifting the center of gravity).

[0050] Depending on the application, the volume of the fixed insert 130 may be 20% to 70% of the free internal volume of the crankcase 110, preferably 35% to 55%.

[0051] Thus, the above detailed description of embodiments of the present invention as illustrated in the drawings has demonstrated that the present invention is capable of achieving the stated objectives and, therefore, overcomes the drawbacks and / or disadvantages affecting prior art solutions.

[0052] For example, the present invention makes it possible to provide a ventilation and / or lubrication system whose operating mode is more similar to that of a "dry crankcase" than that of a "wet crankcase," thereby avoiding excessive buildup of lubricating liquid on the crankcase shaft over long periods of time.

[0053] Although the present invention has been made clear above by the detailed description of the embodiments shown in the drawings, the present invention is not limited to the embodiments described above and shown in the drawings. On the contrary, all variations and / or modifications of the embodiments described above and shown in the accompanying drawings that are obvious and self-evident to those skilled in the art are within the scope of the present invention. Therefore, the scope of protection of the present invention is defined by the claims.

Claims

1. 1. A motorcycle internal combustion engine, the internal combustion engine comprising a lubrication system (100), the system comprising a crankcase (110) in which at least one connecting rod is housed, and a basin or pan (120) for collecting lubricating liquid (LL), the crankcase (110) and the basin or pan (120) being arranged in communication with each other by a first opening (111) provided in the crankcase (110), the flow of the lubricating liquid (LL) from the crankcase (110) to the basin or pan (120) through the first opening (111) being regulated by a first switching element (112) adapted to be switched to an open position to allow the lubricating liquid (LL) to drain from the crankcase (110) to the basin or pan (120) when the pressure in the crankcase (110) is equal to or greater than a first predetermined pressure value; the crankcase (110) is arranged in communication with a chain compartment and / or a flywheel cover compartment (500) of the internal combustion engine by a circuit leading to a second opening (140) provided in the crankcase (110), and the crankcase (110) is provided with a second switching element (141) switchable to an open position to allow air to be introduced into the crankcase (110) through the second opening (140) when the pressure in the crankcase (110) is equal to or lower than a second predetermined pressure value; The second opening (140) is provided in a compartment (150) closed by a removable cover (160), and an inlet channel (151) that is in fluid communication with the outside of the compartment (150) leads to the compartment (150) for introducing air into the compartment (150), and a second channel (170) that is in communication with the inside of the crankcase (110) and defines the second opening (140) leads to the compartment (150), and the inlet channel (151) 1) communicates with a compartment defined by the chain compartment and / or the flywheel cover compartment (500) of the internal combustion engine, the chain compartment and / or the flywheel cover compartment (500) then communicating with the basin or pan (120), and a closed recirculation of air is created from the basin or pan (120) to the crankcase (110) without drawing air or gas from outside.

2. 2. An engine according to claim 1, characterized in that the second switching element (141) comprises a first reed valve having an opening threshold equal to the second predetermined pressure value.

3. 3. The engine of claim 1, wherein the system comprises a fixed insert housed in the crankcase, whereby the first predetermined pressure value in the crankcase is achieved in the presence of a volume of lubricating liquid that is less than the volume of lubricating liquid that would be present when the first predetermined pressure value is achieved in the absence of the fixed insert.

4. 4. An engine according to claim 1, wherein the crankcase (110) is shaped to define a collection and drain sump (113) for the lubricating liquid (LL), and wherein the first opening (111) is provided in a bottom (114) of the collection and drain sump (113).

5. An engine according to any one of claims 1 to 4, characterized in that the first switching element (112) comprises a second reed valve having an opening threshold equal to the first predetermined pressure value.

6. 6. An engine according to claim 4, which is dependent on claim 3, or claim 5, which is dependent on claim 4, characterized in that the fixed insert (130) is arranged in the collecting and draining sump (113) at least partially in the protruding part of the first opening (111).

7. A vehicle equipped with a riding saddle, characterized in that it comprises the engine according to any one of claims 1 to 6.

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