An internal combustion engine with a sensor assembly for detecting pressure in a blow-by recovery circuit

Abstract

There is described an internal combustion engine (1) including: - a crankcase (2) comprising one or more cylinders (CY), - a head (3) arranged atop said crankcase (2) and comprising a flow module (4) and a cam carrier module (5), the cam carrier module (5) being arranged atop said flow module (4), said flow module (4) comprising one or more inlet conduits and one or more exhaust conduits, wherein at least one inlet conduit and at least one exhaust conduit are associated with a respective cylinder (CY), - a blow-by recovery circuit (B1, B2, B3) through which fluid communication is established between the crankcase (2), the flow module (4) and the cam carrier module (5), wherein at least one of said crankcase (2) and cam carrier module (5) comprises at least one access port (8, 9, P2) in fluid communication with said blow-by recovery circuit, a sensor assembly (10; 10') comprising a cap (12; 12') fixed at the access port (8, 9, P2) and including an installation seat (13,; 13') for a pressure sensor (15) within which a reading channel (14) is provided, the reading channel (14) having a first end (A) arranged at the access port (8, 9, P2) and a second end (B) at which the pressure sensor (15) is received, wherein the second end (B) of the reading channel (14) is arranged at a higher geometrical elevation than the first end (A) of the reading channel.

Description

[0001] "An internal combustion engine with a sensor assembly for detecting pressure in a blow-by recovery circuit"

[0002] ★ ★ ★ ★

[0003] TEXT OF THE DESCRIPTION

[0004] Field of the Invention

[0005] The present invention relates to internal combustion engines . More speci fically, the invention was developed with regard to the sensor equipment for on board diagnostics ( OBD) .

[0006] Prior Art

[0007] The sensor equipment installed on modern internal combustion engines for on board diagnostics ( OBD) comprises an ever increasing number of sensors , due to the necessity of controlling the engine or due to the requirements of national regulations .

[0008] An example regards the pressure sensors in communication with the engine crankcase , which are configured for detecting the pressure within the crankcase during the engine normal operation, so as to make such data available for controlling, i . a . , the blowby circuit for recovering the gas leakages which occur within the crankcase , due to a less than optimal tightness between the cylinder walls and the piston segments . Some national regulations make the presence of such sensors compulsory, due to the need of controlling the emissions into the atmosphere : i f the motor does not comprise such sensors , the sale thereof is not approved in that state .

[0009] For this reason, the known solutions which are currently implemented envisage installing a pressure sensor at ports or openings generally arranged on the engine block and being in fluid communication with the environment inside the crankcase .

[0010] The known solutions exhibit two technical problems . First of all , the implementation of openings suitable for installing pressure sensors to detect the pressure within the crankcase , i . e . adapted to detect the pressure in the blow-by recovery circuit , may involve complications in the practical implementation, because it may require changes in design which are di f ficult to carry out , and generally because the room available for such arrangements is getting smaller and smaller, as the number of accessories and the si ze of after-treatment systems are constantly increasing . Secondly, the known solutions may be unreliable in the pressure readings in the blow-by recovery circuit , as the pressure sensors are af fected by the condensation of liquid fractions in the fluid flow they come in contact with . The build-up of moisture at the sensor and the impossibility of venting it lead to very unreliable readings .

[0011] Obj ect of the Invention

[0012] The present invention aims at solving the technical problems outlined in the foregoing . Speci fically, the invention aims at providing an internal combustion engine wherein it is possible to read information about the pressure within the crankcase while avoiding the adverse ef fects due to the condensation of liquid fractions , and substantially with no need to implement any changes in the design of the engine itsel f .

[0013] Summary of the Invention

[0014] The obj ect of the invention is achieved by means of an internal combustion engine having the features set forth in the claims that follow, which form an integral part of the technical disclosure provided herein in relation to the invention .

[0015] Brief Description of the Figures

[0016] The invention will now be described with reference to the attached Figures , which are provided by way of non-limiting example only and wherein :

[0017] - Figure 1 is a perspective view of an internal combustion engine according to a f irst embodiment o f the invention,

[0018] - Figure 2 is a partially exploded view of the embodiment of Figure 1 ,

[0019] - Figure 3 is a sectional view along line I I I- I I I of Figure 1 ,

[0020] - Figure 4 and Figure 5 are perspective views of a second embodiment of the engine according to the invention, wherein Figure 5 is a partially exploded view along arrow V of Figure 4 , and

[0021] - Figure 6 is a sectional view along line VI-VI of Figure 5 .

[0022] Detailed Description

[0023] Reference 1 in Figure 1 - and, generally speaking, in the Figures - globally denotes an internal combustion engine according to a first embodiment of the invention .

[0024] The engine 1 comprises a crankcase 2 (which is completely visible in Figure 4 and Figure 5 which, albeit referring to a second embodiment , show components belonging to all embodiments ) comprising one or more cylinders , and a head 3 arranged atop the crankcase 2 . Figure 6 , albeit referring to the second embodiment , shows a cross section of a cylinder CY of crankcase 2 .

[0025] The head 3 comprises a flow module 4 and a cam carrier module 5 , wherein the flow module 4 is arranged atop the crankcase 2 whereas the cam carrier module is arranged atop the flow module 4 .

[0026] The flow module 4 comprises one or more inlet conduits and one or more exhaust conduits , wherein at least one inlet conduit and at least one exhaust conduit are associated with a respective cylinder of the crankcase 2 , in a way known in itsel f .

[0027] With reference to Figures 4 and 5 , the engine 1 comprises a blow-by recovery circuit through which fluid communication is established between the crankcase 2 , the flow module 3 and the cam carrier module 5 . The structure of said circuit is wholly conventional , and in the presently described embodiment it is shown by highlighting three flow paths Bl , B2 , B3 which depart from the crankcase , flow upwards along the cylinders in a position between the cylinders , on the periphery of the crankcase , flow upwards along the flow module 3 and enter the cam carrier module 5 . In a way known in itsel f , the cam carrier module 5 comprises a flow path which is adapted to facilitate the condensation of suspended oil drops in the fluid flow, and a vent which sends the air separated from the oil to the engine intake .

[0028] The cam carrier module 5 comprises a first plurality of ports arranged coaxially to a first axis X6 , and a second plurality of ports arranged coaxially to a second axis X7 , which is parallel to the first axis X6 . The ports of the first plurality are configured for receiving and supporting a first camshaft rotatable around axis X6 , while the ports of the second plurality are configured for receiving and supporting a second camshaft rotatable around the second axis X7 , speci fically by means of a hydrodynamic support of camshaft bosses having a shape matching the ports of the first and of the second plurality . It will be observed, in any case , that an internal combustion engine according to the invention may comprise a cam carrier module with a single camshaft , with the corresponding access port .

[0029] The camshafts are inserted axial ly along the axes X6 , X7 , respectively through a f irst access port 8 and through a second access port 9 , each being arranged at an end position of the cam carrier module 5 . Each access port 8 , 9 implements a so-called "technical opening" which is used for the installation operations o f the camshafts , and speci fically for the installation of the timing gear among the camshafts , with a 1 : 1 gear ratio according to the so-called "cam-to-cam" architecture , wherein the timing gear ensures the rotation at the same angular speed of the camshafts , while one of them receives motion from the crankshaft of the engine 1 by means of a wheel or a pulley arranged at the opposite end with respect to the ports 8 , 9 , and rotatably connected to either camshaft ( e . g . the camshaft coaxial to axis X6 ) . The access ports 8 , 9 are preferably arranged coaxial to the axes X6 , X7 .

[0030] According to the invention, at the access port 9 there is arranged a sensor as sembly 10 , which is configured for detecting a pressure across the respective access port 9 . At the port 8 , on the other hand, there is arranged a vacuum pump for a brake booster 11 , but it shall be borne in mind that other installation layouts are possible . The sensor assembly 10 may be installed at port 8 , and the vacuum pump ( or another accessory, e . g . a phase shifter device ) may be installed at port 9 . Generally speaking, the possibility of installation does not strictly depend on the selection of either port 8 or port 9 , but rather on the possibility of implementing - for some accessories such as the vacuum pump or the phase shi fter - a torsional connection with the camshaft being located at the access port 8 , 9 .

[0031] Referring back to the installation depicted in the Figures , the access port 9 ( in the same way as the access port 8 ) is in fluid communication with the blow-by recovery circuit , therefore it is subj ected to the pressure of the fluid stream flowing upwards along the flow paths Bl , B2 , B3 .

[0032] Referring to Figures 1 to 3 , the sensor assembly 10 comprises a cap 12 including an installation seat 13 , wherein there is provided a reading channel 14 having a first end A arranged at the access port 9 and a second end B whereat a pressure sensor 15 is received, which is preferably fixed to the cap 13 by means of a screw 16 . The cap 12 is fixed to the cam carrier module 5 by means of one or more screws F12 .

[0033] Speci fically, the pressure sensor 15 comprises an influence surface 15S whereat the exchange of forces takes place with the fluid the pressure whereof must be detected, such surface facing into the reading channel 14 at the end B, preferably in a position within the reading channel 14 proj ecting beyond end B . The reading channel 14 extends along a first direction A14 in a first section between the end A and an elbow E of the channel 14 (preferably, the first section extends from end A up to the elbow E itsel f ) , and extends along a second direction B14 in a second section between the end B and the elbow E (preferably, the second section extends from section B up to the elbow E itsel f ) , wherein the first direction A14 and the second direction B14 are incident with each other . Preferably, an angle between the directions A14 and B14 is between 90 ° and 150 ° . Such an angle is shown in Figure 3 between the two sections of the reading channel 14 , starting from the direction A14 and advancing anti-clockwise until meeting the direction B14 ; therefore , it is an angle equal to or greater than 90 ° .

[0034] In the preferred embodiment shown in the Figures , the directions A14 and B14 are the axes of the sections of channel 14 which converge into elbow E , the direction A14 being arranged parallel to the axes X6 , X7 . According to the invention, the end B is arranged at a higher geometrical elevation than the end A.

[0035] The di f ference in elevation is denoted by reference D14 in Figure 3 , and it is meant as a di f ference in elevation with respect to an absolute reference system (which, given the orientation of the engine 1 as installed in a vehicle , may be applied to engine 1 without any trans formation) , wherein the end B is uniquely arranged, so to say, "higher" than end A.

[0036] This means that it is not strictly mandatory, albeit it is preferable , to have the channel 14 include the elbow E , as the relative position of the ends A and B may be obtained by means of a reading channel 14 which is straight and inclined, with respect to the axes X6 , X7 , by an angle higher than 90 ° ( in an anti-clockwise direction in Figure 3 , starting from axis X7 ) .

[0037] In this way, sensor 15 is adapted to detect the pressure present at port 9 ( as wel l as at port 8 ) , which corresponds to the pressure in the blow-by recovery circuit , and ultimately to the pressure inside the crankcase 2 , due to the existence of fluid communication .

[0038] Therefore , this of fers a solution to the problems af fecting the sensor assemblies in known engines , because the position of the ends A, B brings about a slope that naturally causes the condensed liquid fraction of the oil vapours to flow towards the blow-by recovery circuit ( in the present case , towards the cam carrier module 5 ) . The surface of influence 15S is therefore constantly exposed to a substantially dry fraction of the oil vapours , the pressure whereof can be detected in a reliable and repeatable fashion .

[0039] With reference to Figures 4 to 6 , in a second embodiment of the engine 1 according to the invention the installation of the sensor assembly is implemented at crankcase 2 ; speci fically, a sensor assembly 10 ' is provided - which is similar to the sensor assembly 10 , and therefore generally has the same reference numbers - which is installed at an access port P2 in fluid communication with the blow-by recovery circuit , speci fically which is substantially open at a transverse fluid communication section between the path B2 and the path B3 . Similarly to sensor assembly 10 , the sensor assembly 10 ' comprises a cap 12 ' including an installation seat 13 ' , within which there is provided the reading channel 14 , wherein the first end A is arranged at the access port P2 ( Figure 6 ) , while the second end B receives the pressure sensor 15 , which is preferably fixed to the crankcase 2 by means of the screw 16 . The cap 12 is fixed to the crankcase 2 by means of one or more screws , which are not shown in the Figures 4 to 6 .

[0040] As already remarked with reference to sensor assembly 10 , the pressure sensor 15 comprises a surface of influence 15S at which an exchange of forces occurs with the fluid the pressure whereof is to be detected, such surface of influence facing into the reading channel 14 at the end B, preferably at a position which proj ects beyond end B within the reading channel 14 . Unlike sensor assembly 10 , the reading channel 14 of the sensor assembly 10 ' may include , at the end A, an enlarged section 14X having a diameter which substantially coincides with the port P2 , so as to better connect to the latter .

[0041] The reading channel 14 extends along a first direction A14 ' in a first section between the end A and the elbow E of channel 14 (preferably, the first section extends from the end A up to the elbow E itsel f ) , and it extends along a second direction B14 ' in a second section between the end B and the elbow E (preferably, the second section extends from the end B up to the elbow E itsel f ) , wherein the first direction A14 ' and the second direction B14 ' are incident to each other ( the references di f fering from the sensor assembly 10 are due to the fact that they not always coincide with the directions A14 , B14 ) .

[0042] In the preferred embodiment shown in the Figures , the directions A14 ' and B14 ' are the axes of the sections of channel 14 which converge into the elbow E , the direction A14 being arranged substantially orthogonal ly ( or, generally, incident ; in any case , the conditions of orthogonality and incidence comprise slanted arrangements ) to an axis ZCY of the cylinder CY . Preferably, an angle between the directions A14 ' and B14 ' is between 90 ° and 150 ° . Such an angle is shown in Figure 6 between the two sections of the reading channel 14 , starting from the direction A14 ' and advancing in an anti-clockwise direction until meeting direction B14 ' ; therefore , such an angle is equal to or greater than 90 ° .

[0043] In the same way as in sensor assembly 10 , the end B is arranged at a higher geometrical elevation than the end A, always with respect to an absolute reference system . The di f ference in elevation is denoted by reference D14 in Figure 6 . Again, this means that it is not strictly mandatory, albeit it is preferable , to have the channel 14 include the elbow E , as the relative position of the ends A and B may be obtained with a reading channel 14 which is straight and inclined with respect to axis ZCY by an angle smaller than 90 ° ( in an anti-clockwise direction in Figure 6 , starting from axis ZCY) .

[0044] In this way, the sensor 15 is able to detect the pressure existing at port P2 , which corresponds to the pressure in the blow-by recovery circuit and ultimately to the pressure in the crankcase 2 , thanks to the existence of fluid communication (which in this case is even more direct than in sensor assembly 10 ) .

[0045] Generally speaking, embodiments are possible wherein only one sensor assembly 10 or 10 ' is present on the cam carrier module 5 or on the crankcase 2 , as shown in the Figures ( therefore , wherein there is at least one access port 8 , 9 or P2 in fluid communication with the blow-by recovery circuit ) , but embodiments are also possible wherein both the cam carrier module 5 and the crankcase 2 are provided with an access port ( therefore there are more than one access port , which are arranged on di f ferent components ) whereat there is respectively provided the sensor assembly 10 , 10 ' .

[0046] Of course , the implementation details and the embodiments may vary, even appreciably, from what has been described and illustrated, without departing from the scope of the present invention, as defined in the annexed claims .

Claims

CLAIMS1. An internal combustion engine (1) including:- a crankcase (2) comprising one or more cylinders (CY) ,- a cylinder head (3) arranged atop said crankcase (2) and comprising a flow module (4) and a cam carrier module (5) , said cam carrier module (5) being arranged atop said flow module (4) , said flow module (4) comprising one or more inlet conduits and one or more exhaust conduits, wherein at least one inlet conduit and at least one exhaust conduit are associated with a respective cylinder (CY) ,- a blow-by recovery circuit (Bl, B2, B3) through which fluid communication is established between the crankcase (2) , the flow module (4) , and the cam carrier module (5) , wherein at least one of said crankcase (2) and said cam carrier module (5) comprises at least one access port (8, 9, P2) in fluid communication with said blow-by recovery circuit,- a sensor assembly (10; 10' ) comprising a cap (12; 12' ) fixed at the access port (8, 9, P2) and including an installation seat (13; 13' ) for a pressure sensor (15) within which a reading channel (14) is provided, the reading channel (14) having a first end (A) at the access port (8, 9, P2) and a second end (B) at which the pressure sensor (15) is received, wherein the second end (B) of the reading channel (14) is arranged at a higher geometrical elevation than the first end (A) of the reading channel.

2. The internal combustion engine (1) according to claim 1, wherein the pressure sensor (15) comprises an influence surface (15S) facing into the reading channel (14) at the second end (B) .

3. The internal combustion engine (1) according to claim 1 or claim 2, wherein the reading channel (14)extends along a first direction (A14; A14' ) in a first section between the first end (A) and an elbow (E) of the reading channel (14) , and extends along a second direction (B14; B14' ) in a second section between the second end (B) and the elbow (E) , wherein the first direction (A14; A14' ) and the second direction (B14; B14' ) are incident with each other.

4. The internal combustion engine (1) according to claim 3, wherein the cam carrier module (5) comprises at least one camshaft rotatably mounted about a first axis of rotation (X6 , X7) , wherein the first direction (A14) of the reading channel (14) is parallel to said first axis of rotation, wherein said at least one access port (8, 9) is arranged coaxially to the axis of rotation of a corresponding camshaft.

5. The internal combustion engine (1) according to claim 3, wherein the access port (P2) is provided on said crankcase (2) , and wherein the first direction (A14' ) of the reading channel (14) is incident, preferably orthogonal, to an axis (ZCY) of a cylinder of said crankcase (2) .

6. The internal combustion engine (1) according to claim 5, wherein the first direction (A14' ) is slant with respect to the axis (ZCY) of said cylinder (2) .

7. The internal combustion engine (1) according to claim 3, wherein the first section of the reading channel (14) extends from the first end (A) to the elbow (E) , and wherein the second section of the reading channel extends from the second end (B) to the elbow (E) .

8. The internal combustion engine (1) according to claim 3, wherein an angle between the first direction and the second direction is between 90° and 150°.

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