Patent Publication Number: US-11396855-B2

Title: Spacer for use in an air intake system of an internal combustion chamber

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority under 35 USC § 119 and the Paris Convention to Great Britain Patent Application 2004712.2 filed on Mar. 31, 2020. 
     TECHNICAL FIELD 
     The present invention refers to a spacer for use in an air intake system of an internal combustion chamber and to an internal combustion engine which is equipped with such a spacer. 
     TECHNOLOGICAL BACKGROUND 
     Internal combustion engines, such as reciprocating engines, are equipped with an air intake system for receiving, processing, and guiding fresh intake air into combustion chambers of the engine. As internal combustion engines usually comprise a plurality of cylinders, each of which accommodates one combustion chamber, known air intake systems typically divide intake air into a corresponding number of separate or partial intake air streams which are guided into one of the combustion chambers, respectively. For doing so, the air intake system is equipped with an intake manifold configured for dividing an air intake stream into the plurality of separate air intake streams before being directed into the cylinder. 
     For properly mounting the intake manifold to an engine block of the engine accommodating the plurality of cylinders, the use of spacers is known which are interposed between the intake manifold and the engine block and provide an airtight connection between these components. 
     However, during operation of the engine, e.g. upon actuation of an air intake valve, vibrations and pressure waves may be generated in the air intake system which may propagate from the air intake valve in an upstream direction through the air intake system, i.e. an intake duct thereof. As a result, e.g. by causing resonances in the air intake passage, the flow of intake air through the intake duct and thus the supply of intake air into the combustion chamber may be affected, thereby causing, for example, pollutant emissions of the engine, such as nitrogen oxides or particulate matter. 
     SUMMARY OF THE INVENTION 
     Starting from the prior art, it is an objective to provide a solution for preventing an air intake system of an internal combustion engine from being subjected to a disturbed flow of intake air through its intake passage. 
     This objective is solved by means of a spacer for use in an air intake system of an internal combustion engine and an internal combustion engine according to the independent claims. Preferred embodiments are set forth in the present specification, the Figures as well as the dependent claims. 
     Accordingly, a spacer for use in an air intake system of an internal combustion engine is provided. The spacer is intended and designed for delimiting an intake duct between an intake manifold and a cylinder head of the engine and is provided with at least one flow-through passage and at least one air-accumulation cavity which are fluid-communicatively connected and constitute the intake duct. 
     Furthermore, an internal combustion engine is provided which has an air intake system being equipped with a spacer as described above. 
     Since the internal combustion engine is equipped with the above-described spacer, technical features which are described in connection with the spacer in the present disclosure may also relate and be applied to the proposed internal combustion engine, and vice versa. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure will be more readily appreciated by reference to the following detailed description when being considered in connection with the accompanying drawings in which: 
         FIG. 1  schematically shows a sectional view of an internal combustion engine which is equipped with a spacer for mounting an intake manifold to a cylinder head of the engine; and 
         FIG. 2  schematically shows a perspective view of a spacer plate used in the spacer depicted in  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     In the following, the invention will be explained in more detail with reference to the accompanying Figures. In the Figures, like elements are denoted by identical reference numerals and repeated description thereof may be omitted in order to avoid redundancies. 
       FIG. 1  schematically shows a sectional view of an internal combustion engine  10 , also referred to as “the engine” in the following, which is provided in the form of a reciprocating engine, such as a diesel engine. The engine  10  may be installed in a vehicle, e.g. a vessel, as a main or auxiliary engine. Alternatively, the engine  10  may be used in power plants. 
     In the shown configuration, the engine  10  comprises at least one cylinder  12 , preferably three cylinders  12 , but may also comprise more or less than three cylinders  12 . Each cylinder  12  is provided with a combustion chamber  14  which is delimited by an inner wall of the cylinder  12  and a piston  16  accommodated in the cylinder  12 . The piston  16  is configured for reciprocatingly moving within the cylinder  12  and is connected to a crankshaft (not shown) of the engine  10  via a connecting rod  18 . 
     During operation of the engine  10 , each one of the combustion chambers  14  is supplied with a fuel mixture which is to be ignited therein so as to produce high-temperature and high-pressure gases which apply forces to and thus axially move the associated pistons  16 , thereby rotating the crankshaft of the engine  10 . In this way, chemical energy is transformed into mechanical energy. 
     The fuel mixture to be supplied to and ignited in the combustion chambers  14  is formed by mixing a fuel medium, i.e. diesel fuel, with intake air, i.e. comprising fresh air or ambient air from outside the vehicle. 
     For supplying intake air into each one of the combustion chambers  14 , the engine  10  comprises an air intake system  20  which is configured to collect air from outside the vehicle, to process the thus received air, e.g. by loading or pressurizing it using a turbocharger and/or by mixing it with exhaust gas from the engine, and to guide it into the combustion chambers  14 . In the context of the present disclosure, the term “intake air” refers to a gas or gas stream which is provided by the air intake system  20  to be supplied into the combustion chamber  14  so as to form the fuel mixture. Typically, intake air comprises fresh air from outside the vehicle. Additionally, intake air may comprise exhaust gas which may be recirculated from an exhaust passage of the engine  10  into the air intake system  20 . 
     More specifically, the air intake system  20  comprises an intake passage  22  which forms an intake duct  24  through which intake air flows prior to being feed into the combustion chambers  14 . In the context of the present disclosure, the term “intake duct” refers to a flow section or flow passage through which intake air is passed and guided prior to being discharged into the combustion chamber  14 . 
     For supplying intake air into the different combustion chambers  14 , the intake passage  22  comprises an intake manifold  26  which is configured to divide a common intake air stream  28  flowing through a common flow passage  30  of the intake passage  22  into separate and partial intake air streams  32 , each of which is guided to an associated one of the combustion chambers  14  via separate flow passages  34  of the intake manifold  26 . In other words, each one of the separate flow passages  34  of the intake manifold  26  is associated to one of the plurality of combustion chambers  14  and configured to direct one separate intake air stream  32  thereinto. 
     Each one of the cylinders  12  is provided with an intake air valve  36  which is configured to selectively direct and thus to variedly adjust the supply of intake air into the combustion chamber  14 . Each intake air valve  36  is provided in a cylinder head  38  and arranged at a downstream end of the intake duct  24 , i.e. of the corresponding separate flow passage  34 . 
     In the context of the present disclosure, the terms “downstream” and “upstream” refer to a flow direction of gases within the engine  10 , i.e. a flow direction of intake air flowing through the intake passage  24 . 
     To that end, for supplying the fuel medium into the combustion chamber  14 , each cylinder  12  is provided with a fuel injection valve or pump  40  which is arranged in the cylinder head  38  and provided for variedly injecting the fuel medium into the combustion chamber  14 . In an alternative configuration of the engine, the fuel medium may be injected into the intake duct, i.e. the separate flow passages  34 , before being supplied to the combustion chamber  14 . 
     The combustion chamber  14  of each cylinder  12  is further connected to an exhaust passage  42  for expelling combustion gases from the combustion chamber  14 , i.e. after combustion of the fuel mixture took place. For controlling the expelling of combustion gases, each cylinder  12  is provided with an exhaust gas valve  43  which is configured for variedly and selectively expelling exhaust gases from the associated combustion chamber  14  into the exhaust passage  42 . Exhaust gases are separately expelled from the combustion chambers  14  and are merged to a common exhaust gas stream  44  flowing through the exhaust passage  42  by means of an outtake manifold  46  which is arranged downstream of the combustion chamber  14 . 
     The basic structure and function of such an internal combustion engine  10  and its components are well known to a person skilled in the art and are thus not further specified. Rather, characteristics of the engine&#39;s air intake system  20  which are interlinked with the present invention are addressed in the following. The skilled person will understand that, although not further specified in the present disclosure, the internal combustion engine  10  may be equipped with further components, such as a turbocharger, an air intake filter, an exhaust gas recirculation system, etc. 
     For properly connecting the intake manifold  26  to an engine block of the engine  10 , in particular the cylinder head  38 , the air intake system  20  is equipped with a spacer  50  which, in a mounted state of the engine  10 , is disposed between the intake manifold  26  and the cylinder head  38 . In this way, intake air flowing through the intake duct  24  is successively guided through the intake manifold  26 , the spacer  50  and the cylinder head  38  before being discharged into the combustion chamber  14  via the intake air valve  36 . More specifically, upon flowing through the intake passage  22 , the common intake air stream  28  is, at first, guided through the common flow passage  30  and thereby is directed into the intake manifold  26 . Upon flowing through the intake manifold  26 , the common intake air stream  28  is then divided into the separate intake air streams  32 , each of which is directed into the associated one of the plurality of cylinders  12  via the associated separate flow passage  34 . By doing so, i.e. upon flowing through the separate flow passage  34 , the separate intake air stream  32  successively passes through the intake manifold  26 , the spacer  50  and the cylinder head  38 . In other words, the intake manifold  26 , the spacer  50  and the cylinder head  38  form and delimit successively arranged flow sections of the intake duct  24 , in particular the separate flow passage  34 . 
     Accordingly, the provided spacer  50  is designed and configured to delimit the intake duct  24 , in particular a flow section of the intake duct  24 , between the intake manifold  26  and the cylinder head  38 . Thus, as can be gathered from  FIG. 1 , the spacer  50  fluid-communicatively connects a flow section of the intake duct  24  provided in the intake manifold  26  with another flow section of the intake duct  24  provided in the cylinder head  38 . In other words, the intake duct  24  forms a flow passage of intake air which extends through the intake passage  22 , the spacer  50  and the cylinder head  38 . Accordingly, the intake duct  24  is formed by the intake passage  22 , the spacer  50  and the cylinder head  38 . 
     For doing so, the spacer  50  is provided with a plurality of flow-through passages  52  each of which is associated to one of the separate flow passages  34 , respectively. In other words, each one of the flow passages  52  forms a part of the intake duct  24 , in particular a part of the associated separate flow passage  34 . Accordingly, the spacer  50  comprises a number of flow-through passages  52  which corresponds to the number of separate flow passages  34  of the intake manifold  26 . 
     In the shown configuration, the spacer  50  is provided as a multi-piece part which comprises or consists of a spacer plate  54  and a gasket  56 . In other words, the spacer  50  is provided in the form of an assembly unit. In an alternative configuration, the spacer may be provided as a one-piece or integral part. 
     As can be gathered from  FIG. 1 , the spacer plate  54  and the gasket  56  are arranged one after the other, in particular directly one after the other. Accordingly, upon flowing through the spacer  50 , i.e. its flow-through passage  52 , intake air is subsequently guided through the spacer plate  54  and the gasket  56 . Thus, each one of the flow-through passages  52  is formed by both the spacer plate  54  and the gasket  56 . 
     In the shown configuration, the gasket  56  is interposed between the spacer plate  54  and the engine head  38 . Alternatively, the spacer  50  may be provided such that intake air, upon flowing through the flow-through passage  52  is, at first, guided through the gasket  56  and then through the spacer plate  54 . Accordingly, the gasket  56  may be interposed between the spacer plate  54  and the intake manifold  26 . Alternatively or additionally, the spacer  50  may be provided with a further gasket such that the spacer plate  52  is interposed between the gasket  56  and the further gasket. According to this configuration, each one of the flow-through passages may be formed or delimited by the spacer plate  54 , the gasket  56  and the further gasket. 
       FIG. 2  shows a perspective view of the spacer plate  54  in a disassembled state in which the spacer plate  54  is disassembled from the spacer  50 . Specifically,  FIG. 2  provides a perspective view onto a front surface  58  of the spacer plate  54  which is configured to be mounted to and to get in contact with a correspondingly designed front surface of the gasket  56 . In other words, in an assembled state of the spacer  50  in which the spacer plate  54  and the gasket  56  are mounted to one another, the front surface  58  of the spacer plate  54  is connected to and fit tightly against the correspondingly designed front surface of the gasket  56 . 
     As can be gathered from  FIG. 2 , the spacer plate  54  and thus the spacer  50  are provided with three flow-through passages  52  each of which is associated to one separate flow passage  34  and thus to one cylinder  12  of the engine  10 . The flow-through passages  52  are provided with a cross-sectional shape which is designed correspondingly to a cross-sectional shape of the intake duct  24  provided in the intake manifold  26 , i.e. the separate flow passages  34 , and in the cylinder head  38  so as to ensure a smooth transition of the intake duct among the spacer  50 . 
     Furthermore, the spacer  50  is provided with at least one air-accumulation cavity  60  which is fluid-communicatively connected to at least one of the flow-through passages  52 . Specifically, in the shown configuration, the spacer  50  comprises two air-accumulation cavities  60 , each of which is fluid-communicatively connected to two of the plurality of flow-through passages  52 . 
     In the context of the present disclosure, the term “air-accumulation cavity” refers to a cavity provided by or in the spacer  50  which is designed and configured such that, in the mounted state of the spacer  50  and during operation of the engine  10 , it accumulates intake air, while ensuring that a mass flow of intake air maintains constant or substantially constant upon flowing through the spacer  50 . In the following, the air-accommodation cavity  60  is also referred to as “the cavity”. 
     In the provided spacer  50 , the flow-through passages  52  and the cavities  60  constitute the intake duct  24 , in particular a part of the intake duct  24  delimited by the spacer  50 . Specifically, in the shown configuration, each one of the cavities  60  is designed and configured to prevent gases or intake air present in the cavity  60  from being discharged from the intake duct  24 . To that end, each one of the cavities  60  is designed and configured to prevent gases from outside the intake duct  24  and the spacer  50  from being supplied into the cavity  60 . In other words, each one of the cavities  60  constitutes a section of the intake duct  24  which is hermetically sealed from an outside of the intake duct  24  and the spacer  50 . 
     By such a configuration, the spacer  50  is configured to, in the mounted state and during operation of the engine  10 , prevent a mass flow of a gas stream, in particular the air intake stream, flowing through the intake duct  24  from being increased or decreased upon flowing through the spacer  50 . Specifically, the spacer  50  is configured such that in each operational state of the engine  10  it prevents that the mass flow of the gas stream flowing through the intake duct  24  is increased or decreased. 
     During operation of the engine  10 , the intake air valves  36  are actuated in accordance with the reciprocating movement of the piston  16  in the associated cylinder  12 . In this way, i.e. upon actuation or operation, the intake air valves  36  may generate vibrations or waves, e.g. shockwaves, which propagate from the cylinder head  38  through the intake duct  24  in an upstream direction. 
     Each one of the cavities  60  is designed such that it is tuned to a frequency of vibrations generated in or waves propagating through the intake duct  24  during operation of the engine  10 , e.g. upon actuation of the intake air valves  36 . In this way, the cavities  60  may be designed to counteract, attenuate or affect the vibrations or waves propagating through the intake duct  24  during operation. In particular, the cavities  60  may be designed to counteract or attenuate resonances in the air intake system  20  which may be caused by the vibrations or waves propagating through the intake duct  24 . In this way, each one of the cavities  60  may form a Helmholtz resonator. For doing so, the cavities  60  are configured and intended for increasing a volume of the intake duct  24 . In this way, vibration characteristics, e.g. a natural frequency, of the intake duct  24  and the gas stream flowing therethrough may be affected. 
     As set forth above, the flow-through passages  52  are fluid-communicatively connected to at least one of the air-accumulation cavities  60 . In the configuration depicted in  FIG. 2 , for doing so, communication conduits  62  are provided which fluid-communicatively connect the cavities  60  to the flow-through passages  52 , respectively. Specifically, each one of the communication conduits  62  is provided such that it opens into the flow-through passage  52  in a direction that is substantially perpendicular to a flow direction of intake air to be fed through the flow-through passage  52  in the mounted state. Each one of the communication conduits  62  is provided in a side wall  64  of the spacer plate  54  which is arranged between a flow-through passage  52  and a cavity  60  and in particular delimits a flow-through passage  52  from a cavity  60 . 
     As can be gathered from  FIG. 2 , each one of the two cavities  60  of the spacer  50  is arranged between and connected to two different flow-through passages  52 . Specifically, each one of the two cavities  60  is fluid-communicatively connected to a first flow-through passage  52  by means of a first communication conduit  62  and to a second flow-through passage  52  by means of a second communication conduit  62 , wherein the first and the second communication conduit  62  are arranged on opposed sides of the cavity  60 . In other words, the first and the second communication conduit  62  are provided in opposed sidewalls  64  of the spacer plate  54 . 
     Alternatively, the spacer  50  may comprise more or less than three flow-through passages  52  and more all less than two cavities  60 . For example, the spacer  50  may comprise a number of n flow-through passages  52  and a number of n−1 cavities  60 , wherein n is a natural number greater than or equal to two. In such a configuration, each one of the plurality of cavities  60  may be arranged between two different flow-through passages  52 . 
     As set forth above, the spacer  50  in the shown configuration comprises or constitutes the spacer plate  54  and the gasket  56 . Specifically, in the shown configuration, the cavity  60  and the communication conduits  62  are delimited by both, the spacer plate  54  and the gasket  56 . For doing so, the spacer plate  54  is provided with a plurality of recesses which extend from the front surface  58  of the spacer plate  54  in a thickness direction of the spacer plate  54  and which form the cavities  60  and the communication conduits  62 . 
     It will be obvious for a person skilled in the art that these embodiments and items only depict examples of a plurality of possibilities. Hence, the embodiments shown here should not be understood to form a limitation of these features and configurations. Any possible combination and configuration of the described features can be chosen according to the scope of the invention. 
     This is particular the case with respect to the following optional features which may be combined with some or all embodiments, items and/or features mentioned before in any technically feasible combination. 
     Accordingly, a spacer for use in an air intake system of an internal combustion engine may be provided. The spacer may be configured and intended for delimiting an intake duct between an intake manifold and a cylinder head of the engine, wherein the spacer is provided with at least one flow-through passage and at least on air-accumulation cavity which are fluid-communicatively connected and constitute the intake duct. 
     By being provided with the air-accumulation cavity, flow and vibration characteristics of the intake duct may be affected so as to counteract or suppress unfavorable vibration or wave propagation phenomena occurring during operation of the engine. 
     It has been found that, during operation of the engine, an intake air valve configured for selectively injecting fresh air flowing through the intake duct into an engine&#39;s combustion chamber may induce vibrations or waves, e.g. shockwaves, which propagate therefrom in a flow upstream direction through the intake duct. These vibrations or waves, however, may induce resonances or other unfavorable vibration or wave phenomena which may affect flow of intake air through the intake duct and thus may disturb proper supply of intake air into the combustion chamber. Accordingly, by being provided with the at least one air-accumulation cavity, the suggested spacer may purposefully change the volume of the intake duct so as to change flow and/or vibration characteristics thereof, thereby affecting, in particular suppressing or counteracting, propagation of vibrations or waves through the intake duct. 
     The proposed spacer may be used and employed in an air intake system of any suitable internal combustion engine, in particular reciprocating engine, such as a diesel engine, a gas engine or dual fuel engine. For example, such an internal combustion engine may be utilized or be installed in vehicles, e.g. as main or auxiliary engines, or in power plants. 
     According to one configuration, the spacer may be provided as a separate part, i.e. which is provided separately from the intake passage, i.e. the intake manifold, and the cylinder head. Accordingly, the spacer may be detachably attached to the intake manifold and the cylinder head. However, the present invention is not limited to this configuration. Rather, the spacer, at least partly, may be provided in, in particular integrally provided, i.e. may at least partly form an integral part together with, the intake manifold and/or the cylinder head. Accordingly, in a further development, the at least one air-accumulation cavity may be provided or machined into an upstream end of the cylinder head which is closed off with a gasket provided between the cylinder head and the intake manifold. In this configuration, the gasket together with the upstream end section of the cylinder head constitute the spacer in the sense of the present disclosure. Alternatively or additionally, the air-accumulation cavity provided or machined into the upstream end of the cylinder head may be sealed or closed off with a correspondingly designed front surface of the intake manifold. In a further development, the front surface of the intake manifold may be provided with a recess which constitutes a part of the air-accumulation cavity. In this configuration, the downstream end of the intake manifold and the upstream end of the cylinder head constitute the spacer in the sense of the present disclosure. Alternatively or additionally, the at least one air-accumulation cavity may be provided or machined into the downstream end of the cylinder head which is closed off with a gasket provided between the cylinder head and the intake manifold. In this configuration, the gasket together with the upstream end section of the cylinder head constitute the spacer in the sense of the present disclosure. 
     As set forth above, the spacer may be used to delimit an intake duct, in particular a part of the intake duct, between the intake manifold and the cylinder head of the engine. In this way, the spacer may be employed to fluid-communicatively connect the intake manifold to the cylinder head. Further, the spacer may be configured and intended for properly mounting the intake manifold to an engine block, in particular the cylinder head of the engine. In the engine, at least one spacer may be provided. In general, the number of spacers used in the engine may depend on or correspond to the number of intake manifolds or number of cylinders of the engine. 
     As set forth above, the spacer is provided with at least one air-accumulation cavity, also referred to as “the cavity” in the following. The cavity may be designed and configured to prevent intake air present in the cavity from being discharged from the intake duct. Alternatively or additionally, the cavity may be designed and configured to prevent the cavity from being supplied with a fluid from outside the intake duct. Alternatively or additionally, the cavity may constitute a section of the intake duct which hermetically seals the intake duct from an outside of the intake duct. 
     Further, the spacer may be provided such that, in a mounted state of the spacer in which the spacer is installed in the engine and during operation of the engine, the spacer is configured to prevent a mass flow of a gas stream flowing through the intake duct from being increased or decreased upon flowing through the spacer. 
     In a further development, the cavity may be designed such that it is tuned to a frequency of vibrations generated in the intake duct or waves propagating through the intake duct upon operation of the engine. Specifically, the cavity may form a Helmholtz resonator. 
     For fluid-communicatively connecting the cavity to the flow-through passage, the spacer may be provided with at least one communication conduit. In other words, the cavity is fluid-communicatively connected to the flow-through passage by means of the at least one communication conduit. Optionally, the fluid conduit may be provided such that it opens into the flow-through passage and/or the cavity in a direction that is perpendicular or substantially perpendicular to a flow direction of intake air to be fed through the flow-through passage in a mounted state. 
     In a further development, the spacer may be provided with a cavity which is fluid-communicatively connected to or which opens into at least two different and separately provided flow-through passages. Specifically, the cavity may be connected to a first flow-through passage by means of a first communication conduit and to a second flow-through passage by means of a second communication conduit. Optionally, the first and the second communication conduits may be arranged on opposed sides of the cavity. In this way, a compact design of the spacer may be provided. 
     The spacer may comprise at least two cavities, for example three or more cavities. Alternatively or additionally, the spacer may comprise at least two flow-through passages. The number of flow-through passages may correspond to or depend on a number of cavities provided in the spacer. By providing a plurality of cavities, in particular the number of which depends on the number of provided flow-through passages in the spacer, the vibration characteristics of the intake duct may be changed in a more effective and more precise way. Further, the number of flow-through passages may correspond to a number of cylinders the engine. 
     For example, the spacer may comprise a number of n flow-through passages and a number of n−1 cavities, wherein n is a natural number greater than or equal to two. In such a configuration, each one of the cavities may be arranged between two different and separately provided flow-through passages. In this way, a compact design of the spacer may be provided. 
     In a further development, the spacer may be provided as an integral part. Alternatively, the spacer may be provided in the form of an assembly which is built up from more than one part. Specifically, the spacer may comprise or consist of at least two parts. In this way, the spacer may contribute to an improved or simplified manufacturing and/or maintenance process. 
     Specifically, the spacer may comprise or consist of a spacer plate and at least one gasket which, in an assembled state of the spacer in which the spacer plate and the gasket are mounted to one another, are connected to one another or fit tightly against each other at correspondingly designed front surfaces. In this configuration, the at least one cavity may be delimited by both the spacer plate and the gasket. 
     In a further development, the spacer plate may be provided with at least one recess which extends from a front surface of the spacer plate in a thickness direction thereof. The at least one recess may form the at least one cavity and/or the at least one communication conduit. By such a configuration, manufacturing of the spacer may be improved and/or simplified. 
     Furthermore, an internal combustion engine may be provided which has an air intake system being equipped with a spacer as described above. 
     INDUSTRIAL APPLICABILITY 
     With reference to the Figures and their accompanying description, a spacer for use in an air intake system of an internal combustion engine and an internal combustion engine being equipped with such a spacer are suggested. The spacer as mentioned above is applicable in any internal combustion engine, in particular in reciprocating engines. The suggested spacer may replace conventional spacers and may serve as a replacement or retrofit part.