Abstract:
Springs of an intake air heater of an internal combustion engine that are used to account for expansion of the intake air heating element are replaced by other appropriate materials with similar and additional properties. A first compliant material and a second compliant material allow for the expansion of the intake air heating element and each is designed in a way such that collection of soot within the intake air heater is reduced or prevented. By preventing the collection of soot in the intake air heater, the intake air heating element has room to expand, and therefore, does not buckle, thereby increasing the life span of the intake air heater.

Description:
TECHNICAL FIELD 
       [0001]    The present disclosure relates generally to the field of air heater systems for an air intake of an internal combustion engine. 
       BACKGROUND 
       [0002]    Motor vehicles are used throughout the world in a variety of climates. Many of the operating climates experience ambient temperatures significantly below 40 degree F. While the injected diesel fuel self-ignites from mixing with the hot compressed intake air in the combustion chamber, at low ambient temperatures, the temperature within the combustion chamber may not be high enough to ensure proper ignition of the injected diesel fuel. This results in issues with starting the engine in cold weather conditions, especially if the engine has been soaked for an extended time in a cold ambient condition. 
         [0003]    Incomplete combustion of diesel fuel at low temperatures results in unburned hydrocarbons in the engine exhaust. These unburned hydrocarbons cause the undesirable phenomenon known as ‘white smoke’. The side effect of ‘white smoke’ is attributable to misfiring or incomplete combustion in some or all cylinders of an engine. White smoke is a respiratory and optical irritant and has an adverse effect on visibility. To avoid the issues of white smoke and engine cold starting, intake air heaters having electrically controlled heated elements have been added to the engine assembly upstream of the intake manifold to raise the temperature of the intake air to ensure proper ignition of the diesel fuel in the combustion chamber during cold start conditions. 
         [0004]    The intake air heater is typically located in an environment that can get very dirty, especially in a diesel engine that uses Exhaust Gas Recirculation. This is because some of the soot that may be generated during combustion may be recirculated along with exhaust gases back into the intake manifold, which is typically downstream of the intake air heater. The soot may clog different components in the intake air heater which affects the performance and reduces the life of the intake air heater. There is a desire to improve the life and performance attributes of intake air heaters in diesel engines by reducing or preventing the deposition of soot. 
       SUMMARY 
       [0005]    Embodiments described herein relate to an intake air heater for use with an internal combustion engine that includes an intake air heating element for heating intake manifold air and a first insulating part and a second insulating part for securing the electrically controlled intake air heating element. The first insulating part and the second insulating part, in turn, is each secured by a first housing and a second housing, respectively. A first compliant material, capable of elastically responding to an applied force, is placed between the first insulating part and a first surface of the first housing and a second compliant material, capable of elastically responding to an applied force, is placed between the second insulating part and a first surface of the second housing. 
         [0006]    Embodiments described herein, relate to a method of reducing or preventing the collection of soot around the intake air heating element of an intake air heater in an internal combustion system. The method comprises a control system for enabling and disabling the intake air heating element based on a coolant temperature, the first insulating part to protect the first housing from excessive heat and the second insulating part to protect the second housing from excessive heat respectively. The first compliant material operable to elastically respond to changes in size of the intake air heating element and prevent the accumulation of soot is fixed between the first insulating part and the first surface of the first housing and the second compliant material operable to elastically respond to changes in size of the intake air heating element and prevent the accumulation of soot is placed between the second insulating part and the first surface of the second housing. When accumulation of soot is reduced or prevented, the intake air heating element can expand without any buckling, thereby extending the life of the intake air heater. Other embodiments to reduce or prevent the collection of soot are possible. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  is a schematic block diagram of a portion of a diesel engine incorporating the EGR system and the intake manifold system; 
           [0008]      FIG. 2  and  FIG. 3  show a first embodiment of an Intake Air heater described herein; 
           [0009]      FIG. 2A  is a close-up side view of the first housing; 
           [0010]      FIG. 4  shows the assembly of the Intake air heater in an engine; 
           [0011]      FIG. 5  is a second embodiment of an Intake air heater described herein; 
           [0012]      FIG. 6  is a third embodiment of an Intake air heater described herein; 
           [0013]      FIG. 6A  is a detailed representation of the spring assembly from  FIG. 6   
           [0014]      FIG. 7  is a fourth embodiment of an intake air heater described herein 
       
    
    
     DETAILED DESCRIPTION 
       [0015]    As is shown in  FIG. 1 , pressurized fresh engine intake air  11  is obtained from an engine mounted turbocharger compressor  10  and is carried to the engine cylinders (not shown) in the combustion chamber  18  by an air intake system line  12  to an air intake manifold  13 . Exhaust gas  20  produced in the cylinders (not shown) upon combustion carries chemical constituents and soot. The amount of exhaust gas  20  to be recirculated is controlled by an exhaust gas recirculation system of the engine as described. In this embodiment, a predetermined portion of the exhaust gas  20  exiting the turbine  13  is reintroduced into the engine mixer  16  through the exhaust gas recirculation valve  15 , which is electronically controlled by an engine control module, ECM  21 , along with the fresh intake air  11  from the compressor  10  through the intake throttle valve  17 , which is also electronically controlled by the ECM  21 . The exhaust gas  20  and the fresh intake air  11  are mixed in the engine mixer  16  and travel to the intake manifold  14 , from where this mixture of exhaust gas  20  and fresh intake air  11  is combusted again, in an attempt to reduce in-cylinder NOx generation. An intake air heater  19 , electronically controlled by the ECM  21 , is attached to the engine mixer  16  so that the exhaust gas  20  and fresh intake air  11  mixture travels through the intake air heater  19  before entering the air intake manifold  14 . 
         [0016]    Soot may form during incomplete fuel combustion. The intake air heater  19 , downstream of the engine mixer  16  and upstream of the air intake manifold  14  in this embodiment, has a tendency to become fouled by the deposition of soot contained in the recirculated exhaust gas  20 . The deposition of soot, combined with thermal expansion of the intake air heating element  22  in the intake air heater  19  when the intake air heating element  22  is activated compromises the efficiency of the intake air heater  19 . 
         [0017]      FIG. 2  and  FIG. 3  show a detailed embodiment of the intake air heater  19 . The intake air heater  19  constitutes one or more electrical intake air heating element  22 , such as a ribbon type heating element with at least two folds, such as first fold  59  and second fold  60 , arranged in a parallel configuration. Other configurations and arrangements of the folds are possible. As is known in the art, heating elements are typically made of nichrome, which is an alloy of Nickel and Chromium. Other materials, such as Iron alloys may also be used. The intake air heating element  22  is attached to a first insulating part  23  made from a material such as ceramic and designed to fit compatibly with the shape and features of the intake air heating element  22  along a first surface  24  and a second insulating part  25  made from a material such as ceramic and designed to fit compatibly with the shape and features of the intake air heating element  22  along a second surface  26 . The first insulating part  23  is enclosed in a first housing  27  which may be a ‘c-shaped’ ramp housing as shown in detail in  FIG. 2A . The first insulating part  23  is supported by a first ramp  28  and is held in place by a folded first top end  29  of the first housing  27 . A first spring  30 , which may be a wavy spring, is affixed between the first insulating part  23  and the first folded top end  29 . Similarly, the second insulating part  26  is enclosed in a second housing  31 , which may be a ‘c-shaped’ ramp housing. The second insulating part  26  is supported by a second ramp  32  and is held in place by a second folded top end  33  of the second housing  31 . A second spring  34 , which may be a wavy spring, is affixed between the second insulating part  25  and the second folded top end  33 . When the intake air heater  19  is activated, the first wavy spring  30  and the second way spring  34  allow for thermal expansion of the intake air heating element  22  from heat generated during activation. This would ensure that there is no buckling of the at least two parallel configurations of the intake air heating element  22 . Buckling may cause the at least two parallel configurations of the intake air heating element  22  to touch each other which would cause failure of the intake air heating element  22  through a power surge or short circuit. A third end of the intake air heating element  22  is bolted into the engine mixer  16  using a bolt  35 . A fourth end of the intake air heating element  22  has a bolt  36  that is connected to a source of electricity such as a wire (not shown). The bolt  35  attached to the third end of the intake air heating element  22  is used as a ground connection. Electricity is converted into heat by the intake air heating element  22 . Recirculated exhaust gas  20  carries with it soot and other particles. Since the intake air heater  19  is in the path of the exhaust gas  20 , the soot collects in a first area  37  and a second area  38  as highlighted in  FIG. 2  and  FIG. 4 . As can be seen, the soot collects in between and around the first spring  30  and the second spring  34 . This collection of soot in the first area  37  and second area  38  disables the ability of the first spring  30  and the second spring  38  to allow for any thermal expansion of the intake air heating element  22 . When the intake air heater  19  is enabled under appropriate conditions, which may be determined by a measurement of a coolant temperature (not shown), the intake air heating element  22  heats up, starts expanding, and, since the intake air heating element  22  has no room to expand because of the presence of soot, the at least two parallel configurations of the intake air heating element  22  buckle. If the at least two parallel configurations of the intake air heating element  22  touch because of buckling, it would cause shorting and the intake air heater  19  would fail. The failure of the intake air heater  19  results in incomplete combustion during cold starting conditions, which negatively affects the engine and emissions.  FIG. 5  demonstrates an embodiment of a solution to this failure mode. 
         [0018]    As is shown in  FIG. 5 , the first spring  30  and the second spring  34  are each removed and replaced by a different material of a certain size and shape. In this embodiment, the first spring  30  is replaced by a first compliant material  39  that may be of rectangular shape and cross-section, such as a closed cell silicone sponge, operable to elastically respond to a force. Closed cell silicone sponge is a material that can withstand a large range of temperatures, and has compression properties similar to the first spring  30  and the second spring  34  used in the intake air heater  19  in the original embodiment. Similarly, the second spring  34  is replaced by a second compliant material  40 , such as a closed cell silicone sponge, operable to elastically respond to a force. This may also be rectangular in shape and have a rectangular cross-section. The first compliant material,  39  has a first adhesive layer,  41  that may cover the entire area of a first surface  45  of the first compliant material  39 , and is used to affix the first surface  45  of the first compliant material  39  to a first inner surface  43  of the first housing  27 . Similarly, the second compliant material,  40 , has a first adhesive layer  42  that may cover the entire area of a first surface  46  of the second compliant material  40 , and may be used to affix the first surface  46  of the second compliant material,  40 , to a first inner surface  44  of the second housing  31 . The adhesive may be a material that can withstand high temperatures, that is up to 700 degree Fahrenheit. When the intake air heater  19  is enabled, the intake air heating element  19  will have room to expand through the compression of the first compliant material  39  and the second compliant material  40 . Additionally, since the first compliant material  39  fills up a first area between and around the first insulating part  23 , and the first housing  27  and the second compliant material,  40  fills up a second area between the second insulating part  25  and the second housing  31 , there is relatively less room for the soot being carried in the exhaust gas  20  to be collected between the first insulating part  23  and the first housing  27  and between the second insulating part  25  and the second housing  31 . Therefore, the intake air heating element  22  will not buckle when the intake air heater  19  is enabled. 
         [0019]    Referring now to  FIG. 6  and  FIG. 6A , a third embodiment of an intake air heater  19  is shown. In this embodiment, a first spring  30  is encased in a first hollow part,  47  as shown in detail in  FIG. 6A , which may be made of a material such as closed cell silicone sponge. Another suitable material such as polytetrafluoroethylene and the like may also be used. While polytetrafluoroethylene material is stiff compared to the closed cell silicone sponge, the relatively soft surface of the polytetrafluoroethylene material along with its positioning will reduce soot from collecting within the intake air heater  19 . A second spring,  34  is encased in a second hollow part  48 , which may be made from closed cell silicone sponge or any other suitable material such as polytetrafluoroethylene and the like. Both the first hollow part  47  and the second hollow part  48  may be of a rectangular shape. A first surface  49  of the first hollow part  47  has a first adhesive layer  41 , which may be of the same shape and area as first surface  49 , to affix the first hollow part  47  to the first inner surface  43  of the first housing  29 . Similarly, a first surface  50  of the second hollow part  48  has a second adhesive layer  42 , which may be of the same shape and area as the first surface  50  to affix the second hollow part  48  to the first inner surface  44  of the second housing  31 . This embodiment combines the benefit of the wavy spring along with the protection, elasticity and flexibility of the closed cell silicone sponge, since the closed cell silicone sponge can block any open areas that are prone to soot collection as highlighted in the original embodiment. 
         [0020]      FIG. 7  shows a fourth embodiment of the intake air heater  19 . In this embodiment, a first spring,  30 , which may be a wavy spring, is placed between a first insulating part  23  and a first folded top end  29  of a first housing  27 . A first piece of rectangular cross-section  51 , that may be made of a material like a closed cell silicone sponge is fixed between a first wavy portion  59  of the first wavy spring  30  and a second piece of a rectangular cross-section,  52 , that may be made of a material like a closed cell silicone sponge is fixed between a second wavy portion  60  of the first spring  30  and the first inner surface  43  of the first housing  29 . Additionally, a third piece of rectangular cross-section  53 , that may be made of a material such as a closed cell silicone sponge is fixed onto the first inner surface  43  of the first folded top end  29  and a fourth piece of rectangular cross-section  54 , that may be made of a material such as a closed cell silicone sponge is fixed onto the first inner surface  43  of the first folded top end  29  on the opposing end as shown in  FIG. 7 . The spring like properties of the first piece of rectangular cross section  51 , the second piece of rectangular cross section  52 , the third piece of rectangular cross-section  53  and the fourth piece of rectangular cross-section  54  allow for the flattening of the first spring  30  without significant hindrance, while simultaneously preventing accumulation of soot by covering critical open areas such as those highlighted in  FIG. 4 . Similarly, a fifth piece of rectangular cross-section  55 , and a sixth piece of rectangular cross-section  56 , placed between the second spring,  34  and the second housing  31 , prevent accumulation of soot between the second insulating part  25  and the second housing  31  while allowing for the flexibility of the second spring  34  and a seventh piece of rectangular cross-section  57  and an eighth piece of rectangular cross-section  58 , affixed to either end of the folded top end  33  of the second housing  33  prevent accumulation of soot between the second insulating material  25  and the second housing  31 . Other shapes and cross-sections of the closed cell silicone sponge may be possible for similar implementation and effect.