Patent Publication Number: US-7913661-B2

Title: Protective system for a crank angle sensor

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Patent Application No. 60/980,600, entitled “Protective System for a Crank Angle Sensor”, and filed on Oct. 17, 2007, which application is hereby incorporated by reference. 
    
    
     BACKGROUND 
     The present invention relates to motor vehicles and in particular to a protective system for a crank angle sensor. 
     Devices related to a crank angle sensor have been previously disclosed. Tanaka et al. (Japanese patent number 2006-184134) is directed to a casing for a crank angle detecting device. Tanaka teaches a casing that is intended to inhibit water from penetrating into an internal space of the crank angle detecting device. Tanaka teaches a casing and an internal space that is opened to the atmosphere through a pressure buffering hole. The internal space houses a rotating member and a sensor. Air is received at the pressure buffering hole through a ventilation tube, having a portion extending downward in the vertical direction. 
     Tanaka teaches that whenever the temperature of the internal space falls rapidly, air will be inhaled at the ventilation tube in order to maintain a constant pressure within the internal space. Tanaka also teaches that any moisture in the air absorbed through the ventilation tube may gather within the tube and is thus prevented from entering the internal space through the pressure buffering hole. Tanaka also teaches a heat insulating coating that can be applied to an outer surface of the crank angle detecting device. 
     Dobashi (Japanese patent number 2005-30311) is directed to a vehicular internal combustion engine having a detector mounted on an engine block. Dobashi teaches a system for protecting a detector from bounced water or pebbles while a vehicle is traveling without increasing the number of parts. 
     Dobashi teaches a crank angle sensor mounted to an engine block. Dobashi also teaches a compressor mounted on a lower block and an oil pan via a bracket for an auxiliary engine. The crank angle sensor is mounted so as to be covered by the bracket that is interposed between the lower block and the compressor. 
     Nishio (Japanese patent number 8021242) is directed to a cooling piping structure for an engine. Nishio teaches a system that protects a crank angle sensor by cooling piping, in order to eliminate a need for a separate protection cover for the crank angle sensor. Also, Nishio teaches this system to prevent an increased number of parts and to reduce the cost. Nishio teaches a crank angle sensor disposed on a rear end of an engine. Also located at the rear end of the engine are a water outlet cap and an engine cooling water flow pipe. Nishio teaches that the cap and the pipe are disposed in such a manner to surround the crank angle sensor in the advancing direction of a vehicle. Additionally, the engine cooling water flow pipe is extended between the crank angle sensor and the exhaust manifold that is also attached to the engine. 
     The prior art lacks provisions for protecting the crank angle sensor from heat sources that may cause electrical components of the crank angle sensor to overheat. There is a need in the art for a solution to this problem. 
     SUMMARY 
     A system for protecting a crank angle sensor is disclosed. Generally, this system can be used in connection with an engine of a motor vehicle. The invention can be used in connection with a motor vehicle. The term “motor vehicle” as used throughout the specification and claims refers to any moving vehicle that is capable of carrying one or more human occupants and is powered by any form of energy. The term motor vehicle includes, but is not limited to cars, trucks, vans, minivans, SUVs, motorcycles, scooters, boats, personal watercraft and aircraft. 
     In some cases, the motor vehicle includes one or more engines. The term “engine” as used throughout the specification and claims refers to any device or machine that is capable of converting energy. In some cases, potential energy is converted to kinetic energy. For example, energy conversion can include a situation where the chemical potential energy of a fuel or fuel cell is converted into rotational kinetic energy or where electrical potential energy is converted into rotational kinetic energy. Engines can also include provisions for converting kinetic energy into potential energy, for example, some engines include regenerative braking systems where kinetic energy from a drivetrain is converted into potential energy. Engines can also include devices that convert solar or nuclear energy into another form of energy. Some examples of engines include, but are not limited to: internal combustion engines, electric motors, solar energy converters, turbines, nuclear power plants, and hybrid systems that combine two or more different types of energy conversion processes. 
     In one aspect, the invention provides a motor vehicle, comprising: a sensor configured to measure a crank angle; a protective member configured to cover the sensor, the protective member including an interior portion and where a portion of the sensor is disposed within the interior portion; a heat insulating member substantially spaced from the protective member; and where the heat insulating member is disposed between the protective member and a heat source. 
     In another aspect, the invention provides a motor vehicle, comprising: a sensor configured to measure a crank angle; a protective member configured to cover a portion of the sensor, the protective member having an interior portion and where a portion of the sensor is disposed within the interior portion; an airflow deflecting member associated with the protective member; and where the airflow deflecting member is configured to direct air into the interior portion of the protective member and thereby cool the portion of the sensor disposed within the interior portion. 
     In another aspect, the invention provides a motor vehicle, comprising: a sensor configured to measure a crank angle; a protective member configured to cover a portion of the sensor, the protective member having an interior portion and where a portion of the sensor is disposed within the interior portion; an airflow deflecting member associated with the protective member; and at least one hole disposed on a portion of the protective member proximate to the airflow deflecting member and configured to receive air directed from the airflow deflecting member. 
     Other systems, methods, features and advantages of the invention will be, or will become, apparent to one of ordinary skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description and this summary, be within the scope of the invention, and be protected by the following claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention can be better understood with reference to the following drawings and description. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. Moreover, in the figures, like reference numerals designate corresponding parts throughout the different views. 
         FIG. 1  is an exploded isometric view of an exemplary embodiment of a portion of an engine; 
         FIG. 2  is an assembled isometric view of an exemplary embodiment of a portion of an engine; 
         FIG. 3  is an exemplary embodiment of an assembly of a protective system for a crank angle sensor; 
         FIG. 4  is an exemplary embodiment of a heat insulating member and a portion of a protective member; and 
         FIG. 5  is a side cross sectional view of an exemplary embodiment of a protective system for a crank angle sensor. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is an exploded isometric view of an exemplary embodiment of a portion of engine  100 .  FIG. 2  is an assembled isometric view of an exemplary embodiment of a portion of engine  100 . Referring to  FIGS. 1 and 2 , engine  100  may be associated with a motor vehicle of some kind. Generally, engine  100  could be associated with any type of motor vehicle, including, but not limited to cars, trucks, vans, minivans, SUV&#39;s, motorcycles, scooters, boats, personal watercraft and aircraft. 
     In some embodiments, an engine may include provisions for measuring the rotation of a crankshaft associated with an engine. In some embodiments, the engine may include a crank angle sensor that is configured to determine the current angular position of the crankshaft. In some cases, the crank angle sensor may be configured to provide information for fuel injection timing. In other cases, the crank angle sensor may provide information that is used to determine ignition timing. In still other cases, the crank angle sensor may be used to determine a current engine speed. In an exemplary embodiment, the crank angle sensor may be used to determine fuel injection timing, ignition timing and current engine RPMs. 
     In the current embodiment, engine  100  may include sensor  102 . In some embodiments, sensor  102  may be a crank angle sensor. Generally, sensor  102  may be any type of crank angle sensor. In an exemplary embodiment, sensor  102  is associated with an electromagnetic pickup that is positioned near a rotary body configured to turn with the crankshaft. As the rotary body turns, sensor  102  may be configured to measure the angle of rotation of the crankshaft. Examples and further details of crank angle detectors have been previously disclosed in U.S. Pat. No. 6,058,766, the entirety of which is hereby incorporated by reference. 
     In some embodiments, sensor  102  may be disposed on lower portion  106  of engine  100 . In some cases, sensor  102  may be associated with an oil pan of engine  100 . In other embodiments, however, sensor  102  could be disposed on other portions of engine  100 . Sensor  102  may be disposed proximate to a portion of the crankshaft. 
     Sensor  102  may be further associated with harness  110 . In some embodiments, harness  110  may be configured to secure sensor  102  in place with respect to engine  100 . Furthermore, in some embodiments, harness  110  may be configured to receive and protect one or more electrical wires that may connect sensor  102  with an electronic control unit or another electronic device. In this exemplary embodiment, harness  110  may wrap around a portion of engine  100  to help prevent any electrical wires associated with sensor  102  from protruding outward from engine  100 . 
     Engine  100  may include provisions for protecting a sensor from pebbles, rocks or other debris that may cause damage to parts associated with an underside of an engine during movement. In some embodiments, the sensor may be associated with a protective member that is configured to partially cover the sensor. In an exemplary embodiment, the protective member may be a chipping cover that is configured to protect against rocks and other debris. 
     Referring to  FIGS. 1 and 2 , sensor  102  may be associated with protective member  120 . Generally, protective member  120  has a shape that is configured to cover sensor  102  and that conforms generally to lower portion  106  of engine  100 . In particular, protective member  120  may include generally convex outer portion  122  and interior portion  124  disposed opposite of convex outer portion  122 . This shape allows protective member  120  to receive a portion of sensor  102 , as illustrated in  FIG. 2 . 
     In some cases, air disposed within an interior portion of a protective member could be heated due to nearby heat sources. Examples of possible heat sources include portions of an exhaust system or portions of the engine block. In some embodiments, a protective member may include one or more provisions to prevent air disposed within the interior portion of the protective member from transferring excessive amounts of heat to the sensor. Such provisions are important since a portion of the sensor disposed within the interior portion may include one or more electrical components that may be adversely affected by excessive heat. 
     In some embodiments, the protective member may be associated with heat insulating provisions. In this embodiment, protective member  120  may be further associated with heat insulating member  130 . Generally, heat insulating member  130  may be configured to associate with protective member  120  at lower portion  126  of protective member  120 . With this arrangement, heat insulating member  130  may be disposed between protective member  120  and heat source  135  to prevent the transfer of heat from heat source  135  to protective member  120 . 
     In the current embodiment, heat source  135  may be a portion of an exhaust system. For example, heat source  135  may be a portion of a pipe of the exhaust system. In other embodiments, however, heat source  135  could be another system associated with a motor vehicle that generates heat. 
     Because a crank angle sensor may be disposed near an oil pan portion of an engine, heat may be radiated directly from the engine as well. In some cases, the radiated heat may raise the temperature of the air disposed within an interior portion of a protective member configured to cover the sensor. Therefore, as the temperature of the air rises, the temperature of one or more electronic components associated with the sensor may also increase. 
     In some embodiments, a protective member may include provisions for cooling the air in the interior portion of the protective member. In some embodiments, the protective member may include provisions to circulate air through the interior portion. In an exemplary embodiment, the protective member may include provisions to receive driving wind created as a motor vehicle moves in the forward direction. 
     In this embodiment, protective member  120  may be associated with airflow deflecting member  140 . Airflow deflecting member  140  may have a generally flattened shape. Additionally, airflow deflecting member  140  may be oriented in a generally vertical direction. In other words, airflow deflecting member  140  may be directed toward a driving surface. 
     Generally, members  120  and  140  may be made of any materials. In some embodiments, members  120  and  140  may be made of similar materials. In other embodiments, members  120  and  140  may be made of different materials. Members  120  and  140  may be made of substantially durable materials. In an exemplary embodiment, protective member  120  and airflow deflecting member  140  may each be made of a metallic material or metallic alloy. 
     Generally, heat insulating member  130  could be made of any material that is configured for thermal insulation. In some cases, heat insulating member  130  may be made of a metal or metallic alloy that has a low thermal conductivity. In other cases, heat insulating member  130  could be made of another thermally insulating material, including fibrous, cellular or granular materials. In an exemplary embodiment, heat insulating member  130  may be made of a thermally insulating metallic alloy that is rigid enough to withstand collisions with rocks, pebbles or other debris. 
     Protective member  120 , heat insulating member  130  and airflow deflecting member  140  may be collectively referred to as a protective system. Using this protective system, a crank angle sensor can be protected from various types of damage, including physical damage and/or heat damage. 
       FIGS. 3 and 4  illustrate an exemplary embodiment of the assembly of members  120 ,  130  and  140 . For purposes of clarity, portions of sensor  102  and harness  110  are shown in  FIG. 3  in phantom. Referring to  FIG. 3 , protective member  120  may include provisions for associating with one or more components. In some cases, protective member  120  includes first side portion  302 . In some embodiments, first side portion  302  includes first attachment hole  304 . Protective member  120  may also include second side portion  306 . In some embodiments, second side portion  306  includes second attachment hole  308 . In some cases, second attachment hole  308  may be associated with tab  309 . Finally, in some embodiments, second side portion  306  may also be associated with third attachment hole  310 . 
     In an exemplary, first attachment hole  304  and second attachment hole  308  are configured to receive first bolt  330  and second bolt  332 , respectively, that may be further inserted into a portion of engine  100  (see  FIG. 2 ). Also, third attachment hole  310  may be a harness fixing hole that is configured to engage with harness  110  via screw  334 . With this arrangement, protective member  120  may be bolted directly to engine  100  via bolts or other provisions at first attachment hole  304  and second attachment hole  308 . Furthermore, in some cases, protective member  120  may be attached directly to harness  110  or sensor  102  using third attachment hole  310 . This configuration allows sensor  102  to be fixed in place with respect to protective member  120 . 
     Although the exemplary embodiment uses bolts to attach protective member  120  to a portion of an engine, in other embodiment different provisions may be used. For example, in some embodiments, an engine could be provided with a bracket that is configured to receive a protective member. In still other embodiments, a protective member could be partially welded to a portion of an engine. Generally any method for attaching a protective member to a portion of an engine that is known in the art may be used. 
     Referring to  FIGS. 3 and 4 , heat insulating member  130  may include provisions for attaching directly to protective member  120 . For purposes of clarity, only heat insulating member  130  and protective member  120  are shown in  FIG. 4 . In this case, heat insulating member  130  includes mounting portion  320 . Mounting portion  320  may include mounting hole  322 . In an exemplary embodiment, mounting hole  322  is configured to associate with first attachment hole  304  or protective member  120 . In particular, mounting hole  322  and first attachment hole  304  may be fastened together via first bolt  330 . This arrangement allows heat insulating member  130  to be fastened securely in place with protective member  120  as protective member  120  is secured to a portion of engine  100 . 
     In order to decrease thermal conductivity between heat insulating member  130  and protective member  120 , heat insulating member  130  may be configured so that a majority of heat insulating member  130  does not directly contact protective member  120 . Instead, as seen in  FIGS. 3 and 4 , heat insulating member  130  includes insulating portion  350  that is spaced away from lower portion  360  of protective member  120  by a distance D 1 . Additionally, insulating portion  350  is also disposed away from mounting portion  320  of heat insulating member  130 . This arrangement may facilitate a small contact area between protective member  120  and heat insulating member  130  that helps to prevent heat from being conducted to protective member  120 . 
     Generally, the separation distance between insulating portion  350  and lower portion  360  of protective member  120  may vary. In some cases, the separation distance D 1  may vary between 1 millimeter and 10 millimeters. In other cases, the separation distance D 1  may be greater than 10 millimeters. In still other embodiments, the separation distance D 1  may be less than 1 millimeter. 
     In some embodiments, heat insulating member  130  may also include large tab portion  352 . In some cases, large tab portion  352  may be configured to associate with second side portion  306 . In other cases, large tab portion  352  may be spaced slightly apart from second side portion  306 . This arrangement may help facilitate increased insulation from heat at second side portion  306 . 
     In an exemplary embodiment, an airflow deflecting member includes provisions for associating with a protective member. In this embodiment, airflow deflecting member  140  may be disposed between lower portion  360  of protective member  120  and insulating portion  350  of heat insulating member  130 . In some embodiments, airflow deflecting member  140  may be fused directly to protective member  120 . In other embodiments, airflow deflecting member  140  could be fused directly to heat insulating member  130 . Generally, airflow deflecting member  140  may be attached in any manner to protective member  120  and/or heat insulating member  130 . 
     A protective member may include additional provisions for receiving air from an airflow deflecting member. In some embodiments, the protective member may include holes that are disposed proximate to the airflow deflecting member. In some cases, the protective member may include at least one hole. In other cases, the protective member may include at least one partial hole that is associated with an edge of the protective member. Generally, the protective member may be associated with any number of holes or partial holes. Additionally, the sizes of the holes and partial holes may vary. 
     Referring to  FIG. 3 , protective member  120  may include additional provisions for receiving air from airflow deflecting member  140 . In some cases, protective member  120  may be provided with one or more holes. In this exemplary embodiment, protective member  120  may include first hole  362  and second hole  364  on lower portion  360  of protective member  120 . Additionally, protective member  120  may include first partial hole  366  and second partial hole  368 . Using this arrangement, as air travels up airflow deflecting member  140 , the air may be transported through holes  362 ,  364 ,  366  and  368  into interior portion  124 . In some embodiments, holes  362 ,  364 ,  366  and  368  have a size that prevents pebbles or other large debris from entering interior portion  124 . In other embodiments, any or all of holes  362 ,  364 ,  366 , and  368  may be excluded. Air may flow through protective member  120  regardless of the inclusion of holes  362 ,  364 ,  366 , and  368 , albeit through a smaller pathway around the edges of protective member  120 . Therefore, holes  362 ,  364 ,  366 , and  368  may be included to increase the amount and rate of airflow or eliminated to decrease the amount and rate of airflow. 
     Although the current embodiment includes provisions for holes at an edge of a lower portion of a protective member, in other embodiments, one or more holes could also be disposed at a central region of a lower portion of the protective member. With this alternative arrangement, hot air may be pulled out of the holes disposed at the central region as cool air is pulled in via the airflow deflecting member. Generally, one or more holes could be disposed at any region of the protective member to help facilitate the intake of cool air and the release of hot air. 
       FIG. 5  is a side cross sectional view of an exemplary embodiment of members  120 ,  130  and  140  configured to protect and provide cooled air to sensor  102 . In some embodiments, sensor  102  includes first end  502  that is disposed within interior portion  124 . First end  502  may house one or more electronic components, such as a microprocessor, associated with sensor  102 . Additionally, sensor  102  may include second end  504  that is disposed within engine  100 . In this case, second end  504  is further associated with rotating member  506  that is attached to a crankshaft. With this arrangement, as rotating member  506  turns with the crankshaft, convex portions  508  associated with rotating member  506  are disposed proximally to second end  504  of sensor  102 . In an exemplary embodiment, second end  504  includes an electromagnetic pickup that is configured to monitor the rotation of convex portions  508 . This information can then be transmitted to an electrical component to determine the current angular position, or crank angle, of the crankshaft. 
     In this embodiment, as the motor vehicle moves in the forwards direction, incoming air  510  passes through the motor vehicle. Incoming air  510  generally moves from a front of the motor vehicle toward a rear of the motor vehicle. Generally, the lower surface of a vehicle is shaped to reduce wind drag, so that incoming air  510  flows beneath lower portion  106  of engine  100 . Under normal circumstances, incoming air  510  would not contact sensor  102 . However, the presence of airflow deflecting member  140  beneath engine  100  may help to redirect incoming air  510 . In particular, incoming air  510  may flow upwards, in front of airflow deflecting member  140  and into interior portion  124  through various holes. In this cross sectional view, incoming air  510  is seen entering interior portion  124  through hole  362 . Furthermore, as air is transported into interior portion  124 , the pressure of additional air pushing up from airflow deflecting member  140  forces the air up and out of top portion  560  of protective member  120 . 
     With this arrangement, air is constantly being pushed through interior portion  124 . Therefore, the air disposed with interior portion  124  is constantly being circulated, and this helps to reduce the amount of heat that is transferred to sensor  102 . The air disposed within interior portion  124  remains relatively cool and helps to prevent sensor  102  from overheating during operation. 
     While various embodiments of the invention have been described, the description is intended to be exemplary, rather than limiting and it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible that are within the scope of the invention. Accordingly, the invention is not to be restricted except in light of the attached claims and their equivalents. Also, various modifications and changes may be made within the scope of the attached claims.