Abstract:
An engine diagnostic tool for simulating turbocharger operation within an engine of a motor vehicle, while the engine is not running, includes a turbocharger with an air inlet, an inner surface and an outer surface. The diagnostic tool includes a plug adapted to sealingly engage the inlet of the turbo. The plug includes an aperture for supplying pressurized air to the inlet. The diagnostic tool also includes a clamp adapted to selectively restrict movement of the plug relative to the inlet. The clamp is adapted to be removably coupled to the inlet.

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention generally relates to an apparatus and method to perform vehicle engine diagnostic tests. More particularly, the present invention pertains to an arrangement to simulate turbocharger operation without running the vehicle engine. 
     2. Discussion 
     Vehicles having engines equipped with turbochargers have presented a challenge to service technicians and other repair personnel attempting to diagnose the cause of a customer complaint. The diagnosis is challenging due to the method in which the turbocharger functions. As is commonly known, a turbocharger is an air pump used to increase the volume of air entering into the combustion chamber of the engine. The increased air volume thereby increases the power output of the engine. The turbocharger is driven by a turbine located in the exhaust gas path. Accordingly, as engine speed increases, exhaust gas volume increases to turn the turbine at an increased rate. Subsequently, intake air pressure, or boost, also increases. Using this mechanism, the turbocharger supplies a charge of air to the engine at a pressure greater than atmospheric pressure. Therefore, to properly diagnose turbocharger operation, air pressures greater than atmospheric must be generated. Unfortunately, the higher pressures have typically been generated by running the engine at a relatively high speed while attempting to diagnose the problem. 
     Performing engine diagnostics while the engine is operating at a very high speed it is undesirable for a variety of reasons. When an engine is operating near maximum RPM, its power output is also near its maximum. If the energy is inadvertently released, the likelihood of damage to engine components and service personnel working nearby is high. Additionally, the difficulty of diagnosing a leak within the intake air system greatly increases because of the noise generated from the engine operating at a high speed. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide a method and apparatus for engine diagnostics by generating the boost pressure created by a turbocharger without requiring the engine to be running. 
     It is another object of the present invention to provide a portable, cost effective tool for variably pressurizing the charge air cooling system of an engine equipped with a turbocharger. 
     It is yet another object of the present invention to provide a method and apparatus for quickly and accurately determining the cause of a customer complaint associated with the turbocharger system. 
     The present invention pertains to an engine diagnostic tool for simulating turbocharger operation within an engine of a motor vehicle while the engine is not running. The turbocharger includes an air inlet having an inner surface and an outer surface. The diagnostic tool includes a plug adapted to sealingly engage the inlet of the turbo. The plug includes an aperture for supplying pressurized air to the inlet. The diagnostic tool also includes a clamp adapted to selectively restrict movement of the plug relative to the inlet. The clamp is adapted to be removably coupled to the inlet. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of an exemplary motor vehicle including an engine equipped with a turbocharger; 
     FIG. 2 is a fragmented perspective view of the turbocharger with the intake air duct removed; 
     FIG. 3 is an exploded perspective view of an engine diagnostic tool constructed in accordance with the teachings of the present invention; and 
     FIG. 4 is a cross-sectional view of the preferred engine diagnostic tool mounted to an exemplary turbocharger inlet. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With initial reference to FIG. 1, an exemplary vehicle  10  includes an engine  12  to supply power to the vehicle during operation. Engine  12  is equipped with an intake air system  14  including an intake duct  16  and a turbocharger  18 . As discussed above, turbocharger  18  is operatively coupled to an exhaust system  20 . 
     As most clearly shown in FIG. 2, turbocharger  18  includes an impeller  22  having a plurality of vanes  24  radially extending from a hub  26 . Hub  26  is rotatably mounted to a shaft  28  such that impeller  22  rotates once the turbine (not shown) is contacted by exhaust gasses emitted from engine  12 . Accordingly, intake air is drawn from outside of vehicle  12  into duct  16  (FIG. 1) and turbocharger  18 . The air is pressurized by impeller  22  to provide air at a pressure greater than atmospheric pressure to the cylinders of engine  12 . 
     Turbocharger  18  also includes a generally circular cylindrical hollow inlet  30  having a sidewall  32  with an inner surface  34  and an outer surface  36 . Inlet  30  includes a proximal end  38  mounted to a housing  40  and a distal end  42 . A flange  44  radially extends from distal end  42 . Turbocharger  18  further includes a wastegate (not shown) to divert exhaust gases into the atmosphere to prevent over-boost. Typically, the wastegate is set to open at 27-29 PSI. 
     With reference to FIG. 3, an engine diagnostic tool constructed in accordance with the teachings of the present invention is generally identified at reference numeral  46 . It should be appreciated that engine diagnostic tool  46  operates to pressurize intake air system  14  downstream of inlet  30  to simulate turbocharger function at a relatively high engine speed. Therefore, engine diagnostic tool  46  provides a technician the opportunity of pressurizing intake air system  14  without having to run engine  12  at near peak horsepower output conditions. As such, the operator of engine diagnostic tool  46  may closely inspect and service vehicle  10  without interference from moving engine components and/or engine noise. One skilled in the art will appreciate that engine diagnostic tool  46  may be utilized to detect leaks in intake air system  14 , including inspection of clamps, hoses, inter-coolers and intake manifold gaskets. Furthermore, engine diagnostic tool  46  is useful in detecting wastegate leaks and improper actuation. Also, cylinder compression and cylinder ring blow-by may be investigated. 
     Engine diagnostic tool  46  includes a plug  48 , a clamp assembly  50 , an air line  52  and a pressure regulator  54 . As shown in FIG. 3, diagnostic tool  46  is a simple, easily portable tool capable of supplying regulated pressurized air to inlet air system  14 . In the preferred embodiment, plug  48  is sized to mate with turbocharger inlets found on model year 1994 to 2001 DaimlerChrysler 5.9 liter Cummins turbo diesels. However, it should be appreciated that engine diagnostic tool  46  may be equipped with a variety of plugs having different diameters designed to cooperate with a variety of turbocharger inlet configurations. 
     Plug  48  has a generally circular cylindrical body  56  with an outer surface  58 , a first face  60  and a second face  62 . Outer surface  58  includes a ring groove  64  for receipt of a seal  66 . Plug  48  also includes a first aperture  68  extending from first face  60  to second face  62 . Preferably, first aperture  68  includes an internal thread  70  to secure a quick connect fitting  72  to plug  48 . Plug  48  also includes a second aperture (not shown) extending therethrough. The second aperture also includes an internal thread (not shown) to receive a pressure relief valve  76 . Pressure relief valve  76  includes a poppet  78  to allow pressurized air to escape once a target pressure is met. 
     Typically, inlet air is pressurized an additional 10 pounds per square inch during optimum turbocharger operation. However, pressures exceeding 25 PSI may be generated. As mentioned earlier, turbocharger  18  includes a wastegate to relieve pressures greater than 27 PSI and exhaust them to atmosphere. Accordingly, it is desirable to introduce pressures ranging from 25 to 30 PSI to test proper wastegate operation. Pressures greater than 30 PSI are undesirable since they may overload components such as hoses or clamps within intake air system  14  possibly causing damage to these components. Therefore, pressure relief valve  76  is preferably constructed to exhaust pressures greater than 30 PSI to atmosphere. 
     Clamp assembly  50  includes a generally circular band  80  having a first end  82  and a second end  84 . First end  82  includes a first station  86  to receive a portion of an adjustment mechanism  88 . Second end  84  includes a second station  90  to receive another portion of adjustment mechanism  88 . Adjustment mechanism  88  includes a T-bar  92 , a cross-pin  94  and a nut  96 . T-bar  92  includes a first cylindrical portion  98  orthogonally intersecting a second cylindrical portion  100 . First cylindrical portion  98  includes a threaded segment  102  positioned on the distal end thereof. Second cylindrical portion  100  is disposed within second station  90  to couple T-bar  92  to second end  84 . Similarly, cross-pin  94  is disposed within first station  86 . Cross-pin  94  includes a through aperture  104  sized such that first cylindrical portion  98  may be slidably disposed therethrough. Nut  96  is threadingly engaged with threaded segment  102  to provide an operator a simple method to collapse band  80  and couple clamp assembly  52  to outer surface  36  of inlet  30 . 
     Clamp assembly  50  also includes a set of three arms  106  integrally formed with band  80 . Each of arms  106  includes a longitudinally extending portion  108  and a radially extending portion  110 . Each radially extending portion  110  includes a contact face  112  to engage second face  62  of plug  48  as will be described in greater detail hereinafter. 
     Air line  52  includes a hose portion  114  with female quick connect fittings  116  attached at each end. Pressure regulator  54  includes an inlet  118 , an outlet  120 , an adjustment knob  122  and a gage  124 . In operation, inlet  118  is coupled to a source of pressurized air such as a compressor. Outlet  120  is coupled to one of the quick connect fittings  116 . To regulate pressure entering inlet  30 , an operator simply rotates adjustment knob  122  until the desired pressure is displayed on gage  124 . 
     As earlier noted, installation and operation of engine diagnostic tool  46  is accomplished by removing duct  16  from intake air system  14  and exposing impeller  22  and inlet  30  as shown in FIGS. 1 and 2. More particularly and with reference to FIG. 4, plug  48  is positioned within inlet  30 . It should be appreciated that outer surface  58  defines an outer diameter slightly less in magnitude than an inner diameter defined by inner surface  34  of inlet  30 . However, seal  66  protrudes from groove  64  to define an outer diameter greater than the inner diameter defined by inner surface  34 . Accordingly, seal  66  is compressed by sidewall  32  to sealingly engage plug  48  with turbocharger  18 . 
     To assure retention of plug  48  within inlet  30  during pressurization, clamp assembly  50  is removably coupled to inlet  30 . Nut  96  (FIG. 3) is rotated to collapse band  80  into contact with outer surface  36  until clamp assembly  50  is firmly secured to inlet  30 . Clamp assembly  50  is axially positioned along outer surface  36  to assure engagement of second face  62  with contact faces  112  prior to disengagement of seal  66  with inner surface  34 . In this manner, plug  48  will be sealingly retained within inlet  30  to allow an operator to pressurize intake air system  14  without operating engine  12 . 
     Therefore, certain operational and functional advantages have been provided by the engine diagnostic tool of the present invention. Specifically, a low cost, easily portable tool is provided to simulate turbocharger inlet air pressurization. 
     The foregoing discussion discloses and describes merely exemplary embodiments of the present invention. One skilled in the art will readily recognize from such discussion, and from the accompanying drawings and claims, that various changes, modifications and variations may be made therein without departing from the spirit and scope of the invention as defined in the following claims.