Patent Publication Number: US-6668633-B2

Title: Electronic fuel injector tester

Description:
TECHNICAL FIELD 
     The present invention relates, in general, to a tester for electronic fuel injectors, and, more particularly, to an electronic fuel injector testing probe that produces a visual and audible signal each time the pintle within the fuel injector being tested opens. 
     BACKGROUND ART 
     Testers to determine whether fuel injectors are operating properly are readily available. For example, U.S. Pat. No. 4,523,458 (Daniel) discloses a fuel injector tester which utilizes a piezoelectric crystal that converts mechanical impulses caused by the actuation of the pintle within the fuel injector into electrical signals. In this case, the piezoelectric crystal is comprised of two piezoelectric substrates with a metal layer interposed therebetween. The piezoelectric crystal is interposed between permanent magnets, one permanent magnet allowing the tester to be magnetically attached to the fuel injector being tested. The permanent magnets are provided with end plates which retain the piezoelectric crystal permitting the mechanical vibrations of the end plates, caused by the opening of the pintle within the fuel injector tester, to be transmitted to the piezoelectric crystal wherein the vibrations are converted into voltage signals. The resulting structure of the tester disclosed in this reference is rather complex since it includes two piezoelectric substrates with a metal layer interposed therebetween and also includes permanent magnets and end plates to retain the piezoelectric crystal and to transmit mechanical vibrations from the fuel injector to the piezoelectric crystal. 
     The Pool, et. al. reference (U.S. Pat. No. 6,260,412) discloses a device for testing the output control voltage of an electronic fuel injection system. The invention disclosed in this reference is directed to a device that can be used to test a fuel injection control system to determine if it is producing the necessary electrical signals required to actuate the fuel injectors. As such, the device disclosed in this reference cannot be used to test the operation of the fuel injectors individually. 
     The VanTassel, et. al. reference (U.S. Pat. No. 4,141,243) discloses apparatus for measuring the volumetric output of fuel injector system components, such as a fuel injector and/or a fuel pump. As such, by measuring the volumetric output of a fuel injector, a determination can be made as to whether the fuel injector is operating properly. In this case, the volumetric output of the fuel injector must be measured in order to evaluate the operability of the injector, and thus, a direct determination cannot be made as to whether the fuel injector is operating properly. 
     SUMMARY OF THE INVENTION 
     The present invention solves the problems associated with the prior art fuel injector testers, and other problems, by providing an electronic fuel injector testing probe which permits individual fuel injectors to be tested when the car is at idle. The fuel injector testing probe of the present invention detects the impact or vibration which occurs when the pintle within a fuel injector opens by using a piezoelectric transducer which is provided in the pistol-type handle of the probe. A light emitting diode is provided in the pistol-type handle and flashes each time the pintle within the fuel injector opens. In addition, the testing probe emits an audible sound each time the pintle within the fuel injector opens. 
     The electronic fuel injector testing probe of the present invention remains in the “sleep” mode when not in use. The testing probe is activated by tapping the probe on a hard surface. Once the testing probe is “awakened”, the light emitting diode flashes and the probe emits an audible sound. The tip of the testing probe can then be placed against the body of the fuel injector being tested to determine whether the fuel injector is operating properly. Opening of the pintle within the fuel injector causes both the light emitting diode within the pistol-type handle of the testing probe to flash and the probe to emit an audible sound. When testing has been completed, the fuel injector testing probe emits an audible sound, flashes and then goes back into the “sleep” mode. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of the electronic fuel injector testing device of the present invention and illustrates the placement of the end of the testing probe against the fuel injector being tested. 
     FIG. 2 is an elevational view, partially broken away in cross-section, of the electronic fuel injector testing device of the present invention. 
     FIG. 3 is an elevational view of the probe portion of the electronic fuel injector testing device of the present invention. 
     FIG. 4 is a cross-sectional view taken across section-indicating lines  4 — 4  in FIG.  3 . 
     FIG. 5 is a schematic diagram of the electronic circuitry utilized by the electronic fuel injector testing device of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings where the figures illustrate the preferred embodiment of the present invention, and are not intended to limit the invention described herein, FIG. 1 is a perspective view of the electronic fuel injector tester  10  of the present invention and illustrates the placement of the end of the probe portion of the tester  10  against a fuel injector being tested. FIG. 2 is an elevational view, partially broken away in cross-section, of the electronic fuel injector tester  10  of the present invention. The fuel injector tester  10  is comprised of a probe tip  12  and a pistol grip handle  14  which includes the electronic circuitry  16  and a battery  18  used as the power source for the tester  10 . 
     As shown in FIGS. 3 and 4, the probe tip  12  is comprised of a metallic probe having a point  22  at one end thereof. The other end  24  of the probe  20  is press fit within a blind bore  26  in one end  28  of a metallic hub member  30 . The other end of hub member  30  has a threaded blind bore  32  therein. The metallic hub member  30  provides mechanical conductivity, i.e., transmits vibrations, from the metallic probe  20  to the pistol grip handle  14 . A non-metallic sleeve  34  is received over hub member  30 . 
     As shown in FIG. 2, the pistol grip handle  14  includes a metallic male threaded portion  40  which is received within threaded blind bore  32  in hub member  30  of probe tip  12 . A light emitting diode  42  is provided within pistol grip handle  14  adjacent to the male threaded portion  40 . 
     Referring now to FIG. 5, a schematic diagram of the electronic circuitry  16  utilized by the fuel injector tester  10  is illustrated. The electronic circuitry  16 , which is received within the pistol grip handle  14  of the tester  10 , includes a piezoelectric transducer  50 , a signal conditioning and clamping circuit  52 , a low voltage comparator  54 , a voltage reference  56 , and a microprocessor  58  having a switched power source  60  therein. The probe tip  12  is mechanically connected to the input to the piezoelectric transducer  50  whose output is connected to the input to the signal conditioning and clamping circuit  52 . One output of the signal conditioning and clamping circuit  52  is connected to an input to the low voltage comparator  54 . The other output of the signal conditioning and clamping circuit  52  is connected to an input to the microprocessor  58 . Battery  18  is connected to the input to the switched power source  60  which provides power to the microprocessor  58 , the voltage reference  56  and the low voltage comparator  54 . The output of the voltage reference  56  is applied as an input to the low voltage comparator  54 . The output of the low voltage comparator  54  is applied as an input to the microprocessor  58 . The output of the microprocessor  58  is connected to a super bright light emitting diode  62 . 
     Operationally, the fuel injector tester  10  is in the “sleep” mode when not in use. In order to use the tester  10 , the tester  10  is tapped on a hard surface causing the piezoelectric transducer  50  to generate an output voltage which is processed by signal conditioning and clamping circuit  52  and applied as an input to microprocessor  58  causing switched power source  60  to be actuated applying power to the reference voltage  56  and the low voltage comparator  54 . Actuation of switched power source  60  also causes the piezoelectric transducer  50  to emit an audible beeping sound and causes the light emitting diode  62  to flash. The probe tip  12  is then placed against the body of the fuel injector (not shown) being tested and each time the pintle within the fuel injector snaps open, the vibration from the opening of the pintle causes the piezoelectric transducer  50  to generate an output voltage which is processed by signal conditioning and clamping circuit  52  and applied as an input to the low voltage comparator  54 . If the voltage produced by the piezoelectric transducer  50  exceeds the reference voltage, such as 30 mv, set by voltage reference  56 , the voltage comparator  54  produces an output voltage which is applied as an input to the microprocessor  58  which, in turn, causes the light emitting diode  62  to flash and causes the piezoelectric transducer  50  to emit an audible beeping sound. If the voltage comparator  54  does not produce an output signal for a pre-determined period of time, such as 40 seconds, the microprocessor  58  causes the piezoelectric transducer  50  to emit an audible beeping sound and causes the light emitting diode  62  to flash. The microprocessor  58  then causes the tester  10  to automatically turn off, i.e., it causes the tester  10  to go back into the “sleep” mode. 
     Consistent steady flashing of the light emitting diode  62  and the simultaneous emission of audible beeping sounds from the piezoelectric transducer  50  indicates that the fuel injector being tested is operating properly. No response or an inconsistent response from the fuel injector tester  10  indicates that the fuel injector being tested is not firing or is firing intermittently. Such a condition can be caused by the fuel injector being mechanically stuck. Alternatively, an electrical open or short might be present in the fuel injector or an electrical fault might exist in the electrical harness or control module for the fuel injector. 
     Certain modifications and improvements will occur to those skilled in the art upon reading the foregoing. It is understood that all such modifications and improvements have been deleted herein for the sake of conciseness and readability, but are properly within the scope of the following claims.