Automotive engine analyzer for indicating a no-connection condition of engine test leads
First Claim
1. An engine analyzing device for analyzing the operational characteristics of an internal combustion engine, comprising:
- a test lead electrically connectable to an internal combustion engine for receiving an engine test signal, said test lead developing a disconnect voltage level when said test lead is disconnected from the engine;
a ground lead electrically connectable to the internal combustion engine for providing a ground reference;
signal referencing means interconnected between said test lead and said ground lead for representing said test signal as a voltage signal having a voltage magnitude lying within a predetermined range, said referencing means including;
(i) an output conductor for transmitting said voltage signal as an output voltage signal; and
(ii) impedance source means connected to said test lead and establishing a non-zero reference signal as an output voltage signal on said output conductor when said test lead is disconnected from the internal combustion engine, said output voltage signal on said output conductor remaining relatively unaffected by said impedance source means when said test lead is connected to said engine despite the presence of a test signal on said test lead of a voltage level substantially equal to said disconnect voltage level; and
signal processing means for receiving said output voltage signal and being responsive to said non-zero reference signal for generating an error indication to the operator.
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Accused Products
Abstract
A voltage divider network comprising three series connected resistors serve to reference a test signal lead connectable to an internal combustion engine, with respect to ground for providing a voltage test signal on an output conductor representative of test data to be retrieved from the engine. Whenever the test signal lead is disconnected from the engine, the voltage divider network provides a non-zero voltage level on the output conductor, having a magnitude lying without a predetermined voltage range of possible test signals. A signal processing circuitry analyzes the test signals for providing a visual analysis display for the operator of the analyzer, and further is responsive to the aforesaid non-zero voltage level for blanking the portion of the visual display which is reserved for displaying analysis data.
24 Citations
10 Claims
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1. An engine analyzing device for analyzing the operational characteristics of an internal combustion engine, comprising:
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a test lead electrically connectable to an internal combustion engine for receiving an engine test signal, said test lead developing a disconnect voltage level when said test lead is disconnected from the engine; a ground lead electrically connectable to the internal combustion engine for providing a ground reference; signal referencing means interconnected between said test lead and said ground lead for representing said test signal as a voltage signal having a voltage magnitude lying within a predetermined range, said referencing means including; (i) an output conductor for transmitting said voltage signal as an output voltage signal; and (ii) impedance source means connected to said test lead and establishing a non-zero reference signal as an output voltage signal on said output conductor when said test lead is disconnected from the internal combustion engine, said output voltage signal on said output conductor remaining relatively unaffected by said impedance source means when said test lead is connected to said engine despite the presence of a test signal on said test lead of a voltage level substantially equal to said disconnect voltage level; and signal processing means for receiving said output voltage signal and being responsive to said non-zero reference signal for generating an error indication to the operator. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification