Boots – shoes – and leggings
Patent
1994-10-07
1996-11-26
Trammell, James P.
Boots, shoes, and leggings
36442602, G06F 770
Patent
active
055792359
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of PCT/DE93/00249 filed Mar. 18, 1993.
BACKGROUND OF THE INVENTION
The present invention relates to a method of monitoring rpm sensors and, more particularly, to a method which specifically detects short circuits between rpm sensors and their feed lines.
In known error detection circuits for inductive rpm sensors, a defective rpm sensor caused by an open line or a short circuit in the power line can be detected by monitoring a voltage level triggered by a superposed direct current. However it is desirable to improve the known method of testing individual rpm sensors and their sensor circuits by specifically monitoring to detect short circuits between rpm sensors and/or their feed lines.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved method of monitoring a plurality of rpm sensors by which short circuits between rpm sensors and/or their feed lines are detected.
This object and others which will become more apparent hereinafter are attained in a method for monitoring a plurality of rpm sensors comprising superposing a direct current voltage on an alternating voltage signal from one rpm sensor in one rpm sensor circuit to form a combined voltage signal and monitoring a voltage level of the combined voltage signal at a monitoring point of the one rpm sensor in one rpm sensor circuit to detect an error.
According to the invention, the method for monitoring the rpm sensors is improved by changing the voltage level at the monitoring point of the one rpm sensor by feeding a test voltage pulse to a pole of the one rpm sensor for a predetermined time interval during a test stage; and monitoring a voltage level at a monitoring point of at least one other rpm sensor and/or its feed lines in the at least one other rpm sensor circuit to determine if the voltage level at the monitoring point of the at least one other rpm sensor changes when the voltage level is changed at the monitoring point of the one rpm sensor in the one rpm sensor circuit and thus to determine if and when a short circuit exists between the at least one other rpm sensor and the one rpm sensor.
In a preferred embodiment of the invention the one rpm sensor circuit is not monitored for the fault during the predetermined time interval during the test stage.
BRIEF DESCRIPTION OF THE DRAWING
The objects, features and advantages of the present invention will now be illustrated in more detail by the following detailed description, reference being made to the accompanying drawing in which:
FIG. 1 is a schematic circuit diagram of circuitry for performing a method of monitoring plural rpm sensors according to the invention, this circuitry being shown with a short circuit indicated between individual rpm sensor circuits with a dashed line; and
FIG. 2 is a graphical illustration of the voltage at a connection or monitoring point of one rpm sensor circuit during the testing process for the short circuit.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 shows circuitry for performing one embodiment of a method of monitoring two rpm sensors 1,8 according to the invention to detect a short circuit between the rpm sensors and/or their feed lines 14,14'. The one rpm sensor circuit 20 shown in the upper part of FIG. 1 includes one rpm sensor 1, while the other rpm sensor circuit 22 shown in the bottom part of FIG. 1 includes another rpm sensor 8. In the one rpm sensor circuit 20 shown in FIG. 1 the amplifier 2 converts the sine-wave or alternating voltage signal from the rpm sensor 1 to a square-wave voltage. The output of the amplifier 2 is connected to a microprocessor 3. The rpm sensor 1 is connected in a voltage divider with two additional resistors 4 and 5 for monitoring. The microprocessor monitors the voltage level by means of a line 6 with a resistor 7 at the point CP of connection between the rpm sensor 1 and resistor 7. The voltage level at the connection point CP changes when there is a break in the line or a short circuit in the power line. The microprocessor 3 detects this level
REFERENCES:
patent: 4635508 (1987-01-01), Tatsumi
patent: 4722576 (1988-02-01), Matsuda
patent: 5109675 (1992-05-01), Hwang
patent: 5291578 (1994-03-01), Kalami
patent: 5341282 (1994-08-01), Brambilla et al.
patent: 5406485 (1995-04-01), Wise et al.
Blanc Martin
Dittmar Christian
Haefele Klaus
Purat Thomas
Schlichenmaier Andreas
Robert & Bosch GmbH
Striker Michael J.
Trammell James P.
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