JPH0325275Y2 - - Google Patents

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention is a vehicle speed sensor abnormality detection method that detects a disconnection or short circuit in one or more of the power supply line, output signal line, or ground line of the vehicle speed sensor. Regarding equipment. In particular, it relates to a vehicle speed sensor abnormality detection device using a Hall IC.

[Description of prior art]

Conventionally, when this type of vehicle speed sensor is used in a vehicle's power steering controller, for example, it is connected via a signal line to a microcomputer that uses the vehicle speed sensor as a control input to control the vehicle's power steering actuator. . Therefore, if this signal line is disconnected, a power steering operation force appropriate for the vehicle speed cannot be obtained, and the microcomputer may not be sensitive to the vehicle speed.

In order to solve this problem, the applicant has made the operating potential of the vehicle speed sensor higher than the normal operating potential and raised the ground potential by the same amount as the increased operating potential to detect a disconnection of the signal line of the vehicle speed sensor. He devised a wire breakage detection device and applied for utility model registration under Utility Model Application No. 57-196948.

However, the above-mentioned detection device has a drawback that it cannot detect an abnormality when the signal line and the ground line contact each other and cause a short circuit, or when the signal line or the ground line contacts the power supply line and causes a short circuit.

[Purpose of invention]

The present invention solves the above-mentioned drawbacks, and in addition to detecting disconnections in the power supply line, output signal line, and ground line of a vehicle speed sensor with a high operating potential, it also detects short-circuits between the output signal line and the ground line, or An object of the present invention is to provide a device capable of detecting a short circuit between a power supply line and a power supply line.

[Characteristics of the invention]

The present invention includes a first switching element that is connected to an output signal line of a vehicle speed sensor whose operating potential and ground potential are respectively set high, and which is turned off when no potential appears on this output signal line; an output signal line abnormality detection terminal connected to the switching element; a second switching element connected to the ground wire of the vehicle speed sensor and turned off when no potential appears on the ground wire; a ground wire abnormality detection terminal connected to the element; a third switching element connected to the output signal line and configured to turn off the first switching element when the operating potential exceeds a predetermined potential; and the ground wire. and a fourth switching element that is connected to and turns off the second switching element when the ground potential exceeds a predetermined potential.

[Explanation based on examples]

An explanation will be given below based on the drawings of the embodiment.

FIG. 1 is a block diagram of a control section using a detection device according to an embodiment of the present invention. In FIG. 1, an abnormality detection device 1 includes a vehicle speed sensor 2 of a vehicle, and this sensor 2.
The harness wire 5 is interposed between the microcomputer 4 and the microcomputer 4, which controls the power steering actuator 3 based on the detected output. 6
is an abnormality detection alarm circuit.

FIG. 2 is a configuration diagram showing a specific example of this detection device 1 and vehicle speed sensor 2. As shown in FIG. A harness wire 5 interposed between the detection device 1 and the vehicle speed sensor 2 includes a power supply line 5a, an output signal line 5b, and a ground line 5c. +12V is applied to the power supply line 5a from the power supply terminal 10 of the detection device 1.

FIG. 3 is a cutaway perspective view of the main parts of the vehicle speed sensor 2. FIG. In the vehicle speed sensor 2, a Hall IC 14, which is an integrated circuit version of a Hall element, which is a magnetoelectric conversion element, is fixedly attached between two disc-shaped permanent magnets 12 and 13 that are connected to an axle 11 and rotate. These permanent magnets 12 and 13 are each provided with S poles and N poles alternately in the rotation direction, and the two permanent magnets 12
and 13 have different polarities facing each other, and extract pulse signals from the Hall IC 14 in response to changes in the direction of magnetic force of the two permanent magnets 12 and 13 when the axle 11 rotates.

Returning to FIG. 2, the output signal line 5b of the Hall IC 14 is connected to the base electrodes of the transistors 16 and 17. A vehicle speed signal terminal 18 is connected to the collector electrode of the transistor 6, and an output signal line abnormality detection terminal 19 is connected to the collector electrode of the transistor 17. Also Hall IC
The base electrode of the transistor 20 is connected to the ground line 5c of the transistor 14. A ground wire abnormality detection terminal 21 is connected to the collector electrode of this transistor 20 . These vehicle speed signal terminal 18, output signal line abnormality detection terminal 19, and ground line abnormality detection terminal 21 are connected to the microcomputer 4 shown in FIG.
connected to.

In addition, the collector electrodes of transistors 16, 17, and 20 are connected to power supply terminal 22, and +5V is applied to them. Further, the emitter electrodes of the transistors 16, 17 and 20 are grounded.

The characteristic configuration of this embodiment is that first, the base electrode of a transistor 26 is connected to the output signal line 5b via voltage dividing resistors 24 and 25, and the collector electrode of this transistor 26 is connected to the transistor 17.
Second, the base electrode of a transistor 29 is connected to the ground line 5c via voltage dividing resistors 27 and 28, and the collector electrode of this transistor 29 is connected to the base electrode of the transistor 20. At the point where it is connected. The emitter electrodes of transistors 26 and 29 are each grounded.

The resistance values of the voltage dividing resistors 24 and 25 are set so that when the operating potential of the output signal line 5b exceeds a predetermined value, a base current is applied to the base electrode of the transistor 26, and the transistor 26 is turned on. Ru. Further, the resistance values of the voltage dividing resistors 27 and 28 are set so that when the ground potential of the ground line 5c exceeds a predetermined value, a base current is applied to the base electrode of the transistor 29, and the transistor 29 is turned on. Ru.

The operation of the apparatus of this embodiment having such a configuration will be explained.

(a) Disconnection Detection When the power supply line 5a is disconnected: Since no potential appears on the output signal line 5b and the ground line 5c, the transistors 17 and 20 are turned off, and the output signal line abnormality detection terminal 19 and the earth line abnormality detection are detected. Power terminal 2 is connected to both terminals of terminal 21.
Output potential appears from 2.

When the output signal line 5b is disconnected: Since no potential appears only in the output signal line 5b, the transistor 17 is turned off, and the output potential from the power supply terminal 22 appears at the output signal line abnormality detection terminal 19.

When the ground wire 5c is disconnected: Since no potential appears only in the ground wire 5c, the transistor 20 is turned off, and the output potential from the power supply terminal 22 appears at the ground wire abnormality detection terminal 21.

(b) Short-circuit detection When the power supply line 5a and the output signal line 5b are short-circuited: Since the potential of the output signal line 5b exceeds a predetermined potential, the transistor 26 is turned on. As a result, the base potential of the transistor 17 becomes the ground potential, so the transistor 17 is turned off.
An output potential appears at the output signal line abnormality detection terminal 19 from the power supply terminal 22 .

When the power supply line 5a and the ground line 5c are short-circuited: Since the potential of the ground line 5c exceeds a predetermined potential, the transistor 29 is turned on. As a result, the base potential of the transistor 20 becomes the ground potential, so the transistor 20 is turned off.
An output potential appears at the ground wire abnormality detection terminal 21 from the power supply terminal 22 .

When the output signal line 5b and the ground line 5c are short-circuited: Similarly to the above, the transistor 29 is turned on, the transistor 20 is turned off, and the output potential from the power supply terminal 22 appears at the earth line abnormality detection terminal 21.

An abnormality signal is sent to the microcomputer 4 from the terminals 19 and/or 21 where the disconnection or short circuit has been detected and a potential has appeared. As a result, the operation of the power steering actuator 3 is prohibited, and the abnormality detection alarm circuit 6 can alert the driver of the vehicle of information on disconnection or short circuit of each line.

In the above example, a Hall IC is used as the vehicle speed sensor.
Although we have shown an example using a Hall IC, other electric elements may be used instead.

Furthermore, the detection device of the present invention can also be applied to devices that detect disconnections and short circuits in various sensors other than the vehicle speed sensor.

[Effect of idea]

As described above, according to the present invention, the switching element 17 that sends an abnormal signal when the operating potential exceeds a predetermined potential is connected to the output signal line of the conventional disconnection detection device, and the ground wire of the detection device By connecting another switching element that sends out an abnormal signal when the ground potential exceeds a predetermined potential, it is possible to detect not only disconnection but also short circuits between the wires.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a control system using a detection device according to an embodiment of the present invention. FIG. 2 is a detailed electrical circuit configuration diagram of the detection device of this embodiment. FIG. 3 is a cutaway perspective view of the main parts of the vehicle speed sensor of this embodiment. 1... Abnormality detection device, 2... Vehicle speed sensor, 3...
...Power steering actuator, 4...Microcomputer, 5...Harness wire, 5
a...Power supply line, 5b...Output signal line, 5c...
...Earth wire, 6...Abnormality detection alarm circuit, 10, 2
2...Power terminal, 14...Hall IC, 16,1
7, 20, 26, 29...transistor, 18...
... Vehicle speed signal terminal, 19 ... Output signal line abnormality detection terminal, 21 ... Earth wire abnormality detection terminal, 24, 2
5, 27, 28...Voltage dividing resistor.

Claims (1)

[Claims for Utility Model Registration] Connected to the output signal line 5b of the vehicle speed sensor 2 whose operating potential and ground potential are respectively set high,
A first switching element 17 that is turned off when no potential appears on this output signal line 5b, an output signal line abnormality detection terminal 19 connected to this first switching element 17, and a ground line 5c of the vehicle speed sensor. a second switching element 20 connected to the ground line 5c and turned off when no potential appears on the ground line 5c; and a ground line abnormality detection terminal 21 connected to the second switching element 20; A vehicle speed sensor abnormality detection device configured to detect a disconnection of the power supply line, output signal line, or ground line of the vehicle speed sensor when any one of the power supply line, output signal line, or ground line of the vehicle speed sensor is disconnected. A third switching element 26 that turns off the first switching element when the operating potential exceeds a predetermined potential is connected to the output signal line, and the ground potential reaches a predetermined potential to the ground wire. A vehicle speed sensor abnormality detection device characterized in that a fourth switching element 29 is connected which turns off the second switching element when the speed exceeds the threshold.