JPS61251777A - Detector for state change - Google Patents

Abstract

PURPOSE:To detect the breaking of three kinds of wires used for a potentiometer (PM), wire by wire, by applying a bias voltage from a power line to the signal line of the PM. CONSTITUTION:Bias resistances Rb1 and Rb2 are provided among the three kinds of wires, i.e. power line L1, signal line L2, and earth line L4 of the PM 21, and the signal line L2 is connected to a microcomputer 33 through an A/D converter 37. The resistances Rb1 and Rb2 are both set to values larger than the resistance value of a resistor 21R. A divided voltage is developed on the signal line L2 by the resistances Rb1 and Rb2 and the resistance from the slider 21a of the PT 21 to an earth point. If the power line L1 is broken between a sensor 20 and a detector 30, the divided voltage inputted to the computer 33 becomes lower than the minimum voltage of the measurement range of the PT 21. If the earth line L4 is broken, the divided voltage is close to a source voltage. Further, if the signal line L2 is broken, the divided voltage becomes constant regardless of the sliding of the slider 21a of the PT 21. The computer 33, therefore, judges accurately which wire is broken.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a state change detection device using a so-called potentiometer, which generates a linear voltage detection signal in response to changes in the position, angle, etc. of an object to be measured. In particular, the present invention relates to a state change detection device that can easily detect disconnection of a power supply line, a ground line, and a signal line interposed between the potentiometer and a processing device that processes its detection signal.

[Prior Art] In the past, along with advances in automatic control technology and semiconductor technology, various complicated devices and the like have come to be centrally monitored and controlled by computers.

For example, vehicles are no exception, and in-vehicle computers not only control the internal combustion engine that is the driving force source of the vehicle, but also control the transmission, brakes, etc.

With these advances, a large number of wires have become complex and serve as information transmission paths between centralized monitoring and control devices such as computers and the devices they control, such as internal combustion engines and brake hydraulic systems. , new vehicle failures such as disconnection of these wires have begun to occur in large numbers.

Therefore, in recent years, there has been an urgent need to develop a device with a self-diagnosis function that can accurately detect failures caused by these disconnections.

A state change detection device using a potentiometer is a sensor that detects various events in the above-mentioned centralized monitoring control system.
For example, it is widely used as a throttle position sensor, air flow meter, etc. Due to its structure, this state change detection device requires wiring of three types of wires: a ground wire that supplies power to the potentiometer, a power supply wire, and a signal wire that provides a detection output, and the self-diagnosis function described above is particularly required. There is.

Therefore, a state change detection device as shown in FIG. 2 has been proposed. Sensor 3 consisting of potentiometer 1
Power is supplied to the detector 7 from the detection device 7, which is composed of a one-chip microcomputer 5, through the ground line G and the power line Vc. Since the slider 9 of the potentiometer 1 slides on the resistance wire R following the change in the object to be measured, a voltage corresponding to the change in the object to be measured is generated in the signal line S, and the analog-digital converter ( The signal line is input to the A/D converter 11. Also, the signal line is pulled down by a resistor RD on the input side of the A/D converter 11. Note that 13 supplies power to the one-chip microcomputer 5 and potentiometer 1. This is the power supply.

According to the above-mentioned conventional state change detection device, disconnection of the ground line G or signal line S (both A/
The input of the D converter 11 becomes open. ) can be identified. That is, when the ground line G has a disconnection failure, the potential pulled up by the pull-down resistor RD is input to the A/D converter 11, and when the signal line S has a disconnection failure, the potential grounded by the pull-down resistor RD (ground potential) is input to the A/D converter 11. Since the signal is input to the converter 11,

[Problems to be Solved by the Invention] However, the state change detection device as described above is still not sufficient and has the following problems.

In other words, as is clear from FIG. 2, even if the power line VC is disconnected, the input of the A/D converter 11 is at ground potential, so it is difficult to distinguish between the power line VC and the signal line S. However, they do not yet have a complete self-diagnosis function.

The present invention was made in view of the above-mentioned problems, and provides a state change detection device using a potentiometer that requires three types of wires. It is an object of the present invention to provide a state change detection device equipped with a self-diagnosis function that can detect a change in state.

[Means for solving the problems] The means configured by the present invention to solve the above problems are as follows:
As shown in the basic configuration diagram in Fig. 1, power is supplied from the power line LV which is at a predetermined potential difference from the ground voltage of the ground line LG, and any voltage signal up to the voltage of mV of the power line is applied to the object to be measured. a potentiometer C1 that outputs an output from a signal line LS in response to a change in state; and a recognition means C2 that receives a voltage signal from the signal line of the potentiometer C1 and recognizes a change in state of the object to be measured.
The gist of the state change detection device is a state change detection device comprising: a bias means C3 for applying a bias voltage from the power supply line mV to the pre-distribution line LS.

[Function] The potentiometer C1 in the present invention is a ground wire LG.
, a general sensor that requires three types of wire connections: a power line LV and a signal line LS.It is driven by applying a voltage between the ground line LG and the power line LV, and changes the state of the object to be measured. A voltage signal corresponding to the voltage is output from the signal line LS. for example,
The most common configuration is one in which both ends of an open resistor are connected to a ground line LG or a power line LV, and a signal line LS is connected to a slider. This slider slides in accordance with the position, angle, etc. of the object to be measured, and a voltage signal is generated in the signal line LS in accordance with a change in the state of the object to be measured.

The recognition means C2 receives a voltage signal from the signal line LS of the potentiometer C1 to recognize changes in the state of the object to be measured. Therefore, this can be achieved by understanding the relationship between the output voltage of the signal line LS and the state change of the object to be measured in advance. Also, the voltage change on the signal line LS is caused by the ground line L.
Since the change in potential is based on G, the recognition means C2 has a reference potential that is the same as that of the ground line [G]. For example, a configuration in which the potentiometer C1 and the ground line are common, and which performs switching operations according to voltage changes on the signal line LS, or converts voltage changes on the signal line LS into digital information and uses it for various program processing. is achieved.

The state change detection device of the present invention further includes bias means C3 as described below. This has the effect of applying a bias voltage from the power supply line LV to the signal line LS representing the state change of the object to be measured as described above.

For example, between the power supply line LV and the signal line LS, and between the signal line LS
A resistor is connected between the ground line LG and the ground line LG, and a voltage divided by the two resistors is applied to the signal line. For example, when the potentiometer C1 is a sliding resistor as in the example described above, and the voltage of the signal line LS is divided by a voltage dividing resistor as described above, the signal voltage of the signal line LS may change due to the voltage dividing resistor. Conceivable. Therefore, it is preferable to design the voltage dividing resistor to have a value much larger than the resistance value of the potentiometer C1 so that most of the current from the power supply line LV flows into the potentiometer C1.

EXAMPLES Hereinafter, in order to explain the present invention more specifically, the present invention will be described in detail by giving examples.

[Embodiment] FIG. 3 shows an electric circuit diagram of a state change detection device according to an embodiment. In the figure, reference numeral 20 denotes a sensor section, which incorporates a potentiometer 21 whose slider 21a slides on a resistance wire 21R in response to a change in the state of an object to be measured (not shown), for example, a change in rotation angle. In addition, 23 is a state switch that detects state changes in a binary manner, and when the rotation angle of the object to be measured (not shown) changes to θS, it becomes an "ON" state, and when it changes to 06 or more, it becomes an rOFFJ state. It is. A voltage O is constantly applied to the power supply line L1 from the power supply 31 built into the detection device 30, and the potentiometer 21
is connected to one end of the resistance wire 21R. This resistance wire 21R
The other end of is connected to the same ground line L4 as one end of the status switch 23, and this ground line L4 is connected to the power source 31.
Power is supplied to the resistance wire 21R by being connected to the ground point of the resistor wire 21R. Slider 21a of potentiometer 21
The detection device 30 recognizes the angular change of the object to be measured (not shown) through two wires: the signal line L2 connected to the state switch 23, and the switch output line L3 connected to the other end of the state switch 23. The one-chip microcomputer 33 in the detection device 30 performs this recognition, and detects the rotation angle of the object to be measured by processing the following input signals according to a program stored in an internal ROM. One of the input signals is the output of the buffer 35 to which the switch output line L3 of the state switch 23 is connected, and the other is the output of the A/D converter 37 to which the signal line L2 is connected. That is, detection is performed from two states: the binary state of "ON" or rOFFJ of the state switch 23, and the digital conversion value of the analog changing voltage of the signal line L2. Furthermore, this signal line L2 is connected to bias resistors Rb1 and Rb.
2 and biased to voltage VM.

FIG. 4 illustrates the relationship between the output of the sensor 20 and the rotation angle of the object to be measured. It is assumed that the object to be measured has an arbitrary rotation angle between θ1 and θ2 due to its structure. Signal line L2 of potentiometer 21
As is clear from the above explanation, the output varies from O[V] to VO[
V], but the bias resistors Rb1 and Rb2 are both selected to have very large values compared to the resistance value of the resistance wire 21R within the rotatable range of the object to be measured,
This can be easily obtained by linearly designing the characteristics of the resistance wire 21R in the potentiometer. In addition, the output from the switch output line L3 is "ON" with the angle θS as the boundary, and rOF
Makes a binary change in FJ.

According to such a state change detection device, it is possible to detect a change in the rotation angle of the object to be measured as a linear voltage change.
If a map as shown in FIG. 4 is prepared in the OM, the rotation angle can be accurately recognized from the detected voltage.

Furthermore, the state change detection device of this embodiment has three wires L1 connected to the potentiometer 21 by the following operation.
, L2, and L4 are connected from the sensor 20 to the detector 30.
If a disconnection fault occurs during the period up to this point, the fault can be accurately detected.

First, when the power supply line L1 is disconnected, the signal line L2 includes a bias resistor Rbl, another bias resistor Rb2, and a resistor from the point where the slider 21a of the potentiometer 21 is located to the ground point. A divided voltage is generated on the signal line L2. As mentioned above, since the resistance value of the resistance wire of the potentiometer 21 is set to a small value compared to the bias resistance, this divided voltage has an extremely low value. Therefore, the resistance wire 21R and bias resistors Rb1 and R
By designing b2, disconnection detection of the power supply line L1 can be easily achieved. For example, the resistance ratio is about 300 times (21R = 5Ω, R
b1=1.5M, Rb2=1M).

Next, a case will be described in which a disconnection failure occurs in the grounding wire L4. At this time, the voltage generated in the signal line L2 is the resistance of the bias resistor Rbl, the resistance line 21R from the power supply line L1 to the slider 21a, and the other bias resistor Rb.
This is the voltage obtained by dividing the power supply voltage by 2 and 2. As mentioned above, the resistance value of the resistance line 21R is extremely low compared to the bias resistance. Therefore, the voltage generated on the signal line due to such voltage division has a value extremely close to the power supply voltage 0. Therefore, it is only necessary to design the voltage value (VH>) close to this power supply voltage VO to be a value higher than the voltages 1 to V5 used for measurement of the potentiometer 21.
Compared to the resistance value of the resistance line 21R, the bias resistance Rbl,
The condition is that the value of Rb2 is extremely large, and for example, the resistance ratio as described above may be used.

Next, a case where a disconnection failure occurs in the signal line [2 will be described.

At this time, the voltage input to the signal line L2 is a value (VM) divided by the bias resistors Rbl and Rb2, and is a value uniquely determined by the values of the bias resistors Rb1 and Rb2. Therefore, if the output from the potentiometer 21 becomes constant at the voltage value (VM) and does not change in any way, it can be determined that a disconnection failure has occurred in the signal line L2, as determined by the one-chip microcomputer 33.

Furthermore, in order to accurately detect the disconnection of the signal line L2, the switch output may be used. For example, as shown in FIG. 4, it is assumed that the output voltage VM at the time of the disconnection of the signal line L2 is within the voltage used for detection of the potentiometer 21 (Vl to V5). At this time, the output from signal line L2 is V
M, and the rotation angle of the object to be measured is recognized as if it were θM. However, if the switch output at that time is "ON", it is determined that the angle of the object to be measured is less than .theta.S and that the output from the potentiometer 21, which is the angle .theta.M, is abnormal. That is, signal line L2
Only when the output of
Otherwise, it is difficult to judge whether the bias voltage is due to a disconnection of the signal line L2. Therefore, if the state of the object to be measured is constantly changing and the constant output is not continuous, the voltage VM By using a new detection device that determines whether the value of is correct or not, and the switch output of the previous example, it is possible to detect wire breaks with high accuracy.

One-chip microcomputer 3 performs the above-mentioned disconnection judgment.
FIG. 5 shows a flowchart when executing step 3.

When the output from the A/D converter 37 is input, it is first determined whether the value VAD is equal to VM (step 10).
0), if VAD=VM, another determination is made as to whether the switch output is "ON" or rOFFJ (step 102). If the output is "ON", it is determined that the signal line L2 is clearly disconnected (step 104), and if the switch output is rOFFJ, the signal line L2 is not disconnected and the object under test is accidentally disconnected. is in the state of angle θM, it is determined that the VM output has occurred, and it is determined that a disconnection failure has not occurred (step 106). On the other hand, when it is VADf-VM, the question is whether or not VAD is an output within the measurement range of the potentiometer 21.
A comparison is made with l (step 108). If VAD has a value even smaller than the minimum value ■1, it is determined that the power line L1 is disconnected (step 110). Further, when VAD is larger than Vl, a comparison is made with V5, which is the maximum in the measurement range (step 112>
, VAD>V5 TEIP>, it is determined that the grounding wire is disconnected (step 114); otherwise, that is, v1
When ≦VAD≦v5 and VAD≠VM, it is determined that no disconnection fault has occurred (step 106).

Therefore, the state change detection device of this embodiment can accurately recognize a change in the state of the object to be measured from the output of the potentiometer 21, and also detects a break in any one of the three types of wires used for the potentiometer 21. In some cases, it becomes possible to identify and detect the broken wire, and it also has an extremely excellent self-diagnosis function.

Moreover, when detecting a disconnection in the signal line L2, a double check is performed using the output of the status switch 23 in order to further improve accuracy. This results in a device with an extremely reliable self-diagnosis function.

As an application of the above embodiment, it is possible to use the sensor 20 as a throttle sensor of a vehicle, for example. According to this application, the slider 21a of the potentiometer 21 moves one time according to the opening degree of the throttle valve, and the status switch 23 is set to the "ON" state only when the throttle valve is idle. It can be used as an idle switch. As mentioned above, such a throttle sensor not only helps improve the reliability of the entire vehicle control system because it has a highly reliable self-diagnosis function, but also can accurately report the location of a disconnection in the event of a disconnection. This makes it possible to improve services such as maintenance and inspection. - Also, for example, in the above embodiment, the state switch 23 is not essential and may be substituted in various ways. That is, considering the case where the potentiometer 21 is used as the throttle sensor of the vehicle as in the above example, the opening of the throttle valve should be controlled to the same extent as in the W11 vehicle. Therefore, if step 102 shown in FIG. 5 is determined and the L2 signal output is VM despite the high rotational speed, it may be determined that there is an L2 disconnection failure state.

[Effects of the Invention] As described above in detail with reference to the embodiments, the state change detection device of the present invention receives power from a power line at a predetermined potential difference from the ground voltage of the ground line, and receives power from the power line at a predetermined potential difference from the ground voltage of the ground line to the voltage of the power line. A potentiometer that outputs an arbitrary voltage signal from a signal line in response to a change in the state of the object to be measured, and a recognition means that receives the voltage signal from the signal line of the potentiometer and recognizes a change in the state of the object to be measured. The state change detection device includes a bias means for applying a bias voltage to the signal line from the power supply line.

Therefore, even if any of the three types of wires used in the potentiometer (power wire, ground wire, or signal wire) has a disconnection fault, it is always possible to accurately detect which wire has the disconnection fault. This means that it has an excellent self-diagnosis function.

If such a state change detection device is used, for example, in a vehicle control device, not only the reliability of the control device as a whole can be improved, but also services such as maintenance for disconnection failures can be improved.

[Brief explanation of the drawing]

Fig. 1 is a basic configuration diagram of the present invention, Fig. 2 is an electric circuit diagram of a conventional potentiometer system, Fig. 3 is an electric circuit diagram of a state change detection device according to an embodiment, and Fig. 4 is an explanatory diagram of its output. , FIG. 5 shows a flowchart of the disconnection determination routine. C1... Potentiometer C2... Recognition means C3... Bias means L
V...Power line LS...Signal line LG...
Ground wire 31...Power supply 33...One-chip microcomputer 37...
A/D converter

Claims (1)

[Scope of Claims] Power is supplied from a power line that is at a predetermined potential difference from the ground voltage of a ground line, and any voltage signal up to the voltage of the power line is output from the signal line in response to changes in the state of the object to be measured. Input a potentiometer and a voltage signal from the signal line of the potentiometer,
and recognition means for recognizing a change in the state of the object to be measured, the state change detection apparatus comprising bias means for applying a bias voltage to the signal line from the power supply line.