JPH0654336B2 - State change detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a state change detection device using a so-called potentiometer, which generates a linear voltage detection signal according 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 facilitates detection of disconnection of a power supply line, a ground line, and a signal line interposed between the potentiometer and a processing device that processes a detection signal of the potentiometer.

[Prior Art] Conventionally, along with the progress of automatic control technology and the progress of semiconductor technology, various kinds of complicated devices have been centrally monitored and controlled by a computer.

For example, a vehicle is not an exception, and the vehicle-mounted computer controls not only the internal combustion engine, which is the driving force source, but also the transmission and the brake. With such progress, a large number of wires, which are information transmission paths, connecting the centralized monitoring control device such as a computer and the device to be controlled by the device, such as an internal combustion engine or a brake hydraulic system, have become complicated and wired. , A lot of new vehicle failures such as disconnection of these wires have come to occur. Therefore, in recent years, development of a device having a self-diagnosis function for accurately detecting failures due to these disconnections has been urgently required.

A state change detection device using a potentiometer is a sensor that detects various events in the centralized monitoring control system,
For example, it is widely used as a throttle position sensor, an air flow meter, and the like. Due to its structure, this state change detection device requires wiring of three kinds of wires, that is, a ground line for supplying power to the potentiometer, a power line, and a signal line from which a detection output can be obtained, and the self-diagnosis function is particularly required. ing.
Therefore, conventionally, a state change detecting device as shown in FIG. 2 has been proposed. Sensor 3 consisting of potentiometer 1
Is supplied with power from the detection device 7 mainly including the one-chip microcomputer 5 through the ground line G and the power supply line Vc. Since the slider 9 of the potentiometer 1 slides on the resistance line R following the change of the measurement target, a voltage corresponding to the change of the measurement target is generated in the signal line S, and the analog-digital converter (A / D converter) 11 is input. The signal line on the input side of the A / D converter 11 is pulled down by the resistor RD. Reference numeral 13 is a power supply that supplies power to the one-chip microcomputer 5 and the potentiometer 1.

According to the above-mentioned conventional state change detection device, since the pull-down resistor RD is used, the disconnection failure of the ground line G or the signal line S which has been impossible to detect until then (including A /
The input of the D converter 11 is open. ) Can be identified. That is, the potential pulled up by the pull-down resistor RD is input to the A / D converter 11 when the ground line G is broken, and the potential (ground potential) grounded by the pull-down resistor RD is input to the A / D converter 11 when the signal line S is broken. It is input to the converter 11.

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

That is, as is apparent from FIG. 2, even when the power supply line Vc has a disconnection failure, the input of the A / D converter 11 is at the ground potential, so that the disconnection failure between the power supply line Vc and the signal line S cannot be distinguished. However, they have not yet completed the self-diagnosis function.

In addition, the actual development number 59-42978 (actual fair 1-38534
No. 2), the reference voltage is input to the A / D converter regardless of whether the ground line is disconnected or the signal line is disconnected. Therefore, it is impossible to distinguish between the two failures.

The present invention has been made in view of the above problems, and in a state change detection device using a potentiometer that requires three types of wires, it is possible to reliably distinguish which of the three types of wires has a wire breakage failure. An object of the present invention is to provide a state change detection device having a self-diagnosis function that can detect the state change.

[Means for Solving Problems] Means configured according to the present invention for solving the above problems are as follows.
As shown in the basic configuration diagram of FIG. 1, the power supply line LV having a predetermined potential difference from the ground voltage of the ground line LG.
Is supplied with power, and an arbitrary voltage signal up to the voltage of the power supply line LV is supplied to the signal line LS in accordance with the state change of the object to be measured.
In the state change detection device, the potentiometer C1 further outputs the voltage signal from the signal line LS of the potentiometer C1 and the recognition means C2 for recognizing the state change of the object to be measured. High resistance elements R1 and R2 are connected in parallel with the potentiometer C1 between the signal line LS and the power line LV and between the signal line LS and the ground line LG, and the power line LV is connected to the signal line LS.
Bias means C3 for applying a bias voltage intermediate between the voltage of the signal line and the ground voltage, and the signal line LS, power line LV, and ground line LG of the potentiometer C1 based on the voltage signal from the signal line LS.
A state change detecting device is characterized in that it has a disconnection detecting means C4 for discriminating which one has a disconnection.

[Operation] The potentiometer C1 in the present invention means the ground wire L
A general sensor that requires three types of wire connections of G, a power supply line LV, and a signal line LS, is driven by applying a voltage between the ground line LG and the power supply line LV, and changes the state of the measured object. The voltage signal according to the above is output from the signal line LS. For example,
The most general configuration is one in which both ends of the sliding resistor are connected by a ground line LG or a power supply line LV and the signal line LS is connected to the slider. The slider slides according to the position, angle, etc. of the object to be measured, and a voltage signal corresponding to the change in the state of the object to be measured is generated on the signal line LS.

The recognizing means C2 is for recognizing a change in the state of the object to be measured by inputting a voltage signal from the signal line LS of the potentiometer C1. Therefore, this is achieved by grasping the relationship between the output voltage of the signal line LS and the state change of the measured object in advance. In addition, the voltage change of the signal line LS depends on the ground line L.
Since it is a change in potential with G as a reference, the recognizing means C2 has a reference potential that is the same as the ground line LG therein. For example, the configuration in which the potentiometer C1 and the ground line are common is used to perform a switching operation according to the voltage change of the signal line LS, and the voltage change of the signal line LS is converted into digital information for use in various program processes. Etc.

The state change detecting device of the present invention further has the following bias means C3. This is the signal line LS and the power supply line LV,
Also, the high resistance elements R1 and R2 are connected in parallel with the potentiometer C1 between the signal line LS and the ground line LG to connect the signal line LS.
Is between the voltage of the power supply line LV and the ground voltage, that is, 2
A bias voltage, which is a voltage divided by the two high resistance elements R1 and R2, is applied to the signal line LS. For example, when the potentiometer C1 is a sliding resistance as in the above-described example, and when the signal line LS is divided by the voltage dividing resistance as described above, the signal voltage of the signal line LS changes due to the voltage dividing resistance. Can also be considered. 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. Also,
The disconnection detection means C4 determines the potentiometer based on this voltage signal because the voltage signal from the signal line LS is different depending on the disconnection position, that is, which of the signal line LS, the power supply line LV, and the ground line LG is disconnected. This is to determine which of the signal line LS, the power supply line LV, and the ground line LG of the meter C1 is disconnected.

Hereinafter, in order to describe the present invention more specifically, examples will be described in detail.

[Embodiment] FIG. 3 shows an electric circuit diagram of a state change detecting device of an embodiment. In the figure, reference numeral 20 denotes a sensor portion, which has a built-in potentiometer 21 in which a slider 21a slides on a resistance wire 21R according to a change in the state of an object to be measured (not shown), for example, a change in a rotation angle. Reference numeral 23 is a state switch for detecting a state change in a binary manner, which is in an "ON" state when the rotation angle of the object to be measured (not shown) changes up to θs, and an "OFF" state when the rotation angle is θs or more. It will be. The voltage V0 is constantly applied to the power supply line L1 from the power supply 31 built in the detection device 30, and the potentiometer 21
Is connected to one end of the resistance wire 21R. This resistance wire 21R
Is connected to the same ground line L4 as the one end of the state switch 23 described above, and this ground line L4 is connected to the power supply 31.
Power is supplied to the resistance wire 21R by being connected to the ground point. Slider 21a of potentiometer 21
The detection device 30 recognizes an angle change of the object to be measured (not shown) by the two wires of the signal line L2 connected to and the switch output line L3 connected to the other end of the state switch 23. The one that performs this recognition is the one-chip microcomputer 33 in the detection device 30, which detects the rotation angle of the object to be measured by processing the following input signals according to the program stored in the 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, the detection is performed based on two states, that is, the binary state of the state switch 23, which is “ON” or “OFF”, and the digital conversion value of the analog changing voltage of the signal line L2. Further, the signal line L2 is biased to the voltage VM by the bias resistors Rb1 and Rb2.

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 can take an arbitrary rotation angle between the angles θ1 and θ2 due to its structure. As apparent from the above description, the output of the signal line L2 of the potentiometer 21 is from O [V] to V0.
Although it can be changed to [V], the linearity of the voltage rotation angle characteristic from V1 [V] to V5 [V] is guaranteed within the rotatable range of the measured object. This characteristic is that the above-mentioned bias resistors Rb1 and Rb2 are both connected to the resistance line 21.
It can be easily obtained by selecting a very large value as compared with the resistance value of R and designing linearly the characteristic of the resistance wire 21R in the potentiometer. In addition, the output from the switch output line L3 is “ON” or “OFF” with the angle θs as a boundary.
Make a value change.

According to such a state change detection device, a change in the rotation angle of the object to be measured can be detected as a linear voltage change. Therefore, for example, the R in the one-chip microcomputer 33 is changed.
If the map as shown in FIG. 4 is prepared in the OM, the rotation angle can be accurately recognized from the detected voltage. Further, in the state change detecting device of the present embodiment, any of the three wires L1, L2, L4 connected to the potentiometer 21 is disconnected between the sensor 20 and the detector 30 by the following operation. When a failure occurs, it can be detected accurately. First of all, the power line L
When 1 is disconnected, at this time, the signal line L2 is divided by the bias resistance Rb1, another bias resistance Rb2, and the resistance from the point where the slider 21a of the potentiometer 21 is located to the ground point. Voltage is signal line L2
Occurs in. As described above, since the resistance value of the resistance wire of the potentiometer 21 is smaller than the bias resistance, the divided voltage has an extremely low value.
Therefore, the resistance wire 2 is set so that this voltage value (VL) becomes lower than the voltages V1 to V5 used for the above-described measurement.
Power line L1 if 1R and bias resistors Rb1 and Rb2 are designed
Disconnection detection can be easily achieved. For example, the resistance ratio is about 30
0 times (21R = 5KΩ, Rb1 = 1.5M, Rb2 = 1M)
If

Next, a case where a disconnection failure of the ground line L4 occurs will be described. At this time, the voltage generated on the signal line L2 is a voltage obtained by dividing the power supply voltage by the bias resistance Rb1 and the resistance of the resistance line 21R from the power supply line L1 to the slider 21a and another bias resistance Rb2. . As described above, the resistance value of the resistance wire 21R is extremely lower than that of 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 V0. Therefore, the voltage value (VH) close to the power supply voltage V0 may be designed to be higher than the voltages V1 to V5 used for the measurement of the potentiometer 21. This is the same condition as described above, and the values of the bias resistors Rb1 and Rb2 are extremely large compared to the resistance value of the resistance line 21R. For example, the resistance ratio may be set as described above.

Next, a case where the signal line L2 has a disconnection failure will be described.
At this time, the voltage input to the signal line L2 is a value (VM) divided by the bias resistors Rb1 and Rb2, and is a value uniquely determined by the values of the bias resistors Rb1 and Rb2. Therefore, when the output from the potentiometer 21 becomes constant at the voltage value (VM) according to the judgment of the one-chip microcomputer 33 and no change occurs, it can be judged that the signal line L2 has a disconnection failure.

Further, in order to detect the disconnection of the signal line L2 with high accuracy, the switch output may be used. For example, as shown in FIG. 4, it is assumed that the output voltage VM when the signal line L2 is disconnected is within the use voltage (V1 to V5) for the detection of the potentiometer 21. At this time, the output from the signal line L2 is V
M, which is recognized as if the rotation angle of the measurement target is θM. However, if the switch output at that time is “ON”, the angle of the object to be measured is θs or less, and the output from the potentiometer 21, which is the angle θM, is found to be abnormal. That is, the signal line L2
Only when the output of is the VM, it is judged whether the measured object is actually the normal output with the angle θM or the bias voltage due to the disconnection of the signal line L2. . Therefore, when the measured object is constantly changing the state and the constant output does not continue, it is determined that the voltage VM is output for a certain period of time by the disconnection of the signal line L2 or the like. It is possible to detect the disconnection with high accuracy by using a new detection device for determining whether the value of VM is correct or the switch output of the previous example.

The above-mentioned disconnection judgment is performed by the one-chip microcomputer 3
FIG. 5 shows a flow chart when it is executed in 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, it is judged whether the step output is "ON" or "OFF" for another judgment (step 102). Then, if the output is "ON", it is decided that the signal line L2 is obviously disconnected (step 104), and if the switch output is "OFF", the signal line L2 is not disconnected and the measured line is accidentally measured. Since the target is in the state of the angle θM, it is determined that the VM output has occurred, and it is determined that the disconnection failure has not occurred (step 106). On the other hand, when VAD ≠ VM, it becomes a problem whether VAD is an output within the measurement range of the potentiometer 21. First, V1 of the minimum measurement range is set.
Is compared (step 108). And V
If AD is a value smaller than the minimum value V1, the power supply line L
It is determined that 1 is disconnected (step 110). Also,
When VAD is larger than V1, this time, the size is compared with V5, which is the maximum measurement range (step 112), and V
If AD> V5, it is determined that the ground wire is broken (step 114), otherwise, that is, V1 ≦ VAD.
When ≦ V5 and VAD ≠ VM, it is determined that no disconnection failure has occurred. (Step 106).

Therefore, the state change detection device of this embodiment can accurately recognize the state change of the object to be measured from the output of the potentiometer 21, and any one of the three types of wires used for the potentiometer 21 can be detected. When the wire is broken, it becomes possible to detect the wire that has been broken, and it has an extremely excellent self-diagnosis function.
Moreover, when the disconnection of the signal line L2 is detected, the double check is executed by using the output of the state switch 23 in order to improve the accuracy. As a result, the device has a highly 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 slides according to the opening degree of the throttle valve, and the state switch 23 is set to the "ON" state only when the throttle valve is fully closed. It can be used as an idle switch. According to such a throttle sensor,
As mentioned above, since it has a highly reliable self-diagnosis function, it not only helps improve the reliability of the entire vehicle control system, but it can also accurately notify the disconnection point in the event of a disconnection failure, and maintenance and inspection etc. Can be achieved.

Further, for example, in the above-mentioned embodiment, the state switch 23 is not indispensable and can be substituted in various modes. That is, considering the case where the potentiometer 21 is used as the throttle sensor of the vehicle as in the above example, if the rotational speed during the internal combustion period of the vehicle rises above a certain level, the bias voltage VM is naturally generated from the signal line L2. The throttle valve should be controlled to open. Therefore, instead of the process of step 102 shown in FIG. 5, it is determined whether the signal L2 output is VM or higher when the internal combustion period rotational speed is increased to a certain level or more, and the rotational speed is high regardless of the high rotational speed. If the L2 signal output is VM, it may be determined that the L2 disconnection failure state exists.

[Effects of the Invention] As described in detail with reference to the above embodiments, the state change detection device of the present invention includes any one of the three types of wires used in the potentiometer, the power supply line, the ground line, and the signal line. Even if a disconnection failure occurs, it has an excellent self-diagnosis function that can always accurately detect which wire has a disconnection failure.

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

[Brief description of drawings]

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 detecting device of an embodiment, and FIG. 5 and 5 show a flowchart of the disconnection judgment routine. C1 ... Potentiometer C2 ... Recognition means, C3 ... Biasing means LV ... Power supply line, LS ... Signal line LG ... Ground wire 31 ... Power supply 33 ... One-chip microcomputer 37 ... A / D converter

Claims (1)

[Claims] 1. A potentiometer which receives power from a power supply line having a predetermined potential difference from the ground voltage of the ground line and outputs an arbitrary voltage signal up to the voltage of the power line from the signal line in accordance with a change in the state of an object to be measured. Meter and the voltage signal from the signal line of the potentiometer,
A state change detection device comprising: a recognition unit that recognizes a state change of the measurement target; and a high resistance element in parallel with the potentiometer between the signal line and the power line and between the signal line and the ground line. Bias means for connecting and applying a bias voltage between the voltage of the power supply line and the ground voltage to the signal line, and a signal line of the potentiometer based on a voltage signal from the signal line, a power supply A state change detecting device comprising: a disconnection detecting means for determining which of a wire and a ground wire is disconnected.