JP2001194256A - Sensor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sensor device capable of detecting a trouble resulting from the loose connection or the like of the connection part between a sensor part and a control part with high accuracy. SOLUTION: The sensor device that a sensor part 20 and a control part 10 are electrically connected through a power line Lp, output line Lo, and ground line Lg, is provided with a switching means 12 switching power supply to the sensor part 10 to either the power line Lp or output line Lg, and a trouble judging means 13, which measures the value of a current that flows from the output line Lo to the ground line Lg when power is supplied to the output line Lo, and then compares this measured current value and a reference value with each other to judge trouble occurrence.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a sensor device having a failure detecting function.

[0002]

2. Description of the Related Art A configuration of a sensor device for detecting various pressures in a vehicle, such as a brake pressure and a fuel pressure, which has been conventionally used, will be described with reference to FIG. The sensor device is shown in FIG.
As shown in FIG. 1, a sensor unit 20 that outputs a signal corresponding to the applied pressure, and a control unit 10 such as an ECU that performs various controls based on an output signal from the sensor unit 20 are provided.

A battery power (for example, 12 V) is converted into a constant voltage (for example, 5 V) via a regulator 11 provided in a control unit 10 and the like, and then supplied to a sensor unit 20 via a power supply line Lp. The sensor unit 20 uses this supply voltage as a power supply and performs functions such as pressure detection, output amplification and adjustment, and outputs a voltage V proportional to the applied pressure.
o is output from the output line Lo. The control unit 10 performs various controls based on the output voltage Vo.

A power supply line Lp, an output line Lo, and a ground line L are provided between the control unit 10 and the sensor unit 20.
g, an electrical connection via the
0 and the sensor unit 20 obtain electrical connection using various methods such as connector, soldering, welding and the like.

[0005]

However, there is a possibility that a failure may occur at the connection point between the control unit 10 and the sensor unit 20 due to an increase in resistance due to poor contact or the like. In particular, when such a failure occurs in the output line Lo, a new resistor (ΔR) is added to the connection portion, and the output voltage Vo is determined by the current value Io of the output line Lo.
Varies by ΔVo (= Io × ΔR).
Therefore, when the output voltage of the sensor unit fluctuates, there is a problem that it is difficult to determine whether the output fluctuation is caused by pressure fluctuation or failure.

Consider a case where a failure such as a resistance failure is detected by monitoring the output voltage value Vo in a state where no pressure is applied to the sensor section. For example, a load resistance R of 330 kΩ is connected between the output line Lo and the ground line Lg.
Is provided, and assuming that the output voltage Vo = 0.5 V in a state where the pressure application of the sensor unit is zero, the current value Io = 1.5 μA in the output line Lo is obtained. At this time, for example, a standard of ± 0.1 V is provided for the output voltage Vo, and when the output voltage Vo exceeds the range of 0.5 ± 0.1 V, it is determined that a failure has occurred in the pressure sensor.
In this case, assuming that the resistance increases by ΔR due to poor contact or the like, ΔR = 66 kΩ (= 0.1 V / 1.5 μA)
An increase in resistance to a degree results in an undetectable result.
The above-mentioned ± 0.1 V is a value in consideration of the manufacturing variation of the pressure sensor and the like, and narrowing this standard causes a decrease in the yield of the sensor and causes a significant cost increase, so that there is a problem that the feasibility is poor. is there.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a sensor device capable of detecting a failure caused by a poor contact at a connection portion between a sensor unit and a control unit with high accuracy. .

[0008]

In order to achieve the above object, according to the first aspect of the present invention, a sensor unit (20) includes:
The sensor unit (20) is electrically connected via a power line (Lp), an output line (Lo), and a ground line (Lg).
a control unit (10) for processing a sensor signal output through the control unit (o) and performing various controls,
Power supply to the sensor unit (10) is performed by a power supply line (L
p) and switching means (12) for switching to one of the output line (Lo), and a current flowing from the output line (Lo) to the ground line (Lg) when power is supplied to the output line (Lo). A failure determining means (13) for measuring a value and comparing the measured current value with a reference current value to determine the occurrence of a failure.

With such a configuration, the output line (L
o) In the resistance (R34) between the ground line (Lg) and LoLg, when the resistance value fluctuates due to poor contact or the like, it can be easily detected with high accuracy. That is, as in the second aspect of the present invention, the failure determination means (13) is provided at least in the connection between the sensor unit (20) and the control unit (10) in the output line (Lo) or the ground line (Lg). When the contact resistance (Rx) occurs, it can be determined that a failure has occurred. The measured current value is the resistance value of the contact resistance (Rx) and the sensor unit (2).
0) output line (Lo) and ground line (Lg)
And a resistance value including the resistance value of the resistor (R34).

According to the third aspect of the present invention, the sensor unit (20), the power supply line (Lp), and the output line (L
o) and the sensor unit (2) via the ground line (Lg).
0), and processes a sensor signal output from the sensor unit (20) via the output line (Lo);
A sensor device including a control unit (10) for performing various controls, which measures a current value flowing from a power supply line (Lp) to a ground line (Lg) and compares the measured current value with a reference current value. A failure determining means (13) for determining occurrence of a failure.

With such a configuration, the power supply line (L
p), the resistance (R12, R34) between the ground line (Lg) and LpLg can be easily and accurately detected when the resistance value fluctuates due to poor contact or the like. That is, as in the invention described in claim 4,
The failure judging means (13) includes at least a power line (L
p) or the sensor section (2) on the ground line (Lg).
0) and a contact resistance (Ry) at a connection portion between the control unit (10) and the control unit (10), it can be determined that a failure has occurred. The measured current value is the resistance value of the contact resistance (Ry), It can be measured based on a resistance value including a resistance value of the resistance (R12, R34) between the power supply line (Lp) and the ground line (Lg) in the sensor section (20).

Further, in the invention described in claim 5, the reference current value is characterized in that an initial value of the measured current value is stored in a memory circuit in advance.

By using the initial value of the measured current value instead of the fixed value as the reference current value, it is possible to reduce the influence of manufacturing variations of the sensor device.

Further, the invention according to claim 6 is characterized in that the measured current value and the reference current value are each used after being converted into a voltage value.

The reference numerals in parentheses of the above-mentioned means indicate the correspondence with the concrete means described in the embodiments described later.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A first embodiment of the present invention will be described below with reference to FIGS. In the first embodiment, the sensor device is applied to a pressure sensor that measures a pressure such as a brake fluid pressure of a vehicle brake device or a fuel pressure of a fuel injection device. FIG. 1 shows the first
FIG. 2 is a circuit diagram illustrating a schematic configuration of a pressure sensor device according to the embodiment, and FIG. 2 is a circuit diagram illustrating a schematic configuration of a sensor unit of the pressure sensor. As shown in FIG. 1, the sensor device according to the first embodiment includes a switch 12 for switching a power supply path to a sensor unit 20 and a current flowing through an output line Lo, as compared with the sensor device of the related art (FIG. 4). Failure determination circuit (failure determination means) 13 for performing failure determination based on value Io
Is added.

The pressure sensor device includes a control unit (ECU) 10 for performing various controls and a sensor unit 2 for detecting an applied pressure.
0. The control unit 10 and the sensor unit 20 are connected to a power supply line L for supplying power to the sensor unit 20.
p, an output line Lo for outputting an output signal from the sensor unit 20 to the control unit 10, and a ground line Lg. These connections are made by means of, for example, a connector, soldering, welding, or the like.

That is, the sensor section 20 is provided, for example, around the brake device or the fuel injection device.
The control unit 10 is provided in a case or the like arranged in an engine room or a vehicle interior. The power line Lp, the output line Lo, and the ground line Lg connecting the sensor unit 20 and the control unit 10 are provided as external wiring grounded in the engine room or the vehicle interior. The wirings in the control unit 10 and the sensor unit 20 shown in FIGS. 1 and 2 are, for example, wirings such as a printed circuit board, wirings provided on a semiconductor chip, and wirings including wire bonding.

The power line Lp, the output line Lo, and the ground line Lg are connected to the sensor unit 20 and the control unit 10 via respective power terminals P, output terminals O, and ground terminals G.

In each of the embodiments described below, the power supply line Lp, the output line Lo, and the ground line Lg are all the same.

The control section 10 is provided with a regulator 11 for converting a power supply voltage (for example, 12 V) from the constant voltage power supply Vcc to a predetermined voltage (for example, 5 V). After being converted by the regulator 11, the power supply voltage is supplied to the sensor unit 20 via the power supply line Lp. Further, the output line Lo and the ground line L
A load resistance RA for measuring the output voltage Vo of the sensor section 20 is provided between the load resistor RA and the load resistor RA.

In the first embodiment, a switch (switching means) 12 is provided between the regulator 11 and the power supply line Lp in the control unit 10. This switch 12
Is connected to the power supply line Lp during normal operation and connected to the output line Lo when a failure is detected, in order to switch the power supply path to the sensor unit 20.

The control unit 10 further includes a failure determination circuit 13
Is provided. The failure determination circuit 13 includes the switch 12
, A switching signal for switching the connection to the power supply line Lp side or the output line Lo side is generated. The switching of the switch 12 by the failure determination circuit 13 is periodically performed using, for example, a timer.

The output line Lo is connected to the sensor unit 20.
Is provided with an ammeter 14 for measuring a current value Io flowing from the output line Lo to the ground line Lg when the power supply to is switched to the output line Lo side. This ammeter 14 has a resistance R34 between the output line Lo → LoLg →
It is sufficient that the value of the current flowing through the ground line Lg can be measured. For example, it may be provided on the ground line Lg. Failure determination circuit 13
Then, the current value Io measured by the ammeter 14 is input,
The failure is determined by comparing the measured current value Io with a preset reference current value. In the present embodiment, the measured current value I
It is configured to convert o and the reference current value into voltage values, compare them with a window comparator or the like, and determine a failure.

As described above, the sensor unit 20 is connected to the control unit 10 via the power line Lp, the output line Lo, and the ground line Lg. Power is supplied from the power line Lp, and the applied pressure is supplied from the output line Lo. Is output so as to output a voltage value (sensor signal) Vo corresponding to.

As shown in FIG. 2, the sensor section 20 includes a bridge circuit 21 in which four gauge resistors (diffusion resistors) R1 to R4 are connected in a bridge. This bridge circuit 2
Numeral 1 is formed in a thin diaphragm portion of a silicon substrate (not shown). Among the resistors constituting the bridge circuit 21, the resistors R1 and R4 are formed at the center of the diaphragm, and the resistors R2 and R3 are formed at the periphery of the diaphragm. When pressure is applied to the diaphragm, the resistances of the resistors R1 to R4 change in the direction of the arrow in FIG.
1 and R4 are configured so that the resistance value decreases, and the resistors R2 and R3 are configured so that the resistance value increases. Then, after the potential difference between the midpoint potentials of the resistors R1 and R3 and the midpoint potentials of the resistors R2 and R4 is subjected to processing such as amplification by the amplification adjustment circuit 22,
Output to the control unit 10 from the output line Lo.

Further, a series resistor circuit composed of output resistors Ro1 and Ro2 is connected to the subsequent stage of the output adjusting circuit 22, thereby adjusting the output.

R12 and R34 in FIG. 1 are composed of the output resistors Ro1 and Ro2 in FIG. 2 and the resistors R1 to R4 of the diaphragm connected to these resistors.
The combined resistance of the sensor unit 20 as viewed from the output terminal O of the sensor unit 20 is shown.

Hereinafter, the operation of the pressure sensor device having the above configuration will be described.

First, the normal operation for measuring the pressure applied to the sensor section 20 will be described. During normal operation,
The switch 12 is connected to the power supply line Lp, and a voltage is applied to the power supply line Lp. In the sensor unit 20, when pressure is applied, the resistance values of the gauge resistors R1 to R4 change. Then, after the potential difference between the two midpoint potentials of the bridge circuit 21 is subjected to processing such as amplification by the amplification adjustment circuit 22,
Output to the control unit 10 from the output line Lo. Control unit 10
Then, various processes are performed based on the output signal from the sensor unit 20.

Next, a description will be given of a failure detection for detecting a change in resistance due to a contact failure or the like. When performing failure detection, a switching signal is output from the failure determination circuit 13 to the switch 12, and accordingly, the switch 12 is connected to the output line Lo of the sensor unit 20, and a voltage is applied to the output line Lo. The current is output from the output line Lo → LoLg
The resistance flows in the order of the resistance R34 → the ground line Lg. At this time, a current also flows through the load resistor RA, but by setting the resistance R34 between LoLg to be smaller than the load resistor RA, the current flowing through the load resistor RA can be ignored.

In this state, the current value Io of the output line Lo is measured by the ammeter 14, and the measured current value Io is input to the failure judgment circuit 13. The failure determination circuit 13 converts the measured current value Io and the reference current value into voltage values and compares them. At this time, if the measured current value Io exceeds a failure determination level (threshold) set in advance with respect to the reference current value, it is determined that a failure has occurred. If it is determined that a failure has occurred, the failure generation circuit 13 outputs a failure signal, and performs, for example, processing such as turning on a warning lamp.

The reference current value is obtained by storing the initial value of the current value Io of the output line Lo when a voltage is applied to the output line Lo side in a memory circuit (not shown) as a reference current value. Can reduce the influence of manufacturing variations. The failure determination level is
The failure determination, which can be appropriately set by giving the reference current value a certain width in consideration of the manufacturing variation of the pressure sensor, the failure detection request, and the like, will be specifically described. For example, when a voltage of 5 V is applied to the output line Lo, the resistance R34 between LoLg in the sensor unit 20 becomes 1 kΩ.
, The current value Io of the output line Lo = about 5 m
A. This 5 mA is set as a reference current value. Here, the sensor unit 20 and the control unit 1 in the output line Lo
Considering the case where the contact resistance Rx of 1 kΩ is increased at the connection portion with 0 due to poor contact or the like, the current value Io of the output line Lo is 2.5 mA. In this case, the output current value Io is reduced by half with respect to the reference current value of 5 mA, so that a failure can be easily detected. In this example, an increase in resistance of 1 kΩ can be detected, and the detection sensitivity is 66 times higher than the failure determination level of 66 kΩ described in the above-mentioned problem.

The failure determination level of the output current value Io can be appropriately set according to the failure detection request. For example, in the above example, a range of ± 1 mA is set with respect to the reference current value of 5 mA, and the current value of the output line is set. When Io exceeds the range of 5 ± 1 mA, it can be configured to determine that a failure has occurred.

Note that, in response to the demand for detecting a resistance failure, the resistance between the LoLg R
If the optimization of 34 is performed, the fault detection sensitivity can be further improved. Specifically, by reducing the resistance value of the resistance L34 between LoLg with respect to the load resistance RA, the influence of the load resistance RA can be suppressed and a smaller resistance increase can be detected.

In the first embodiment, the case where the increase in resistance due to a contact failure or the like at the connection portion is detected has been described. However, the present invention is not limited to this case. It is possible to detect in the same way. That is, as in the first embodiment, by applying a voltage to the output line Lo and monitoring the value of the current flowing from the output line Lo to the ground line Lg, the resistance R34 between the output line Lo, the ground line Lg and LoLg is monitored.
, It is possible to detect the occurrence of a failure such as a contact failure.

When a failure is detected, a voltage is applied to the output line Lo in a direction opposite to that in the normal operation.
In the sensor unit 20, for example, by providing a cutoff circuit or designing an appropriate circuit, destruction of the sensor can be prevented.

When pressure is applied to the sensor section 20, the resistance values of the resistors R1 to R4 of the bridge circuit 21 change. Usually, since the change in the resistance value due to the application of the pressure is very small, the failure can be detected even when the pressure of the sensor unit 20 is applied. Further, for example, a configuration may be adopted in which an interruption circuit is provided in the sensor unit 20 so that the influence of the pressure application becomes zero.

In the pressure sensor device of the first embodiment, the pressure detection is temporarily interrupted when a failure is determined. However, in consideration of the processing speed of the ECU, various controls based on the measured pressure value of the pressure sensor are performed. Is considered to have no substantial effect.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIG. As shown in FIG. 3, the pressure sensor device of the second embodiment has a switch (switching means) 12 for switching the application of a voltage to the sensor unit 20 between a power supply line Lp and an output line Lo, as compared with the first embodiment. Is omitted, and the ammeter 15 is connected to the power line Lp
Is provided. The same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

In the first embodiment, a failure is determined by applying a voltage to the output line Lo and measuring the current value Io of the output line Lo. In the second embodiment, however, the power supply line L
In a state where a voltage is applied to p, a current value Ip flowing from the power supply line Lp to the ground line Lg is measured, and the current value Ip is converted into a voltage value and compared with a preset reference current value. It is configured to make a failure determination. As described above, the power supply line Lp is connected to the ground line Lg.
By monitoring the value of the current flowing through the power line L
p, an increase in the contact resistance Ry due to a contact failure in the ground line Lg, a resistance R12 between LpLg and a resistance R34 between LoLg.
Can be detected.

The failure determination of the second embodiment may be performed in combination with the failure determination of the first embodiment. That is, in the configuration of the pressure sensor device of the first embodiment, the ammeter 15 for measuring the current value Ip in the power supply line Lp is added, and when a voltage is applied to the output line Lo, the output The failure determination is performed using the current value Io, and when a voltage is applied to the power supply line Lp, the failure determination is performed using the current value Ip of the power supply line Lp.

(Other Embodiments) In the above embodiments, the measured current value and the reference current value are converted into voltage values, respectively, and the voltage values are compared with each other to perform the failure determination process. The current value and the reference current value may be directly compared.

In the first embodiment, the switching means 1
Although 2 is provided in the control unit 10, the present invention is not limited to such a configuration, and the switching unit 12 may be provided on the sensor 20 side.

In the sensor device of each of the above embodiments,
The sensor unit used was a bridge circuit composed of a gauge resistor. However, the sensor unit is not limited to this. For example, a metal thin film (Cr-Si
Etc.) can be more suitably implemented. Further, it is also possible to use a sensor such as a capacitive sensor.

In each of the above embodiments, the present invention is applied to a pressure sensor device for measuring various pressures. However, the present invention is not limited to this. For example, if a power supply line, an output line, and a ground line are provided, an acceleration sensor , A yaw rate sensor or the like.

[Brief description of the drawings]

FIG. 1 is a circuit diagram illustrating a schematic configuration of a sensor device according to a first embodiment.

FIG. 2 is a circuit diagram showing a schematic configuration of a sensor unit in the sensor device of FIG.

FIG. 3 is a circuit diagram illustrating a schematic configuration of a sensor device according to a second embodiment.

FIG. 4 is a circuit diagram illustrating a schematic configuration of a sensor device according to the related art.

[Explanation of symbols]

Reference numeral 10: control unit, 11: regulator, 12: switch (switching means), 13: failure determination circuit, 20: sensor unit.

Claims (6)

[Claims] The sensor unit (20) is electrically connected to the sensor unit (20) via a power line (Lp), an output line (Lo), and a ground line (Lg). ) That processes a sensor signal output from the output line (Lo) through the output line (Lo) and performs various controls. Switching means (12) for switching to one of a power supply line (Lp) and the output line (Lo); and when the power is supplied to the output line (Lo), the output line (Lo) is connected to the ground. Line (L
g), and compares the measured current value with the reference current value to determine whether a failure has occurred.
3) A sensor device comprising: 2. The system according to claim 1, wherein the failure determination unit is configured to output at least the output line (Lo) or the ground line (L).
g), the sensor unit (20) and the control unit (1).
0), it is determined that a failure has occurred when a contact resistance (Rx) occurs at a connection portion with the contact resistance of the contact resistance (Rx).
The output line (Lo) in the sensor section (20)
The sensor device according to claim 1, wherein the measurement is performed based on a resistance value including a resistance value of a resistance (R34) between the ground line (Lg) and the ground line (Lg). 3. The sensor unit (20) is electrically connected to the sensor unit (20) via a power line (Lp), an output line (Lo), and a ground line (Lg). ) That processes a sensor signal output from the power line (Lo) through the output line (Lo) and performs various controls. A) measuring a current value flowing through the sensor device, and comparing the measured current value with a reference current value to determine the occurrence of a failure. 4. The failure determination means (13) is provided at least for the power line (Lp) or the ground line (L).
g), the sensor unit (20) and the control unit (1).
0), it is determined that a failure has occurred when a contact resistance (Ry) is generated at a connection portion with the contact resistance, and the measured current value is a resistance value of the contact resistance (Ry);
The power supply line (Lp) in the sensor section (20)
(R12, R3) between the ground line (Lg)
The sensor device according to claim 3, wherein the measurement is performed based on a resistance value including the resistance value of 4). 5. The sensor device according to claim 1, wherein the reference current value is a value in which an initial value of the measured current value is stored in a memory circuit in advance. 6. The sensor device according to claim 1, wherein the measured current value and the reference current value are each used after being converted into a voltage value.