JPH0354765B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a zero point detection device for a pendulum type tilt angle sensor used for detecting the tilt of a vehicle body such as an automobile. The present invention relates to a zero point detection device for a pendulum type inclination angle sensor that outputs the output as a change in .

[Conventional technology]

A pendulum-type tilt angle sensor attempts to detect changes in the relative angle of the pendulum, which normally faces vertically, to the sensor body in the form of electrical output changes when the measurement surface or sensor body is tilted. It has the simplest structure as a tilt angle sensor that uses gravity. As an electrical output extraction method, for example, as shown in Figs. 1 and 2 of Japanese Utility Model Application Publication No. 57-116815,
In addition to the non-contact type, in which a permanent magnet attached to a part of the pendulum generates an output to a magnetic resistance element disposed inside the casing so as to face the locus of the permanent magnet, as shown in Figure 3 of the present application, A part of the tilting movable body made of a conductor is brought into contact with a position detecting body made of a resistor arranged to face the locus of the tilting movable body and to which a constant voltage is applied to both ends, and one end of this resistor and the tilted movable body are brought into contact with each other. There are contact types that output the potential difference between the movable body and the like.

[Problem to be solved by the invention]

For example, when outputting a potential difference between one end of a position detecting body made of a resistor and a tilting movable body as shown in FIG. 3 of the present application, for example, a fourth Since there is a functional relationship as indicated by the symbol A in the figure, a specific tilt angle corresponding to the output voltage is calculated according to this. By the way, in such a tilt angle sensor, the fourth
Approximately 1/2 of its maximum output, as shown by symbol A in the figure.
The sensor is manufactured with the intention that the position at which the output is obtained will indicate a horizontal point on the output, that is, the 0 point, but in reality, there may be errors in the installation of the position detector during sensor manufacture, or changes over time. Due to the error caused in the output voltage-inclination angle characteristic, the output voltage-inclination angle characteristic has variations as shown by the symbol B in FIG. As described above, conventional tilt angle sensors have variations in the correspondence between their output and the actual tilt angle, and when the output is uniquely converted into a tilt angle based on the relationship indicated by reference numeral A in Figure 4, , the detected tilt angle may deviate from the actual tilt angle. The variation in this case is mostly due to the installation error of the position detector of the tilt angle sensor, so the graphs representing the characteristics of each sensor have almost equal slopes and are parallel to each other, as shown in Figure 4. It has the character of The present invention was devised under the above circumstances, and even if there are variations in the characteristics of each individual tilt angle sensor, the output corresponding to the 0 point for each tilt angle sensor is An object of the present invention is to provide a zero point detection device for a tilt angle sensor that can automatically determine the output-tilt angle characteristic of each tilt sensor based on the detected zero point.

[Means to solve the problem]

In order to solve the above problems, the present invention takes the following technical measures. That is, in a pendulum-type tilt angle sensor configured to be able to detect the swinging position of a swingably suspended pendulum using a position detector, the pendulum is provided with a magnetic portion, and when excited, the above-mentioned An electromagnet is installed that forcibly draws the magnetic part to the position where the pendulum takes the zero point. When detecting the tilt angle of the automobile, the electromagnet can be energized in conjunction with an ignition switch.

[Operation and effects of the invention]

In the zero point detection device for a pendulum-type inclination angle sensor of the present invention, a magnetic portion is provided on the pendulum, and the pendulum is forcibly positioned at the zero point by magnetic force. Therefore, for example, a horizontal sensor is separately provided to detect when the vehicle body is horizontal, and when this horizontal sensor detects that the vehicle body is horizontal, the zero point output of the tilt angle sensor is verified. The configuration is simpler compared to
The zero point of the tilt angle sensor can be detected regardless of whether the vehicle body is in a horizontal state. For example, if the electromagnet used to return the pendulum to the zero point is energized in conjunction with the ignition switch, the zero point of the tilt angle sensor will be detected every time the car starts driving. Therefore, even if the characteristics of the tilt angle sensor change over time, conversion to a tilt angle is always performed based on the accurately detected zero point output. As a result,
The reliability of the tilt angle sensor can be maintained constant over a long period of time.

[Explanation of Examples]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 3 shows an example of the structure of a pendulum type tilt angle sensor 1 incorporating a zero point detection device according to the present invention. That is, this pendulum-type inclination angle sensor 1 has a pendulum 3 made of a conductor supported within a support frame 2 so as to be able to swing within a fixed plane, and an arc-shaped resistor 4 attached to the shaft portion 4 of the pendulum 3. A position detecting body 5 consisting of
It is possible to use a device configured to apply a constant voltage to the resistor and output a potential difference between one end 4a of the resistor and the shaft portion 3b of the pendulum 3 in contact with the end 4a. Such a uniaxial tilt sensor 1 is configured such that, for example, when detecting a tilt in the longitudinal direction of the vehicle body, the pendulum 3 swings in the longitudinal direction, and when detecting a tilt in the vehicle width direction, the pendulum 3 swings in the longitudinal direction. is placed at an appropriate location on the vehicle body so that the pendulum 3 swings in the vehicle width direction. Furthermore, in the present invention, in the pendulum type inclination angle sensor 1, the pendulum 3 is provided with a magnetic portion 6, and when excited, the pendulum 3 is forcibly oriented in a direction perpendicular to the reference plane in the support frame 2. An electromagnet 7 is provided. In the illustrated example, the ball 3a at the tip of the pendulum
is made of a magnetic material, and an electromagnet 7 is provided at a predetermined position within the support frame 2 of the sensor 1. When this electromagnet 7 is excited, the pendulum 3 attracted by it is oriented at right angles to the reference plane 8.
In other words, it is installed accurately so that it faces in the direction it should face if the vehicle body is not tilted at all. In addition,
The switch 9 of the electromagnet 7 may be configured to close for a certain period of time in conjunction with turning on an ignition switch (not shown), or may be configured to close for a certain period of time, for example, every 15 minutes. configured to close for a certain period of time, for example, 1 second,
The sensor is configured to detect the zero point when the switch 9 is closed. FIG. 2 is a block diagram showing an example of the configuration of a device for detecting the tilt angle of a vehicle body using a pendulum type tilt angle sensor equipped with the zero point detection device of the present invention. The output of the pendulum type tilt angle sensor 1 to which an electromagnet 7 is added as a component of a zero point detection device is digitized by an A/D converter 11 after vibration components above a certain frequency are removed by a low-pass filter 10. and input to the central processing unit CPU. In addition,
As shown in the separate functional block diagram in FIG. 1, the central processing unit CPU has a tilt angle calculation function that converts the data input from the sensor 1 into a tilt angle based on the reference characteristic indicated by the symbol A in FIG. 4, for example. Means 1
2. Compare the zero point data sampled from the sensor 1 when the electromagnet 7 is on with the reference zero point value determined from the reference characteristic indicated by reference symbol A in Figure 4 to find a deviation, and store this in the storage means. 13 is included. In the illustrated example, the output of the vehicle speed sensor 15 is input to the central processing unit CPU in order to separate and calculate the acceleration component from the output from the tilt angle sensor 1. The operations of the comparison means 14, storage means 13, and inclination angle calculation means 12 will be explained in more detail as follows. Assume now that the standard relationship between the output voltage V and the tilt angle θ of a standard tilt angle sensor, assuming that there is no error, is as shown by the symbol A in FIG. 4, for example. At this time, the tilt angle θ is expressed as a relationship between the output voltages, and this can be expressed by the following conversion formula: θ=F(V)=KV−θ ₀ (K is a constant) (1). From this conversion formula, the reference value of the output voltage at the 0 point, that is, in the horizontal state, is Vθ=0=θ ₀ /K=V ₀ (2), and this value is stored in the memory in the comparing means 14. There is. Next, it is assumed that the relationship between the actual output voltage of the tilt angle sensor 1 mounted on the vehicle body and the tilt angle is as shown by the symbol B in FIG. 4. In this case, since the slopes of the graphs of symbols A and B are the same, it can be expressed by the following equation: θ=F'(V)=KV−θ ₁ (3). Here, when the electromagnet 7 of the zero point detection device is excited and the pendulum 3 faces in the direction it should face when it is horizontal, the output voltage of the tilt angle sensor 1 that is sampled becomes θ ₁ /K=V ₁ . . This output voltage V ₁ and the reference value V ₀ are compared to calculate a deviation V ₁ −V ₀ , which is rewritten with the previous deviation value stored in the storage means 13 . When the electromagnet 7 is de-energized, the device enters the normal tilt angle detection state, and in this state, the output from the tilt angle sensor 1 is corrected by the deviation value read from the storage means 13. After that, it is converted into an inclination angle θ using the above conversion formula (1), and this inclination angle is outputted to an output means such as a vehicle body inclination angle display device. In this way, even if there are variations in the deviation of the characteristics of each tilt angle sensor from the reference characteristics,
The output of the tilt angle sensor can be corrected according to the deviation. In addition, due to its nature, the tilt angle sensor outputs frequently in the region surrounding the 0 point, but when the present invention is used, the characteristics are corrected based on the 0 point, so the output frequency in the region surrounding the 0 point is high. The reliability of data near a point increases. Of course, the scope of the invention is not limited to the embodiments described above. For example, in the embodiment, the ball at the tip of the pendulum is made of a magnetic material, but a magnetic material may be attached to other parts, such as the shaft of the pendulum.

[Brief explanation of drawings]

FIG. 1 is a functional block diagram of a tilt angle detection device using a pendulum tilt angle sensor equipped with a zero point detection device of the present invention, and FIG. 2 is a block diagram of the device shown in FIG. 1.
FIG. 3 is a sectional view showing an example of a pendulum-type tilt angle sensor equipped with the zero point detection device of the present invention, FIG. 4 is a graph illustrating the output characteristics of the tilt angle sensor, and FIG. 5 is a diagram showing the operation of the comparison means. This is a flowchart showing an example program for. 1... Pendulum type tilt angle sensor, 5... Position detection body, 6... Magnetic part, 7... Electromagnet.

Claims (1)

[Claims] 1. In a pendulum-type tilt angle sensor configured to be able to detect the swinging position of a swingably suspended pendulum using a position detector, the pendulum is provided with a magnetic part, and when excited, the magnetic part A 0-point detection device for a pendulum-type inclination angle sensor, characterized by being provided with an electromagnet that forcibly draws a portion of the pendulum to a position where the pendulum takes the 0-point.