JPS58124913A - Device for detecting number of revolution, angle and position - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Related Technical Field The invention starts from a device according to the preamble of claim 1.

It is known to measure the mutual position or relative velocity of two objects, in which case the angular position or rotational speed of a movable object relative to a fixed object can be determined. In this case, it is furthermore possible to provide electrical or magnetic discontinuities in one of the objects, for example teeth and grooves in toothed plates or racks, or magnetically conductive and non-magnetic parts, or good conductive and bad conductive parts. It is known to use sensors that include conductive parts and are responsive to discontinuities in the upper screen in each other object. For example, an induction sensor is known in which a toothed plate moves in the vicinity of an induction coil in a rotational speed sensor. However, this type of device has the following drawbacks. The induced signal thus depends on the rotational speed and the distance between the sensor and the toothed plate, so that disturbances can occur if the air gap changes due to vibrations during operation or due to wear of the device.

Furthermore, it is known to use the following sensors in the device according to the preamble of claim 1. That is, the signal of that sensor depends only on the position of the discontinuity with respect to the sensor, and not on the relative velocity between the discontinuity and the sensor. Sensors for this purpose are, for example, sensors that cooperate with electrical discontinuities, by means of which eddy current changes occur or conductive surfaces that change the inductance of, for example, a planar coil are reflected. Furthermore, it is known to use sensor devices that operate with varying capacitance or sensors that respond to magnetic discontinuities, such as veegant sensors, magnetoresistive elements or Hall elements.

Since these sensors generate signals with amplitudes that are independent of the relative velocity, usually only the signal frequency is evaluated.

Advantages of the Invention In contrast, the device of the invention having the features set out in the subject matter of claim 1 has the following advantages. This means that by additional monitoring of the signal amplitude and/or amplitude fluctuations, periodic air gap fluctuations that exceed permissible values or are indicative of wear are detected at an early stage.

This makes it possible to detect impending faults in the sensor device in a timely manner and to readjust the sensor before the fault reaches such an extent as to cause erroneous measurement results. This is of particular importance when important functions are monitored by means of sensors, for example in anti-lock systems of motor vehicles. Since the anti-locking device regulates the operation of the braking device under limit driving conditions, a disturbance in the detection of the wheel rotational speed has a particularly serious effect. This is because brake system malfunctions occur precisely under extreme driving conditions.

An advantageous embodiment of the device according to claim 1 is possible with the features described in the embodiment section of the patent claim.

Thus, in an advantageous embodiment of the invention, a dual device consisting of two sensors is used, which additionally makes it possible to detect low rotational speeds, for example when the vehicle is locked, so that when the wheels are locked, the locking Transmission of false signals is avoided by operating the prevention device.

Further advantages are apparent in the description of the exemplary embodiments with the aid of the accompanying drawings.

Description of examples Next, the present invention will be explained in detail using illustrated embodiments.

In FIG. 1, a motor vehicle toothed disc is shown at 10, using teeth 11 and tooth spaces 12.

At a distance d with respect to the toothed disc 10, a sensor 13.13
a is placed. The sensor 13 used to detect the rotational speed of the toothed disc 10 is connected to the evaluation branch 14, and the sensor 13a, which is still used to form the reference, has the same configuration as the evaluation branch 14. It is then connected to a reference branch 14a, which is preferably arranged in the vicinity of the evaluation branch. The shunt 14, 14a is connected to the input circuit 15.15a,
It consists of a series connection of a high-pass filter 16.16&, a threshold value 17.17a and a timing element 18.18a. Timing element 1
δ, 18a is O controlling a switch 20 arranged in the connection path between the sensor 13 and the anti-lock device 21.
R-gate 19. A line extends from the output side of the input circuit 15 of the sensor 13 to the peak value measurement circuit 22. The peak value measuring circuit is connected on the one hand via a threshold value 23 to an indicating device 24 and on the other hand via a high-pass filter 25 and a threshold value 26 to an indicating device 27 . The indicating device 24.27 likewise switches 2
Can be connected to the control line for 0.

The operation of the circuit shown in FIG. 1 is as follows.

The signal detected by the sensor 13 is detected by the normally closed switch 2 due to the customary processing known per se.
0 to the anti-lock device 21. Of course, the signal to be supplied to the anti-locking device 21 can then also be tapped off at the output of the input circuit 15. Input circuit 15 evaluates the signal of sensor 13. The circuit is constructed in a known manner depending on the type of measuring principle of the sensor used. A voltage pulse is then tapped off at the output of the input circuit 15. The frequency of the voltage pulses corresponds to the rotational speed of the toothed disk lO, and the amplitude corresponds to the gap d present in each case. The amplitudes of these .xi. pulses are detected in a peak value detector 22 and, in the illustrated embodiment, are fed to a threshold value 23 which marks the tolerance region, within which no output signal is emitted. This tolerance area marks the permissible variation range of the air gap d. The lower threshold value of the threshold value 23 is exceeded when the sensor is in close proximity to the toothed disc 10, resulting in a mechanical contact and thus a risk of destruction of the sensor 13. Also, if the sensor 13 becomes slack and thus the air gap d widens unacceptably, the upper threshold value of the threshold value 23 will be exceeded. In both cases a signal is sent to the indicating device 24. At the same time or at a correspondingly high threshold, the line from sensor 13 can be disconnected and the connection interrupted. This ensures that, in extreme cases, completely false signals do not reach the anti-locking device 21.

If quasi-steady changes in the gap d are excluded, the value is within the allowable range, but this type of gap change, which is caused by the eccentricity of the toothed disc 10 and therefore has periodicity, is also important. , the repetition frequency of the periodicity may be in the order of the useful signal. A high-pass filter 25 is provided to detect this noise as well. A threshold value 26 with a correspondingly low response threshold is connected downstream of the high-pass filter. Therefore, using this threshold value 26, periodic air gap fluctuations of relatively small amplitude can be detected and the indicating device 2
7, and is also used to shut off the sensor 13 via the control line of the switch 2o, if necessary.

In a preferred embodiment of the invention, a further sensor 13a is also provided for forming the reference. The spatial distances of the sensors 13.13a are determined in such a way that in each case one sensor faces the tooth 11 and the other sensor faces the tooth space 12. The sensor signal is input to input circuit 1
5.15a, filtered in a filter 16.16a and fed to a threshold value 17.17a, where it is detected whether the sensor signal still has an acceptable amplitude, for example 8Q mV. Threshold price 17.17a
The output signals of control the timing elements 18, 18a by shifting each one by half the interdental distance, so that the timing elements 1δ
, 18a, the OR gate 19
Superimposition control is performed on the input side.

As a result, the output side of the OR gate 19 continues to close the switch 20 up to a minimum rotational speed that can be adjusted by the time constant. If the toothed disk 10 falls below the minimum rotational speed, for example in a state where the rotation of the toothed disk is almost blocked or stopped,
The output signal of the timing element 18.18a is no longer superimposed and the output signal of the OR gate becomes zero, so that the switch 20 is opened, as schematically shown in FIG.

FIG. 2 shows a longitudinal section (FIG. 2a) and a plan view (FIG. 2b) of a sensor 13, 13a such as can be used in the device of FIG. At that time, the original sensors 13, 13
a is placed inside the sensor sleep 30. The sensor sleeve advantageously has an input circuit 15 molded into it.
．． 15a and optionally downstream circuit elements 1
6 to 20 are also included. The sensor sleeve 30 is fitted into the casing 31. An insertion port 32 is integrally molded into the casing. Since the casing 31 is fixed to a brake piece support 33 that is spaced apart from the toothed disc 1o, a desired gap d can be adjusted and set. Using the screw 34 biased by the spring 35, the sensor sleeve 30, the i-1r sensor 13.
l 3 a can be offset in the radial direction with respect to the toothed disc 1o. The casing 31 includes a cover 37 made of synthetic resin. The force has a slot 38 which lies tangentially in relation to the toothed disc 10. Adjustment screws in these slots therefore allow the device to be tangentially displaced.

That is, when assembling the device described so far, the position of the device is adjusted using the square slot 38 so that one sensor 13 is exactly facing the tooth 11 and the other sensor 13a is facing the tooth groove 12. . In this case, the sensor 13.13a is
It has a maximum to minimum signal that can be adjusted to the target value by tightening or loosening the screw 34. This position can be adjusted to the desired value in each case during maintenance work on the motor vehicle, for example at regular inspection intervals. Corresponding adjustment settings are of course also indicated by means of the indicating device 24.27 when it is detected that the air gap d is in an unacceptable adjustment position.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram of a device according to the invention, and FIG. 2 shows a sensor used in the device according to the invention, in which a) is a longitudinal sectional view and b) is a plan view. 10... Toothed disk, 11... Teeth, 12... Tooth groove,
13.1, 1Sa=・Sensor, 15.15a-input circuit, 16.16a, 25 river high band filter, 17° 17a,
23. ．． 26... Threshold price, 18', 18a... Delay element, 19... OR element, 20... Switch, 21
... Lock prevention device, 22 ... Peak value detector, 2
4.27...Indication device, 3o...Sensor sleeve

Claims (1)

Claims: 1. The first object comprises a magnetic or electrical discontinuity disposed in the direction of motion, and the first object comprises at least one magnetic or electrical discontinuity responsive to the distance to the discontinuity. facing a second object having two sensors (13, 13a);
The amplitude of the signal generated by said upper sensor ('13.13a) is then independent of the speed of movement of said object;
The sensor (13, 13a) in a device that detects rotation speed, angle, and position between two objects in relative motion.
A device for detecting rotational speed, angle and position, characterized in that the signal generated by the is fed to a circuit arrangement for monitoring the amplitude and/or amplitude fluctuations. 2. The first object is a toothed disc (10
), and the second object is a body part of a vehicle. 3. The sensor (13, 13a) is an eddy current inductance reflection, a vegant sensor magnetoresistive, capacitive or Hall effect element having a soft magnetic core and a ferromagnetic line provided on the surface. The device according to item 1 or item 2. On the other hand, the sensor signal is transmitted to the anti-lock device (21
) and on the other hand a peak value detector (2
2), at least one post-connected threshold price (23,
26) Apparatus according to claim 2 or 3, which can be supplied to 26). 5. a first threshold value (23) with a post-connected indicating device (24) and a pre-connected high-pass filter (25);
2. Device according to claim 1, characterized in that a second threshold value (26) is provided with a second threshold value (26) having an indicator device (27) connected downstream. 6. Two adjacent sensors (13, 13a) at the interval from the tooth (11) to the tooth groove (12) of the toothed disc (10)
) is provided, and the signal of the sensor is passed through a timing element (18
, 18a), the timing elements (18, 18a)
3. A device according to claim 1, wherein the output of 18a) is connected to a switch (20) which disconnects the sensor output via an OR logic combination. 7. Device according to claim 5 or 6, wherein the indicating device (24, 27) is operatively connected to the switch (20). 8. The sensor (13, 13a) is arranged in a sensor sleeve (30) which is shiftable in the radial and tangential directions with respect to the toothed disc (10). The device according to item 7.