Signal measuring circuit and device for wheel speed sensor

Abstract

The utility model provides a signal measuring circuit and device for a wheel speed sensor, and relates to the technical field of wheel speed detection, and the signal measuring circuit is characterized in that an I / V conversion circuit is connected with a signal input end so as to convert a current signal output by the signal input end into a voltage signal; the I / V conversion circuit is also connected with the input end of the signal identification circuit through the blocking circuit and the signal amplification circuit in sequence; the signal identification circuit is provided with a first signal output port and a second signal output port, the first signal output port and the second signal output port are both configured to determine to output high level or low level according to the amplitude of an input voltage signal, and the control module is connected with the first signal output port and the second signal output port. And target information is measured according to the transmitted high level or low level. According to the utility model, the problem of low noise margin of the existing wheel speed sensor signal measuring circuit is solved.

Description

Technical Field

[0001] The utility model relates to the technical field of wheel speed detection, in particular to a wheel speed sensor signal measurement circuit and device. Background Art

[0002] The AK protocol wheel speed sensor is a wheel speed sensor that transmits signals via the AK protocol. Compared with traditional wheel speed sensors, it is an active sensor and is widely used in the automotive field.

[0003] The AK protocol wheel speed sensor outputs a frame signal containing speed pulses and data protocol bits, corresponding to speed signals and data signals. The speed pulse represents the vehicle speed signal, and the wheel speed can be calculated based on the time interval between two adjacent speed pulses and the number of teeth on the gear. The data protocol bits represent other additional information, such as the direction of rotation of the wheel, the amplitude of the magnetic field, and other information. The AK signal characterizes the signal characteristics by the magnitude of the current, and the current is divided into three levels. High-level current (I H , HIGH-level supply current), generally 28mA, used for speed pulses; medium-level current (I M , MID-level supply current), generally 14mA, for data protocol bits; low-level current (I L , LOW-level supply current), generally 7mA, is used to indicate the low level of the signal.

[0004] The AK wheel speed sensor uses current to transmit signals, but its load capacity is not strong. Its load resistance is relatively small, and the maximum load resistance is between 50Ω and 100Ω. At the same time, the output current signal error of the wheel speed sensor is large, and the maximum error can reach ±20%.

[0005] In the known Figure 1 In the measurement system of the AK wheel speed signal, the sampling resistor RS (i.e., the load resistor of the wheel speed sensor) converts the current signal Is into a voltage signal WSI, whose voltage is compared with the reference voltage V by means of the comparator U1. REFH Compare the output characteristic signal WSO1 with the reference voltage V REFM Compare and output characteristic signal WSO2.

[0006] Since the value of the sampling resistor is limited, in the known solution, the noise tolerance of the WSO1 and WSO2 signal outputs is limited to several hundred millivolts. REFH Error, V REFMThe error and RS error will be reduced, even down to tens of millivolts. As the system working environment changes and the product ages, the sampling resistor RS, the reference voltage V REFH 、V REFM There are also temperature drift and aging drift errors. The noise tolerance of the system will further decrease, that is, the tolerance capability will weaken and the anti-interference ability will deteriorate, resulting in the output of abnormal signals, causing wheel speed measurement failures, affecting the vehicle's ABS, TCS and other active safety control calculations, and posing a hidden danger to the vehicle's travel safety. Utility Model Content

[0007] In view of the deficiencies in the prior art, the utility model provides a wheel speed sensor signal measurement circuit and device, which solves the problem of low noise tolerance of the existing wheel speed sensor signal measurement circuit.

[0008] At least one embodiment of the utility model provides a wheel speed sensor signal measurement circuit, comprising: a signal input terminal, an I / V conversion circuit, a DC isolation circuit, a signal amplification circuit, a signal identification circuit and a control module, wherein:

[0009] The I / V conversion circuit is connected to the signal input terminal to convert the current signal output by the signal input terminal into a voltage signal;

[0010] The I / V conversion circuit is also connected to the input end of the signal recognition circuit through the DC isolation circuit and the signal amplification circuit in sequence;

[0011] The signal identification circuit has a first signal output port and a second signal output port, and the first signal output port and the second signal output port are both configured to output a high level or a low level according to the amplitude of the input voltage signal. The control module is respectively connected to the first signal output port and the second signal output port to obtain target information based on the transmitted high level or low level measurement.

[0012] The technical solution disclosed by the utility model has at least the following beneficial effects:

[0013] This circuit utilizes the characteristics of the DC isolation circuit that passes AC and blocks DC to filter out the DC component in the voltage pulse signal after passing through the I / V conversion circuit, eliminate the DC error of the voltage pulse signal, and provide a larger amplitude space for the subsequent signal amplifier circuit, so that the voltage pulse signal can be amplified with a larger signal amplitude through the signal amplifier circuit, thereby increasing the tolerance capability of this circuit, that is, improving the corresponding noise tolerance capability.

[0014] In one embodiment of the present invention, the I / V conversion circuit includes a resistor RS, the signal input end is connected to one end of the resistor RS, and the end is also connected to the DC isolation circuit;

[0015] The other end of the resistor RS is connected to the common end.

[0016] The technical solution disclosed by the utility model has at least the following beneficial effects:

[0017] By using the resistor RS, the pulse current signal from the wheel speed sensor received at the signal input terminal can be converted into a corresponding voltage pulse signal to facilitate reception by subsequent circuits.

[0018] In one embodiment of the present invention, the DC blocking circuit includes a capacitor C1 and a resistor R1, wherein:

[0019] The signal input terminal is connected to one end of the capacitor C1 through the I / V conversion circuit, the other end of the capacitor C1 is connected to the common terminal through the resistor R1, and the other end of the capacitor C1 is also connected to the signal amplification circuit.

[0020] The technical solution disclosed by the utility model has at least the following beneficial effects:

[0021] By utilizing the characteristic of capacitor C1 that it passes AC but blocks DC, the DC component in the voltage pulse signal can be filtered.

[0022] In one embodiment of the present invention, the signal amplification circuit includes an operational amplifier U1, a resistor R2 and a resistor R3, wherein:

[0023] The non-inverting input terminal of the operational amplifier U1 is connected to the DC blocking circuit;

[0024] The reverse input terminal of the operational amplifier U1 is connected to the common terminal through the resistor R2, and the reverse input terminal is also connected to the output terminal of the operational amplifier through the resistor R3;

[0025] The output end of the operational amplifier U1 is also connected to the input end of the signal recognition circuit.

[0026] The technical solution disclosed by the utility model has at least the following beneficial effects:

[0027] The resistors R2 and R3 of the operational amplifier U1 provide gain for the operational amplifier U1, ensuring that the voltage output of the voltage signal can be increased after passing through the operational amplifier U1, thereby improving the noise margin.

[0028] In one embodiment of the present invention, the signal input terminal is used to output signals I that increase in sequence to represent three current pulse levels. H , signal I M and signal I L , the gain configuration of the signal amplifier is V1 / U'H , where V1 represents the maximum voltage that the operational amplifier U1 can output, U' H Indicates signal I H The signal obtained after passing through the I / V conversion circuit and the DC isolation circuit.

[0029] The technical solution disclosed by the utility model has at least the following beneficial effects:

[0030] By configuring the signal gain, the tolerance capability or noise tolerance capability provided by the signal amplifier is maximized.

[0031] In one embodiment of the present invention, the signal recognition circuit includes a voltage comparator U2 and a voltage comparator U3, wherein:

[0032] The signal amplification circuit is connected to the same-direction input terminals of the voltage comparator U2 and the voltage comparator U3 respectively, and the reverse input terminal of the voltage comparator U2 is connected to the reference voltage V REFH The reverse input terminal of the voltage comparator U3 is connected to a reference voltage V REFM ;

[0033] The output end of the voltage comparator U2 is connected to the control module as a first signal output port, and the output end of the voltage comparator U3 is connected to the control module as a second signal output port.

[0034] The technical solution disclosed by the utility model has at least the following beneficial effects:

[0035] Through the reference voltage V REFH With reference voltage V REFM The configuration can compare the input voltage signal with the above-mentioned reference voltage to obtain a high level or a low level that can reflect the wheel speed information.

[0036] In one embodiment of the present invention, the reference voltage V REFH =0.5×(V' M +V1)

[0037] Reference voltage V REFM =0.5×V' M , where V' M Indicates signal I M The signal is obtained after passing through the I / V conversion circuit (200), the DC isolation circuit (300) and the operational amplifier U1 in sequence.

[0038] The technical solution disclosed by the utility model has at least the following beneficial effects:

[0039] Through this reference voltage VREFH and reference voltage V REFM The selection of voltage comparator can maximize the tolerance or noise tolerance of the voltage comparator.

[0040] In one embodiment provided by the present utility model, an ADC converter and a programmable voltage source are also included, wherein:

[0041] The input end of the signal recognition circuit is connected to the control module through the ADC converter, and the reverse input end of the voltage comparator U2 and the reverse input end of the voltage comparator U3 are both connected to the control module through the programmable voltage source. The ADC converter is used to collect the signal of the input end of the signal recognition circuit to configure the reference voltage V through the control module and the programmable voltage source. REFH and reference voltage V REFM .

[0042] The technical solution disclosed by the utility model has at least the following beneficial effects:

[0043] The reference voltage V can be programmed using an ADC converter and a programmable voltage source. REFH and reference voltage V REFM Dynamically adjust the reference voltage to always keep the noise margin at the system maximum value.

[0044] In one embodiment of the present invention, the signal identification circuit includes: a voltage regulator tube VZ521, a resistor R511, a resistor R512, a resistor R513, a resistor R514, a resistor R521, a resistor R522, a resistor R523, a resistor R524, and a switch tube Q511, a switch tube Q512, a switch tube Q521, a switch tube Q522 and a power supply VCC, wherein:

[0045] The signal amplifying circuit is connected to the control end of the switch tube Q511 through the voltage regulator tube VZ521 and the resistor R511 in sequence, the control end of the switch tube Q511 is also connected to the first output end of the switch tube Q511 through the resistor R512, and the first output end of the switch tube Q511 is grounded, the power supply VCC is connected to the second output end of the switch tube Q511 and the control end of the switch tube Q512 through the resistor R513, the power supply VCC is connected to the second output end of the switch tube Q512 through the resistor R514, the first output end of the switch tube Q512 is connected to the common end, and the second output end of the switch tube Q512 is the first signal output port;

[0046] The signal amplifying circuit is connected to the control end of the switch tube Q521 through the resistor R521, and the control end of the switch tube Q521 is also connected to the first output end of the switch tube Q521 through the resistor R522, and the first output end of the switch tube Q521 is grounded. The power supply VCC is respectively connected to the second output end of the switch tube Q521 and the control end of the switch tube Q522 through the resistor R523, and the power supply VCC is connected to the second output end of the switch tube Q522 through the resistor R524. The first output end of the switch tube Q522 is connected to the common end, and the second output end of the switch tube Q522 is the second signal output port.

[0047] The technical solution disclosed by the utility model has at least the following beneficial effects:

[0048] By selecting the stabilizing voltage of the voltage regulator tube VZ521 and the on-voltage of the switch tubes Q511 and Q521, it is possible to distinguish three ranges, that is, voltage pulse signals corresponding to three different voltages. Compared with directly using the operational amplifier U1 for signal recognition, this embodiment can reduce the corresponding cost investment while ensuring that the basic functions can be realized.

[0049] The utility model also provides a wheel speed sensor signal measuring device, comprising the wheel speed sensor signal measuring circuit as described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 It is a measurement circuit diagram of a wheel speed sensor in the prior art;

[0051] Figure 2 A schematic diagram of a wheel speed sensor signal measurement circuit provided by the utility model;

[0052] Figure 3 A schematic diagram of the circuit connection relationship of one embodiment of the utility model;

[0053] Figure 4 The schematic diagram of the input and output relationship of the signal recognition circuit;

[0054] Figure 5 It is a schematic diagram of the connection relationship of the ADC converter;

[0055] Figure 6 The waveform diagram for dynamically adjusting the reference voltage using the ADC converter;

[0056] Figure 7 A circuit diagram of one embodiment of a signal recognition circuit.

[0057] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0058] 100, signal input terminal; 200, I / V conversion circuit; 300, DC isolation circuit; 400, signal amplification circuit; 500, signal identification circuit; 600, control module; 700, ADC converter; 800, programmable voltage source; 510, first feature identification circuit; 520, second feature identification circuit. DETAILED DESCRIPTION

[0059] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0060] Furthermore, those skilled in the art may combine and associate different embodiments or examples and features of different embodiments or examples described in this specification without mutual contradiction.

[0061] In the known Figure 1 In the measurement system of the AK wheel speed signal, the sampling resistor RS (i.e., the load resistor of the wheel speed sensor) converts the current signal Is into a voltage signal WSI, whose voltage is compared with the reference voltage V by means of the comparator U1. REFH Compare the output characteristic signal WSO1 with the reference voltage V REFM Compare and output characteristic signal WSO2.

[0062] Reference voltage V REFH 、V REFM The voltage between the high-level current and the medium-level current, and the voltage between the medium-level current and the low-level current are preset respectively, so that the system has the maximum noise tolerance. According to the definition of digital circuit noise tolerance = min{high-level noise tolerance, low-level noise tolerance}, the noise tolerance of WSO1 is min{WSI H -V REFH , V REFH -WSI M}, the noise tolerance of WSO2 is min{WSI M -V REFM , V REFM -WSI L},WSI H For high level current I H The voltage generated at WSI, WSI M For medium current I M The voltage generated at WSI, WSI L The low level current I L The voltage generated at the WSI.

[0063] Since the value of the sampling resistor is limited, in the known scheme, the noise tolerance of the WSO1 and WSO2 signal outputs is limited to several hundred millivolts, especially 100mV to 300mV. Considering the wheel speed sensor error, V REFH Error, V REFM The error and resistance RS error will be reduced, even down to tens of millivolts. As the system working environment changes and the product ages, the sampling resistor RS, the reference voltage V REFH 、V REFM There are also temperature drift and aging drift errors. The noise tolerance of the system will further decrease, that is, the tolerance capability will weaken and the anti-interference ability will deteriorate, resulting in the output of abnormal signals and wheel speed measurement failures, affecting the vehicle's ABS, TCS and other active safety control calculations, posing a hidden danger to the vehicle's travel safety.

[0064] In order to solve the above problems, the present invention provides a wheel speed sensor signal measurement circuit, please refer to Figure 2 The invention comprises: a signal input terminal 100, an I / V conversion circuit 200, a DC isolation circuit 300, a signal amplification circuit 400, a signal identification circuit 500 and a control module 600, wherein:

[0065] The I / V conversion circuit 200 is connected to the signal input terminal 100 to convert the current signal output by the signal input terminal 100 into a voltage signal;

[0066] The I / V conversion circuit 200 is also connected to the input end of the signal recognition circuit 500 through the DC isolation circuit 300 and the signal amplification circuit 400 in sequence;

[0067] The signal identification circuit 500 has a first signal output port and a second signal output port, and the first signal output port and the second signal output port are both configured to output a high level or a low level according to the amplitude of the input voltage signal. The control module 600 is respectively connected to the first signal output port and the second signal output port to obtain target information based on the transmitted high level or low level measurement.

[0068] This circuit utilizes the characteristic of the DC isolation circuit 300 that passes AC and blocks DC, filters out the DC component in the voltage pulse signal after passing through the I / V conversion circuit 200, eliminates the DC error of the voltage pulse signal, and provides a larger amplitude space for the subsequent signal amplification circuit 400, so that the voltage pulse signal can be amplified with a larger signal amplitude after passing through the signal amplification circuit 400, thereby increasing the tolerance capability of this circuit, that is, improving the corresponding noise tolerance capability.

[0069] Next, combine Figure 3 right Figure 2 For further explanation:

[0070] Specifically, the signal input terminal 100 is connected to a power supply VBAT, the voltage output by the power supply VBAT is V1, the I / V conversion circuit 200 includes a resistor RS, the signal input terminal 100 is connected to one end of the resistor RS, and the end is also connected to the DC isolation circuit 300;

[0071] The other end of the resistor RS is connected to the common end.

[0072] By using the resistor RS, the pulse current signal from the wheel speed sensor received by the signal input terminal 100 can be converted into a corresponding voltage pulse signal. After the wheel speed pulse current signal Is passes through the resistor RS, a voltage pulse signal is generated at both ends of the resistor RS to facilitate the subsequent circuit to receive. That is, in this embodiment, the signal input terminal 100 mainly outputs I H ,I M ,I L Three levels of current, which in turn generate voltage signals U on the sampling resistor RS H , U M , U L .

[0073] Specifically, the DC blocking circuit 300 includes a capacitor C1 and a resistor R1, wherein:

[0074] The signal input terminal 100 is connected to one end of the capacitor C1 through the I / V conversion circuit 200 , the other end of the capacitor C1 is connected to the common terminal through the resistor R1 , and the other end of the capacitor C1 is also connected to the signal amplification circuit 400 .

[0075] By utilizing the characteristics of capacitor C1 that it passes AC and blocks DC, the DC component signal in the voltage pulse signal can be filtered to eliminate the DC error of the voltage pulse signal. The DC component signal contains the low-level signal U L And the abnormal DC signal such as leakage current on the line caused by the change of external environment. H、 I M、 I L The voltage signals U′ of the three current levels after passing through the I / V conversion circuit 200 and the DC isolation circuit 300 are shown in FIG. H , U' M , U' L ,Right now Figure 3 The signal at U' can be translated to U H -U L , U M -U L , GND, and then get the corresponding U' H , U' M and U' which is equivalent to GND LThe three-level voltage signal, the isolation circuit eliminates the DC signal, eliminates the DC offset of the signal, and amplifies U' H , U' M The voltage signal provides a larger amplitude space. The selection of R1 should ensure that R1 is much larger than the capacitive reactance of C1 at the signal frequency so that the signal does not lose accuracy.

[0076] Specifically, the signal amplifying circuit 400 includes an operational amplifier U1, a resistor R2 and a resistor R3, wherein:

[0077] The non-inverting input terminal of the operational amplifier U1 is connected to the DC blocking circuit 300;

[0078] The reverse input terminal of the operational amplifier U1 is connected to the common terminal through the resistor R2, and the reverse input terminal is also connected to the output terminal of the operational amplifier through the resistor R3;

[0079] The output terminal of the operational amplifier U1 is also connected to the input terminal of the signal recognition circuit 500 .

[0080] The gain configuration of the signal amplifier is V1 / U' H , where V1 represents the maximum voltage that the operational amplifier U1 can output, U' H Indicates signal I H The signal is obtained after passing through the I / V conversion circuit 200 and the DC isolation circuit 300.

[0081] The power supply of operational amplifier U1 is VBAT (battery power supply), which provides power supply for V1. The operational amplifier is a rail-to-rail amplifier. The gain of the signal amplifier circuit 400 is composed of resistors R2 and R3, and its gain is R2 / (R2+R3). The gain selection ensures that U' H After the signal passes through the operational amplifier, it is close to V1, ensuring that U' M After the signal passes through the operational amplifier, the signal is located between V1 and GND. After the pre-stage signal processing, the tolerance capability of the signal recognition circuit 500 is improved, and the noise tolerance capability is improved to V1 / 4.

[0082] Specifically, in one embodiment of the present invention, the signal recognition circuit 500 includes a voltage comparator U2 and a voltage comparator U3, wherein:

[0083] The signal amplifying circuit 400 is connected to the same-direction input terminals of the voltage comparator U2 and the voltage comparator U3 respectively, and the reverse input terminal of the voltage comparator U2 is connected to the reference voltage V REFH The reverse input terminal of the voltage comparator U3 is connected to a reference voltage V REFM ;

[0084] The output terminal of the voltage comparator U2 is connected to the control module 600 as the first signal output port, and the output terminal of the voltage comparator U3 is connected to the control module 600 as the second signal output port.

[0085] Through the reference voltage V REFH and the reference voltage V REFM configuration, the input voltage signal can be compared with the above reference voltage, and then a more accurate high level or low level that can reflect the corresponding information can be obtained.

[0086] The voltage comparator U2 is used to identify the speed pulse signal of the AK signal. The non-inverting input terminal of the voltage comparator U2 receives the voltage signal WSI output by the operational amplifier U1, and compares it with the reference voltage V REFH at the inverting input terminal. When the voltage of the voltage signal WSI is greater than or equal to V REFH , a high level is output. When the voltage of the voltage signal WSI is less than V REFH , a low level is output, and the signal WSO1 is output after passing through the voltage comparator U2. The reference voltage V REFH is selected to meet: V' M < V REFH < V1, and 0.5×(V' M + V1) is preferably selected.

[0087] V' M represents the signal obtained after the signal I M successively passes through the I / V conversion circuit (200), the DC blocking circuit (300), and the operational amplifier U1.

[0088] The voltage comparator U3 is used to identify the data protocol bit signal of the AK signal. The non-inverting input terminal of the voltage comparator U3 receives the voltage signal WSI output by the operational amplifier U1, and compares it with the reference voltage V REFM at the inverting input terminal. When the voltage of the voltage signal WSI is greater than or equal to V REFM , a high level is output. When the voltage of the voltage signal WSI is less than V REFM , a low level is output, and the signal WSO2 is output after passing through the voltage comparator U3. The reference voltage V REFM is selected to meet: 0 < V REFM < V' M , and 0.5×V' M is preferably selected.

[0089] The control module 600 collects the two characteristic signals WSO1 and WSO2, and performs operations and processing through the built-in software, so as to calculate the rotational speed of the wheel and identify information such as the rotation direction of the vehicle.

[0090] Figure 4The waveform diagram at the top is the voltage signal WSI, and the highest level represents the voltage signal U'. H , the middle level signal represents the voltage signal U' M and the lowest level represents the voltage signal U' L ;

[0091] WSO1 is the first characteristic signal output by the voltage comparator U2; WSO2 is the second characteristic signal output by the voltage comparator U3.

[0092] Specifically, please refer to Figure 5 As shown, it also includes an ADC converter 700 and a programmable voltage source 800, wherein:

[0093] The input end of the signal recognition circuit 500 is connected to the control module 600 through the ADC converter 700, and the reverse input end of the voltage comparator U2 and the reverse input end of the voltage comparator U3 are connected to the control module 600 through the programmable voltage source 800. The ADC converter 700 is used to collect the signal of the input end of the signal recognition circuit 500 to configure the reference voltage V through the control module 600 and the programmable voltage source 800. REFH and reference voltage V REFM .

[0094] It should be understood that the programmable voltage source 800 may be a built-in unit of the control module 600 . Generally, the ADC converter 700 may also be a built-in unit of the control module 600 .

[0095] The implementation process is as follows: the high-level pulse voltage, the medium-level pulse voltage, and the low-level voltage of the voltage signal WSI are collected through the ADC converter 700, and then the reference voltage V is configured by configuring the built-in programmable voltage source 800 through the internal register according to the collected voltage signal. REFH and reference voltage V REFM , the configuration principle is V REFH The voltage is configured as 0.5 times the sum of the high-level pulse voltage and the medium-level pulse voltage, V REFM It is configured as 0.5 times the sum of the medium level pulse voltage and the low level pulse voltage. Since the error of the wheel speed sensor is a slow changing process, it is only necessary to power on or regularly update the reference voltage V REFH and reference voltage V REFM That's it.

[0096] Figure 6It is a waveform diagram of dynamically adjusting the reference voltage. Due to the sensor or system error, the second wheel speed pulse signal input to the signal recognition circuit 500 has an overall increase in amplitude compared to the first wheel speed pulse signal. Under the function of dynamically adjusting the wheel speed pulse, the reference voltage of the comparator increases in amplitude synchronously with the signal, always ensuring that the reference voltage is located at the center of the signal, eliminating the sensor or system error. Obviously, if the reference voltage of the second wheel speed pulse signal is not adjusted, the medium pulse signal voltage will be recognized abnormally.

[0097] That is, the reference voltage V that can be programmed by using the ADC converter 700 and the programmable voltage source 800 REFH and reference voltage V REFM Dynamically adjust the reference voltage to always keep the noise margin at the system maximum value.

[0098] Specifically, considering that the voltage signal WSI output by the operational amplifier U1 has a large amplitude, in order to save costs, the utility model also provides another embodiment of the signal identification circuit 500 to separate the first characteristic signal WSO1 and the second characteristic signal WSO2. Figure 7 As shown, the signal recognition circuit 500 may also include: a voltage regulator tube VZ521, a resistor R511, a resistor R512, a resistor R513, a resistor R514, a resistor R521, a resistor R522, a resistor R523, a resistor R524, and a switch tube Q511, a switch tube Q512, a switch tube Q521, a switch tube Q522 and a power supply VCC, wherein:

[0099] In this example, the switch tubes are all connected using NPN transistors, the control end of each transistor is the base, the first output end of each transistor is the emitter, and the second output end of each transistor is the collector;

[0100] Then the signal amplifying circuit 400 is connected to the base of the transistor Q511 through the voltage regulator tube VZ521 and the resistor R511 in sequence, the base of the transistor Q511 is also connected to the emitter of the transistor Q511 through the resistor R512, and the emitter of the transistor Q511 is grounded, the power supply VCC is respectively connected to the collector of the transistor Q511 and the base of the transistor Q512 through the resistor R513, the power supply VCC is connected to the collector of the transistor Q512 through the resistor R514, the emitter of the transistor Q512 is connected to the common end, and the collector of the transistor Q512 is the first signal output port;

[0101] The signal amplification circuit 400 is connected to the base of the triode Q521 through the resistor R521. The base of the triode Q521 is also connected to the emitter of the triode Q521 through the resistor R522, and the emitter of the triode Q521 is grounded. The power supply VCC is connected to the collector of the triode Q521 and the base of the triode Q522 respectively through the resistor R523. The power supply VCC is connected to the collector of the triode Q522 through the resistor R524. The emitter of the triode Q522 is connected to the common terminal, and the collector of the triode Q522 is the second signal output port.

[0102] By selecting the regulated voltage of the zener diode VZ521, the voltage pulse signals in three range intervals, that is, corresponding to three different voltages, can be distinguished. Compared with directly using the operational amplifier U1 for signal recognition, this embodiment can reduce the corresponding cost input under the condition of ensuring the realization of basic functions.

[0103] The signal recognition circuit 500 is composed of a first feature recognition circuit 510 and a second feature recognition circuit 520.

[0104] The first feature recognition circuit 510 recognizes the speed pulse signal of the AK signal. When the voltage signal WSI is greater than or equal to the sum of the regulated voltage of the zener diode VZ521 and the conduction voltage of the triode Q511 (i.e., V Z +V BEQ511 ), the triode Q511 conducts and outputs a low level; when the voltage signal WSI is less than the sum of the regulated voltage of the zener diode VZ521 and the conduction voltage of the triode Q511 (i.e., V Z +V BEQ511 ), the triode Q511 is cut off and outputs a high level. The circuit composed of the triode Q512 and the resistor R514 reverses the signal. The recognition of the first feature signal WSO1 depends on the sum of the regulated voltage of the zener diode VZ521 and the conduction voltage of the triode Q511. Select to meet: U' M <V Z +V BEQ511 <V1, and preferably select 0.5×(U' M +V1). Through this selection, high-level pulse voltages can be selected;

[0105] The second feature recognition circuit 520 recognizes the data protocol signal of the AK signal. When the voltage signal WSI is greater than or equal to the conduction voltage of the triode Q521 (i.e., V BEQ521 ), the triode Q521 conducts and outputs a low level; when the voltage signal WSI is less than the conduction voltage of the triode Q521 (i.e., V BEQ521), the transistor Q521 is cut off and outputs a high level. The circuit composed of the transistor Q522 and the resistor R524 reverses the signal. The identification of the second characteristic signal WSO2 depends on the conduction voltage of the transistor Q522. Through this selection, the low-level voltage can be separated, and then the high-level pulse voltage and the medium-level pulse voltage can be selected.

[0106] The utility model also provides a wheel speed sensor signal measuring device, comprising the wheel speed sensor signal measuring circuit as described above.

[0107] The above examples all use AK wheel speed sensor as a demonstration solution, which can also be adapted to the standard PWM type and intelligent PWM type currently on the market.

[0108] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations of the present invention. Ordinary technicians in the field can change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A wheel speed sensor signal measurement circuit, characterized in that: include: A signal input terminal (100), an I / V conversion circuit (200), a DC isolation circuit (300), a signal amplification circuit (400), a signal identification circuit (500) and a control module (600), wherein: The I / V conversion circuit (200) is connected to the signal input terminal (100) to convert the current signal output by the signal input terminal (100) into a voltage signal; The I / V conversion circuit (200) is also connected to the input end of the signal recognition circuit (500) via the DC isolation circuit (300) and the signal amplification circuit (400) in sequence; The signal identification circuit (500) has a first signal output port and a second signal output port, and the first signal output port and the second signal output port are both configured to output a high level or a low level according to the amplitude of an input voltage signal, and the control module (600) is respectively connected to the first signal output port and the second signal output port to obtain target information according to the transmitted high level or low level measurement.

2. A wheel speed sensor signal measurement circuit according to claim 1, characterized in that: The I / V conversion circuit (200) comprises a resistor RS, the signal input terminal (100) is connected to one end of the resistor RS, and the end is also connected to the DC isolation circuit (300); The other end of the resistor RS is connected to the common end.

3. A wheel speed sensor signal measurement circuit according to claim 1, characterized in that: The DC isolation circuit (300) comprises a capacitor C1 and a resistor R1, wherein: The signal input terminal (100) is connected to one end of the capacitor C1 through the I / V conversion circuit (200), the other end of the capacitor C1 is connected to the common terminal through the resistor R1, and the other end of the capacitor C1 is also connected to the signal amplification circuit (400).

4. A wheel speed sensor signal measurement circuit according to claim 1, characterized in that: The signal amplification circuit (400) comprises an operational amplifier U1, a resistor R2 and a resistor R3, wherein: The non-inverting input terminal of the operational amplifier U1 is connected to the DC isolation circuit (300); The reverse input terminal of the operational amplifier U1 is connected to the common terminal through the resistor R2, and the reverse input terminal is also connected to the output terminal of the operational amplifier through the resistor R3; The output end of the operational amplifier U1 is also connected to the input end of the signal recognition circuit (500).

5. A wheel speed sensor signal measurement circuit according to claim 4, characterized in that: The signal input terminal (100) is used to output signals I that increase in sequence to represent three current pulse levels. H , signal I M and signal I L , The gain configuration of the signal amplifier is V1 / U' H , where V1 represents the maximum voltage that the operational amplifier U1 can output, U' H Indicates signal I H A signal is obtained after passing through the I / V conversion circuit (200) and the DC isolation circuit (300).

6. A wheel speed sensor signal measurement circuit according to claim 5, characterized in that: The signal recognition circuit (500) comprises a voltage comparator U2 and a voltage comparator U3, wherein: The signal amplifying circuit (400) is connected to the same-direction input terminals of the voltage comparator U2 and the voltage comparator U3 respectively, and the reverse input terminal of the voltage comparator U2 is connected to a reference voltage V REFH The reverse input terminal of the voltage comparator U3 is connected to a reference voltage V REFM ; The output end of the voltage comparator U2 is connected to the control module (600) as a first signal output port, and the output end of the voltage comparator U3 is connected to the control module (600) as a second signal output port.

7. A wheel speed sensor signal measurement circuit according to claim 6, characterized in that: Reference voltage V REFH =0.5×(V' M +V1) Reference voltage V REFM =0.5×V' M Among them, V' M Indicates signal I M The signal is obtained after passing through the I / V conversion circuit (200), the DC isolation circuit (300) and the operational amplifier U1 in sequence.

8. A wheel speed sensor signal measurement circuit according to claim 6, characterized in that: Also included is an ADC converter (700) and a programmable voltage source (800), wherein: The input end of the signal recognition circuit (500) is connected to the control module (600) through the ADC converter (700), and the reverse input end of the voltage comparator U2 and the reverse input end of the voltage comparator U3 are both connected to the control module (600) through the programmable voltage source (800). The ADC converter (700) is used to collect the signal at the input end of the signal recognition circuit (500) so as to configure the reference voltage V through the control module (600) and the programmable voltage source (800). REFH and reference voltage V REFM .

9. The wheel speed sensor signal measurement circuit according to claim 1, characterized in that: The signal recognition circuit (500) comprises: a voltage regulator tube VZ521, a resistor R511, a resistor R512, a resistor R513, a resistor R514, a resistor R521, a resistor R522, a resistor R523, a resistor R524, a switch tube Q511, a switch tube Q512, a switch tube Q521, a switch tube Q522 and a power source VCC, wherein: The signal amplifying circuit (400) is connected to the control end of the switch tube Q511 through the voltage regulator tube VZ521 and the resistor R511 in sequence; the control end of the switch tube Q511 is also connected to the first output end of the switch tube Q511 through the resistor R512, and the first output end of the switch tube Q511 is grounded; the power supply VCC is respectively connected to the second output end of the switch tube Q511 and the control end of the switch tube Q512 through the resistor R513; the power supply VCC is connected to the second output end of the switch tube Q512 through the resistor R514; the first output end of the switch tube Q512 is connected to the common end, and the second output end of the switch tube Q512 is the first signal output port; The signal amplifying circuit (400) is connected to the control end of the switch tube Q521 through the resistor R521, the control end of the switch tube Q521 is also connected to the first output end of the switch tube Q521 through the resistor R522, and the first output end of the switch tube Q521 is grounded, the power supply VCC is respectively connected to the second output end of the switch tube Q521 and the control end of the switch tube Q522 through the resistor R523, the power supply VCC is connected to the second output end of the switch tube Q522 through the resistor R524, the first output end of the switch tube Q522 is connected to the common end, and the second output end of the switch tube Q522 is the second signal output port.

10. A wheel speed sensor signal measuring device, characterized in that: The invention comprises a wheel speed sensor signal measuring circuit as claimed in any one of claims 1 to 9.

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