CN201259505Y - Accurate wheel speed sensor - Google Patents

Abstract

The utility model provides an accurate wheel speed sensor, which overcomes the disadvantages of low sensitivity of wheel speed measurement, bad output signal stability and safety, and the like of the existing prior art. The accurate wheel speed sensor consists of a sensor head, a cable, a socket and an electronic circuit; wherein the top of the sensor head is encapsulated with a Hall chip and a permanent magnet; the cable integrates the sensor head and the socket into a whole body; the sensor head is arranged on the gear top of a hub bearing assembly; and a socket interface is connected with an automobile ABS electric control unit. When the wheels move, the Hall chip can accurately detect the frequency signal of gear rotation through the rotation of the gear arranged inside the hub, the signal is transmitted to the automobile ABS system through the cable, the automobile ABS system accurately detects the rotating speed of the wheels according to the electric signal of the gear inside the automobile hub. The sensor has the advantages of small volume, convenient installation, simple design of peripheral circuits, stable voltage amplitude of the output signal without rotation speed influence, high frequency response, strong electromagnetic interference resistance and contamination resistance performance, stable and reliable output signal, and the like.

Description

Accurate wheel speed sensors

Affiliated technical field

The utility model relates to the accurate wheel speed sensors of a kind of instrument of measurement of vehicle speed, particularly car.

Background technology

Tradition reluctance type abs sensor is made of discrete elements such as electromagnetism steel, coils.This passive sensor provides cheap rotating speed induction technology in moderate speed range, be widely used in the detection of automobile wheel speed.Have following deficiency: the sensitivity of 1, measuring wheel speed is low.The maximum working gap of sensor and gear has only 0.3～0.5mm, and the amplitude of its output signal changes, and slower when the speed of a motor vehicle, the output signal amplitude just can't detect during less than 1V; Its frequency response simultaneously is not high yet, and when rotating speed reached fair speed, the sensor frequency response was not come, and easily produce rub-out signal, and its anti-electromagnetic interference capability is also relatively poor; 2, stable output signal is relatively poor, is subject to extraneous factor and disturbs; 3, when galloping, because of installing insecure or be subjected to mechanical vibration, sensor easily and gear bump, security is relatively poor; 4, this sensor produces is that amplitude is very low and change analog voltage signal slowly, need through becoming steep numerical frequency signal after amplification, the shaping, just can be transferred to digital rotational speed meters or digital frequency meter and measure vehicle wheel rotational speed, and the peripheral circuit more complicated; 5, can't measure the rotating speed of very low (approaching zero), because at this moment sensor may detect less than the wheel wheel speed signal; 6, the structural behaviour of induction wheel speed sensors is perfect inadequately, and working environment is poor again, is easy to cause intermittent defect, easily causes the amber alerts lamp in the anti-lock braking system in automobiles (ABS) to be lighted once in a while in running car.

Summary of the invention

Goal of the invention of the present utility model is exactly the above-mentioned deficiency at electromagnetic wheel speed, and provides a kind of sound construction, frequency response height, antijamming capability strong and antipollution accurate wheel speed sensors.

For achieving the above object, the technical scheme that its technical matters that solves the utility model adopts is: sensor comprises sensing head, cable, socket and electronic circuit, cable connects as one sensing head, socket, it is characterized in that: the sensing head top encapsulation has Hall chip and permanent magnet, and the magnetic steel material of permanent magnet is the rare-earth cobalt permanent magnet material.

The said Hall chip of the utility model is made of three groups of Hall unit of line spread, every group of Hall unit all by 4 independently, be arranged in the criss-cross Hall plate parallel connection in space and constitute, place an IMC (integrated magnetic field concentrator) at the center position of two pairs of plane Hall plates of cruciform.

During use, the gear that the sensor senses head is installed in the hub bearing assembly pushes up, jack interface is connected with the automobile ABS ECU (Electrical Control Unit), when wheel movement, Hall chip can accurately detect the frequency signal of gear rotation by the rotation that is installed in the gear in the wheel hub, signal is transferred to the automobile ABS ECU (Electrical Control Unit) by cable, and automobile ABS system just can accurately detect the rotating speed of wheel according to the electric signal of automotive hub annular wheel like this.

The utility model is compared with induction wheel speed sensors owing to adopted Hall chip, has the following advantages:

1, can realize multifunctional integrated, intelligent, blocking, the miniaturization and of car sensor;

2, frequency response height.Its response frequency is up to 20KHz, and being equivalent to the speed of a motor vehicle is 1000km/h time institute detection signal frequency;

3, the output signal voltage amplitude is not influenced by rotating speed.Even also can provide accurate tach signal under for zero situation at vehicle wheel rotational speed;

4, stable output signal is reliable, not disturbed by extraneous factor;

5, anti-electromagnetic interference capability is strong;

6, the utility model output signal is the numerical frequency signal, can directly the wheel speed signal that records be transferred to digital wheel speed instrument and measure vehicle wheel rotational speed, has simplified the ABS peripheral circuit;

7, precision height, the linearity is good, and working temperature is wide, and the life-span is long, and is easy for installation, and power consumption is little, vibration resistance, the pollution or the corrosion of not being afraid of dust, greasy dirt, steam and salt fog etc.;

8, volume is little, the working clearance is big, can test gap and direction;

9, highly sensitive, the working clearance is big, even also can not bump with gear when galloping, has improved the security of working sensor;

10, owing to the raising of sensing head and gear clearance, solved the installation matching problem of sensor and hub bearing assembly effectively, greatly improved the installation effectiveness of sensor.

Description of drawings

Below in conjunction with accompanying drawing the utility model is further described:

Fig. 1 is the utility model structural representation; Fig. 2, Fig. 3 are the utility model magnetic circuit sketches; Fig. 4 is the utility model electrical structure block diagram.

Embodiment

As shown in Figure 1, the utility model is made up of sensing head 1, permanent magnet 2, Hall chip 3, cable 4, socket 5 and electronic circuit.Permanent magnet 2, Hall chip 3 is encapsulated in sensor senses 1 top, Chip Packaging is ultra-thin biserial plastic packaging, plastic packaging surface and chip surface spacing only have 0.2～0.3mm, and dual inline lead is wide as much as possible, to allow connecting line directly to weld, technological core is to adopt bare chip to install, this technology open ended pin number in the Chip Packaging of various same sizes is maximum, internal wiring length is the shortest, only right 0.8～1.0mm, parasitic lead capacitance lead resistance and lead-in inductance are all very little, thereby signal transmission delay is shortened dramatically, its advantage is no inside chip encapsulation delay and has increased substantially component package density, and the elasticity of encapsulation bumps and thermoplastic adhesives is fine, stress be can not produce, therefore just needn't filler time and filler expense have been saved yet at bottom filling because of chip is different with the substrate thermal expansivity.The magnetic steel material of permanent magnet 2 is the key factors that influence sensor output signal stability, the utility model is selected high-magnetism and directionally-solidified machinable rare-earth cobalt permanent-manet material for use, this material has stronger magnetic property, have good toughness again concurrently, magnet can carry out turning, boring, available inner circle cutting machine is cut into thickness and only is the thin slice of 0.2mm, but also can produce flexible very high soft magnetic bodies, not only effectively improve the stability of sensor output signal, and reduced rejection rate in sensor production and the installation process greatly because of its good toughness.

As Fig. 2, shown in Figure 3, the magnetic line of force of permanent magnet 2 passes Hall chip 3, leads to gear, and at this moment gearing is equivalent to a collection chinaware, and when gear was in Fig. 2 state, the magnetic line of force disperseed, the magnetic field of passing Hall element relatively a little less than; When gear was in Fig. 3 state, the magnetic line of force was intensive, and the magnetic field of passing Hall element is stronger, so just caused that Hall voltage changes.Hall wheel speed sensors core is a Hall chip, Hall chip is by the quasi-sine-wave voltage of the motion output millivolt level of gear, UGN3019 switching mode integrated hall element with the automobile ABS system peripheral circuit, can realize that with the quasi-sine-wave voltage transitions be standard impulse voltage, signal is transferred to the automobile ABS ECU (Electrical Control Unit) by cable 4, and automobile ABS system just can accurately detect the rotating speed of wheel according to the electric signal of automotive hub annular wheel.

As shown in Figure 4, Hall chip 3 is made of three groups of Hall unit of line spread, every group of Hall unit all by 4 independently, be arranged in the criss-cross Hall plate parallel connection in space and constitute, and the temperature that has corresponding circuit to reduce the hall device parameter is floated, when using with the collocation of SmCo magnet, compensation effect the best of this device.This structure has been given full play to the high and high advantage of DMOS circuit voltage of the cmos circuit linearity, thereby sensor is accurately worked under the environment that requires.The Hall unit adopts three Hall technology, can sense all three components of magnetic flux at single-point, its implementation is to place the IMC (integrated magnetic field concentrator) of diameter 200 μ m, thick 25 μ m at the center position of two pairs of plane Hall plates of cruciform, and what play the sensing effect is Hall plate.

The utility model is a kind of mixed signal magnetic field transducer.It has the big scope that tests the speed (0-2500HZ) and the operating temperature range (40 ℃～150 ℃) of broad; (series of characteristics such as 30V), it can carry out the measurement of the speed of a motor vehicle and rotation direction to the vehicle target wheel at bigger vehicle speed range to have diagnosis of two-wire system current practice, air gap and reverse-voltage protection simultaneously.Its mode of operation adopts two-wire system current return mode of operation, be suitable at-40～150 ℃ temperature range ,+20V direct current supply situation under continuous firing, and still can keep operate as normal during up to+27V at instantaneous voltage.The output current pulse of Hall-type chip wheel speed sensors wheel speed sensors is the wheel hub that the rising edge of the output current pulse of 7mA or this sensor of 14mA (static bias is 7mA) can accurately be positioned target wheel.Output pulse width then can be decided by the direction of motion and the magnetic field intensity of target wheel, and can be encoded to one group of direction of motion and predefined time interval of magnetic field intensity according to target wheel according to the existing industrial standard that the main flow system manufacturer is recommended; Its pulse width can be according to the difference of measured differential mode magnetic field intensity and different: Δ B〉have different width output in three kinds of different magnetic fields of 4mT (normal magnetic field), 2mT＜Δ B＜4mT (low magnetic scope), Δ B＜2mT (extremely low magnetic scope).In addition, under normal and low magnetic situation, it also can provide the measurement of wheel direction; initially power on, target wheel stops or other reason when causing detection less than Dynamic Signal, the failure signal that safety stops will to repeat with the frequency of about 1.5Hz to produce.

Claims (3)

1, a kind of accurate wheel speed sensors, comprise sensing head (1), cable (4), socket (5) and electronic circuit, cable (4) connects as one sensing head (1), socket (5), it is characterized in that: sensing head (1) top encapsulation has Hall chip (3) and permanent magnet (2).

2, accurate wheel speed sensors according to claim 1 is characterized in that: the magnetic steel material of permanent magnet (2) is the rare-earth cobalt permanent magnet material.

3, accurate wheel speed sensors according to claim 1, it is characterized in that: Hall chip (3) is made of three groups of Hall unit of line spread, every group of Hall unit all by 4 independently, be arranged in the criss-cross Hall plate parallel connection in space and constitute, place an integrated magnetic field concentrator at the center position of two pairs of plane Hall plates of cruciform.

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