RU2317522C2 - Programmable contact-free angular movement indicator with linear angular range within limits of 360° - Google Patents

Abstract

FIELD: tool-making industry, possible use in electronic automobile control systems to determine opening angle of butterfly throttle, degree of pressing of accelerator pedal, position of processed gases recirculation valve, etc.

SUBSTANCE: sensor stator represents an integration chip, programmable in EEPROM memory by two or several calibration points, aforementioned chip belonging to two-axial angular encoder, which contains integrated cross-like array of planar Hall elements with analog output or PWM-interface, fitted with integrated magneto-concentrating disk (disks). Rotor magnet in process of assembly on basis of balancing results is rigidly installed in rotor unit, which contains mounting bushing made of material which does not conduct magnetic field. Programming of format, points of calibration, displacement, rotation direction, sensitivity (amplification) of analog or PWM transfer characteristic are performed after device is assembled.

EFFECT: simplicity, manufacturability, reliability, high precision in full range of angles φ=0-360°, adaptation for concrete working conditions.

5 cl, 19 dwg, 1 tbl

Description

The invention relates to automotive electronic instrumentation and can be directly used in electronic vehicle control systems to determine the opening angle of the throttle, the degree of depressing the accelerator pedal, the position of the exhaust gas recirculation valve [basics, in other automotive systems requiring an analog or PWM signal of absolute angular the position of a rotating object (shaft), as well as for non-contact detection of the absolute angular position of a large number of rotating their facilities in many other sectors of light and heavy industry.

An analogue of the claimed sensor is an accelerator pedal position sensor (United States Patent 4915075 dated April 10, 1990).

The device includes a potentiometer installed in the pedal and a board with a PWM signal generating circuit with an output duty cycle proportional to the position of the pedal.

The disadvantages of this device include the susceptibility to wear, characteristic of potentiometers, a short service life, low reliability, sensitivity to vibration and dust.

An analogue of the claimed device is an angular position sensor with a Hall device and a permanent magnet of a given shape (United States Patent 5159268 dated October 27, 1992.).

In the description of the device, two preferred variants of the shape of the magnet are indicated - oblong and bell-shaped, allowing to achieve high linearity during its rotation.

The disadvantage of this device is the complexity of the magnetic system. the need to use magnets of a special form and the application of computational mathematical methods.

An analogue of the claimed device is a magnetic angle sensor with improved output linearity (United States Patent 5444369 of August 22, 1995).

The device uses massive stationary axial magnetic circuits and a rotating magnetic circuit to which one or more magnets are attached.

The disadvantages of this device include cumbersomeness, structural complexity, the need to use both design methods and settings and adjustments when developing the device, lack of adaptability to the special requirements for the mechanics of automotive sensors operating in a limited range of rotation angles.

An analogue of the claimed device is a pedal position sensor with a magnet. moving relative to a magnetic field sensor located in the stator channel (United States Patent 6577119 dated June 10, 2003).

The device is a non-contact position sensor in which the stator surface includes two areas of magnetic material, the magnet is mechanically connected to the accelerator foot pedal, the relative movement of which along one or two Hall sensors in the stator channel causes the formation of an electrical signal proportional to the movement of the magnet, which is processed in integrated sensor circuits and one or two external ASICs (Application Specific Integrated Circuit) with programming capabilities, for example, in EEPROM. linear output characteristics and temperature compensation, as well as the formation of a signal for transmission via a serial protocol, for example via CAN bus.

The disadvantage of this device is the complexity of the described magnetic system, the need to use two Hall sensors to improve measurement accuracy, one or two external interface ASICs to implement the required interface.

An analogue of the claimed device is an angular position sensor with two radial magnets fixed to the rotor, creating a working zero. which, when the rotor is rotated, is measured by an external magnetic field sensor (preferably a magnetoresistive AMP sensor, or by a Hall sensor) (United States Patent 6806702 of October 19, 2004.).

The disadvantage of this device is the bulkiness, the need to use two magnets and one or more external ASIC - bridge signal processors; the functional angular range of the AMP sensor does not exceed 180 °.

The prototype of the proposed sensor is a measuring device for non-contact determination of the angle of rotation (United States Patent 6534971 dated March 18, 2003).

This device includes a rotor, on which is located a permanent magnet having a diametrical direction of magnetization, and a Hall element located asymmetrically and describing the elliptical rotational movement of the permanent magnet. However, no magnetic flux concentrators are used in this design. The indicated magnetic system makes it possible to obtain an output characteristic region with a steep lowering region and characteristic flat regions.

The disadvantage of this device is the narrowing of the range of the measured angle due to insufficient uniformity of the output characteristic (the description of the invention indicates the angular region of linearity to 80 °, while in many cases for the effective operation of the sensor it is necessary to measure angles of 100 ... 120 ° or more, up to 360 ° or , for some types of devices, angles of several full revolutions).

Conventional linear Hall effect sensors recommended for this prototype device have many disadvantages: low sensitivity. sensitivity drifts, displacement and displacement drifts, and significant non-linearity (up to 3% in the full range, which is usually less than 90 °).

The device also lacks special circuitry and mechanical means of adaptation to specific working conditions.

The objectives of the invention are improving the accuracy of measurements, linearity (absolute and relative linearity of the analog signal or the PWM signal duty cycle drift), improving repeatability, expanding the mechanical angular range, the functional range and the linear portion of the measured angle to any value within 0-360 °, increasing sensitivity, the development of adaptive signs to specific working conditions, including the direct replacement of analog three-wire and two-wire (PWM) potentiometers and classical sensors based on the Hall effect, improving reliability, further simplifying the design of the device and the technology of its assembly and installation.

The tasks are solved in that in a non-contact angle encoder in which a rotor with a magnet rotates in a detectable angular range relative to a fixed stator - an integrated circuit (IC) of a Hall effect magnetic field sensor, a light axis of magnetization and the base of a diametrically magnetized cylindrical rotor magnet at its rotation is parallel to the front surface of the IS - stator, which is a programmable in the EEPROM memory for two or more calibration points of the IS biaxial angle encoder containing an integrated cruciform array of planar Hall elements, with an analog output or PWM interface, formed by digitizing and digital processing using the arctangent function of the signals of the integrated cruciform array of planar Hall elements, sensitive to the gradient of the working magnetic field components perpendicular to the front surface of the IC equipped with an integrated magnetoconcentrating (IMC) disk (s) through which the converted e parallel field components in perpendicular to the front surface of the IC, which is sealed by surface mounting on a printed circuit board with circuit components of a three-wire analog or two-wire PWM sensor, the rotor magnet during assembly according to the alignment results is rigidly mounted in the rotor assembly containing an installation sleeve of material not conducting a magnetic field, with an orienting flat or an orienting groove made therein for mounting on a shaft with a given initial orientation and cylindrical or horses a mechanical torsion spring and having the possibility of rotation in the housing to an angle φ detected within the full mechanical angular range of the device, limited at extreme mechanical positions by stops in the base of the housing and protrusions of the rotor mounting sleeve, for mechanical isolation of the stator from moving mechanical parts and mechanical limitation of axial displacements the rotor assembly in the sensor contains an internal limiter cap, which is rigidly fixed in the housing over the rotor assembly, the magnetic sensor for - the two-axis angular Hall encoder allows selection of the format and programming after assembling the entire device of the main parameters of its analog or PWM output characteristics - limiting output voltage levels, calibration points, rotation direction, offset and gain (sensitivity) or programming calibration points and sensitivity individually for all linear sections of the output characteristic for multi-point calibration, the connector of the device housing contains only the functional conclusions used in the further process of operation after programming the sensor, and in the process of programming the device uses only the functional conclusions of the IC.

The base of the rotor diametrically magnetized cylindrical permanent magnet can be circular or annular.

In the particular case for alignment, the magnet is rigidly mounted in the sleeve with grooves for a screwdriver, rigidly installed in the rotor assembly according to the results of alignment of the magnet.

To protect the Hall sensor from reverse voltage, overvoltage, output short circuit, impulse noise in the power supply and output circuits, if this protection is not provided in the Hall integrated circuit (IC), the device circuit located on the sensor circuit board contains the necessary protection circuits (zener diode, rectifier filter capacitors).

A programmable non-contact angle encoder with a linear range of 360 ° is shown in FIGS. 1-19.

Figure 1-5 shows the design of a programmable analog non-contact throttle position sensor.

Figure 1-4 shows the main embodiment of the device. Figure 1 shows the projection views and a general axonometric view of the device, figure 2 shows a sectional view illustrating the principle of operation of the sensor, figure 3 shows views of a device with an axial limiter without a top cover, figure 4 shows a view of the device with mechanical limiters of the range of the measured angle to 360 °.

Figure 5 shows a design variant of a device for mass production without a sleeve that identifies the position of the poles of a magnet, the poles of which are visually distinguishable.

Figure 6 shows an example of a circuit diagram of the inventive device with programmable in the EEPROM IC biaxial angular magnetic encoder MLX90316 Melexis, figure 7 shows the functional diagram of the IC MLX90316.

On Fig shows the main elements of the magnetic system and illustrates the principle of operation of the claimed device.

On figa-g illustrates in detail the working principle of the sensor with an array of Hall elements and IMC, implemented in the technology "Triaxis" Melexis:

on figa shows the conversion of components In _|| parallel working magnetic field into perpendicular B _⊥ by means of IMC-disk for reading zero by plenary Hall elements;

on figb shows: the location of the IMC disk and the array of Hall elements on the substrate in the IC and the conversion of the parallel magnetic field components B _X and B _Y in the direction of the measuring axes X and Y;

on figv shows the principle of obtaining sinusoidal and cosine signals from an array of Hall elements for detecting the angle φ;

on Figg shows the sine-cosine voltage signals generated at the primary stage of signal formation in the IP MLX90316.

Figure 10 illustrates the working principle of a 12-bit analog biaxial magnetic angle encoder (resolution of the DAC of the analog output is MLX90316-12 bit), figure 11 illustrates the principle of calculating the angle MLX90316 in the SOIC-8 package and shows examples of analog output characteristics of the IC, on Fig.12 shows the output PWM interface MLX90316, Fig.13 shows examples of analog output modes of the inventive device, the design of which corresponds to that shown in Fig.1-5, in a limited range of angle φ.

On Fig-17 shows: the primary stage of formation of the transfer characteristics (Fig) and typical programmable output characteristics of the classic Hall sensor (Fig-17).

On Fig shows a comparison of the analog output modes of the device with a typical characteristic of the classic Hall sensor and typical examples of the characteristics of the encoder IC (for example, AS5043 Austriamicrosystems encoder IC once programmed in the OTPROM memory), Fig. 19 shows a comparison of the programming methods of the analog characteristics of the MLX90316 and AS5043:

on figa shows the programming of the zero position (offset) of the output characteristics of AS5043;

on figb shows a multi-point calibration of the output characteristics of the MLX90316.

The table shows the main technical specifications of the MLX90316.

The throttle position sensor, the design of which is shown in Fig.1-5. implements the operating mode of the device with the rotation of the dipole magnet in a limited angular range of the mechanical angle φ _max = 120 °. The sensor IC scans the two-dimensional distribution of the magnetic field to form an analog signal (for compatibility with most existing processing units). The programmed effective electric angle φ _eff and the linear portion φ _lin are also 120 ° (any angle in the range 0-360 ° can be set), as shown in Figs. 11 and 13.

The throttle position sensor shown in FIGS. 1-5 consists of: a fixed housing 1, a rotor assembly 2, which is a single assembly unit or rotor module including a torsion spring 10 and a rotating installation sleeve 9 with a diametrically magnetized cylindrical permanent magnet 3, rigidly installed in the rotor assembly 2 and, as shown in FIGS. 1-4, pressed into the plastic adjustment sleeve — the housing 4, covers 5 —the travel stop (axial beats) of the rotor assembly 2, mounted on the screws 12, of the printed circuit board 6, the integral sensor - IS Hall 7, the contacts of the connector 8. torsion springs 10 as part of the rotor assembly 2, the cover of the sensor 11.

The main elements of the stator of the sensor include the housing 1 and the integral component of the sensor - IS 7 (as well as all other elements that are not part of the rotor, belong to the stator), the rotor (the moving part of the sensor) is a rotor assembly 2, made on the basis of parts, rigidly interconnected, an assembly module, which consists of a mounting sleeve 9, a diametrically magnetized permanent magnet 3, pressed into the sleeve 4, and a torsion spring 10.

The sleeve 4 in the design of the rotor assembly 2 may not be used, as shown in Fig.5.

In the design of the throttle position sensor (FIGS. 1-5), the rotor assembly 2 is mechanically connected to the rotating shaft of the detected object (target) and has the ability to be rotated by a limited angle φ, determined by the rotation of the object shaft, in the base of the housing 1. From the back of the installation sleeve 9, the rotor assembly 2 has orienting grooves (or flats) for mounting the device on a shaft with a given initial orientation. The housing 1 is rigidly fixed with two screws to the fixed part of the object.

The device has the ability to provide the main rotation of the rotor relative to the stator clockwise and reverse movement counterclockwise. A cylindrical or conical torsion return spring 10 serves to effect the return movement of the rotor and counteract the rotational movement of the shaft of the control drive.

The housing 1 is made in the assembly with the contacts of the connector 8 (according to the technology of pouring or pressing). Integral Hall Sensor - a two-axis magnetic angle encoder 7 is mounted on the board 6 and sealed. Board 6 is installed in the housing 1 over the thrust pins of the bottom of the housing 1, the upper part of which is fused. The preferred mechanical arrangement of the sensor 7 on the board 6 in the housing 1 is selected constructively. Contacts 8 are soldered on the board 6.

To mechanically limit the axial movements of the rotor assembly 2 in the housing 1, a restrictor cover 5 is inserted, which is fixed in the housing 1 over the rotor assembly 2 by screws 12. The maximum angle φ, by which the object shaft rotates, is mechanically limited by the stops 13 at the base of the housing and the protrusions 14 of the installation sleeve 9 rotor assembly 2 (figure 4).

The permanent magnet 3 is rigidly installed (pressed and glued) in the rotor assembly 2 according to the results of its alignment, which is necessary to obtain identical technical characteristics of the batch of products.

Any mechanical position of the magnet 3 relative to the housing 1 can correspond to a zero magnetic vector with a zero value of magnetic field induction (or the easy axis of magnetization), but the rotation of the zero vector (or easy axis of magnetization) of magnet 3 when programming the transfer characteristic must be consistent with the measuring principle this IC, as shown in figure 11 for the analog characteristics of the MLX90316.

When programming, the limiting voltage levels U _ClampLo , U _ClampHigh , offset U _0q (voltage at zero field induction), tilt direction (magnet rotation direction) and other parameters of the output characteristic are set.

For the inventive device, the circuit diagram of which is shown in Fig.6, IC MLX90316 is the first commercially available product. The measuring principle of the MLX90316 in the SOIC-8 package is shown in FIGS. 8-11. With this relative position of the magnetic poles of the magnet 3 and the IS 7 in the design shown in figures 1-5, the zero angle of rotation of the magnet 3 relative to the IS 7 corresponds to a zero value of the magnetic induction of the field.

Given this mutual arrangement in the design of the sensor, the zero magnetic vector indicated by the groove 15 of the sleeve 4 (see Figs. 3 and 4) may coincide or differ from the zero reference vector of the angle φ in the housing 1 by a constant angular value, which in case of mismatch, it is advisable to take equal to φ _max / 2 (see Fig. 11 and 13). The rotation of magnet 3 in this example design will actually be carried out counterclockwise relative to the front surface of the IC, which is set programmatically.

Since in serial production it is desirable to obtain identical characteristics of the claimed device, for this purpose it is advisable to install magnet 3 according to the results of its alignment in the rotor assembly 2, which should be identical for a batch of manufactured products.

To install the magnet 3 can be used sleeve 4, which is provided with a groove 15 for a screwdriver for the possibility of preliminary orientation of the zero plane of symmetry or the easy axis of magnetization of magnet 3 (figures 3 and 4) before its rigid installation (according to the results of measurements of the magnetic field, for example, teslameter , a gaussmeter, calibrated linear Hall IS, or using special hardware and software).

In addition, through the use of the sleeve 4 provides:

1) the ability to align the zero position of the magnet 3 during the assembly process;

2) an increase in the working area of alignment - the initial angular tolerances with a small magnet 3 (allows you to increase the groove for the screwdriver in the cover-stop 5);

3) the use of small working gaps between the magnet 3 and IS7 is allowed.

Instead of the alignment groove 15 of the sleeve 4, the zero plane of symmetry of the magnet 3 can also be indicated by a groove on the surface of the magnet 3 or marked with paint. To visually distinguish between the poles, the magnet 3 can also be coated with two colors of paint.

In mass production, as well as in the case where the use of the sleeve 4 reduces the required working air gap, the option with two-color paint is preferred.

The magnet 3 can be combined with the installation sleeve 9 of the rotor assembly 2 (figure 5). stroke limiter 5 in these cases is provided with an orienting groove for adjusting the position of magnet 3 during assembly.

The stroke limiter 5 can also be made without a groove if the installation (pressing) of the magnet 3 is made with the necessary accuracy at the preliminary stage of assembly. (A preliminary non-rigid installation of magnet 3 can also be performed in the inner sleeve of the travel stop 5. This assembly is then glued on the side of the magnet in the rotor assembly 2 and the travel stop 5 is screwed on with screws 12).

In the inventive device can be used any of the above combinations of options for installing a magnet. In all cases, the alignment of the magnet 3 relative to the sensor IC 7 is provided during the assembly of the inventive device. although at different stages, according to the alignment results, the magnet 3 is rigidly installed (sealed) in the rotor assembly 2 (also in the case of the use of the sleeve - housing 4),

3 - pin output connector for angle encoder with MLX90316. the electrical circuit diagram of which is shown in FIG. 6, is intended to form the analog data transmission channel shown in FIGS. 11, 13. An alternative is the two-wire PWM interface shown in FIG. 12.

In the process of programming the MLX90316, only the functional outputs of the IS 3 and the contacts of the connector 8 are used. No special wire leads, process jumpers and / or connectors are required for programming the device.

The programmable magnetic angle encoder MLX90316, recommended for the magnetic system of the inventive sensor, operating on the basis of the working principle shown in Figs. 8-11, is the latest and most preferred component of the element base existing at the time of filing of this application, two-axis magnetic angle encoders supporting analog or PWM -interface.

MLX90316 is a hybrid absolute magnetic rotary encoder IC in the range 0 ... 360 ° based on the Melexis Triaxis ™ technology, the sensor part of which consists of one integrated magnetically concentrating (IMC) disc 16 with a diameter D on a CMOS substrate 18 IS 7 in the housing SOIC-8 (or located on a double substrate of two IMC in the TSSOP16 case), and an integrated cruciform array (arrays) of mutually orthogonal planar Hall elements 17, located under the IMC 16, pairwise sensitive to the X and Y directions, respectively, in a plane parallel to Eve IC surface 7 (Figure 9).

The use of IMC provides the conversion of components In _|| magnetic field parallel to the surface of the IP, perpendicular to B _⊥ (figa-b). Due to this conversion, the physical sensitivity of the sensor is achieved specifically to the magnetic field components B _X and B _Y parallel to the surface of the IS 7, which, when the magnetic vector of dipole magnet 3 is rotated in the described magnetic system without IMI, dominates perpendicular. MLX90316 with IMC 16 and an array of planar Hall elements 17 produces an electric display of the converted IMC 16 of the working magnetic field B _пер perpendicular to the surface of the IC 7, to which the Hall elements of the IC 17 are sensitive.

Thus, increasing the sensitivity of the sensor due to the effects of the concentration of the components of the magnetic field precisely in the direction of the measuring axes of the sensor simultaneously means a significant increase in the sensitivity of the sensor to the field components in the vertical axis Z and an increase in the touch distance d (Fig. 10).

Functional diagram of the MLX90316 is shown in Fig.7, the technical characteristics are shown in the table.

In addition to the sensor part itself, the stages of signal processing in the IC include: multiplexing (MUX), amplification, ADC, DSP with a microcontroller. RAM, ROM and EEPROM. Then the obtained digital angle value is converted into an analog or PWM signal.

The first stage of the circuit is designed to encode mechanical angle signals into two differential signals with a phase difference of 90 ° - sine and cosine (Fig.9g). The sine-cosine signals U _X and U _Y , proportional to the magnitude of the magnetic flux, are processed in a differential analog circuit using classical techniques for canceling shifts (“spinning” and “chopper” - a stabilized amplifier that allows you to achieve bias values of the order of several μT), and then ADCs are digitized with a resolution configurable in 14 or 15 bits, and transmitted to the DSP block.

The main element of the DSP block is a 16-bit SHZ microcontroller. using the digital representation of the signals to calculate the angle by means of the table function of the arc tangent applied to the signal ratio U _Y / U _X :

The ADC and DSP block provide a high-precision calculation of the angular position of the magnet relative to the IC (the angle of rotation of the magnetic vector parallel to the surface of the IC).

The DSP functionality is controlled by a special microcontroller microcode (firmware - F / W) stored in ROM memory.

In addition to the "ATAN" arc tangent function, the F / W microcode controls the entire analog circuit, output transfer characteristic, output protocol, calibration, programming, and self-diagnosis modes.

Since the “ATAN” function is calculated from the ratio U _Y / U _X (as when using magnetoresistive sensors), the angular information is independent of variations in flux density due to changes in the air gap d, magnetic inhomogeneities, temperature effects, inconsistencies of the two quadrature signals U _Y and U _X . The MLX90316 Hall IC has the ability to measure angles of 0 ... 360 °, in contrast to AMP sensors (0 ... 180 °) and classical Hall sensors (0 ... 120 °), with high linearity, regardless of the relative position of the IC and magnet poles in construction.

In the described magnetic system (Figs. 8-10), the axis of rotation of the cylindrical dipole magnet 3 should be centered with the array of measuring elements 17, being the reference point of the polar coordinate system for determining the angle φ of rotation of the easy axis (Fig. 10), but the measurement principle under consideration is stable also to the displacements of magnet 3 from its optimal position in the plane of the measuring axes X, Y.

The current digital angle value calculated in the DSP unit can then be converted by a 12-bit DAC into analog form (Figs. 10, 11). Other types of output format supported by ICs are 12-bit PWM (Fig. 12) and serial output (see table).

As mentioned above, the output transfer characteristic of the sensor is fully programmable (offset U _0q (rms voltage), gain, limiting levels U _ClampLo , U _ClampHigh ) directly under operating conditions, and, unlike Austriamicrosystems once programmable encoders, programming of operating settings and coefficients The MLX90316 runs in a reprogrammable non-volatile EEPROM.

When programming with the RTS-04 Melexis kit the transfer characteristics of the inventive sensor corresponding to those shown in Fig. 13 for the design example shown in Figs. 1-5, the following parameters are set:

- Output (transfer characteristic) - analog voltage U (φ).

- Lower limit level ClampLo = 0.25 V (U _ClampLo ) for φ≤0 °.

- The upper limiting level ClampHi = 4.75B (U _ClampHigh ) for φ≥120 °.

- Offset V _offset (U _0q ) = 2.25 V.

- The direction of rotation, depending on the location of the MLX90316 in the structure, is counterclockwise (CCW): CLOCKWISE = CCW = 1 (in other designs of the claimed device, the direction of rotation can be clockwise - CW (Fig. 11)).

- Slow (accurate) high-speed DSP operation mode HIGHSPEED = 0 (Slow Mode).

As mentioned above, since the programming of the IC is carried out through the functional outputs, only the functional outputs of the sensor are included in the contact interface. There are no sensor conclusions that are not used later after programming it in the reprogrammable EEPROM memory in the claimed design, which means simplifying the design of the device and the technology of its assembly and installation.

An alternative IC element base for this type of construction is magnetic angle encoders with linear analog or PWM output, designed for one-time programming using special outputs (AS5043 Austriamicrosystems, the new AS5045 12-bit IC with PWM output) or factory-only programming ( AM512 RLS ICs), as well as encoders with special output configuration (iC-MA iC-Haus).

It should be noted that the MLX90316 allows you to get exactly the analog characteristic, for example, for the throttle position sensor optimal from the point of view of unification and compatibility with existing automotive systems, which can be programmed after assembly of the device within the entire mechanical angular range φ _max within 0 ° ≤ φ≤120 °, which will be both the full range of φ _eff (φ _eff is the effective electric angle or the full range), and the functional linear angular range of φ _lin .

The use of a programmable IC of a biaxial angular encoder in combination with a rotating permanent magnet creating a working field allows one to obtain four (by the number of Hall elements) or two analogue working signals (Fig. 9d) in the range 0 ... 360 °, which is equivalent to using four or at least two analogue discrete hall sensors of the classical type in alternative designs and means simplification of the design, as well as assembly and installation technology.

Due to the build quality and uniformity of the magnetic surfaces of the magnet, a further increase in the accuracy and repeatability of measurements, an increase in reliability is achieved.

Special attention is paid to the choice of magnets: magnets should be cylindrical in shape, diametrically magnetized. In the sensor design shown in FIGS. 1-5, a ⌀6 × 3 magnet is used.

The magnetic material can be any of the following types: AINiCo, SmCo5 or NdFeB. In automotive systems with elevated operating temperatures, SmCo is the most preferred material, having better thermal stability properties.

A magnetic field perpendicular to the surface of the sensor array should be approximately ± 50 mT in a radius of about 1 mm (see table). In the design of the sensor, magnets of other geometries can also be used, but this can affect the magnitude of the distance d to the IC.

With a ⌀6 × 3 magnet, the recommended working magnetic field is achieved at a distance of 0.5 ... 1.5 mm to the surface of the IC (plus 0.46 mm to the surface of the IMC).

The maximum flux density for ICs with IMC cannot exceed ± 1 T (± 700 mTl is recommended for MLX90316), so in strong fields, IMC induces significant non-linearity.

Unlike classical Hall sensors, the magnets used in the inventive device are smaller and may be weaker; The described measuring principle provides improved temperature accuracy, the ability to measure 360 ° angles with high linearity, independent of the mutual position of the IC and the magnet poles in the structure.

The diametrically magnetized cylindrical magnet for Hall encoders is much smaller than magnets for AMP sensors. previously used in a similar measuring configuration when detecting angles in the range 0 ... 180 °.

The high sensitivity of the magnetic angular Hall encoders, after amplification, is comparable with the sensitivity of the AMP effect (of the order of 20 mV / mTl), it allows the use of a working air gap d in all configurations, sufficient to isolate the mechanical and electrical parts from each other.

Unlike alternative devices based on the AMP effect, which require a special bridge signal processor, the number of external discrete components in the sensor circuit is minimal.

The design of the inventive sensor is characterized by simplicity, adaptability. reliability, a minimum set of mechanical and electrical components and a maximum set of adaptive features to specific working conditions.

The development of adaptive features is also achieved through the use of mechanical stops-limiters of the measured angle, rigidly fixed in the sensor housing of the axial displacement limiter of the rotor assembly and the torsion spring.

The introduction of an axial displacement limiter, in addition to protecting the sensor IC from physical damage, allows one to regulate (as a rule, increase) the sensor magnetic sensitivity (steepness of working magnetic signals), use smaller working gaps d and weaker magnets, or, conversely, larger gaps with slightly more strong magnets than specified by the sensor IC specification (MLX90316 working field must be less than ± 700 mT).

Increasing the sensitivity of the device also means that the amplitude of the sinusoidal and cosine working signals increases, which in this case will be more noise-resistant.

At small operating clearances, the limiter completely eliminates the risk of physical destruction of the microcircuit due to axial beats of the throttle actuator. pedals, etc., and mechanical vibration.

By introducing orienting grooves (flats) in the sensor installation sleeve and the magnet housing for quick mechanical adjustment of the magnet position with a screwdriver, mechanical axial displacement of the rotor assembly with the magnet and the measured angle (stops in the sensor housing and protrusions of the installation sleeve), technological design is ensured. Flats in the sensor mounting sleeve, a groove for a screwdriver in the body or body of the magnet, or the ability to visually distinguish the poles when painting the magnet provide identical technical specifications for mass-produced products.

In total, due to the use of the stops of the stator housing (protrusions of the rotor) at the boundaries of the measured angle, limiter and spring, when using orienting grooves, an increase in reliability, an increase in the accuracy of measurements, repeatability, and manufacturability are achieved.

The inventive sensor reflects, first of all, the introduction of a Hall effect angular position sensor, for example, a throttle position sensor, of the magnetic system described above, based on a bi-axis magnetic angular encoder with a linear analog or PWM output programmed in the EEPROM with an IMC in the range angle 0 ... 360 ° and a cylindrical dipole magnet, the magnetic vector of which during rotation is parallel to the front surface of the IC.

Due to the capabilities of an integrated encoder signal processing circuit. programming ICs with EEPROM in specific operating conditions, the availability of a ready-made analog or PWM interface and integrated protection circuits, high accuracy of the sensor, adaptability to specific operating conditions, the minimum number of circuit components and sensor contacts, and high reliability are achieved.

Minimization of electronic components is achieved precisely through the use of Hall encoder ICs with a high degree of integration (the minimum set of external interface components is used only in the absence of identical integrated tools).

After assembly of the entire device, programming of the main parameters of its analog or PWM output characteristic — limiting levels of the output voltage and calibration points, direction of rotation, displacement and amplification (sensitivity), and other parameters ensures arbitrary or optimal (for serial production) selection of the position of the zero magnetic plane symmetry of the magnet relative to the sensor housing and corresponding to the given position of the detected angular value, which significantly increases daptivnost and device manufacturability.

On Fig shows a comparison of the classic transfer characteristics of the Hall sensor (for more details on the operation of the classic Hall sensors is illustrated in Fig.14-17), the modes of an alternative device based on AS5043 and an example of the output characteristics of the inventive device. Fig. 18 illustrates the expansion of the maximum mechanical φ _max , effective electrical φ _eff, and linear ranges φ _{lin of} measured angles φ in the inventive sensor (1 - output characteristic of the classic Hall sensor; 2 - high-linear analog mode of the claimed device; 3, 4 - diagnostic analog modes of the device AS5043).

On Fig-18 shows that the classic Hall sensor allows you to provide only a very small full range φ (effective electric angle φ _eff = 90 °, the linear range φ _lin with no more than 80 °) due to the fact that the working magnetic field B ( or the Hall voltage signal U _H ) during rotation of the magnet is a sinusoidal signal B (φ), which is linearly approximated in the range of the effective electric angle φ _eff , usually not exceeding 100-120 ° (Fig. 14b, Fig. 15). Conventional Hall sensors are significantly affected by magnetic inhomogeneities and non-equalization tolerances, which means the presence of some non-zero bias B _off or (-B _off ) of the Hall element with sensitivity σ (Fig. 14a), as well as the influence of temperature bias drifts ± B _off and sensitivity σ.

The standard analog transfer characteristic of a classic Hall sensor programmed in EEPROM for two calibration points at the linear range boundaries is shown in Fig. 15. On Fig shows the definition of the RMS 50% duty cycle at zero value of the magnetic induction of field B and PWM outputs at the calibration points for the inventive device with a PWM transfer characteristic.

Programming a classical linear Hall sensor with EEPROM at two calibration points allows us to obtain output characteristics U (φ) proportional to the supply voltage U _pit = 5 V in the normalized reference frame of the angular position φ (Fig. 17). During programming, the rms voltage U _{0q is set} and the calculated value of the magnetic sensitivity S _M is stored, for example, the rms voltages U _0q1 , U _0q2 , U _0q3 and the sensitivities S _M1 , S _M2 , S _{M3 of} signals 1, 2 and 3 shown in FIG. 17 (1 - bipolar characteristic (classical); 2 - unipolar characteristic; 3 - inverted unipolar characteristic).

Programming of the inventive device in EEPROM is performed similarly. but in the linear range φ _lin within the full range - the effective electric angle φ _lin = φ _eff = 0 ... 360 °.

On the example of the characteristics of the sensor with AS5043 in Figs. 18 and 19a, it is shown that the linear range detected by the alternative device can take values in the range 0 ... 360 ° programmed during assembly, when the value range is selected 360 ° / 180 ° / 90 ° / 45 °. Depending on the actual angle programmed within 0 ... 360 ° of the zero position and zero offset, the transfer characteristic of the AS5043 can electrically “rotate” (see FIG. 19a).

Within the programmed angular range, the slope of the AS5043 characteristic can be further controlled by changing the gain of the output gain stage.

In contrast to the alternative device described above, the analog mode of the inventive device with MLX90316 allows to obtain the output characteristic precisely within the functional or full mechanical range of the detected angle (Fig. 19b), formed by two or more calibration points.

MLX90316 supports two-point or multi-point calibration of the transfer characteristic (Fig.11-13, 18, 19b). For most automotive sensors, only two-point calibration is sufficient, but the ability to accurately correct the signal, which in some cases can also be used, is an advantage of the claimed sensor.

Thus, high linearity of the output signal (<2%) and angular accuracy (≤ ± 0.5 °) are ensured largely due to the use of high integral technologies in the device based on the described magnetic system: the differential principle of the quadratic array of elements, methods of elimination offsets, for example, spinning current, chopper stabilization, computing and interface capabilities of encoders (embedded in their theoretical principles), programming the output characteristic in EEPROM memory after a complete assembly of the application removable device (using only functional conclusions).

In total, improving the accuracy of measurements, absolute and relative indicators of linearity, repeatability, expanding the functional range and linear portion of the measured angle to 360 °, increasing sensitivity, developing adaptive features to specific working conditions, including for the direct replacement of analog three-wire and two-wire ( PWM) potentiometers, increasing reliability, further simplifying the design of the device and the technology of its assembly and installation are achieved through the use of structurally optimized a magnetic system sensor with an operating mode that is designed for specific operating conditions, which implements a rotation of the direction of the magnetic vector of a cylindrical dipole magnet within the detectable angle parallel to the front surface of the IS of a two-axis angular Hall encoder with IMC and an adapted linear analog or PWM transfer characteristic programmed after the complete assembly of the device two or more calibration points in the memory of the EEPROM IC using only the functional conclusions of the claimed device Properties.

Table.
Specifications of Hall IC - Biaxial Angle Encoder MLX90316 Hall IP MLX90316 Technology Tria⊗is ™ (array of planar Hall elements with IMC) Functional Description 12/14 bit programmable magnetic angle encoder Supply voltage 5 (4.5 ... 5.5); absolute range -10 ... + 20 Consumption Current, mA 10 (slow mode - Slow mode); 16 (fast mode - Fast mode) Output interface 12-bit analog, 12-bit PWM - output with a programmable frequency of 100 Hz - 1 kHz or serial protocol for transmitting angular information with a resolution of up to 14 bits Programmable Parameters and Modes Limiting levels, gain (sensitivity), bias; output format (analog, PWM or serial output), many other settings: rotation direction, DSP speed, PWM frequency, low-pass filter parameters, diagnostic modes, blocking, 40-bit identification number, etc. The frequency of rotation of the magnet, rpm - * Working magnetic field, mT 50 (20-70); ± 700 mTl maximum Working gap between the IC and the magnet, mm - * Update rate, kHz / Update time, μs 600 μs (Slow mode); 200 μs (Fast Mode) Power-on time, ms 15, in slow and fast modes Maximum angular alignment error, ° '- * Magnetic nonlinearity,% '- * Integral nonlinearity with optimal alignment of the magnet, ° ± 2 Integral Nonlinearity, ° ± 4LSB ** Differential nonlinearity, ° 0.05-2LSB ** Transient Noises, ° 0.03-0.06 in slow mode; Slow mode; 0.1-0.2 in fast mode Fast mode Operating temperature range, ° С S (-20 ... 85 ° C); E (-40 ... 85 ° C); K (-40 ... 125 ° C) Housing Types DC (SOIC-8), GO (TSSOP-16) Manufacturer Melexis LSB ** - Least significant bit; least significant least significant bit

Claims (5)

1. A programmable non-contact angular position sensor with a linear range of 360 °, in which a rotor with a magnet rotates in a detectable angular range relative to the fixed stator - an integrated circuit (IC) of the Hall effect magnetic field sensor, characterized in that the light axis of magnetization and the base of the diametrically magnetized cylindrical magnet of the rotor during its rotation is parallel to the front surface of the stator IC, which is a programmable EEPROM memory for two or more Calibration chambers for a biaxial angular encoder IC containing an integrated cruciform array of planar Hall elements with an analog output or PWM interface, formed by digitizing and digital processing using the arctangent function of the signals of the integrated cruciform array of planar Hall elements, perpendicular to the gradient of the working magnetic field components the front surface of the IC, equipped with an integrated magnetoconcentrating (IMC) disk (s), by Conversely, the parallel components of the magnetic field are transformed into perpendicular to the front surface of the IC, which is sealed by surface mounting on a printed circuit board with circuit components of a three-wire analog or two-wire PWM sensor, the rotor magnet is rigidly installed in the rotor assembly in the rotor assembly containing the installation sleeve from a material that does not conduct a magnetic field, with an orienting flat or an orienting groove made in it for installation on a shaft with a predetermined orientation and a cylindrical or conical torsion return spring and having the ability to rotate in the housing to an angle φ detected within the full mechanical angular range of the device, limited at extreme mechanical positions by stops at the base of the housing and protrusions of the rotor mounting sleeve for mechanical isolation of the stator from moving mechanical parts and mechanical restriction of axial displacements of the rotor assembly, the sensor contains an internal limiter cap, which is rigidly fixed in the housing all on top of the rotor assembly, the magnetic field sensor - a two-axis angular encoder allows format selection and programming after assembly of the entire device the basic parameters of its analog or PWM output characteristics - limiting output voltage levels, calibration points, direction of rotation, bias and gain (sensitivity), housing connector the device contains only the functional conclusions used in the further process of operation after programming the sensor, and during the programming of the device only the functional conclusions of the IP are used. 2. A programmable proximity sensor of angular position with a linear range within 360 ° according to claim 1, in which the base of the rotor diametrically magnetized cylindrical permanent magnet is a circle or ring. 3. A programmable proximity sensor of angular position with a linear range within 360 ° according to claim 1, in which for alignment the magnet is rigidly mounted in the sleeve with grooves for a screwdriver, rigidly installed in the rotor assembly according to the results of alignment of the magnet. 4. A programmable non-contact angular position sensor with a linear range of 360 ° according to claim 1, wherein if the stator IC is a two-axis angular Hall encoder with support for multi-point calibration, the parameters are programmed individually for all sections of the output transfer characteristic. 5. A programmable proximity sensor of angular position with a linear range within 360 ° according to claim 1, in which to protect the sensor from reverse voltage, overvoltage, output short circuit, impulse noise on the power supply and output, if this protection is not provided in the integrated circuit Hall sensor, the device circuit located on the sensor board contains the necessary protection circuits (zener diode, rectifier, filter capacitors).

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