Speed sensor

Abstract

The utility model provides a speed sensor which comprises a PCB and a sensor circuit arranged on the PCB, the sensor circuit comprises a power-assisted control unit MCU, a Hall element U1 and a Hall element U2, the Hall element U1 is connected with the input end IN1 of the power-assisted control unit MCU, the Hall element U2 is connected with the input end IN2 of the power-assisted control unit MCU, the Hall element U1 is connected with the input end IN1 of the power-assisted control unit MCU, and the Hall element U2 is connected with the input end IN2 of the power-assisted control unit MCU. The output end OUT of the power-assisted control unit MCU outputs a control signal Signal, the Hall element U1 and the Hall element U2 are arranged in tandem in the rotating direction of the rotating shaft, and the triggering magnetic field intensity of high and low level conversion output by the Hall element U1 and the Hall element U2 is + / -5Gs. The two Hall elements are arranged in tandem, so that the rotating direction of the middle shaft can be judged while the speed is detected, and a wrong power-assisted signal is prevented from being output.

Description

TECHNICAL FIELD

[0001] The utility model relates to sensor technical field, in particular to a kind of speed sensors. BACKGROUND

[0002] Power-assisted bicycle needs to determine the size of the assistance provided by detecting its speed, and the speed sensor is used to detect the speed of the axle in the power-assisted bicycle in the prior art. The existing speed sensor is realized by a single Hall element, which cannot determine the rotation direction of the axle and can only determine the size of the speed. In addition, the detection range of the current speed sensor is generally in the high-speed area, and the detection accuracy is low in the low-speed area, which affects the provision of assistance. SUMMARY

[0003] The utility model provides a kind of speed sensors to overcome the deficiencies in the prior art.

[0004] The utility model discloses a kind of speed sensors, including PCB board and the sensor circuit being set on PCB board, the sensor circuit includes power-assisted control unit MCU, Hall element U1 and Hall element U2, Hall element U1 is connected with the input end IN1 of power-assisted control unit MCU, Hall element U2 is connected with the input end IN2 of power-assisted control unit MCU, the output end OUT of power-assisted control unit MCU outputs control signal Signal, Hall element U1 and Hall element U2 are set along the rotation direction of rotation axis one before and after, and the trigger magnetic field intensity of Hall element U1 and Hall element U2 output high-low level conversion is ±5Gs.

[0005] Further, the power supply end of the power-assisted control unit MCU, Hall element U1 and Hall element U2 is connected with 5V DC power supply.

[0006] Further, the power-assisted control unit MCU uses 32-bit MCU chip. Such as the RH850 / P1x series 32-bit MCU of Renesas company, the core sea technology CS32F031 series 32-bit MCU, etc.

[0007] Further, it further includes filter capacitor C1, and the 5V DC power supply is grounded after filter capacitor C1, and the input end of power supply is filtered.

[0008] Further, it further includes LED indicator, and the LED indicator is used to indicate the pulse period output by Hall element U1 and Hall element U2.

[0009] Further, the speed sensor operating voltage range is 4.0V-5.5V.

[0010] Further, the speed sensor detects the speed range of 90 RPM -120RPM.

[0011] Further, the size of the length L and the width D of the PCB board is 34.0mm *8.0mm.

[0012] The speed sensor has the advantages that: (1) two Hall elements are arranged in front and back, so that the rotation direction of the middle shaft can be determined while detecting the speed, and the error force signal is avoided; (2) two Hall elements are arranged, and the redundancy design is realized, so that the speed sensor can detect the speed normally when one of the Hall elements is damaged; (3) the detection range of the speed is reduced, the speed range of the speed sensor meets the speed range of the force bicycle, the detection precision is improved, and the detection and control are more accurate; (4) the size of the PCB board is reduced, the installation is facilitated, and the occupied space is reduced; (5) the state of the Hall element is indicated by the LED indicator, so that whether the Hall element is in normal work can be determined, and maintenance can be carried out in time. BRIEF DESCRIPTION OF DRAWINGS

[0013] The utility model will be further described below in combination with the drawings and examples.

[0014] Figure 1 It is the circuit board drawing of the speed sensor.

[0015] Figure 2 It is the principle schematic drawing of the Hall element and MCU.

[0016] Figure 3 It is the schematic drawing of the PCB board.

[0017] In the drawing: 1, PCB board, 2, LED indicator, 3, connector. DETAILED DESCRIPTION

[0018] The utility model will be further described below in combination with the drawings and examples.

[0019] As Figure 1 And Figure 2As shown, the speed sensor of the utility model, including PCB board 1 and sensor circuit set on PCB board 1, the sensor circuit includes power control unit MCU, hall element U1 (that is Hall1) and hall element U2 (that is Hall2), hall element U1 is connected with the input end IN1 of power control unit MCU, hall element U2 is connected with the input end IN2 of power control unit MCU, the output end OUT of power control unit MCU exports control signal Signal, hall element U1 and hall element U2 are set in front of the rotation direction of rotation shaft, and the trigger magnetic field intensity of high-low level conversion output by hall element U1 and hall element U2 is ± 5Gs. The power supply end of power control unit MCU, hall element U1 and hall element U2 is connected with 5V DC power supply, further including filter capacitor C1, 5V DC power supply is connected with ground through filter capacitor C1, and the input end of power supply is filtered. Power control unit MCU adopts 32-bit MCU chip. Such as Renesas company's RH850 / P1x series 32-bit MCU, core sea technology CS32F031 series 32-bit MCU etc. Further including LED indicator 2, the LED indicator 2 is used to indicate the pulse period output by hall element U1 and hall element U2. The speed sensor of this embodiment is applied to the central axis of power-assisted bicycle, and the rotation speed of the central axis is detected to realize power assistance, and the number of pulses output by the central axis rotation is 12, therefore, the number of times of lighting LED indicator 2 for the central axis rotation is 12. The working voltage range of the speed sensor is 4.0V-5.5V. The rotation speed range detected by the speed sensor is 90 RPM -120RPM. Connector 3 is further provided on PCB board 1, which is used to connect with external power supply and output control signal to the outside. Hall element U1 and hall element U2 can adopt straight insertion packaging device, and can also adopt paster packaging device. Such as Figure 3 As shown, the size of the length L and the width D of the PCB board 1 is 34.0mm *8.0mm.

[0020] Working principle:

[0021] Direction sensing: when the rotation of the shaft is sensed, through two Hall elements U1 and U2, one in front of the other, the direction of the rotating shaft is sensed, that is, from top to bottom movement, when the magnetic field strength of Hall element U2 is higher than 5Gs, Hall element U2 is triggered to output high level and latch high level, until the magnetic field of Hall element U2 is lower than -5Gs, Hall element U2 is triggered to output low level and latch low level. With the movement of the rotating shaft, when the magnetic field strength of Hall element U1 is higher than 5Gs, Hall element U1 is triggered to output high level and latch high level, until the magnetic field of Hall element U1 is lower than -5Gs, Hall element U1 is triggered to output low level and latch low level. Through the triggering of Hall element U1 and Hall element U2 in sequence, the direction of rotation of the rotating shaft can be determined.

[0022] Speed sensing: with the rotation of the shaft, when the magnetic field strength of Hall element U2 is higher than 5Gs, Hall element U2 is triggered to output high level and latch high level, until the magnetic field of Hall element U2 is lower than -5Gs, Hall element U2 is triggered to output low level and latch low level. Through the repetition period of high and low levels calculated by the assistance control unit MCU, the speed is calculated.

[0023] Output signal: the assistance control unit MCU compares the sensed speed and direction with the set direction, if the direction is consistent with the set direction, the assistance system assistance control unit MCU automatically calculates the speed period, thereby triggering the output of high level. With the change of speed, the period of the output signal also changes, and the duration of high level also changes. If the direction is opposite to the set direction, the assistance system stops outputting.

[0024] Based on the above ideal embodiments of the present application, through the above description, relevant personnel can make various changes and modifications without deviating from the scope of the present application. The technical scope of the present application is not limited to the contents of the specification, and must be determined according to the scope of the claims.

Claims

1. A speed sensor characterized by: The sensor circuit includes a PCB board and sensors arranged on the PCB board, the sensor circuit includes a power control unit MCU, a Hall element U1 and a Hall element U2, the Hall element U1 is connected with an input end IN1 of the power control unit MCU, the Hall element U2 is connected with an input end IN2 of the power control unit MCU, an output end OUT of the power control unit MCU outputs a control signal Signal, the Hall element U1 and the Hall element U2 are arranged in front of and behind a rotation direction of a rotating shaft, and trigger magnetic field intensity output by the Hall element U1 and the Hall element U2 is converted from high level to low level, and the trigger magnetic field intensity is ±5Gs.

2. The speed sensor of claim 1, wherein: The power supply ends of the power control unit MCU, the Hall element U1 and the Hall element U2 are connected with a 5V direct current power supply.

3. The speed sensor of claim 1, wherein: The power control unit MCU adopts a 32-bit MCU chip.

4. The speed sensor of claim 2, wherein: The 5V direct current power supply is connected with the ground through a filter capacitor C1.

5. The speed sensor of claim 1, wherein: An LED indicator is further included, and the LED indicator is used for indicating a pulse period output by the Hall element U1 and the Hall element U2.

6. The speed sensor of claim 1, wherein: The working voltage range of the speed sensor is 4.0V-5.5V.

7. The speed sensor of claim 1, wherein: The rotating speed range detected by the speed sensor is 90RPM-120RPM.

8. The speed sensor of claim 1, wherein: The size of the PCB board is 8.0mm*34.0mm.

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