Gravity sensing circuit for automobile luggage rack

Abstract

The utility model relates to a gravity sensing circuit for an automobile luggage rack, and relates to the related field of weight measuring equipment. The device comprises a pressure detection unit and a controller, and the output end of the pressure detection unit is electrically connected to the input end of the controller; the pressure detection unit is used for detecting the weight of the automobile luggage rack and outputting a pressure analog signal to the controller; the zero setting unit is used for performing zero setting on the pressure detection unit; the output end of the controller is further electrically connected with a communication unit used for awakening the system and a voltage detection unit used for detecting the working voltage in the current circuit. The luggage rack has the effect of being capable of detecting the weight of an object placed on the luggage rack.

Description

Technical Field

[0001] The present application relates to the relevant field of weighing equipment, and in particular to a gravity sensing circuit for a luggage rack of a car. Background Art

[0002] A car luggage rack is a bracket mounted on the roof of a car to conveniently carry large items such as bulky luggage, bicycles, folding beds, etc. It has practical and aesthetic functions, which can increase the appearance of the vehicle, and can also carry things that cannot be placed in the car's luggage compartment.

[0003] In actual use, the weight of the car luggage rack needs to be controlled. If the weight of the car luggage rack is too heavy, it is easy to affect the balance and stability of the car, causing the vehicle to swing or vibrate during driving; or it is easy to increase tire wear and the burden on the vehicle suspension system, affecting the vehicle's handling and braking performance, affecting driving safety. Utility Model Content

[0004] In order to detect the weight of an object placed on a luggage rack, the present application provides a gravity sensing circuit for a car luggage rack.

[0005] The gravity sensing circuit for a car luggage rack provided in the present application adopts the following technical solution:

[0006] A gravity sensing circuit for a car luggage rack comprises a pressure detection unit and a controller, wherein the output end of the pressure detection unit is electrically connected to the input end ADC0 of the controller, and the pressure detection unit is used to detect the weight of the car luggage rack and output a pressure analog signal to the controller.

[0007] By adopting the above technical solution, the weight of the car luggage rack is measured using a pressure detection unit, and the detected pressure value will change as the weight of the object changes; then the controller is used to analyze and calculate the received pressure simulation signal, so as to detect the actual weight of the luggage on the luggage rack.

[0008] Preferably, the pressure detection unit includes a pressure sensor P1 and an instrument amplifier U1, the first output end of the pressure sensor P1 is electrically connected to the non-inverting input end of the instrument amplifier U1, and the second output end of the pressure sensor P1 is electrically connected to the inverting input end of the instrument amplifier U1; a resistor R3 is connected in series between pin 1 and pin 8 of the instrument amplifier U1, and the output end of the instrument amplifier U1 is electrically connected to the input end ADC0 of the controller.

[0009] By adopting the above technical solution, the weight of the luggage rack is collected by the pressure sensor P1 and converted into a pressure analog signal, and then the collected pressure analog signal is amplified by the instrument amplifier U1 for reception by the controller. The controller receives the amplified pressure analog signal and calculates the weight of the luggage rack.

[0010] Preferably, a connection point between the output terminal of the instrumentation amplifier U1 and the controller input terminal ADC0 is grounded via a capacitor C2.

[0011] By adopting the above technical solution, the capacitor C2 is used to perform a filtering function, so as to improve the stability of the amplified pressure analog signal.

[0012] Preferably, it also includes a zeroing unit, which includes a voltage follower U2, the output terminal Pin_2 of the controller is electrically connected to the non-inverting input terminal of the voltage follower U2 through resistors R6 and R7 in sequence, the inverting input terminal of the voltage follower U2 is electrically connected to the output terminal of the voltage follower U2, and the output terminal of the voltage follower U2 is electrically connected to the reference voltage pin 5 of the instrumentation amplifier U1.

[0013] By adopting the above technical solution, a voltage follower is used to enable the voltage output by the controller to be more stably output to the pressure detection unit as a reference voltage. When zero adjustment is required, the controller outputs a zero adjustment signal, and the zero adjustment signal is converted into a reference voltage Vref through the voltage follower U2 and output to the reference voltage pin 5 of the instrument amplifier U1 to achieve the zero adjustment function.

[0014] Preferably, the zero adjustment unit also includes a capacitor C3 and a capacitor C4, one end of the capacitor C3 is electrically connected between the resistor R6 and the resistor R7, and the other end of the capacitor C3 is grounded; one end of the capacitor C4 is electrically connected to the in-phase input terminal of the voltage follower U2, and the other end of the capacitor C4 is grounded.

[0015] By adopting the above technical solution, the stability of the controller output voltage is improved.

[0016] Preferably, the output end of the voltage follower U2 is grounded via a capacitor C5.

[0017] By adopting the above technical solution, the stability of the output voltage of the zero adjustment unit is improved.

[0018] Preferably, a voltage detection unit is further included, which includes a first switch tube T1 and a second switch tube T2, the control end of the first switch tube T1 is electrically connected to the output pin Pin_4 of the controller, the output end of the first switch tube T1 is grounded, the input end of the first switch tube T1 is electrically connected to the control end of the second switch tube T2, the system input voltage UBi is output to the input end of the second switch tube T2, the output end of the second switch tube T2 is grounded through the resistor R9 and the resistor R10 in sequence, and the connection point of the resistor R9 and the resistor R10 is electrically connected to the input pin Pin_5 of the controller.

[0019] By adopting the above technical solution, when the voltage needs to be detected, the output pin Pin_4 of the controller outputs a high level, so that the first switch tube TI is turned on, and then the second switch tube T2 is turned on. The system input voltage UBi is input to the input pin Pin_5 through the voltage division effect of the resistor R9 and the resistor R10. At this time, the controller can realize real-time detection of the working voltage of the system. If an overvoltage phenomenon occurs, the controller stops working immediately, thereby protecting the controller as much as possible.

[0020] Preferably, a communication unit is further included, the communication unit includes a communication chip and its peripheral circuits, and the communication unit is electrically connected to the controller.

[0021] By adopting the above technical solution, the system can be awakened by utilizing the communication unit.

[0022] In summary, the present application includes at least one of the following beneficial technical effects:

[0023] As the weight of objects on the luggage rack changes, the pressure analog signal output by the pressure detection unit to the controller will also change. The controller can analyze and calculate based on the received pressure analog signal, thereby realizing the detection of the actual weight of the luggage rack load. At the same time, the zeroing unit can be used to zero the measurement system, and the voltage detection unit can be used to detect the system working voltage; the communication unit can be used to wake up the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a principle block diagram of an embodiment of the present application;

[0025] Figure 2 is a circuit diagram of a pressure detection unit in an embodiment of the present application;

[0026] Figure 3 is a circuit diagram of a zeroing unit in an embodiment of the present application;

[0027] Figure 4 is a circuit diagram of a voltage detection unit in an embodiment of the present application;

[0028] Figure 5 It is a circuit diagram of the communication unit in the embodiment of the present application.

[0029] Figure numerals: 1. pressure detection unit; 2. zero adjustment unit; 3. voltage detection unit; 4. communication unit. DETAILED DESCRIPTION

[0030] The following is combined with Figure 1-5 This application is described in further detail.

[0031] The embodiment of the present application discloses a gravity sensing circuit for a car luggage rack.

[0032] Reference Figure 1 A gravity sensing circuit for a car luggage rack includes a controller, and the output end of the controller is electrically connected to a pressure detection unit 1 and a zeroing unit 2. The pressure detection unit 1 is used to collect the weight of the object to be weighed and convert the collected weight into a pressure analog signal. The collected pressure analog signal is output to the controller, which then analyzes and calculates the signal to obtain the weight of the object to be weighed. The output end of the zeroing unit 2 is electrically connected to the reference end of the pressure detection unit 1, and the zeroing unit 2 is used to zero the pressure detection unit 1 so as to detect the weight of the luggage placed on the luggage rack. In addition, this embodiment also includes a voltage detection unit 3 for detecting the working voltage in the current circuit, and the output end of the controller is also electrically connected to a communication unit 4 for waking up the system.

[0033] Reference Figure 2 The pressure detection unit 1 includes a pressure sensor P1 and an instrument amplifier U1. In the embodiment of the present application, a pressure sensor based on a Wheatstone bridge resistor is used, and the strain gauge of the pressure sensor P1 is made of a highly flexible material, which is less prone to damage. When an object is placed on the pressure sensor P1, the strain gauge is deformed, causing the resistance value of the Wheatstone bridge resistor to change, thereby causing the output voltage of the pressure sensor P1 to change. The power supply terminal 4 of the pressure sensor P1 is electrically connected to a power supply V1. In this embodiment, the power supply voltage of the power supply V1 is set to 5V; the ground terminal 2 of the pressure sensor P1 is grounded. The first output terminal 1 of the pressure sensor P1 is electrically connected to the in-phase input pin 3 of the instrument amplifier U1 through a resistor R1, and the second output terminal 3 of the pressure sensor P1 is electrically connected to the in-phase input pin 2 of the instrument amplifier U1 through a resistor R2.

[0034] Pin 7 of the instrument amplifier U1 is electrically connected to the voltage output terminal of the power supply V1, pin 4 of the instrument amplifier U1 is grounded, and output pin 6 of the instrument amplifier U1 is electrically connected to the input terminal ADC0 of the controller through resistor R4. A resistor R3 is connected in series between pin 1 and pin 8 of the instrument amplifier U1, and the amplification factor of the instrument amplifier U1 can be adjusted by adjusting the resistance value of resistor R3. The pressure analog signal output by the pressure sensor P1 can be amplified by the instrument amplifier U1 so that it can be received by the controller. Pin 5 of the instrument amplifier U1 is electrically connected to the output terminal of the zero adjustment unit 2 through resistor R5, and is used to receive the reference voltage Vref.

[0035] In addition, the voltage output terminal of the power supply V1 is grounded through the capacitor C1, thereby improving the stability of the output voltage of the power supply V1. The connection point between the resistor R4 and the controller input terminal ADC0 is grounded through the capacitor C2, and the capacitor C2 is used to improve the stability of the output voltage of the instrumentation amplifier U1.

[0036] Reference Figure 3 , the zero adjustment unit 2, which also serves as the voltage reference of the instrument amplifier U1, includes a voltage follower U2, the ground terminal of the voltage follower U2 is grounded, and the power terminal of the voltage follower U2 is electrically connected to the voltage output terminal of the power supply V1. The output terminal Pin_2 of the controller is electrically connected to the non-inverting input terminal of the voltage follower U2 through resistors R6 and R7 in sequence, and the inverting input terminal of the voltage follower U2 is electrically connected to the output terminal of the voltage follower U2, and the output terminal of the voltage follower U2 is used to output a reference voltage Vref to the pressure detection unit 1. When a zero adjustment operation is required, the output terminal Pin_2 outputs a zero adjustment signal, thereby changing the reference voltage Vref through the voltage follower U2 to achieve zero adjustment.

[0037] In order to improve the stability of the reference voltage Vref, the connection point between the resistor R6 and the resistor R7 is grounded through the filter capacitor C3, and the non-inverting input terminal of the voltage follower U2 is grounded through the filter capacitor C4. The output terminal of the voltage follower U2 is grounded through the capacitor C5, and the output terminal of the voltage follower U2 is also electrically connected to the input terminal Pin_3 of the controller through the resistor R8, which is used to detect the voltage of Vref in real time to form a closed-loop control of Vref, so as to provide an accurate Vref voltage.

[0038] Reference Figure 4The voltage detection unit 3 includes a first switch tube T1 and a second switch tube T2. In this embodiment, the first switch tube T1 is set as an NPN transistor, and the second switch tube T2 is set as a PNP transistor. The base of the first switch tube T1 is electrically connected to the output pin Pin_4 of the controller, the emitter of the first switch tube T1 is grounded, the collector of the first switch tube T1 is electrically connected to the base of the second switch tube T2, the system input voltage UBi is output to the emitter of the second switch tube T2, the collector of the second switch tube T2 is grounded through the resistor R9 and the resistor R10 in turn, and the connection point of the resistor R9 and the resistor R10 is electrically connected to the input pin Pin_5 of the controller. When the output pin Pin_4 outputs a low level, the first switch tube TI is turned off, and the second switch tube T2 is turned off. At this time, the working voltage of the system is not detected. If it is necessary to detect the working voltage of the system, the controller output pin Pin_4 outputs a high level to turn on the first switch tube TI, and then turn on the second switch tube T2. The system input voltage UBi is input to the input pin Pin_5 through the voltage divider of the resistor R9 and the resistor R10. At this time, the controller can realize real-time detection of the working voltage of the system. If overvoltage occurs, the controller will stop working immediately, thereby protecting the controller as much as possible.

[0039] refer to Figure 5 The communication unit 4 includes a communication chip U3 and its peripheral circuits, and the communication chip U3 is set as a LIN communication chip. Pin 8 of the communication chip U3 is electrically connected to the voltage output terminal of the power supply V1 and the VDDA pin and VDD pin of the controller. Pin 6 of the communication chip U3 is electrically connected to the UARTO_TX pin of the controller, pin 5 of the communication chip is electrically connected to the UARTO_RX pin of the controller, pin 2 of the communication chip U3 is electrically connected to the LIN_EN of the controller, and pin 4 of the communication chip U3 is electrically connected to the LIN of the external device, so that the external device can quickly wake up the controller through the communication unit 4.

[0040] The implementation principle of a gravity sensing circuit for a car luggage rack in an embodiment of the present application is as follows: as the weight of an object changes, its pressure value will also change accordingly. The controller can receive the pressure analog signal output by the pressure detection unit 1 to analyze and calculate the weight of the luggage rack, thereby achieving the purpose of detecting the actual weight of the luggage rack.

[0041] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A gravity sensing circuit for a car luggage rack, characterized in that: It comprises a pressure detection unit (1) and a controller, wherein the output end of the pressure detection unit (1) is electrically connected to the input end ADC0 of the controller; the pressure detection unit (1) is used to detect the weight of a luggage rack of a car and output a pressure analog signal to the controller.

2. The gravity sensing circuit for a car luggage rack according to claim 1, characterized in that: The pressure detection unit (1) comprises a pressure sensor P1 and an instrument amplifier U1, wherein a first output terminal of the pressure sensor P1 is electrically connected to a non-inverting input terminal of the instrument amplifier U1, and a second output terminal of the pressure sensor P1 is electrically connected to an inverting input terminal of the instrument amplifier U1; a resistor R3 is connected in series between pins 1 and 8 of the instrument amplifier U1, and an output terminal of the instrument amplifier U1 is electrically connected to an input terminal ADC0 of the controller.

3. The gravity sensing circuit for a luggage rack of a car according to claim 2, characterized in that: The connection point between the output terminal of the instrumentation amplifier U1 and the controller input terminal ADC0 is grounded through a capacitor C2.

4. The gravity sensing circuit for a luggage rack of a car according to claim 2, characterized in that: The invention also comprises a zero adjustment unit (2), wherein the zero adjustment unit (2) comprises a voltage follower U2, wherein the output terminal Pin_2 of the controller is electrically connected to the non-inverting input terminal of the voltage follower U2 through resistors R6 and R7 in sequence, the inverting input terminal of the voltage follower U2 is electrically connected to the output terminal of the voltage follower U2, and the output terminal of the voltage follower U2 is electrically connected to the reference voltage pin 5 of the instrumentation amplifier U1.

5. The gravity sensing circuit for a luggage rack of a car according to claim 4, characterized in that: The zero adjustment unit (2) further includes a capacitor C3 and a capacitor C4, one end of the capacitor C3 is electrically connected between the resistor R6 and the resistor R7, and the other end of the capacitor C3 is grounded; one end of the capacitor C4 is electrically connected to the in-phase input terminal of the voltage follower U2, and the other end of the capacitor C4 is grounded.

6. The gravity sensing circuit for a luggage rack of a car according to claim 4, characterized in that: The output end of the voltage follower U2 is grounded via a capacitor C5.

7. The gravity sensing circuit for a car luggage rack according to claim 1, characterized in that: The device also includes a voltage detection unit (3), the voltage detection unit (3) including a first switch tube T1 and a second switch tube T2, the control end of the first switch tube T1 is electrically connected to the output pin Pin_4 of the controller, the output end of the first switch tube T1 is grounded, the input end of the first switch tube T1 is electrically connected to the control end of the second switch tube T2, the system input voltage UBi is output to the input end of the second switch tube T2, the output end of the second switch tube T2 is grounded via a resistor R9 and a resistor R10 in sequence, and the connection point between the resistor R9 and the resistor R10 is electrically connected to the input pin Pin_5 of the controller.

8. The gravity sensing circuit for a car luggage rack according to claim 1, characterized in that: It also comprises a communication unit (4), the communication unit (4) comprising a communication chip and its peripheral circuits, and the communication unit (4) is electrically connected to the controller.

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