Vehicle-mounted smoke sensor based on dual-wavelength detection

Abstract

The utility model relates to the technical field of photoelectric smog sensing, and discloses a vehicle-mounted smog sensor based on dual-wavelength detection, which comprises an upper shell and a lower shell, the upper shell and the lower shell are detachably connected through screws, the lower shell is detachably connected with a fixed connecting plate, and the fixed connecting plate is detachably connected with the photoelectric smog sensor. The fixed connecting plate is detachably connected with an optical mounting structure, the optical mounting structure is provided with a control circuit, and the smoke sensing circuit comprises a dual-wavelength LED drive circuit, a smoke detection circuit, a detection amplification circuit and a humidity detection circuit. The smoke and non-aerosol such as dust and water mist can be identified by using the difference of long and short dual-wavelength light scattering rules of smoke and non-smoke aerosol interference sources, and the accurate alarm at the early stage of a fire can be realized.

Description

TECHNICAL FIELD

[0001] The utility model relates to photoelectric type smoke sensing technical field, concretely is a kind of vehicle-mounted smoke sensor based on double wavelength detection. BACKGROUND

[0002] At present, with the popularity of new energy vehicles and the gradual improvement of battery pack safety performance requirements, the prevention and management requirements of battery pack for thermal runaway are also improving, so the mounting rate of smoke sensor is gradually increasing. Optical smoke sensor is widely used in fire smoke detection and industrial field due to its simple production and low cost. When the smoke density exceeds the threshold value, the fire sensor will trigger an alarm.

[0003] On the one hand, the battery pack is not absolutely isolated from the outside world, and the car drives in complex road environment, the air with dust flows through the smoke sensor and stays in the smoke maze, which will make the light signal received by the receiving tube exceed the threshold value. Dust, dust and other factors can also trigger the alarm by simply comparing whether the light signal is blocked or scattered; on the other hand, new energy vehicles drive at high speed, or the car fast charges, the battery pack will generate more heat, when the air flowing through the smoke sensor and the surrounding temperature difference is large, the generated water vapor is enough to trigger the alarm. In view of this, we propose a vehicle-mounted smoke sensor based on double wavelength detection. SUMMARY

[0004] The utility model aims at providing a kind of vehicle-mounted smoke sensor based on double wavelength detection to solve the problems raised in the above background.

[0005] To achieve the above object, the utility model provides the following technical scheme: a kind of vehicle-mounted smoke sensor based on double wavelength detection, including upper shell and lower shell, the upper shell and lower shell are detachably connected by screw, the lower shell is detachably connected with fixed connecting plate, the fixed connecting plate is detachably connected with optical installation structure, the optical installation structure is provided with the circuit of control, the smoke sensing circuit includes: double wavelength LED drive circuit, smoke detection circuit, detection amplification circuit and humidity detection circuit.

[0006] Optionally, the double wavelength LED drive circuit includes LED1, the negative electrode of LED1 is electrically connected with VDD_3V3 end, the positive electrode of LED1 is electrically connected with the collector end of triode Q8, the emitter of triode Q8 is electrically connected with one end of resistor R43, the other end of resistor R43 is grounded;The base of triode Q8 is electrically connected with one end of resistor R47, the other end of resistor R47 is electrically connected with P_IR_CTRL end, the LED1 is double wavelength emitting tube, and infrared light and purple light are alternately emitted.

[0007] Optionally, the smoke detection circuit comprises a smoke detection sensor PD2 and a smoke detection sensor PD3.

[0008] Optionally, the detection amplification circuit comprises a common-mode reference voltage buffer, an OPxINP end and an OPxINN end, the OPxINP end is connected with a positive end of the signal needing amplification, the OPxINN end is connected with a negative end of the signal needing amplification, and a gain expression of a detection circuit output is Vout=VHALF+GAIN(OPxINP-OPxINN).

[0009] Optionally, the humidity detection circuit comprises a humidity-sensitive resistor RH1, two ends of the humidity-sensitive resistor RH1 are electrically connected with RH_CT- ends, one end of the humidity-sensitive resistor RH1 is electrically connected with one end of a resistor R12 and one end of a resistor R13 respectively, the other end of the resistor R13 is electrically connected with a RH_ADC_DET end, and the other end of the resistor R12 is electrically connected with a RH_CT+ end.

[0010] Optionally, the optical mounting structure comprises:

[0011] A dual-wavelength emitting tube capable of emitting infrared light and purple light;

[0012] An optical lens;

[0013] A first receiving tube for receiving infrared light;

[0014] A second receiving tube for receiving purple light.

[0015] Compared with the prior art, the vehicle-mounted smoke sensor based on dual-wavelength detection has the following beneficial effects:

[0016] The vehicle-mounted smoke sensor based on dual-wavelength detection utilizes the difference between the long and short dual-wavelength light scattering rules of smoke and non-smoke aerosol interference sources, realizes the identification of smoke and non-aerosols such as dust and water mist, and realizes the accurate early warning of fire. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 It is a structural schematic view of the whole device of the utility model;

[0018] Figure 2 It is a structural schematic view of the optical mounting structure of the utility model;

[0019] Figure 3 It is a structural schematic view of the dual-wavelength LED driving circuit and the smoke detection circuit of the utility model;

[0020] Figure 4The utility model discloses a detection amplification circuit structure schematic diagram.

[0021] Figure 5 The utility model discloses a humidity detection circuit structure schematic diagram.

[0022] In the drawing: 1, lower shell, 2, screw, 3, fixed connecting plate, 4, optical mounting structure, 41, dual-wavelength emitting tube, 42, optical lens, 43, first receiving tube, 44, second receiving tube, 5, upper shell, 6, socket, 7, connecting pipe. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the utility model will be clearly and completely described below with reference to the drawings in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by the person skilled in the art without creative labor belong to the protection scope of the utility model.

[0024] As Figures 1-5 The utility model provides a kind of technical scheme based on dual-wavelength detection's vehicle-mounted smoke sensor, including upper shell 5 and lower shell 1, upper shell 5 and lower shell 1 are detachably connected by screw 2, and detachably connected with fixed connecting plate 3 on lower shell 1, detachably connected with optical mounting structure 4 on fixed connecting plate 3, and circuit of control is provided on optical mounting structure 4, and smoke sensing circuit includes: dual-wavelength LED drive circuit, smoke detection circuit, detection amplification circuit and humidity detection circuit, and circular air hole is opened on upper shell 5 and lower shell 1, for guaranteeing the flowability of air in smoke sensor, and connecting pipe 7 is fixed on the side wall of upper shell 5.

[0025] Dual-wavelength LED drive circuit includes LED 1, the negative electrode of LED 1 is electrically connected with VDD_3V3 end, the positive electrode of LED 1 is electrically connected with the collector end of triode Q8, the emitter of triode Q8 is electrically connected with one end of resistance R43, and the other end of resistance R43 is grounded;The base of triode Q8 is electrically connected with one end of resistance R47, and the other end of resistance R47 is electrically connected with P_IR_CTRL end, and LED 1 is dual-wavelength emitting tube 41, and infrared light and purple light are alternately emitted.

[0026] Smoke detection circuit includes smoke detection sensor PD2 and smoke detection sensor PD3.

[0027] The detection amplification circuit comprises a common-mode reference voltage buffer, an OPxINP end and an OPxINN end, the OPxINP end is connected with the positive end of the signal to be amplified, the OPxINN end is connected with the negative end of the signal to be amplified, and the gain expression of the output of the detection circuit is: Vout=VHALF+GAIN(OPxINP-OPxINN). The amplified signal is directly connected to the ADC channel to realize the conversion of the optical signal into a digital signal.

[0028] The humidity detection circuit comprises a humidity-sensitive resistor RH1, two ends of the humidity-sensitive resistor RH1 are electrically connected with the RH_CT- end, one end of the humidity-sensitive resistor RH1 is electrically connected with one end of a resistor R12 and one end of a resistor R13 respectively, the other end of the resistor R13 is electrically connected with the RH_ADC_DET end, and the other end of the resistor R12 is electrically connected with the RH_CT+ end.

[0029] The optical mounting structure 4 comprises a dual-wavelength emitting tube 41, an optical lens 42, a first receiving tube 43 and a second receiving tube 44; the dual-wavelength emitting tube 41 can emit infrared light and purple light; the first receiving tube 43 receives the infrared light; and the second receiving tube 44 receives the purple light.

[0030] The dual-wavelength emitting tube 41 is mounted on one side of the optical mounting rack plate body, the first receiving tube 43 and the second receiving tube 44 are mounted on the other side of the optical mounting rack plate body, the included angle between the dual-wavelength emitting tube 41 and the first receiving tube 43 and the second receiving tube 44 is about 120°, and the dual-wavelength emitting tube 41, the optical lens 42, the first receiving tube 43 and the second receiving tube 44 jointly constitute a forward light path structure; a socket 6 is welded on the optical mounting rack plate body and is used for connecting a data line.

[0031] As an application of the embodiment, the following is provided:

[0032] The determination content of the embodiment is as follows:

[0033] A paraffin oil smoke generator is used to generate smoke at a concentration of 0.5 dB / m, and the air flow speed of the smoke box is 1 m / s. The parameters of the smoke box all meet the requirements of the national standard.

[0034] First, the purple light is emitted for 0.5 seconds, then the infrared light is turned off, then the infrared light is turned on for 0.5 seconds, then the infrared light is turned off, and the cycle is repeated.

[0035] The ADC increment ΔVp of the purple light in the last 3 seconds is calculated once per second, when the preset purple light ADC increment threshold ΔVpt=450 is exceeded, the ADC increment ΔVr of the infrared light in the last 3 seconds is calculated, when the infrared light ADC increment threshold ΔVrt=100 is exceeded, the ratio of the ADC increments of the purple light and the infrared light is calculated.

[0036] 1The increment ratio R of ADC = ΔVp / ΔVr, when the increment ratio of both is greater than the threshold value R ≥ 3.6, and the ADCs are both in the rising trend, the alarm is triggered, and the rest of the results are all determined as interference signals, which cannot trigger the smoke alarm;

[0037] Dust interference experiment, the test dust (20g, PTI dust) is placed at the bottom of the dust test box, four small power (10W) fans are fixed on both sides of the inner wall of the box, which are used for simulating the dust raising scene;

[0038] When the smoke sensing device encounters dust particles within 3 seconds, the change trends of ΔVp and ΔVr are almost consistent, the ratio of ΔVp and ΔVr of the dust is close to 1, which is less than the preset R (3.6), and the alarm cannot be triggered, so as to exclude the dust interference;

[0039] Water mist interference experiment, the humidifier is placed on the experimental box, the power is rotated to the mist output of 300mL / h, the humidifier is started and the time is counted. The main particle size of the water mist is distributed in 3um-15um;

[0040] The ΔVp and ΔVr of the smoke sensing device are contacted with the water mist within 3s. Due to the strong scattering and refraction of the water mist to the light source, the light flux in the labyrinth increases rapidly, and the concentration detected by the smoke sensor rises rapidly to the full scale. The ratio R of ΔVp and ΔVr of the water mist is always kept between 0.5-2.5, that is, less than the preset R (3.6), so the alarm cannot be triggered, and the water mist interference is excluded. At the same time, after the humidifier is started, the humidity detected by the humidity sensor rises rapidly, and soon exceeds 90%, so the humidity sensor can be used as a judgment basis of the interference source.

[0041] The above general description of the utility model is made in detail, but some modifications or improvements can be made on the basis of the utility model, which is obvious to the general technical personnel in the technical field. Therefore, the modification or improvement without departing from the spirit of the utility model is within the protection scope of the utility model.

Claims

1. A vehicle-mounted smoke sensor based on dual-wavelength detection, comprising an upper shell (5) and a lower shell (1), the upper shell (5) and the lower shell (1) are detachably connected by a screw (2), characterized in that: The lower shell (1) is detachably connected with a fixed connecting plate (3), the fixed connecting plate (3) is detachably connected with an optical mounting structure (4), the optical mounting structure (4) is provided with a controlled circuit, and the smoke sensing circuit comprises a dual-wavelength LED driving circuit, a smoke detection circuit, a detection amplification circuit and a humidity detection circuit.

2. The vehicle-mounted smoke sensor based on dual-wavelength detection according to claim 1, characterized in that: The dual-wavelength LED driving circuit comprises an LED1, a negative electrode of the LED1 is electrically connected with a VDD_3V3 end, a positive electrode of the LED1 is electrically connected with a collector end of a triode Q8, an emitter of the triode Q8 is electrically connected with one end of a resistor R43, the other end of the resistor R43 is grounded, a base of the triode Q8 is electrically connected with one end of a resistor R47, the other end of the resistor R47 is electrically connected with a P_IR_CTRL end, and infrared light and purple light are alternately emitted.

3. The vehicle-mounted smoke sensor based on dual-wavelength detection according to claim 1, characterized in that: The smoke detection circuit comprises smoke detection sensors PD2 and PD3.

4. The dual-wavelength detection based vehicle-mounted smoke sensor according to claim 1, characterized in that: The detection amplification circuit comprises a common-mode reference voltage buffer, an OPxINP end and an OPxINN end, the OPxINP end is connected with a positive end of a signal needing amplification, the OPxINN end is connected with a negative end of the signal needing amplification, a gain expression of a detection circuit output is Vout=VHALF+GAIN(OPxINP-OPxINN), the amplified signal is directly connected to an ADC channel, and optical signal to digital signal conversion is realized.

5. The dual-wavelength detection based vehicle-mounted smoke sensor according to claim 1, characterized in that: The humidity detection circuit comprises a humidity-sensitive resistor RH1, two ends of the humidity-sensitive resistor RH1 are electrically connected with RH_CT- ends, one end of the humidity-sensitive resistor RH1 is respectively electrically connected with one end of a resistor R12 and one end of a resistor R13, the other end of the resistor R13 is electrically connected with a RH_ADC_DET end, and the other end of the resistor R12 is electrically connected with a RH_CT+ end.

6. The dual-wavelength detection based vehicle-mounted smoke sensor according to claim 1, characterized in that: The optical mounting structure (4) comprises: A dual-wavelength emission tube (41) capable of emitting infrared light and purple light; An optical lens (42); A first receiving tube (43) for receiving infrared light; A second receiving tube (44) for receiving purple light.

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