Negative pressure weighing chamber

Abstract

The utility model provides a negative pressure weighing chamber in order to solve the problem that the wind speed in the negative pressure weighing chamber cannot be accurately controlled in the prior art. The negative pressure weighing chamber comprises an exhaust fan, a controller, a wind speed sensor, a speed regulation module, a fault alarm indicating lamp, a standby power supply, a control panel, a display screen and an overcurrent protection circuit. The negative pressure weighing chamber can accurately regulate and control the wind speed in the negative pressure weighing chamber in real time through the cooperative work of the controller, the wind speed sensor and the air exhaust fan. An operator can easily set the required wind speed on the control panel according to the characteristics and weighing requirements of different materials, and it is ensured that the wind speed is always stabilized within a preset range; when the exhaust fan encounters an emergency situation in a complex industrial environment and causes overcurrent, the overcurrent protection circuit can act within milliseconds, and the controller is isolated from the overcurrent danger.

Description

TECHNICAL FIELD

[0001] The utility model relates to pharmaceutical equipment technical field especially, it relates to a negative pressure weighing chamber. BACKGROUND

[0002] In the production process of medicine, the formula needs to be adjusted, and each component of the medicament is weighed. Sometimes the weighed medicament is powder, and dust will be generated during the weighing process. Because there is dust floating in the weighing chamber during weighing, in order to avoid cross contamination between different medicines, the filter is used for filtering, which is easy to be blocked after long time use, so that it needs to be disassembled and cleaned frequently.

[0003] A negative pressure weighing chamber is disclosed in Chinese patent, authorized publication number CN221160068U. The negative pressure weighing chamber disclosed in the patent comprises a weighing chamber body and an operation table. The top of the operation table is fixedly connected with an electronic weighing scale. The bottom of the inner wall of the weighing chamber box is fixedly connected with four supporting legs. The top of each of the four supporting legs is fixedly connected with the bottom of the operation table. The top of the weighing chamber box is fixedly connected with an air extraction fan. The air inlet pipe of the air extraction fan is fixedly connected with a connecting pipe. The bottom of the connecting pipe is fixedly connected with a mounting plate. The inside of the mounting plate is installed with a filter screen. The bottom of the mounting plate is fixedly connected with a suction cover. Two sockets are symmetrically fixedly connected on the inner wall of the weighing chamber box above the operation table. A door curtain is installed on the outside of the weighing chamber box. Two clamping blocks are symmetrically fixedly connected on the outside of the filter screen. Two clamping grooves are symmetrically formed in the inside of the mounting plate and matched with the clamping blocks. The two clamping blocks are slidably connected with the corresponding clamping grooves. Two protective covers are rotatably connected on the outside of the two sockets. The operation table is provided with a hollow structure. A handle is fixedly connected on the side of the filter screen close to the door curtain. The air extraction fan is electrically connected with an external control device.

[0004] However, the negative pressure weighing chamber lacks a wind speed control system, and the wind speed in the negative pressure weighing chamber cannot be accurately controlled. UTILITY MODEL CONTENTS

[0005] The utility model discloses a negative pressure weighing chamber to solve the problem that the wind speed in the negative pressure weighing chamber cannot be accurately controlled in the prior art.

[0006] The utility model discloses the technical scheme that adopts is:

[0007] A negative pressure weighing chamber comprises:

[0008] An air extraction fan;

[0009] A controller connected with the motor driver of the air extraction fan. The controller is used to control the motor rotating speed of the air extraction fan, so as to control the wind speed in the negative pressure weighing chamber.

[0010] a wind speed sensor connected with the controller; the wind speed sensor is used for measuring the wind speed in the negative pressure weighing chamber.

[0011] Further, the soundproof material is a composite structure of sound-absorbing cotton and metal sheet, the thickness of the sound-absorbing cotton is not less than 10 mm, and the thickness of the metal sheet is not less than 0.5 mm.

[0012] Further, the speed regulation module can compare the preset wind speed in the negative pressure weighing chamber with the real-time wind speed fed back by the wind speed sensor, automatically adjust the motor speed of the air exhaust fan, and make the negative pressure and the wind speed in the negative pressure weighing chamber meet the set requirements.

[0013] Further, the wind speed sensor adopts a hot-wire type wind speed sensor, and the measurement accuracy of the hot-wire type wind speed sensor reaches ±0.1 m / s.

[0014] Further, the hot-wire type wind speed sensor head is provided with a detachable protective screen.

[0015] Further, the controller is further connected with a fault alarm indicator; when the air exhaust fan or the wind speed sensor fails, the fault alarm indicator immediately lights up and flashes different colors to distinguish the fault type, and the controller sends a fault signal to an external monitoring system;

[0016] The air exhaust fan is provided with an emergency backup power supply, which automatically starts to maintain the continuous operation of the air exhaust fan when the external power supply is suddenly interrupted;

[0017] The emergency backup power supply is a rechargeable lithium battery pack.

[0018] The controller is further connected with a control panel; the real-time wind speed in the negative pressure weighing chamber can be set through the control panel.

[0019] The controller is further connected with a display screen; the display screen is used for displaying the real-time wind speed of the negative pressure weighing chamber.

[0020] Further, an overcurrent protection circuit is connected between the controller and the motor driver of the air exhaust fan, and the overcurrent protection circuit is used for protecting the safety of the controller circuit.

[0021] Further, the overcurrent protection circuit comprises:

[0022] A current transformer CT, an input end of the current transformer CT is used for detecting the current between the controller and the motor driver of the air exhaust fan;

[0023] An electronic switch SW, an input end of the electronic switch SW is connected with an output end of the current transformer CT; the output end of the current transformer CT is connected with the motor driver of the air exhaust fan.

[0024] a protection diode D, an output terminal of the protection diode D being connected with a gate of the electronic switch SW;

[0025] a comparator CMP, an output terminal of the comparator CMP being connected with an input terminal of the protection diode D, one input terminal of the comparator CMP being connected with an output terminal of the current transformer CT, and the other input terminal of the comparator CMP being connected with the controller;

[0026] a resistor R, one end of the resistor R being connected with the output terminal of the current transformer CT, and the other end of the resistor R being grounded.

[0027] Further, the electronic switch SW is turned on when the current between the controller and the motor driver of the air exhaust fan is normal, and is turned off when the current between the controller and the motor driver of the air exhaust fan is too large.

[0028] Further, the positive input terminal of the comparator CMP is connected with the output terminal of the current transformer CT, the negative input terminal of the comparator CMP is connected with the controller, the output terminal of the comparator CMP generates a high level when the voltage of the positive input terminal is 5% higher than that of the negative input terminal, and the output terminal of the comparator CMP generates a low level when the voltage of the positive input terminal is not higher than 5% than that of the negative input terminal.

[0029] The electronic switch is turned off when the gate voltage is high, and is turned on when the gate voltage is low.

[0030] The utility model discloses a beneficial effect is:

[0031] The utility model discloses a negative pressure weighing chamber passes through the cooperation of controller and air velocity sensor, air exhaust fan, can real -time accurate control the wind -speed in negative pressure weighing chamber. The operator can set the required wind -speed on the control panel according to the characteristics of different materials and weighing requirement, ensure that the wind -speed is always stable in the preset range, effectively avoid the weighing error caused by air flow fluctuation, provide solid guarantee for high -precision weighing operation.

[0032] The utility model discloses a negative pressure weighing chamber's overcurrent protection circuit can ensure the controller accurate operation, when the air exhaust fan encounters the overcurrent when the sudden condition in complex industrial environment, and overcurrent protection circuit can act in the millisecond level, will the controller and overcurrent danger isolate, ensure that the controller is always under the stable, safe current environment work, maintain its to air exhaust fan speed, wind -speed sensor data acquisition etc. accurate control function. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0034] Figure 1 The utility model scheme diagram.

[0035] Figure 2 The utility model negative pressure weighing chamber's circuit diagram of overcurrent protection circuit. Specific implementation

[0036] A negative pressure weighing chamber is disclosed in a Chinese patent with authorization publication number CN221160068U. The negative pressure weighing chamber involved in this patent includes a weighing chamber body and an operation table. The top of the operation table is fixedly connected with an electronic weight scale. The bottom of the inner wall of the weighing chamber box is fixedly connected with four supporting legs. The top of each of the four supporting legs is fixedly connected with the bottom of the operation table. The top of the weighing chamber box is fixedly connected with an air extraction fan. The air inlet pipe of the air extraction fan is fixedly connected with a connecting pipe. The bottom of the connecting pipe is fixedly connected with a mounting plate. A filter screen is installed inside the mounting plate. The bottom of the mounting plate is fixedly connected with an air suction cover. Two sockets are symmetrically fixedly connected to the inner wall of the weighing chamber box above the operation table. A door curtain is installed on the outside of the weighing chamber box. Two clamping blocks are symmetrically fixedly connected to the outside of the filter screen. Two clamping grooves that cooperate with the clamping blocks are symmetrically formed in the inside of the mounting plate. Each of the two clamping blocks is in sliding connection with the corresponding clamping groove. Two protective covers are rotatably connected to the outside of the two sockets. The operation table is in a hollow structure. A handle is fixedly connected to the side of the filter screen close to the door curtain. The air extraction fan is electrically connected with external control equipment.

[0037] However, the negative pressure weighing chamber lacks a wind speed control system, which cannot accurately control the wind speed in the negative pressure weighing chamber.

[0038] The utility model discloses a negative pressure weighing chamber to solve the problem that the wind speed in the negative pressure weighing chamber cannot be accurately controlled in the prior art.

[0039] In the description of the utility model, it is understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" is the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the utility model and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the utility model.

[0040] The embodiments provided in the following disclosure are used to realize the structure of the utility model. In order to simplify the disclosure of the utility model, the components and settings of specific examples are described below. Of course, it is only an example, and the purpose is not to limit the utility model.

[0041] The embodiments of the utility model will be described in detail below with reference to the drawings.

[0042] The background of the negative pressure weighing chamber disclosed in the embodiment is as follows:

[0043] In the pharmaceutical, chemical, food and other industries, the accurate weighing of materials and the safety of the working environment have very high requirements. The traditional weighing chamber is difficult to accurately control ventilation, which is easy to cause dust or harmful gas accumulation, endangering personnel health and product quality. The negative pressure weighing chamber disclosed in the embodiment aims to solve these problems and provide a stable and reliable weighing environment.

[0044] The schematic diagram of the scheme of the negative pressure weighing chamber disclosed in the embodiment is shown in the accompanying Figure 1 Fig. 1.

[0045] The equipment composition of the negative pressure weighing chamber disclosed in the embodiment includes:

[0046] Exhaust fan:

[0047] The exhaust fan of the negative pressure weighing chamber disclosed in the embodiment selects an industrial exhaust fan with a model number of 4-72, the shell of which adopts a composite structure of sound-absorbing cotton and metal sheet, the thickness of the sound-absorbing cotton reaches 12 mm, and high-quality soundproof and sound-absorbing cotton material is selected, which can effectively reduce the noise of the fan during operation. The thickness of the metal sheet is 0.6 mm, and the material is 304 stainless steel, which has good strength and corrosion resistance, can protect the internal sound-absorbing cotton, and also has a protective effect. The exhaust fan is equipped with a motor with a power of 2.2 kW, and the motor driver selects the FR-E700 series of Mitsubishi, which has precise speed regulation performance and can receive the speed regulation signal sent by the controller to control the exhaust air volume.

[0048] Controller:

[0049] The controller of the negative pressure weighing chamber disclosed in the embodiment adopts a Siemens S7-1200 series programmable logic controller (PLC) as a core controller, and is internally provided with a speed regulation module, so that the air exhaust fan can be operated at a speed according to preset requirements.

[0050] The controller of the negative pressure weighing chamber disclosed in the embodiment is connected with a control panel, through which an operator can conveniently set a real-time air speed in the negative pressure weighing chamber, the input range being 0.1-1 m / s, and the accuracy being up to 0.05 m / s. The controller is also connected with a display screen, which can clearly and directly display information such as the real-time air speed of the negative pressure weighing chamber and the running state of the fan, so as to facilitate real-time monitoring by the operator.

[0051] Air speed sensor:

[0052] The air speed sensor of the negative pressure weighing chamber disclosed in the embodiment selects an EE65 hot-wire type air speed sensor of E+E, the measurement accuracy of which is ±0.1 m / s, and which can accurately measure the air speed in the negative pressure weighing chamber. The sensor head is provided with a detachable protective screen, which is woven with 316 stainless steel wires, and the mesh size thereof is 0.5 mm x 0.5 mm, so as to effectively prevent dust and impurities from entering the sensor and affecting the measurement accuracy, and also to facilitate regular disassembly and cleaning, thereby ensuring long-term stable operation of the sensor.

[0053] Fault alarm and emergency system:

[0054] The controller of the negative pressure weighing chamber disclosed in the embodiment is connected with a fault alarm indicator. When the air exhaust fan has a motor overheating fault, and the temperature exceeds 80℃, the fault alarm indicator is lit red and flashes at a frequency of 2 times per second. When the air speed sensor has a line short circuit fault, and the resistance value is lower than 10 ohms, the indicator is lit yellow and flashes at a frequency of 1 time per second. At the same time, the controller sends a fault signal to an external monitoring system through an RS485 communication interface. The external monitoring system is a Kingview 6.55 host computer software installed in a central control room, which can receive and record fault information in real time, and timely notify maintenance personnel.

[0055] The air exhaust fan of the negative pressure weighing chamber disclosed in the embodiment is provided with an emergency backup power supply, which adopts a 50Ah rechargeable lithium battery group of BYD. When external power supply is suddenly interrupted, a detection circuit built in the emergency backup power supply detects voltage change within 0.5 seconds, and automatically starts to provide continuous power support for the air exhaust fan, so as to ensure uninterrupted ventilation function of the negative pressure weighing chamber and maintain stable indoor negative pressure environment.

[0056] Overcurrent protection circuit, the circuit diagram of the overcurrent protection circuit of the negative pressure weighing chamber disclosed in the embodiment is shown in FIG. 2. Figure 2

[0057] ​Current transformer CT: Choose open and close type current transformer, the ratio is selected according to the rated current of the air extractor motor, for example, the motor rated current is 10A, the current transformer with a ratio of 20:1 can be selected, and the measurement accuracy can reach ±1%. It is installed on the main power cable connecting the air extractor motor and the controller to ensure that the current signal of the motor running can be accurately captured, and the secondary winding output current is in the range of 0-5A.

[0058] Electronic switch SW: Choose MOSFET transistor as electronic switch, its input end is connected with the output end of current transformer CT, when the current between the controller and the motor driver of air extractor is normal, the electronic switch SW is on, which ensures the normal power supply of the circuit; when the current is too large, the electronic switch SW is off, which cuts off the power supply of the motor driver to protect the safety of the controller circuit.

[0059] Protection diode D: Choose ordinary silicon diode, such as IN4007, its output end is connected with the gate of electronic switch SW, which is used to prevent damage to electronic switch caused by reverse voltage.

[0060] Comparator CMP: Use LM393 comparator, its positive input end is connected with the output end of current transformer CT, and its negative input end is connected with the controller. When the voltage of the positive input end of comparator CMP is 5% higher than that of the negative input end, the output end of comparator CMP generates high level; when the voltage of the positive input end of comparator CMP is not higher than 5% than that of the negative input end, the output end of comparator CMP generates low level.

[0061] Resistance R: Choose 100Ω resistance, one end is connected with the output end of current transformer CT, and the other end is grounded, which is used to convert the current signal output by current transformer CT into voltage signal for comparison and judgment by comparator CMP.

[0062] The working process of the negative pressure weighing chamber disclosed in the embodiment is as follows:

[0063] Starting stage:

[0064] Turn on the 380V three-phase alternating current external power supply, the controller first performs self-checking to check whether each connected part communicates normally, whether the air speed sensor works normally, and whether the air extractor can start normally. After the self-checking is passed, the controller reads the preset air speed value, and if the control panel is not set, it defaults to start the air extractor according to the air speed of 0.3m / s. The controller sends a start signal to the motor driver of the air extractor, the motor starts, drives the fan blade to rotate, and starts to extract air to form a negative pressure environment in the negative pressure weighing chamber.

[0065] Running stage:

[0066] The wind speed sensor measures the indoor wind speed in real time and transmits the data to the controller. The speed regulation module of the controller automatically adjusts the motor speed of the air extractor according to the comparison between the preset wind speed and the real-time wind speed. For example, when weighing materials prone to dust, the indoor airflow disturbance increases, and the wind speed sensor detects that the wind speed rises to 0.6 m / s. The speed regulation module immediately adjusts the motor speed to make the wind speed fall within the preset range.

[0067] The operator can adjust the preset wind speed at any time through the control panel. If it is necessary to improve the ventilation efficiency, the wind speed is adjusted to 0.8 m / s. After receiving the instruction, the controller quickly adjusts the fan speed to meet the new ventilation demand.

[0068] The display screen updates the indoor wind speed, fan speed, and other key information in real time, making it easy for the operator to monitor the equipment operation status.

[0069] At the same time, the current transformer CT monitors the current between the controller and the motor driver of the air extractor in real time, converts the current signal into a voltage signal, and transmits it to the comparator CMP. The comparator CMP compares the voltage signal with the reference voltage given by the controller. When it detects that the current exceeds the set threshold (i.e., the positive input voltage is 5% higher than the negative input voltage), the comparator CMP outputs a high level, making the protection diode D conductive, and then making the gate voltage of the electronic switch SW high, causing the electronic switch SW to open and cut off the power supply of the motor driver of the air extractor, preventing overcurrent damage to the controller.

[0070] Fault response phase:

[0071] If the air extractor runs for a long time under high load during operation, the motor temperature exceeds 80℃, and the temperature sensor triggers an alarm signal to the controller, the controller determines that the air extractor is faulty, immediately lights up the red fault alarm indicator and sends a fault signal to the external monitoring system, at the same time controls the fan to stop running, starts the emergency backup power supply, maintains the indoor negative pressure, and prevents harmful gas leakage.

[0072] If the wind speed sensor line is short-circuited due to aging, causing abnormal fluctuations in the measurement data, the controller detects that the wind speed data is outside the reasonable range, determines that the wind speed sensor is faulty, lights up the yellow fault alarm indicator, and also sends a fault signal to the external monitoring system, reminding the maintenance personnel to replace or repair the sensor in time. After the maintenance personnel repair the fault, press the reset button on the controller, the equipment reenters the normal operation state.

[0073] The negative pressure weighing chamber disclosed in the embodiment can realize real-time and accurate regulation and control of the wind speed in the negative pressure weighing chamber through the cooperation of the controller, the wind speed sensor and the air extraction fan. The operator can easily set the required wind speed on the control panel according to the characteristics of different materials and weighing requirements, ensure that the wind speed is always stable in the preset range, effectively avoid the weighing error caused by air flow fluctuation, and provide a solid guarantee for high-precision weighing operation. The overcurrent protection circuit of the negative pressure weighing chamber disclosed in the embodiment can ensure the accurate operation of the controller. When the air extractor encounters an overcurrent caused by a sudden situation in a complex industrial environment, the overcurrent protection circuit can act within milliseconds to isolate the controller from the overcurrent danger, ensure that the controller always works in a stable and safe current environment, and maintain its accurate control functions such as air extractor speed and wind speed sensor data acquisition.

Claims

1. A negative pressure weighing chamber, characterized in that, include: Exhaust fan; A controller, which is connected to the motor driver of the exhaust fan; The controller is used to control the motor speed of the exhaust fan, thereby controlling the wind speed in the negative pressure weighing chamber. A wind speed sensor is connected to the controller; the wind speed sensor is used to measure the wind speed in the negative pressure weighing room.

2. The negative pressure weighing chamber according to claim 1, characterized in that, The outer casing of the exhaust fan is made of sound-insulating material, which is a composite structure of sound-absorbing cotton and thin metal plate. The thickness of the sound-absorbing cotton is not less than 10mm, and the thickness of the thin metal plate is not less than 0.5mm.

3. The negative pressure weighing chamber according to claim 1, characterized in that, The controller has a built-in speed control module, which can automatically adjust the motor speed of the exhaust fan by comparing the wind speed in the preset negative pressure weighing chamber with the real-time wind speed fed back by the wind speed sensor, so that the negative pressure and wind speed in the negative pressure weighing chamber can meet the set requirements.

4. A negative pressure weighing chamber according to any one of claims 1 to 3, characterized in that, The wind speed sensor uses a hot-wire wind speed sensor, which has a measurement accuracy of ±0.1 m / s.

5. A negative pressure weighing chamber according to claim 4, characterized in that, The hot-wire anemometer head has a removable protective filter.

6. A negative pressure weighing chamber according to any one of claims 1 to 3, characterized in that, The controller is also connected to a fault alarm indicator light; when the exhaust fan or the wind speed sensor malfunctions, the fault alarm indicator light immediately lights up and flashes different colors to distinguish the fault type, and at the same time the controller sends a fault signal to the external monitoring system. The exhaust fan is equipped with an emergency backup power supply. When the external power supply is suddenly interrupted, the emergency backup power supply will automatically start to keep the exhaust fan running. The emergency backup power source is a rechargeable lithium battery pack. The controller is also connected to a control panel; the real-time wind speed in the negative pressure weighing chamber can be set through the control panel. The controller is also connected to a display screen; the display screen is used to display the real-time wind speed of the negative pressure weighing chamber.

7. A negative pressure weighing chamber according to claim 6, characterized in that, An overcurrent protection circuit is connected between the controller and the motor driver of the exhaust fan. The overcurrent protection circuit is used to protect the controller circuit.

8. A negative pressure weighing chamber according to claim 7, characterized in that, The overcurrent protection circuit includes: A current transformer (CT) is used to detect the current between the controller and the motor driver of the exhaust fan. Electronic switch SW, the input terminal of electronic switch SW is connected to the output terminal of current transformer CT; the output terminal of current transformer CT is connected to the motor driver of the exhaust fan. Protection diode D, the output terminal of protection diode D is connected to the gating connection of electronic switch SW; The comparator CMP has its output connected to the input of the protection diode D; one input of the comparator CMP is connected to the output of the current transformer CT; and the other input of the comparator CMP is connected to the controller. A resistor R is connected at one end to the output terminal of a current transformer (CT); the other end of the resistor R is grounded.

9. A negative pressure weighing chamber according to claim 8, characterized in that, The electronic switch SW is turned on when the current between the controller and the motor driver of the exhaust fan is normal, and turned off when the current between the controller and the motor driver of the exhaust fan is too high.

10. A negative pressure weighing chamber according to any one of claims 8 to 9, characterized in that, The positive input terminal of the comparator CMP is connected to the output terminal of the current transformer CT; the negative input terminal of the comparator CMP is connected to the controller; when the voltage at the positive input terminal of the comparator CMP is 5% higher than the voltage at the negative input terminal, the output terminal of the comparator CMP generates a high level; when the voltage at the positive input terminal of the comparator CMP is no more than 5% higher than the voltage at the negative input terminal, the output terminal of the comparator CMP generates a low level. The electronic switch is open when the gate voltage is high; it is closed when the gate voltage is low.

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