CN206710908U - Forced draft differential pressure controller - Google Patents

Abstract

The utility model discloses a differential pressure controller for positive pressure air supply, which comprises a base, an upper cover, a differential pressure sensor and a control circuit board, wherein the differential pressure sensor and the control circuit board are electrically connected to each other and are arranged on the base In the cavity formed by connecting with the upper cover, the base is provided with a fixing hole; the control circuit board includes a signal amplification and conditioning circuit, a signal processing circuit and a switch control signal output circuit electrically connected to each other. The utility model has simple structure and convenient installation, can improve the precision and reliability of output control, and has strong flexibility and stability.

Description

Differential pressure controller for positive pressure air supply

technical field

The utility model relates to the technical field of electrical control, in particular to a differential pressure controller for positive pressure air supply.

Background technique

Positive pressure air supply, as an effective smoke prevention method for stairwells (hereinafter referred to as "stairwells") and front rooms (shared front rooms), has been widely accepted and adopted in the design of high-rise buildings at home and abroad. Regardless of domestic or foreign fire protection codes, there are consistent pressurization requirements, that is, in the event of a fire, the pressure in the stairwell>the pressure in the front room>the pressure in the corridor or room.

The reason why the residual pressure in the stairwell is greater than that in the front room is because from the evacuation direction of the people at the fire scene, people first enter the corridor from the room, then enter the front room (before the elevator) through the corridor, and then enter the stairwell. When the flow of people is large, the fire doors of the front room and the stairwell will open at the same time. At this time, the flow direction of the positive pressure air supply should flow from the stairwell to the front room and then to the aisle, so as to achieve the effect of smoke prevention.

According to the latest national standard of the People's Republic of China "Code for Fire Protection Design of Buildings" (GB50016-2014), the corresponding provisions are as follows:

8.5.1 Smoke prevention facilities shall be installed in the following places or parts of the building:

1 Smoke-proof stairwell and its front room;

2 The front room of the fire elevator room or the shared front room;

3 The front room and refuge floor (room) of the refuge corridor.

"Code for Fire Protection Design of Buildings" (GB50016-2006) stipulates the residual pressure value of smoke-proof stairwells and elevator front rooms:

9.3.3 The residual pressure of the mechanical pressurized air supply and smoke prevention system in the smoke-proof stairwell should be 40-50Pa; the front room and shared front room should be 25-30Pa.

Relevant provisions of "Code for Fire Protection Design of High-Rise Civil Buildings" (GB 50045-95) (2005 Edition):

8.3.1 The following locations shall be provided with independent smoke prevention facilities for mechanical pressurized air supply:

8.3.1.1 The smoke-proof stairwell, the front room of the fire elevator room or the shared front room without natural smoke exhaust conditions.

8.3.1.2 The smoke-proof stairwell with natural smoke exhaust measures does not have a front room with natural smoke exhaust conditions.

8.3.1.3 Closed refuge floors (rooms).

8.3.7 For the total pressure of the mechanically pressurized blower, in addition to calculating the head loss of the most unfavorable ring pipeline, there should be residual pressure. The remaining pressure values shall meet the following requirements:

8.3.7.1 40Pa to 50Pa for smoke-proof stairwells.

8.3.7.2 25Pa to 30Pa for the front room, shared front room, fire elevator room front room and closed refuge floor (room).

The "Technical Specifications for Smoke Prevention and Exhaust Systems of Buildings" also clearly regulates the residual pressure value of smoke prevention stairwells and elevator front rooms:

3.3.15 The mechanically pressurized air supply should meet the pressure distribution of the corridor-front room-staircase, and the residual pressure value should meet the following requirements:

1. The pressure difference between the front room, the shared front room, the fire elevator front room, the closed refuge floor (room) and the walkway should be 25-30Pa;

2. The pressure difference between the smoke-proof stairwell and the smoke-proof elevator shaft and the walkway should be 40-50Pa.

In the prior art, the following three methods are usually used to realize differential pressure control:

1. Use the residual pressure valve to control the positive pressure value in the stairwell and the front room. The residual pressure valve is a device set up to maintain a certain indoor static pressure and realize the energy-free automatic control of the positive pressure of the air-conditioned room. Hammer position to balance wind pressure. However, there are the following problems in adopting the residual pressure valve: (1) The residual pressure valve is a mechanical structure, which is easy to rust after a long time of use, resulting in failure to operate in the event of a fire. (2) The measurement error of the residual pressure valve is large. (3) The residual pressure valve takes up a lot of space, and it is especially difficult to install on-site in civil high-rise buildings.

2. Use side conversion fan to control the positive pressure value of pressurized air supply. The following problems exist in the use of frequency conversion fans to control the positive pressure of pressurized air supply: (1) The system adds frequency converters and selects speed-adjusting fans, and the cost is high; (2) The wiring of the system is complicated, which is not conducive to on-site construction; (3) The most important One point, according to the "Code for Design of Civil Buildings", the control circuit of fire-fighting equipment must not use frequency converters as control devices. Therefore this scheme fundamentally cannot be applied in this occasion.

3. Use a mechanical differential pressure switch to control the differential pressure value. The following problems exist in this scheme: (1) The differential pressure switch is a mechanical structure. After a long time of use, the internal diaphragm is deformed by gravity, which changes the measured differential pressure value, resulting in failure to operate or no pressure in the event of a fire. Time lag action. (2) The measurement error of the mechanical differential pressure switch is extremely large, which cannot meet the specification requirements. (3) The differential pressure switch takes up a lot of space, especially when it is installed on-site in civil high-rise buildings.

Contents of the invention

The technical problem to be solved by the utility model is to provide a differential pressure controller for positive pressure air supply which is easy to install, has high precision of differential pressure control, and reliable control output.

In order to solve the above technical problems, the utility model provides a differential pressure controller for positive pressure air supply, including a base, an upper cover, a differential pressure sensor and a control circuit board, wherein the differential pressure sensor and the control circuit board are electrically connected to each other connected, and set in the cavity formed by the connection between the base and the upper cover, the base is provided with a fixing hole; the control circuit board includes a signal amplification and conditioning circuit, a signal processing circuit and a switch control signal output electrically connected to each other circuit.

As an improvement to the above solution, the fixing holes include two installation and fixing holes, and the distance between the installation and fixing holes is 55-65 mm.

As an improvement of the above solution, the fixing holes include four connecting and fixing holes, and the distance between two adjacent connecting and fixing holes is 65-75 mm.

As an improvement of the above solution, the upper cover is provided with a display screen for displaying the differential pressure value, and the display screen is connected to the control circuit board.

As an improvement of the above solution, the signal processing circuit includes a control chip, an amplifier circuit, a power processing circuit, and a power indicating circuit that are electrically connected to each other; the control chip is provided with a first pin, a second pin, a third tube pin, the fourth pin, the fifth pin, the sixth pin, the seventh pin and the eighth pin; the first pin is connected to the power supply through the power processing circuit, and the second pin is connected to the jumper circuit, the third pin is connected to the power indicating circuit, the fourth pin is connected to the power supply through the power processing circuit, the sixth pin is connected to the output end of the signal amplification and conditioning circuit, and the seventh pin is amplified The circuit is connected to the input end of the switching value control signal output circuit, and the eighth pin is grounded.

As an improvement to the above solution, the signal amplification and conditioning circuit is provided with an adjustable potentiometer for adjusting the preset upper limit and the preset lower limit, and the adjustable potentiometer is electrically connected to the signal processing circuit.

Implementing the utility model has the following beneficial effects:

The utility model can be widely used in the pressure difference measurement and control of building positive pressure air supply systems, indoor and outdoor pressure difference measurement and control, filter blockage monitoring and other industries. specifically:

The differential pressure controller for positive pressure air supply of the utility model includes a base, an upper cover, a differential pressure sensor and a control circuit board, the base and the upper cover are fixed to form a shell with a cavity, and the differential pressure sensor and the control circuit board are electrically connected to each other It is connected and packaged in the cavity through the base to achieve fixation, the structure is simple, and the installation is convenient.

The base and the lower cover of the utility model are fixed to each other through connection and fixing holes and installation and fixing holes, wherein the distance between two adjacent connection and fixing holes is 65~75mm, and the distance between the installation and fixing holes is 55~65mm , can be efficiently adapted to the standard 86 bottom box, and has strong versatility.

The utility model introduces a special control circuit (signal amplification and conditioning circuit, signal processing circuit and switching value control signal output circuit). When working, the pressure difference sensor detects the pressure difference value in real time, and the signal amplification and conditioning circuit amplifies the pressure difference value and amplifies it. The final pressure difference value is converted into a pressure difference electrical signal. When the pressure difference electrical signal is greater than or equal to the preset upper limit value, the signal processing circuit drives the switching value control signal output circuit to output a closing switch signal or an opening switch signal to reduce the pressure difference. Electric signal, when the differential pressure electric signal is reduced to less than or equal to the preset lower limit, the signal processing circuit drives the switch control signal output circuit to output the open switch signal or close switch signal; thus ensuring that the output action signal and the output reset signal are always It is between the required values, which greatly improves the accuracy and reliability of the output control, and has strong flexibility. At the same time, the utility model introduces a differential pressure sensor as a supporting signal amplification and conditioning circuit for the differential pressure measurement element, so that the signal output has the characteristics of high precision and good stability.

Description of drawings

Fig. 1 is the front view of the differential pressure controller for positive pressure air supply of the present invention;

Fig. 2 is a cross-sectional view of the differential pressure controller for positive pressure air supply of the present invention;

Fig. 3 is a partial enlarged view of part A in Fig. 2;

Fig. 4 is a cross-sectional view of the utility model after the pressure difference controller for positive pressure air supply is installed with the lower cover;

Fig. 5 is a top view of the utility model after the differential pressure controller for positive pressure air supply is removed from the upper cover;

Fig. 6 is a schematic circuit diagram of a differential pressure sensor and a control circuit board in a differential pressure controller for positive pressure air supply of the present invention;

Fig. 7 is a schematic diagram of the first embodiment of the differential pressure controller for positive pressure air supply of the present invention;

Fig. 8 is a schematic diagram of the second embodiment of the differential pressure controller for positive pressure air supply of the present invention.

detailed description

In order to make the purpose, technical solution and advantages of the utility model clearer, the utility model will be further described in detail below in conjunction with the accompanying drawings. It is only a statement that the orientation words such as up, down, left, right, front, back, inside, and outside appearing or about to appear in the text of the utility model are only based on the accompanying drawings of the utility model, and it is not a reference to the utility model. New specific restrictions.

Referring to Figures 1 to 6, Figures 1 to 6 show the specific structure of the differential pressure controller for positive pressure air supply of the present invention, which can meet the dual requirements of measurement and control at the same time.

As shown in Figures 1 to 3, the differential pressure controller for positive pressure air supply of the present invention includes a base 1, an upper cover 4, a differential pressure sensor 3 and a control circuit board 2; the base 1 and the upper cover 4 are fixed to each other to form A housing with a cavity is used to provide a carrier for the differential pressure sensor 3 and the control circuit board 2; the differential pressure sensor 3 and the control circuit board 2 are electrically connected to each other and are packaged in the cavity through the base 1 to achieve fixation; the structure Simple and easy to install.

As shown in FIG. 4 and FIG. 5 , fixing holes (including installation fixing holes and/or connection fixing holes) are provided on the base 1 . Specifically, the base 1 is provided with two installation and fixing holes, and the center distance B between the installation and fixing holes is 55-65 mm. In addition, the base 1 is provided with four connection and fixing holes, and the center distance C between two adjacent connection and fixing holes is 65-75 mm.

It should be noted that the differential pressure controller with switch output can be used in conjunction with the lower cover 6 . Among them, the lower cover 6 can be selected from the standard 86 bottom box in the current market. During the construction process, the lower cover 6 (that is, the 86 bottom box) can be pre-embedded. The fixing holes and/or the four connection fixing holes are directly installed and fixed on the lower cover 6 (namely, the 86 bottom box), which greatly improves the convenience of construction. Correspondingly, ensure that the distance B between the mounting and fixing holes is 55~65mm, and the distance C between two adjacent connecting and fixing holes is 65~75mm, which can be efficiently adapted to the standard 86 bottom box and has strong versatility.

As can be seen from the above, the control part in the utility model is composed of a differential pressure sensor 3 and a control circuit board 2, wherein the differential pressure sensor 3 is used to measure the differential pressure value, and the control circuit board 2 is used to control the differential pressure of the differential pressure sensor 3. The value is amplified, converted, etc., and the switch value is output to control the state of the pressure relief valve to achieve differential pressure adjustment.

As shown in Figure 6, the control circuit board 2 has the functions of signal amplification, conversion and setting switch control signal output, specifically, the control circuit board 2 includes a signal amplification and conditioning circuit D, a signal processing circuit E and a switch Quantity control signal output circuit F, the pressure difference sensor 3, signal amplification and conditioning circuit D, signal processing circuit E and switching quantity control signal output circuit F are electrically connected to each other.

Referring to Fig. 6, during operation, the differential pressure sensor 3 detects the differential pressure value in real time, and the signal amplification and conditioning circuit D amplifies the differential pressure value and converts the amplified differential pressure value into a differential pressure electrical signal, when the differential pressure electrical signal When it is greater than or equal to the preset upper limit value, the signal processing circuit E drives the switching value control signal output circuit F to output a closing switch signal or an opening switch signal to reduce the voltage difference electrical signal, when the voltage difference electrical signal is reduced to less than or equal to When the lower limit is preset, the signal processing circuit E drives the switching value control signal output circuit F to output an open switch signal or a close switch signal.

For example, the differential pressure sensor 3 detects the differential pressure value in real time, and the signal amplification and conditioning circuit D amplifies the differential pressure value and converts the amplified differential pressure value into a differential pressure electrical signal. When the differential pressure electrical signal is greater than or equal to the preset When the upper limit is P1, the signal processing circuit E drives the switching value control signal output circuit F to output a closed switch signal to reduce the differential pressure electrical signal. When the differential pressure electrical signal decreases to less than or equal to the preset lower limit P2, the The signal processing circuit E drives the switching value control signal output circuit F to output a disconnection switch signal. It should be noted that during the process of the voltage difference electrical signal decreasing to less than or equal to the preset lower limit value P2, the switching value control signal output circuit F keeps outputting the closing switch signal to reduce the voltage difference electrical signal. Correspondingly, the preset upper limit P1 is preferably 50PA, and the preset lower limit P2 is preferably 40PA; or, the preset upper limit P1 is preferably 30PA, and the preset lower limit P2 is preferably It is 25PA.

As another example, the differential pressure sensor 3 detects the differential pressure value in real time, the signal amplification and conditioning circuit D amplifies the differential pressure value and converts the amplified differential pressure value into a differential pressure electrical signal, when the electrical differential pressure signal is greater than or equal to the preset When the upper limit P1 is set, the signal processing circuit E drives the switching value control signal output circuit F to output a disconnection switch signal to reduce the differential pressure electrical signal. When the differential pressure electrical signal decreases to less than or equal to the preset lower limit P2 , the signal processing circuit E drives the switching value control signal output circuit F to output a closing switch signal. It should be noted that during the process of the voltage difference electrical signal decreasing to less than or equal to the preset lower limit value P2, the switching value control signal output circuit F keeps outputting the disconnection switch signal to reduce the voltage difference electrical signal. Correspondingly, the preset upper limit P1 is preferably 50PA, and the preset lower limit P2 is preferably 40PA; or, the preset upper limit P1 is preferably 30PA, and the preset lower limit P2 is preferably It is 25PA.

Therefore, the utility model uses the pressure difference sensor 3 to detect the pressure difference value in real time, and converts the pressure difference value into a pressure difference electrical signal through the signal amplification and conditioning circuit D, and at the same time, amplifies and outputs the weak pressure difference electrical signal as a corresponding pressure difference Differential electrical signal (the differential pressure electrical signal is a standard analog signal), and then input the differential electrical signal to the signal processing circuit E, when the electrical differential pressure signal reaches the preset value (preset upper limit, preset lower limit) , through the switch control signal output circuit F, the differential pressure electrical signal is converted into a switch signal (open switch signal, close switch signal), thereby realizing signal conversion control.

Further, the upper cover is provided with a display screen for displaying the differential pressure value, and the display screen is connected with the signal processing circuit E. The display screen can be conveniently used to observe the differential pressure values of the two measured differential pressure areas, which is more intuitive.

Below in conjunction with Fig. 6 the utility model is further described.

The input end of the signal processing circuit E is connected to the output end of the signal amplification and conditioning circuit D, and the output end of the signal processing circuit E is connected to the input end of the switching value control signal output circuit F. Specifically, the signal processing circuit D includes a control chip IC1, an amplification circuit, a power processing circuit, and a power indicating circuit that are electrically connected to each other. Wherein, the control chip IC1 is provided with a first pin, a second pin, a third pin, a fourth pin, a fifth pin, a sixth pin, a seventh pin and an eighth pin; The first pin is connected to a power supply through a power processing circuit; the second pin is connected to a jumper circuit; the third pin is connected to a power indicating circuit, and the power indicating circuit is used to indicate whether the power is turned on; The fourth pin is connected to the power supply through the power processing circuit; the sixth pin is connected to the output end of the signal amplification and conditioning circuit D; the seventh pin is connected to the input end of the switch control signal output circuit F through the amplifying circuit ; The eighth pin is grounded. At the same time, the control chip is provided with a comparison circuit, which can realize a simple comparison function, and the control chip IC1 is preferably a HT46R005 chip.

Correspondingly, the power processing circuit is provided with a second control chip U2, and the second control chip U2 is provided with VIN pins, +5V pins and GND pins, and the VIN pins are connected to the power supply +24V, The +5V pin is the output end of the power processing circuit and is the power supply of +5V output by the signal amplification and conditioning circuit D and the control chip IC1 respectively, the GND pin is grounded, and the second control chip U2 is preferably a 78L05 chip; The amplifying circuit includes a resistor R2, a triode Q1 and a diode LED1 electrically connected to each other, the base of the triode Q1 is connected to one end of the resistor R2, the emitter is grounded, and the collector is respectively connected to the positive pole of the diode LED1 and the switch control signal output circuit The input end of F is connected, the other end of the resistor R2 is connected to the seventh pin, and the cathode of the diode LED1 is connected to the power supply +24V.

It should be noted that the signal processing circuit E mainly amplifies the standard signal output by the signal conditioning circuit D, and controls the control signal output and control signal reset through the control chip IC1. In addition, the signal processing circuit E has an output hold function, that is, after the output action, the action is reset after the pressure difference drops to a certain value, so as to realize the setting and adjustment of the action value and reset value, and ensure the output action signal And the output reset signal is always between the required values, which greatly improves the accuracy and reliability of the output control.

The signal amplification and conditioning circuit D is connected to a power supply through a power processing circuit or to a stable power supply through other means. Specifically, the signal amplification and conditioning circuit D includes a first operational amplifier ICa, a second operational amplifier ICb, a third operational amplifier ICc, and a fourth operational amplifier ICd that are electrically connected to each other, thereby forming a differential amplifier circuit; wherein, the first The positive pole of the power supply of an operational amplifier ICa is connected to the power processing circuit, and the negative pole of the power supply is grounded. connected to the differential pressure sensor 3; the inverting input terminal of the second operational amplifier ICb is connected to the signal processing circuit E through the resistor R6 and connected to the output terminal of the fourth operational amplifier ICd through the resistors (VR2, R7), and connected to the non-inverting output terminal The differential pressure sensor 3, the output terminal is connected to the signal processing circuit; the reverse input terminal of the third operational amplifier ICc is connected to the output terminal of the fourth operational amplifier ICd through a resistor R7, and the non-inverting output terminal is connected to the differential pressure sensor 3 through a resistor VR1, The output terminal is connected to the output terminal of the second operational amplifier ICb and the output terminal of the fourth operational amplifier ICd through resistors (R4, C2); the inverting input terminal of the fourth operational amplifier ICd is connected to the output terminal of the fourth operational amplifier ICd, The non-inverting output terminal is connected to the power processing circuit through the resistor (VR3, R8) and grounded through the resistor VR3, and the output terminal is connected to the signal processing circuit E through the resistor (R7, VR2, R6). Preferably, the utility model adopts the SMI5651-001 differential pressure sensor 3 as the supporting signal amplification and conditioning circuit D of the differential pressure measuring element, so that the signal output has the characteristics of high precision and good stability.

It should be noted that the signal amplification and conditioning circuit D mainly amplifies the weak signal (pressure difference value) measured by the pressure difference sensor 3, and calibrates the pressure difference value through the signal amplification and conditioning circuit D, so that the pressure difference The values correspond to a fixed output voltage, for example, 0~200PA, corresponding to output DC voltage of 0~5V.

In addition, the switching value control signal output circuit F includes at least one intermediate relay KM2, which can convert the signal of the signal processing circuit E into a passive switching value output through the intermediate relay KM2, control the output signal and reset signal, and serve as the control switch of the back-end circuit quantity. Preferably, a backup intermediate relay KM1 can also be added to the switching value control signal output circuit F, and the backup intermediate relay KM1 cooperates with the intermediate relay KM2 to control output signals and reset signals.

Further, the signal amplification and conditioning circuit D is provided with an adjustable potentiometer for adjusting the preset upper limit value and the preset lower limit value, and the adjustable potentiometer is electrically connected with the signal processing circuit E, which has strong flexibility.

Referring to Fig. 7, Fig. 7 shows the first embodiment of the differential pressure controller for positive pressure air supply of the present invention, which can be widely used in building positive pressure air supply systems, indoor and outdoor differential pressure measurement and control, filter blockage monitoring and other industries. Differential pressure measurement and control. The differential pressure controller for positive pressure air supply includes a differential pressure controller for positive pressure air supply, a first pressure introduction pipe 51, a second pressure introduction pipe 52, a power supply circuit, a positive pressure air supply fan, a pressure relief valve and a bypass valve. One end of the first pressure introduction pipe 51 is connected to the high-pressure end nozzle 3a of the differential pressure sensor 3, and the other end is connected to the front chamber, so that the high-pressure end nozzle 3a of the differential pressure sensor 3 communicates with the front chamber space One end of the second pressure introduction pipe 52 is connected to the low-pressure end nozzle 3b of the differential pressure sensor 3, and the other end is connected to the aisle, so that the low-pressure end nozzle 3b of the differential pressure sensor 3 communicates with the aisle space; the power supply The circuit is electrically connected to the differential pressure controller for positive pressure air supply through power supply input lines (21, 22), and supplies power to the differential pressure controller for positive pressure air supply; the positive pressure air supply fan is connected with the front chamber, so The positive pressure air blower blows air to the front chamber, so that the pressure difference between the front chamber and the two sides of the walkway fire door is generated; The switch signal is output to the pressure relief valve through wires (31, 32) to control the opening or closing of the pressure relief valve, and the pressure relief valve controls the bypass pipe to send part of the air sent to the front room back to the front section of the positive pressure air supply fan To adjust the pressure difference between the antechamber and the aisle.

When the positive pressure air supply fan starts to supply air to the front room through the air shaft, because the normally closed fire door is closed, a pressure difference is formed on both sides of the front room and the aisle fire door. When the pressure difference is greater than or equal to the positive pressure When the preset upper limit value of the differential pressure controller for air supply is reached, the control circuit board 2 is connected to the power supply of the pressure relief valve coil, the KM3 contact is closed, the bypass pipe is connected, and the positive pressure air supply fan sends the air from the front chamber side The bypass pipe returns to the front section of the positive pressure air supply fan, thereby reducing the air volume entering the front room and reducing the pressure difference between the front room and the fire doors on both sides of the aisle. After the pressure is released, when the differential pressure controller for the positive pressure air supply detects that the differential pressure between the front room and the fire doors on both sides of the aisle is less than or equal to the preset lower limit, the control circuit board 2 disconnects the coil power supply of the pressure relief valve, and the bypass pipe When the closed state is restored, the air volume sent by the positive pressure air supply fan to the front room increases, and the pressure difference between the front room and the two sides of the aisle fire door increases.

Therefore, through the pressure difference controller for positive pressure air supply of the utility model, the pressure difference value on both sides of the front room and the aisle fire door can always be controlled at the upper limit value and the lower limit value set by the pressure difference controller for positive pressure air supply. between.

Referring to Fig. 8, Fig. 8 shows the second embodiment of the differential pressure controller for positive pressure air supply of the present invention, which includes at least two differential pressure controllers for positive pressure air supply, and the differential pressure for positive pressure air supply The controller is connected to the power supply circuit in parallel, and the differential pressure controller for positive pressure air supply is connected to the pressure relief valve in parallel.

When working, each positive pressure air supply uses a differential pressure controller to measure the differential pressure value at the corresponding position. When the preset upper limit value of the device is used, the pressure difference controller for the positive pressure air supply can be connected to the power supply of the pressure relief valve coil to open the pressure relief valve to release pressure, and when the differential pressure value is less than or equal to the preset lower limit value, close the pressure relief valve, so as to ensure that the pressure difference between the two measured pressure difference areas of the corresponding layer is always between the upper and lower limits of the set pressure difference value. Correspondingly, the differential pressure controller for positive pressure air supply of the present invention can be realized only by four buses, and the whole system is simple and reliable.

It can be seen from the above that the utility model can be widely used in pressure difference measurement and control in building positive pressure air supply system, indoor and outdoor pressure difference measurement and control, filter clogging monitoring and other industries. It is easy to install, high in pressure difference control precision and strong in flexibility.

The foregoing is a preferred embodiment of the present utility model, and it should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present utility model, some improvements and modifications can also be made. These improvements and modifications It is also regarded as the protection scope of the present utility model.

Claims (6)

1. A differential pressure controller for positive pressure air supply, comprising a base, a loam cake, a differential pressure sensor and a control circuit board, characterized in that the differential pressure sensor is electrically connected to the control circuit board, and is arranged between the base and the control circuit board. In the cavity formed by the interconnection of the upper covers, the base is provided with fixing holes; The control circuit board includes a signal amplification and conditioning circuit, a signal processing circuit and a switching value control signal output circuit electrically connected to each other. 2 . The differential pressure controller for positive pressure air supply according to claim 1 , wherein the fixing holes include two fixing holes, and the center distance between the fixing holes is 55-65 mm. 3. The differential pressure controller for positive pressure air supply according to claim 1, wherein the fixing holes include four connecting and fixing holes, and the center distance between two adjacent connecting and fixing holes is 65-75mm . 4. The differential pressure controller for positive pressure air supply according to claim 1, wherein a display screen for displaying the differential pressure value is arranged on the upper cover, and the display screen is connected to a control circuit board. 5. The differential pressure controller for positive pressure air supply according to claim 1, wherein the signal processing circuit comprises a control chip electrically connected to each other, an amplification circuit, a power processing circuit and a power indicating circuit; The control chip is provided with a first pin, a second pin, a third pin, a fourth pin, a fifth pin, a sixth pin, a seventh pin and an eighth pin; The first pin is connected to the power supply through the power processing circuit, the second pin is connected to the jumper circuit, the third pin is connected to the power indicating circuit, and the fourth pin is connected to the power supply through the power processing circuit. The sixth pin is connected to the output end of the signal amplifying and conditioning circuit, the seventh pin is connected to the input end of the switch control signal output circuit through the amplifying circuit, and the eighth pin is grounded. 6. The differential pressure controller for positive pressure air supply according to claim 1, wherein the signal amplification and conditioning circuit is provided with an adjustable potentiometer for adjusting the preset upper limit and the preset lower limit , the adjustable potentiometer is electrically connected to the signal processing circuit.