233 results about "Relay valve" patented technology

A modulator (20) for generating a pressure change in response to a control pressure has a first venting path (25) and a second venting path (26) for venting a pneumatic load (11). The modulator (20) has a relay valve (30) that is configured to vent the pneumatic load (11) via the first venting path (25). The modulator (20) has a vent valve (40) that is configured to vent the pneumatic load (11) via the second venting path (26).

The invention provides a regulation and control method, system and device for a relay valve overrun test and a medium, and belongs to the technical field of air braking systems. The method comprises the steps that pressure response characteristics of a relay valve pipeline system under different opening degrees of a proportional pressure regulating valve are tested, a finite set representing pipeline dynamic response is constructed based on pressure data in a sampling period, and a dynamic matrix model is generated to describe the relation between future pressure output and control quantity; pipeline pressure output at the future moment is predicted based on the dynamic matrix model, an optimized target function is established in combination with the target boosting rate, and the optimal control quantity is solved to adjust the opening degree of the proportional pressure regulating valve in real time; comparing a predicted pressure value with an actual measurement value to obtain an error, dynamically correcting a predicted model parameter by using a weighted error sequence, and adjusting a subsequent control quantity to compensate system hysteresis and external interference; and circularly executing the processes until the pipeline pressure and the regulation and control time reach corresponding target values, and cutting off the gas source.

The utility model relates to a valve device for a vehicle electronic brake system and the vehicle electronic brake system. The valve device comprises a shell; an actuation assembly having a push rod; a first piston; a first spacer in which a pilot chamber in the housing is in fluid communication with a brake pedal side of a brake circuit of the vehicle electronic brake system; a second spacer having a control chamber in fluid communication with a brake side of the brake circuit and a high pressure chamber in fluid communication with a high pressure source side of the brake circuit; a relay valve comprising a second piston, in an unactivated valve position in which the push rod retracts and the second piston abuts against the second spacer to isolate the high pressure chamber from the control chamber, and in a working valve position in which the actuation assembly extends and urges the first piston through the second spacer to urge the second piston to fluidly communicate the high pressure chamber with the control chamber, high-pressure gas from the high-pressure gas source side enters the brake side through the high-pressure cavity and the control cavity so as to be used for generating brake pressure. According to the valve device and system, the risk that the electromagnetic valve fails is reduced.

The utility model discloses a brake hydraulic element fault detection system and a mining dump truck. The brake hydraulic element fault detection system comprises an oil tank, a variable pump, a pedal valve, a relay valve, an angle sensor, a controller, a brake and a pressure sensor. The oil tank is used for storing hydraulic oil; the variable pump is connected with the oil tank, serves as a hydraulic system oil source and outputs hydraulic oil outwards; the pedal valve and the relay valve are respectively connected with the variable pump; the pedal valve outputs pressure oil which is proportional to a pedal angle to a pilot port of the relay valve; the angle sensor mounted on the pedal is used for sending the detected angle of the treaded pedal to the controller; the brake is connected with the relay valve, and the relay valve outputs pressure oil proportional to the pressure of the pilot port to the brake; the pressure sensor is electrically connected with the controller and sends the detected pressure of the brake to the controller, and the controller judges whether the pedal valve and the relay valve break down or not by analyzing the angle of the pedal valve and the pressure of the brake.

The invention discloses a method for realizing a brake cylinder pressure conversion function, which relates to the technical field of railway transportation and comprises the step of integrating a stepless relay valve and a brake cylinder pressure conversion device into a whole, the brake cylinder pressure conversion device comprises a pressure regulating piston arranged on a CV part, a pressure regulating mechanism used for controlling the pressure regulating piston and a judging mechanism used for controlling the pressure regulating mechanism to be opened and closed. The pressure regulating mechanism is used for inflating and deflating the upper part and the lower part of the pressure regulating piston according to the pressure reduction amount of the train pipe so as to control the CV pressure; the stepless relay valve is mainly used for transmitting CV pressure to the acting part through a lever, the acting part generates brake cylinder pressure C with the corresponding size to be balanced with the CV pressure, the position of a fulcrum of the stepless relay valve is controlled by a pressure signal of the weighing valve, and conversion of the brake cylinder pressure C is achieved.

The invention provides a locomotive brake control system based on average pipe pressure control. The locomotive brake control system comprises a brake cylinder control module, an average pipe control module and a main air reservoir. Wherein the brake cylinder control module can output brake cylinder pressure to a brake cylinder for braking; the average pipe control module comprises a second relay valve and a second main air reservoir; wherein the fourth pre-control pressure can reach the control port of the second relay valve; an inlet of the second relay valve is connected to the main air reservoir through the one-way valve, after flow amplification, an outlet of the second relay valve can output average pipe pressure PA to an average pipe, and a brake air source can be provided for an external reconnection locomotive; the second main air reservoir is connected to the main air reservoir through the one-way valve; a first shutoff valve and a second shutoff valve are arranged between the outlet of the second relay valve and the average pipe in parallel; and the two pneumatic valves are provided with control ports.

A brake modulator (1) for providing an ABS brake function to a vehicle (200) includes a main body (17), a first ABS valve unit (47) configured to provide a first brake pressure (pB1) and a second ABS valve unit (53) configured to provide a second brake pressure (pB2), and a main cover (19) for closing of an assembly side (27) of the main body (17). The cover portions (127, 131, 133, 135) for covering corresponding valve cavities (33, 35, 37, 39) are formed separately from a main cover plate (20) of the main cover (19). A relay valve cover plate (137) is formed integrally with or separately from the main cover plate (20). The present disclosure further relates to a commercial vehicle (202) and to an assembly method (300) for a brake modulator (1).

A trailer brake control module (300a; 300b; 300c) for a towing vehicle (502) facilitating braking of a towed vehicle or trailer (504) includes a pressure supply port (P11), a trailer control pressure port (P22), a primary control port (P42) for receiving either directly and / or indirectly a control brake pressure for operating the trailer brake control module (300a; 300b; 300c). The primary control port (P42) receives the control brake pressure from a pneumatically operated pressure medium, a pneumatic control pressure line (308.1) provides alternative control brake pressure for operating the trailer brake control module (300a; 300b; 300c), wherein the pneumatic control pressure line (308.1) receives the alternative control brake pressure from an electronically operated pressure medium, and a relay valve (310) is activated using either the control brake pressure received at the primary control port (P42), or the alternative control brake pressure from the pneumatic control pressure line (308.1).

The invention discloses a trailer axle load control method of a new energy power trailer. The method comprises the steps that vehicle condition information is obtained, the vehicle condition information comprises load information and acceleration information, the load information comprises a load on an axle of a trailer, and the acceleration information comprises transverse acceleration and longitudinal acceleration of the trailer; determining axle load distribution information of the trailer based on the vehicle condition information; a control instruction is generated based on the axle load distribution information, the control instruction is used for adjusting working parameters of target components, and the target components comprise a trailer driving motor, a TEBS electromagnetic relay valve and a suspension system. The technical problem that the stability of the vehicle is poor due to trailer axle load transfer is solved.

The invention relates to an EPB system on a heavy-duty commercial vehicle. The EPB system solves the problems existing in a traditional parking braking system used by the heavy-duty commercial vehicle at present. Comprising an EPB switch, an EPB controller, an ABS-ECU, a CAN bus, a wheel speed sensor, a front axle diaphragm cylinder, an ABS electromagnetic valve, a relay valve, a brake master valve, a temporary parking valve, a two-way one-way valve, a parking memory valve, a process control valve, an air pressure sensor, a driving relay valve, a parking relay valve, a spring brake cylinder, an air compressor, an air processing unit, an air cylinder and a brake pipeline. The operation process is simplified, the vehicle is more intelligent, simpler, more convenient and safer, accidents are reduced, and the comfort and safety of the whole vehicle are improved.

The invention relates to the technical field of intelligent refrigeration control, in particular to a water-cooling air conditioning system control method suitable for overtime, which comprises the following steps: collecting a static pressure value through a differential pressure sensor to calculate differential pressure offset, performing moving average noise reduction and fitting a trend curve, performing multi-window analysis to extract a differential pressure change rate, and generating a flow guide instruction when temperature difference deviates; the valve is adjusted to the target opening degree, a completion signal is generated, a failure time window is generated by grey prediction temperature change, and a compensation signal is generated by detecting the opening degree of the flow matching guide valve. According to the method, the trend is extracted through static pressure and differential pressure analysis, moving average and time sequence fitting are combined, the hidden danger of flow unbalance is dynamically recognized, relay valve step length flow guiding is adjusted, non-target branch expansion is restrained, residual cold failure is predicted through a gray model, a backflow path and response efficiency are optimized, and accurate adjustment and temperature compensation of the guide valve are achieved; a cooling capacity regulation and control closed loop is constructed, and the energy-saving performance and stability of the air conditioning system are improved.

A mine dump truck wet disc brake hydraulic system, including main control valve, one end of main control valve is connected pressure oil source, the other end is connected front brake system and middle and rear brake system, front brake system includes brake pedal, front axle proportional control valve group, front axle brake valve group and front brake cylinder, middle and rear brake system includes brake pedal, slow running valve, middle and rear axle brake valve, rear axle proportional valve group, relay valve group, rear axle brake cylinder and middle axle brake cylinder, the utility model discloses a mine dump truck wet disc brake hydraulic system can realize manual operation brake and line control remote brake function, reaches unmanned operation's requirement, is used for unmanned vehicle or auxiliary driving, and in order to adapt to the distance of middle and rear axle of three axle vehicle and the distance of main brake valve group is longer, two relay valve groups are added, brake corresponding speed is improved, faster brake response is realized, makes travel more safe.

The invention provides a pneumatic valve device, a pneumatic brake system and a commercial vehicle. The pneumatic valve device comprises a first air pressure port used for receiving air source pressure of a lower pressure value; the second air pressure port is used for transmitting trailer braking pressure; the third air pressure port is used for outputting trailer brake control air pressure; the first air pressure port is connected with the third air pressure port through a working cavity of the relay valve; the fourth air pressure port is used for receiving the air source pressure with the higher pressure value; the control end of the energy supply valve is connected with the first air pressure port, an air inlet of the energy supply valve is connected with the fourth air pressure port, an air outlet of the energy supply valve is connected with the second air pressure port, the energy supply valve is constructed to make the air inlet and the air outlet communicated when the pressure of the control end of the energy supply valve is larger than an opening threshold value, and the opening threshold value is smaller than the first pressure value. The air source pressure with the higher pressure value can be introduced into the trailer braking system, the energy storage capacity of the trailer braking system is improved, the trailer braking response time can be shortened, and the whole vehicle braking efficiency is improved.

This utility model relates to the field of pilot-operated relay valves, specifically a pilot-operated relay valve for a control system. The utility model includes a valve body with a first through-hole. A sealing cap is provided at one end of the first through-hole. A first inlet and a second inlet are connected to one side of the first through-hole, and an outlet is connected to the side of the first through-hole away from the first inlet. A control chamber is provided at the end of the first through-hole away from the sealing cap. A piston plate is slidably connected to the control chamber, and a valve core is fixedly connected to the piston plate, extending into the first through-hole. A first locking block is provided within the first through-hole, and a second elastic element is fixedly connected to the sealing cap. A steel ball is provided on the second elastic element, and a second through-hole is provided on the first locking block. A second locking block is provided within the first through-hole, and a third through-hole is provided on the first locking block. A first conical surface is provided within the third through-hole, and a second conical surface is provided on the middle section of the valve core. The technical solution of this utility model can improve the problem of damage to Y-type gaskets after long-term use.

Methods and apparatus for quantifying pneumatic volume usage via valve controllers are disclosed. An example apparatus includes a valve controller operatively couplable to a pneumatic actuator, the pneumatic actuator being operatively coupled to a control valve. In response to an input signal indicating that a flow control member of the control valve is to be moved in a specified direction, the valve controller commands a current-to-pressure (I / P) converter of the valve controller to pulse a relay valve of the valve controller between a closed position and an open position. The pulsing of the relay valve causes the pneumatic actuator to move the flow control member in the specified direction. The valve controller calculates a pneumatic volume usage associated with the moving of the flow control member in the specified direction. The pneumatic volume usage is based on the pulsing of the relay valve.

The present invention relates to the field of intelligent refrigeration control technology, specifically a control method for a water-cooled air-conditioning system suitable for overtime operation, comprising the following steps: collecting static pressure values through a pressure differential sensor to calculate the pressure differential offset, performing sliding average noise reduction and fitting a trend curve, extracting the pressure differential change rate through multi-window analysis, generating a diversion instruction when the temperature difference deviates, adjusting the valve to the target opening and generating a completion signal, gray-predicting the temperature change to generate a failure time window, detecting the flow matching the guide valve opening to generate a compensation signal. In the present invention, trends are extracted through static pressure and pressure differential analysis, combined with sliding average and time series fitting, to dynamically identify the hidden dangers of flow imbalance, adjust the relay valve step diversion, suppress the expansion of non-target branches, use a gray model to predict residual cooling failure, optimize the return path and response efficiency, achieve precise adjustment and temperature compensation of the guide valve, build a closed loop of cooling control, and improve the energy efficiency and stability of the air-conditioning system.

The present invention provides a commercial vehicle brake pedal force control system and vehicle, belonging to the field of vehicle development technology. The system includes: a brake pedal, a brake valve push rod, a brake valve, a rear air reservoir, a front air reservoir, a front circuit pressure-limiting valve, a rear circuit pressure-limiting valve, a front axle relay valve, and a rear axle relay valve. Compressed air in the front air reservoir enters the brake valve through the front circuit pressure-limiting valve and a first air inlet; compressed air in the rear air reservoir enters the brake valve through the rear circuit pressure-limiting valve and a second air inlet. When the brake pedal is depressed, the brake valve push rod moves, and the compressed air in the brake valve is discharged through the first and second air outlets to the rear axle relay valve and the front axle relay valve. When the brake pedal is returned, the brake valve push rod returns, and the compressed air in the brake valve is discharged through the first and second air outlets to the atmosphere. This invention reduces brake pedal force without changing the commercial vehicle assembly, reducing the design and manufacturing costs and difficulty of achieving brake pedal force reduction.

The present invention discloses a control device and control method for temporarily enhancing hill-holding capability, relating to the field of parking spring brake systems. The control device comprises a service brake line, comprising a service brake line, and a second service air reservoir, a foot brake valve, a one-way valve, a first relay valve, and a brake connected in sequence via the service brake line; a parking brake line, comprising a parking brake line, and a parking air reservoir, a hand brake valve, a second relay valve, and a brake connected in sequence via the parking brake line; a first service air reservoir connected to the first relay valve via a first connecting line; a second connecting line connected between the parking air reservoir and the second relay valve; and an exhaust valve, which opens to exhaust air from the control port of the first relay valve when the hand brake valve is in the driving position; and closes when the hand brake valve is in the parking position. The present invention allows a vehicle to temporarily enhance its hill-holding capability when the driver's foot is off the service brake pedal.

The present invention relates to a fail-safe bypass valve assembly (1) for a pneumatic parking brake unit (120) of an electronically controllable pneumatic braking system (100), comprising: a first path (2) with an electromagnetic monostable valve (6); a second path (4) with a bistable valve unit (12); and a relay valve (10); wherein the first path (2) and the second path (4) receive a main parking brake pressure (pPA) from the pneumatic parking brake unit (120), wherein, at a first stable switching position of the bistable valve unit (12), the main parking brake pressure (pPA) is controlled at the relay valve control port (10.4) of the relay valve (10) independently of the switching position of the first monostable valve (6), and at a second stable switching position of the bistable valve unit (12), the relay valve control port (10.4) vents when the first monostable valve (6) is de-energized to vent at least one spring-loaded brake cylinder (125a, 125b).

The utility model relates to the technical field of braking, and provides an integrated relay valve and a braking system. The integrated relay valve is provided with a traveling working cavity and a parking working cavity, a traveling braking assembly which divides a traveling control cavity and a traveling braking cavity is arranged in the traveling working cavity, and a parking braking assembly which divides a parking control cavity and a parking braking cavity is arranged in the parking working cavity. The driving control cavity is independent from the parking working cavity, the driving brake cavity is adjacent to the parking control cavity, and the integrated relay valve is further provided with a valve cavity located between the driving brake cavity and the parking control cavity and communicated with an air outlet of the driving brake cavity, a parking valve connector and the parking control cavity; the valve element is arranged in the valve cavity, and the valve cavity can communicate the air outlet of the service braking cavity or the parking valve connector with the parking control cavity along with movement of the valve element. According to the integrated relay valve, double braking can be effectively prevented, and meanwhile the accuracy and sensitivity of service braking and parking braking are prevented from being affected.

The utility model discloses a relay valve sealing performance test device, relates to the relay valve sealing technology field, and comprises a pedestal, a test box and a first air cylinder, the top end of the pedestal is provided with the first air cylinder and a second air cylinder, and the input end of the first air cylinder and the input end of the second air cylinder are respectively provided with a first stop valve and a third stop valve. One end of the first air storage cylinder and one end of the second air storage cylinder are each provided with a first air pressure meter, a second stop valve is arranged at the output end of the first air storage cylinder, a test box is arranged at the top end of the base, a positioning frame is installed at the top end of the test box, and a relay valve body is arranged in the positioning frame; the device is provided with a test box bottom end drain pipe which is used for draining water into a water tank, an operator can pull a pull rod outwards, so that the pull rod drives a spring to stretch outwards, the pull rod is further separated from the outer wall of a mounting block, quick disassembly is met, and a next group of relay valves can be conveniently tested.

The invention relates to the field of rail transit, in particular to a rail transit vehicle electric pneumatic braking control system and method.The control system comprises an electronic braking control unit, a common pre-control branch, an emergency pre-control branch and a relay valve, and the electronic braking control unit is used for controlling the common pre-control branch to output common pre-control pressure; the emergency pre-control branch comprises an emergency valve, a remote relief electromagnetic valve and an empty and load valve, the empty and load valve outputs emergency pre-control pressure corresponding to vehicle load information, and the relay valve receives common and emergency pre-control pressure and selects one of the common and emergency pre-control pressure to output corresponding compressed air to a brake cylinder; the electronic brake control unit analyzes the service brake instruction, the service pre-control pressure and the pressure value at the output position of the relay valve, can judge the emergency valve fault and control the remote relieving electromagnetic valve to empty compressed air of the emergency pre-control branch, and the problems that after the emergency valve fault occurs, the emergency air path pressure is not relieved, and the relieving capacity of the air path pressure is unstable are solved.

The application provides a JZ-7 remote control braking system, which comprises a total air pipe, a first passage, a second passage and a third passage, a relay valve, an equalizing air cylinder, a first high-speed electric air valve, an overcharge air cylinder, a control device, a CCU and a remote network control unit, the total air pipe is connected with the overcharge pipe of the relay valve after being communicated with the first passage, and the gas outlet of the first passage is also communicated with the exhaust port of the overcharge air cylinder; the total air pipe is connected with the equalizing pipe of the relay valve after being communicated with the second passage, and the gas outlet of the second passage is also communicated with the first high-speed electric air valve and the equalizing air cylinder respectively; the total air pipe is connected with the cut-off pipe of the relay valve after being communicated with the third passage, and the train pipe of the relay valve is also connected with an electric air release valve. The application can realize remote networking operation of the braking system, and the locomotive can implement braking and relieving functions without operating the automatic brake valve.

An electronically controlled pneumatic parking brake system comprises a park brake actuator, first and second electronic control units and an electronic park brake device comprising a bi-stable relay valve selectively feeding the park brake actuator, solenoid valves for controlling the relay valve via a control line and at least one backup pneumatic park brake valve configured to take first and second configurations. The parking brake system also comprises a third solenoid valve, controlling the backup park brake valve, and a fourth solenoid valve selectively connecting the control line to the backup park brake valve. The first electronic control unit pilots the fourth solenoid valve to isolate the control line from the backup park brake valve if the third solenoid valve controls the backup park brake valve to take a second configuration when the first electronic control unit is operational.

This invention relates to an air backup braking system and a locomotive. The system includes: a backup switching valve with two positions: normal and air position; a backup pressure regulating valve; a pressure measuring point; a backup brake valve with three positions: braking, neutral, and release; a backup equalizing pressure cylinder; and a backup relay valve, used to output its A2 port pressure in real time according to the pressure of the equalizing cylinder when the air backup mode is activated. Specifically, in the normal position of the backup switching valve, ports A2 and A3 of the backup switching valve are connected, cutting off the main air supply to the backup brake valve, venting the pressure at the control port C1 of the first, second, and third switching valves, and outputting a high-level signal. In the air position of the backup switching valve, ports A1 and A2 are connected, and the main air supply is simultaneously output through the pressure at port A2 to the control port C1 of the first, second, and third switching valves, and outputting a low-level signal. This invention solves the technical problem of the inability to switch in real time after a locomotive electro-pneumatic brake failure.

The present invention relates to a relay valve (18) for an electropneumatic control device (1), comprising: a pneumatic control input (20) which is connected to a control chamber (42) of the relay valve (18), a working output (28) which is connected to a working chamber (58) of the relay valve (18), at least a first throttling element (30) that connects the working chamber (58) and the control chamber (42), a supply inlet (16) which is connected to a storage chamber (60) of the relay valve (18), a double seat valve (50, 54) with at least one inlet seat (54) and at least one outlet seat (50), a relay piston (46) for actuating the double seat valve (50, 54), wherein the working chamber (58) is connected to a vent (56) when the outlet seat (50) is open and to the storage chamber (60) when the inlet seat (54) is open, and wherein the relay valve (18) has at least one second throttling element (65, 65', 65'', 65'''', 65'''', 65'''''') which is arranged such that the working chamber (58) and the vent (56) are in throttled flow communication with each other at least in an intermediate position of the relay piston (46) between the vent position and the ventilation position via the at least one second throttling element (65, 65', 65'', 65'''', 65'''', 65'''''') and that the at least one second throttling element (65, 65', 65'', 65'''', 65'''', 65'''''') is completely closed in the ventilation position.

The application discloses a kind of warning device and use method applied to density relay valve, it is related to power distribution equipment field, and the warning device applied to density relay valve includes knob, linkage assembly and control component, knob is nested with relay valve cooperation, linkage assembly includes fixed link with knob and switch piece controlled by link, and the power supply is realized by the setting of switch piece to on-off, control component includes power supply and warning piece controlled by switch piece, warning information can be sent to staff by warning piece, staff is constantly prompted, so that staff can know that he needs to close relay valve after maintenance ends, will not lead to forget, staff rotates relay valve to drive knob rotation, triggers power switch, so that warning piece constantly sends early warning prompt.

The invention relates to a failsafe bypass valve arrangement (1) for a pneumatic parking brake unit (120) of an electronically controllable pneumatic braking system (100), having: - a first path (2) with an electromagnetic monostable valve (6); - a second path (4) with a bistable valve unit (12); and - a relay valve (10); wherein the first path (2) and the second path (4) receive a primary parking brake pressure (pPA) of the pneumatic parking brake unit (120), wherein, in a first stable switching position of the bistable valve unit (12), the primary parking brake pressure (pPA) is controlled at a relay valve control port (10.4) of the relay valve (10) independently of a switching position of the first monostable valve (6), and, in a second stable switching position of the bistable valve unit (12), the relay valve control port (10.4) is vented when the first monostable valve (6) is currentless in order to vent the at least one spring reservoir braking cylinder (125a, 125b).

The application relates to a multi-mode brake system of a special vehicle, which comprises an emergency relay valve, a first relay valve, a second relay valve, an ABS controller, a foot brake valve, a hand brake valve, a normally open electromagnetic valve, a normally closed electromagnetic valve, an electric control proportional valve, a first shuttle valve, a second shuttle valve, a third shuttle valve, an air compressor and a plurality of brake chambers. The application can realize various modes of braking, two-by-two interlocking, automatic switching according to the walking mode of the vehicle, satisfy the overall brake system, can not only guarantee traction braking, but also does not affect the braking work when the vehicle independently walks; and is reasonably designed, can satisfy the integrated brake system of a vehicle under various walking mode states, is complete in function and improves work efficiency.

The invention provides a high-speed electromagnetic regulating valve, a vehicle pneumatic brake system thereof and a vehicle. The high-speed electromagnetic regulating valve is arranged between an air storage cylinder and a relay valve of the vehicle air brake system and used for controlling air flow in the air storage cylinder to flow into or stop flowing into the relay valve and controlling the air pressure flowing into the relay valve. The high-speed electromagnetic regulating valve comprises a body, an air pressure sensor and an electromagnetic valve assembly, the body is provided with an air storage cavity, an air inlet end, an air outlet end and an exhaust port, the air inlet end is provided with an air inlet hole, and the air outlet end is provided with an air outlet hole. An air inlet path, an air outlet path and an air outlet path which are communicated are formed between the air inlet, the air outlet and the air outlet and the air storage cavity respectively, the air outlet end is connected with the relay valve in a matched mode and communicated with the relay valve through the air outlet, and the air pressure sensor is installed on the air outlet path and used for sensing the air pressure flowing to the relay valve. The electromagnetic valve assembly comprises two valves which are in one-to-one correspondence with the air inlet hole and the air outlet hole, and the two valves open or close the air inlet hole and the air outlet hole under the power-on and power-off action of the electromagnetic valve assembly.