157results about How to "Avoid reverse flow" patented technology

The invention relates to a steam jet enthalpy heat pump air-conditioning hot water unit which at least comprises a compressor, a four-way reversing valve, the four-way reversing valve, an outdoor heat exchanger, a refrigeration one-way valve, a liquid storage device, an economizer, an EVI electronic expansion valve, a refrigeration electronic expansion valve, an indoor heat exchanger, a steam-liquid separator, a heating one-way valve, a heating electronic expansion valve, a hot water one-way valve and a hot water heat exchanger. The technical problems to be solved by the invention is to provide the air-conditioning hot water system with the steam jet enthalpy function and realize the steam jet enthalpy under different modes through the control of the degree of superheat of the electronic expansion valves and an unique throttling structure, thereby improving the range of applications and the efficiency of an air conditioner, leading the functions of the system to be diverse, having high energy utilization rate, improving the efficiency under various modes to the maximum extent and being characterized by simple structure, easy control, low initial investment and low operation cost.

The invention discloses a method of producing large double metal composite plate and a device thereof. The method and device can continuously produce large-size thick double metal composite plates with high production efficiency, low cost, accurate control of interface layer and good lamination. The device comprises a frame with a sealed chamber, an induction heater arranged inside the sealed chamber, a gap-type heat-insulating caster and a conveying mechanism. The sealed chamber has an oxygen-free protective atmosphere inside. The method includes the following steps: substrate preparation, casting preparation, continuous hot casting, oscillatory crystallization and finishing. The continuous hot casting step includes: continuously heating a continuously forward-moving substrate by the induction heater and the gap-type heat-insulating caster in the oxygen-free protective atmosphere, allowing a molten metal coating for continuous casting to flow towards the substrate through a casting gate in a downward-oblique direction, and completely solidifying the molten metal coating on the substrate by means of oscillatory crystallization.

The invention discloses a centrifugal type multi-channel microfluidic chip; a first layer surface of the chip is provided with a first fluid suite including first reaction tanks, flow paths and solution injection ports, and each flow path is provided with a first solution temporary storage zone for conveying a liquid to the first reaction tank; each flow path includes a first flow path and branches, and each first flow path extends from a valley to the first reaction tank to form a first communication point; the branches and each first reaction tank form a second communication point, and the branches extend from the second communication point to an outlet end along the direction toward a rotation center. The fluid devices of the first layer surface can communicate with those of a second surface layer through channels which communicate with each other in an upper-and-lower manner, and the first fluid suite and a second fluid suite can communicate with each other. The microfluidic chip has an ingenious structure; substances and auxiliary ingredients which can undergo reactions with different substances or ingredients in a to-be-detected sample can be pre-loaded in different reaction devices; reaction results are obtained through one time or multiple times of solution addition.

The deep cooling loop heat pipe includes main evaporator and liquid chamber connected serially via connecting pipe. The main evaporator has casing of stainless steel pipe with axial grooves in the inside surface and main tubular liquid absorbing core of sintered stainless steel powder. The liquid chamber has stainless steel wire screen filled between the right end cap and the casing. There are also capillary connecting part, which has central inside hole, is set inside the hole of the main liquid absorbing core and extends via the connecting pipe to the liquid chamber, and annular coarse stainless steel wire sheet filled between the capillary connecting part and the liquid chamber casing. The present invention can avoid reverse flow of the work medium to ensure the successful starting of deep cooling loop heat pipe, and can raised the heat transferring limit of deep cooling loop heat pipe for stable operation performance.

The invention discloses a support lifting device of a milling machine, which comprises a left support oil cylinder and a right support oil cylinder. The support lifting device is used for adjusting the heights of a left leg and a right leg by flexible actions of the left support oil cylinder and the right support oil cylinder. The support lifting device also comprises a left proportional and directional valve and a right proportional and directional valve which are communicated with the left support oil cylinder and the right support oil cylinder respectively through oil circuits and used for controlling the speed of the flexible actions of the left support oil cylinder and the right support oil cylinder; and a left pressure compensator and a right pressure compensator, which are also included by the device, and are respectively installed on the oil circuits between the left proportional and directional valve and the left support oil cylinder and between the right proportional and directional valve and the right support oil cylinder and used for stabilizing the pressures of the left support oil cylinder and the right support oil cylinder. The proportional valves can not only reverse the directions, but also can adjust the flow rate, thereby being capable of adjusting the direction and the speed of the flexible actions of the support oil cylinders to realize the infinitely variable control of the lifting speed of the legs with comparatively high synchronous precision; and the pressure compensators can stabilize the pressure of the oil cylinder and eliminate the load difference between the support oil cylinders so as to ensure no interaction in the actions of the two oil cylinders. The invention also discloses a road milling machine using the support lifting device.

A hydraulic tensioner is provided to reduce the number of parts, to secure the backlash, and to prevent the plunger from moving backward. A hydraulic tensioner comprising a hollow plunger having rack teeth formed on a portion of an outer circumferential surface, slidably received in a bore of the housing, where the plunger has an inner space to form a fluid chamber with the bore. A slider housing portion, having an inclined surface, located in the housing, receives a wedge-shaped slider having a ratchet portion adapted to engage with the rack teeth of the plunger and a second side surface. The wedge-shaped slider being slidable along the inclined surface of the slider housing portion in a direction crossing an axial centerline of the plunger. The hydraulic tensioner further includes a first spring biasing the plunger in a protruding direction, and a second spring biasing the slider such that the slider moves along the inclined slide surface of the slider housing portion. A ''wedge-effect'' prevents the plunger from moving backwards.

The invention discloses a scattering-structure spray head, comprising a barrel, wherein one end of the barrel is connected with a water inlet pipe; a closed spray end is installed on the other end of the barrel; at least one long strip type spray port is formed in the spray end and / or the barrel. According to the scattering-structure spray head, the spray head is connected onto a water pipe; the long strip type spray ports are arranged horizontally and can properly incline; when water in a water tank is sprayed out through the spray ports after being pressurized, fan-shaped water curtains are formed; one larger fan-shaped water curtain can cover a carriage; alternately, multiple fan-shaped water curtains cover the carriage in a way of forming a similar rectangle shape; only smaller clearance is left; in the course of loading or unloading, the high-pressure water curtains form a dust keeping-out structure; therefore, flying dust which results from material impact is kept out by the high-pressure water curtains and finally falls into the carriage in the course of loading or unloading; the problem of flying dust is fundamentally solved.

A method for controlling a DC-DC converter, which generates a step output voltage smaller than the source voltage Vdd, comprises three-section-switch-condenser structure for receiving the source voltage. The first section comprises two condensers C11, C12 and switches 61, 62, 63 for changing the condensers C11, C12 into series connection or parallel connection. During charge time, the switch 61 is turned on to connect the condensers C11, C12 into a series connection. During discharge time, the switches 62, 63 are turned on to connect the condenser C11, C12 into a parallel connection. In this way, 3.5Vdd step-up voltage can be obtained through the output terminal 40.

The invention discloses an oil filter for an automobile. The oil filter for the automobile comprises a shell, an end cover, a first partition plate, a first filter element, a second partition plate, an elastic sheet, a first unidirectional membrane, a second unidirectional membrane, a first magnetostrictive film and a first coil. The shell is provided with an oil outlet. The end cover is detachably installed on the shell and provided with an oil inlet. The first partition plate is arranged in the shell, is connected with the inner circumferential surface of the shell, divides the internal space of the shell into a first containing cavity and a second containing cavity and is provided with a first through hole. The first filter element is annular and is arranged in the first containing cavity. The first end of the first filter element is connected with the inner circumferential surface of the shell, and the second end of the first filter element is connected with the first partition plate. The first filter element divides the first containing cavity into a first filtering cavity and a second filtering cavity. The first filtering cavity communicates with the oil inlet and the second filtering cavity communicates with the first through hole. The oil filter for the automobile is simple in structure and good in effect.

The invention relates to an integrated preparation technology of a loop heat pipe evaporator, which is realized through the following steps: selecting an evaporation cavity, removing an oxidation film on the inner surface of the evaporation cavity; adding mixed powder of porous wick sintered body powder and a pore creating material, inserting a cylindrical liquid storage cavity mold into the mixed powder, determining the insertion depth as per the size of the liquid storage cavity, compacting the mixed powder between the evaporator and the liquid storage cavity mold, putting the evaporation cavity into a sintering furnace for sintering, drilling a plurality of steam passages along the inner wall of the evaporation cavity by means of a bit after sintering and cooling, and taking out the liquid storage cavity mold, so as to obtain an integrated loop heat pipe evaporator. The porous wicks are directly sintered in the evaporation cavity in an enclosed manner, as a result, not only are theporous wicks tightly combined with the wall of the evaporation cavity to avoid problems of heat leakage or steam counterflow, but also the sintered porous wicks can be used directly to avoid problemsof the porous wick breakage brought by secondary machining and the requirement for high accuracy. Lower strength is allowed to realize high porosity factor, thereby facilitating enhancement of the suction force of the porous wicks.

The invention relates to a refrigerating system for refrigerator. It includes compressor, condenser, and evaporator. The compressor is two parallel one between each of which and the evaporator one way valve is connected. While the refrigerating system needs high load refrigerating, or the refrigerator is used with high frequency, the two compressors can be used together to supply required refrigerating capacity. And the one way valve can make the compressed gas pass the condenser to realize refrigerating effect, but not directly flow to the evaporator. On the contrary, any one of the compressors can realize required refrigerating load. Thus the invention can greatly improve the refrigerating efficiency, effectively save the energy sources.

The invention belongs to the technical field of manufacturing, and relates to equipment for fluid quantitative injection. The injection equipment comprises a power mechanism (1), a piston mechanism (2), and a cylinder body (3); wherein the piston mechanism (2) comprises a transmission nut (2.5), a screw rod (2.8), and a piston (2.1); the power mechanism (1) is connected to the transmission nut (2.5) and drives the transmission nut (2.5) to rotate; then the transmission nut (2.5) drives the screw rod (2.8) to drive the piston (2.1) to move in a straight line in the cylinder body (3); the piston (2.1) pushes the fluid in the cylinder body out of the cylinder body, and thus the quantitative injection is completed. The equipment is difficult to interfere by outer factors, and has the advantages of high quantitative precision, simple structure, and easy maintenance.

The invention relates to the technical field of ultrasonic fingerprint identification, and particularly relates to an ultrasonic driving circuit and a fingerprint identification sensor. The ultrasonicdriving circuit is characterized in that a drain electrode of an MOS (Metal Oxide Semiconductor) transistor Q1 is electrically connected with an external power supply, a source electrode of the MOS transistor Q1 is electrically connected with a first end of a resistor R3, a first end of an inductor L1 and a drain electrode of an MOS transistor Q2 simultaneously, a source electrode of the MOS transistor Q2 is electrically connected with a source electrode of an MOS transistor Q3, a second end of a capacitor C1, a first end of a capacitor C2 and a pin S1 of a switch K1 simultaneously, the source electrode of the MOS transistor Q2 is grounded, a drain electrode of the MOS transistor Q3 is electrically connected with a second end of the resistor R3, a second end of the inductor L1 is electrically connected with a first end of the capacitor C1 and a top electrode of a piezoelectric transducer simultaneously, a bottom electrode of the piezoelectric transducer is connected with a pin S3 of the switch K1, a pin S2 of the switch K1 is connected with a positive electrode of a diode D3, and a negative electrode of the diode D3 is electrically connected with a second end of the capacitor C2 and an acquisition module simultaneously. The fingerprint identification sensor adopts the ultrasonic driving circuit.

The invention discloses a micro-positive pressure auto-compensation rock bit lubricating system which comprises a tooth claw (1) and a tooth wheel (3). A slurry channel (8) is arranged in the tooth claw (1), an oil storage bag hole (9) is arranged on the upper portion of the tooth claw (1), an oil storage bag (10) is arranged in the oil storage bag hole (9) and is internally communicated with an oil passing channel (7) through an oil duct, and a compensation cavity (14) is communicated with the slurry channel (8) through a pressure leading hole (15). The micro-positive pressure auto-compensation rock bit lubricating system has the advantages that pressure of slurry in a bit serves as driving force of the auto-compensation rock bit lubricating system, the pressure leading hole cannot be blocked easily, service life of the rock bit is prolonged; pressure of slurry in the rock bit serves as compensation lubrication power and is larger than annulus pressure, pressure differential of the lubricating system is remarkably increased, and micro-positive pressure auto-compensation is achieved; a roll ball and a spring are arranged, pressure drop is formed, counter flow of the slurry is avoided, stability of the driving force is enhanced, and lubricating efficiency is improved.

The invention provides an electric vehicle insulation detection device and method. In an insulation detection circuit of the detection device, a first detection unit, a first diode and a second detection unit are sequentially connected in series between the positive electrode of a power battery set and a vehicle body, a third detection unit, a second diode and a fourth detection unit are sequentially connected in series between the negative electrode of the power battery set and the vehicle body, and a first capacitor is connected with any point between the first detection unit and the anode of the first diode and the positive electrode of the power battery set; a second capacitor is connected with any point between the third detection unit and the cathode of the second diode and the negative electrode of the power battery set, wherein the detection unit is formed by connecting a resistor and a switch in series; the method includes the steps that an insulation detection circuit measures the voltage difference of the two ends of a capacitor in the charging process, and insulation resistance between a power battery and the vehicle body is then obtained. According to the device and the method, the insulation resistance between a battery high-voltage system and the vehicle body can be rapidly and efficiently detected, and the safety of the human and the vehicle is improved.

A manually operated liquid foaming dispenser is attached to the top of a container of liquid and is manually vertically reciprocated to dispense the liquid from the container as a foam. The dispenser includes a liquid pump chamber and an air pump chamber that respectively pump liquid and air under pressure to a discharge passage of the pump where the liquid and air are mixed, generating the foam dispensed from the dispenser. The air pump chamber has a tube valve controlling the discharge of air from the air pump to the discharge passage, and the air pump chamber is charged with air by opening the air pump chamber to the exterior environment of the dispenser.

The invention provides a photovoltaic reverse power controller, which is applied to a solar photovoltaic generating system. At present, the conventional anti-reverse current relay in the market does not have the photovoltaic reverse power control function, can only control reverse power within a certain range and cannot ensure the photovoltaic generating system is a reverse current-free system. The photovoltaic reverse power controller receives information acquired and processed by a reverse power acquisition and monitoring system, intelligently controls main loops of the photovoltaic generating system to perform synchronization power generation or stop the synchronization power generation, and keeps the output power of the photovoltaic generating system automatically matched with the load consumed power to realize the reverse power control function. In the figure, an input port receives the information of the reverse power acquisition and monitoring system, and outputs a control command to a photovoltaic sub system after the information is calculated and processed by a singlechip.

The invention discloses a gasoline filter not easy to block. The gasoline filter not easy to block comprises a shell, a first separation plate, a first filter screen, a second filter screen, a first support rod, a second support rod, a first stirring blade, a second stirring blade and a driving mechanism; an oil inlet and an oil outlet are formed in the shell; an accommodating cavity is formed in the shell; the first separation plate is positioned in the accommodating cavity for dividing the accommodating cavity into a first accommodating cavity and a second accommodating cavity; the first separation plate is provided with a first through hole for communicating the first accommodating cavity with the second accommodating cavity; the second accommodating cavity is connected with the oil outlet; the filter filter screen and the second filter screen are both positioned in the first accommodating cavity for dividing the first accommodating cavity into a first filter cavity, a second filter cavity and a third filter cavity; the first filter cavity and the third filter cavity are both connected with the oil inlet; and the second filter cavity is connected with the first through hole. The gasoline filter not easy to block is simple in structure, free of blocking and convenient for use.

The invention discloses a multi-virus immunodetection device and method based on a smart phone and a micro-fluidic chip. The device is used for carrying out multi-virus immunodetection on a blood sample infected with viruses of a human body, a horizontally arranged mobile phone slot is formed in the middle of the upper surface of the shell, a horizontally arranged detection device, a reaction chipand a reagent chip are sequentially arranged above the mobile phone slot, and the reagent chip is driven by a lifting device to vertically move up and down. Reagent bottles with different depths andpenetrable adhesive films at the bottoms are designed, and separation and coupling of the reagent bottles and a sharp tube on the reaction chip is realized, and sample purification, incubation, colordevelopment and the like are integrated on one chip. The square air cavity is controlled to contract and expand by the electromagnetic clamp, so that the requirement of driving liquid to flow in different reaction steps is met, and the existing microplate reader can be replaced by only one smart phone for absorbance detection. The reaction chip is independent of other structures, different antibodies or antigens can be coated in reaction tubes in different reaction chips, and multi-virus detection is realized.

The invention discloses an efficient lime powder sprayer, belongs to powder sprayers in the technical field of powder spraying and aims to provide an efficient lime powder sprayer. The efficient lime powder sprayer comprises a material barrel, a feeding adjusting hopper is arranged in an inner cavity of the material barrel, a feeding port of the feeding adjusting hopper penetrates out of the top of the material barrel, the bottom of the material barrel is connected with a driving motor, and a vibration stirring device is arranged in the material barrel and connected with the driving motor. One end of the bottom of the material barrel is connected with a discharging pipe, one end of the discharging pipe is communicated with a blowdown pipe, the middle of the blowdown pipe is communicated with the discharging pipe, and the other end of the blowdown pipe is connected with a fan. A secondary smashing device for protecting high-speed air flow from reverse flowing is further arranged between the material barrel and the blowdown pipe, the two ends of the secondary smashing device are communicated with the material barrel and the blowdown pipe through the discharging pipe, and the discharging pipe between the secondary smashing device and the material barrel is connected with an air inlet adjusting valve.

The present invention relates to an eccentric drive mechanism for volume-action pumps or motors, comprising the following features: a) at least one stroke member (HG) rotatably fixedly connected to the shaft (W) of the crank mechanism and having at least a stroke bearing (HL) eccentric with respect to this axis (XX) of the shaft; b) the stroke bearing (HL) connects the stroke member (HG) to a coupling member (KG) which does not participate in rotational movement, said member is in turn connected via a radial bearing (QL) to at least one pressure member (DG) of the drive mechanism for the oscillating transmission of at least one piston-cylinder unit; c) providing a pressure supply of at least one lubricant source (DQ), which on the output side is connected to the radial bearing (QL) by a channel system; d) starting from a connecting channel (KA) connected to the pressure supply source (DQ), the channel system comprising: at least one A first channel (K1) extending through the stroke member (HG) to the stroke bearing (HL); and at least one second channel (K2) extending from said stroke bearing through the coupling member (KG) to the centripetal bearing (QL).

The invention belongs to the technical field of sensors and relates to a one-way conduction fluid sensor. The one-way conduction fluid sensor is characterized in that a valve seat is arranged on the inner wall of one end of a housing with a fluid channel; a valve element inlaid with a magnet block and being capable of controlling positive conduction and reverse blocking is arranged on the valve seat; a limiting rod is arranged at the tail part of the valve element; the tail end of the limiting rod points to the other end of the housing; a limiting spring seat with a fluid through hole is arranged on the inner wall of the other end of the housing; one side of a reset spring is connected to the limiting rod in a sleeving manner; the other side of the reset spring is propped against and connected to the limiting spring seat; a magnetic switch which is turned on or off by virtue of magnetic force of the magnet block when the valve element is opened or closed is arranged on the outer wall of the housing. The one-way conduction fluid sensor has the advantages as follows: the structure is simple, the manufacture cost is low, the fluid resistance is small, the leakproofness is good, the service life is long, the using performance is stable and the sensor is applicable to high voltage or ultrahigh pressure and capable of controlling fluid flowing unidirectionally.

The invention relates to a novel toothbrush with toothpaste. A toothbrush head and a toothbrush neck are of an integral structure; the toothbrush head is arranged at one end of the toothbrush neck; toothpaste flues which are communicated with each other are formed inside the toothbrush head and the toothbrush neck; brush hair is arranged on the toothbrush head; through holes are formed in the toothbrush head; the through holes are communicated with the toothpaste flues; a toothbrush stem is arranged at the other end of the toothbrush neck; a toothpaste storage cavity is formed inside the toothbrush stem; the toothpaste storage cavity is communicated with the toothpaste flues; toothpaste is stored inside the toothpaste storage cavity; a push block is arranged inside the toothpaste storage cavity; an extrusion part is arranged at the tail part of the toothbrush stem; and the push block is extruded by the extrusion part, and then the toothpaste inside the toothpaste storage cavity can be extruded into the toothpaste flues through the push block, and can flow out through the through holes. As the toothbrush provided by the invention is of a hollow structure, the cavity with the toothpaste is connected with the tail part of the toothbrush, the cavity is communicated with the inner cavity of the toothbrush, and the toothpaste can be extruded out from the inner cavity of the toothbrush and the through holes in the toothbrush head by the extrusion structure, so that tooth brush preparation can be achieved; and the novel toothbrush is convenient to operate and carry over, and is safe and sanitary.

The invention discloses a suction fixing and magnetic fixing combined vehicle navigation instrument. The suction fixing and magnetic fixing combined vehicle navigation instrument comprises a navigation instrument body, a suction plate and a support rod assembly. The support rod assembly comprises a vertical rod, an iron bracket, a clip, a permanent magnet block and a permanent magnet sleeve. The suction plate comprises a suction plate body, a ring-shaped seal ring, an elastic exhaust plate, a connecting rod, a cam and an O-shaped seal ring. When the suction fixing and magnetic fixing combined vehicle navigation instrument is used, the navigation instrument body is connected through the clip, and the positions of the navigation instrument body and the iron bracket are fixed through the permanent magnet block and the permanent magnet sleeve, so that the navigation instrument body is easily disassemble, assemble and adjusted in angular position to facilitate the use; and meanwhile, the suction plate is used for fixing through suction, the ring-shaped seal ring can further enhance the suction force of the suction plate, and the O-shaped seal ring can prevent the air from flowing into an arc-shaped recess in reverse, so that the suction fixing and magnetic fixing combined vehicle navigation instrument is high in suction fixing capacity and solves the problem that an existing suction fixing and magnetic fixing combined vehicle navigation instrument is poor in suction stability and easy to fall.

The invention discloses a mobile communication terminal and a circuit used for protecting charging of the mobile communication terminal. The circuit comprises a comparator, a first MOS (metal oxide semiconductor) tube, a second MOS tube, a diode, a first resistor and a second resistor, wherein an anode of the diode is connected with a drain electrode of the first MOS tube, a cathode of the diode is connected with a source electrode of the first MOS tube, the source electrode of the first MOS tube is further connected with a charging unit of the mobile communication terminal and a negative input end of the comparator, the drain electrode of the first MOS tube is further connected with a charging interface of the mobile communication terminal and a positive input end of the comparator, a grid electrode of the first MOS tube is connected with a drain electrode of the second MOS tube, a grid electrode of the second MOS tube is connected with an output end of the comparator, a source electrode of the second MOS tube is grounded through the second resistor, one end of the first resistor is connected with the grid electrode of the first MOS tube, and the other end of the first resistor is connected with the source electrode of the first MOS tube to protect the mobile communication terminal. By the mode, counterflow of current or voltage can be prevented, so that the mobile communication terminal is protected from damages.

A hydraulic circuit includes a first pressurizing section for pressurizing a wheel cylinder by operating a master cylinder, and a second pressurizing section for pressurizing the wheel cylinder independently of operation of the master cylinder. A control unit determines whether a first operation request according to a physical relationship between a vehicle and an environment surrounding the vehicle is present; determines whether a second operation request according to a physical behavior of the vehicle is present; activates the first pressurizing section when the first operation request is present and the second operation request is absent; activates the second pressurizing section when the first operation request is absent and the second operation request is present; ; and keeps the first pressurizing section activated and activates the second pressurizing section, when the second operation request turns present under condition that the first pressurizing section is activated in response to the first operation request.

The invention relates to a seal charging valve and relates to the field of hoppers. The seal charging valve comprises a hopper; the lower end of the hopper is provided with a discharge hole; the upper end of the hopper is provided with a charging plane sluice gate; the charging plane sluice gate is provided with a bell sealing structure; the discharge hole of the hopper is provided with an automatically controlled seal sluice gate. According to the seal charging valve, a charging hole is provided with the charging plane sluice gate and the discharge hole is provided with the bell; during charging, the charging plane sluice gate is opened, the bell is closed, and materials enter the hopper from a raw material cabin; during discharging, the charging plane sluice gate is closed, the bell is opened, the seal charging valve operates in a recycle mode as above, and the charging plane sluice gate and the bell alternately operate in a combination mode; meanwhile the charging plane sluice gate and the bell are provided with seal structures, dust is prevented from escaping, air flows are effectively prevented from flowing reversibly, and accordingly stabilization of air pressure inside a system and normal discharging of materials are guaranteed.

The invention discloses a backward warming system of a boiler feed pump. The backward warming system of the boiler feed pump comprises a first pipeline and a second pipeline which are arranged between a deaerator and a high-pressure heater, a first booster pump, a first feed pump, a first check valve and a first motorized valve are serially arranged on the first pipeline, a second booster pump, a second feed pump, a second check valve and a second motorized valve are serially arranged on the second pipeline, both the first booster pump and the second booster pump are medium-pressure pumps, a first bypass is arranged between an outlet of the first booster pump and an outlet of the second feed pump, a second bypass is arranged between an outlet of the second booster pump and an outlet of the first feed pump, and a plurality of check valves, throttling orifice plates and check valves are serially arranged on each of the first bypass and the second bypass. The backward warming system of the boiler feed pump has the advantages of simple structure and reasonable arrangement, eroding of pump warming water to pipelines can be reduced obviously, and water pressure that pump warming water pipelines loaded can be lowered obviously, so that possibility of pipeline burst is lowered, safety of water pipes is improved, and maintenance cost caused by water pipe crack is reduced.