CN210564723U - Urea injection system for diesel engine aftertreatment system - Google Patents

Abstract

The utility model discloses a urea injection system for diesel engine aftertreatment system, include: and valves, which are integrated relief valves that open at low pressure but close at high pressure and two check valves that close at low pressure but open at high pressure, or two independent valves in which a normally open exhaust valve and a normally closed relief valve are arranged in parallel, the valves being provided on the return pipe. The utility model discloses utilize one to open but close under the valve collocation low pressure that closes under the high pressure at low pressure and realize evacuation and pressurization nevertheless under the high pressure valve of opening to make this pump can keep the stability of urea supply pressure better, reduce the energy consumption, also can empty when the pump starts rapidly simultaneously.

Description

Urea injection system for diesel engine aftertreatment system

Technical Field

The utility model relates to a diesel engine aftertreatment technical field. More specifically, the present disclosure relates to urea injection systems for diesel aftertreatment systems.

Background

FIG. 1 is a schematic diagram of a urea injection system commonly used in current diesel aftertreatment systems: the liquid inlet end of the urea pump 100 is connected with the urea filter 300 through the liquid inlet pipe 200 to draw urea from a urea tank (not shown in the figure), and the liquid outlet end is connected with the urea nozzle 500 through the injection pipe 400 to inject the urea into the exhaust pipe of the engine; a urea return channel is arranged at the outlet side of the urea pump 100 for returning part of the urea to the urea tank (not shown) via a return line 600.

The urea injection system described above requires the urea pump 100 to deliver urea at a relatively stable pressure to the nozzle 500. Although some current technologies, such as using a large overflow ratio (ratio of overflow amount to injection amount of the nozzle) and using a deformation body such as an air bag or a plastic container, to achieve pressure stabilization, a large fluctuation of the urea pressure is still caused at the moment of opening and closing the nozzle. An electric control valve is arranged on the return channel, and the synchronous control with the nozzle is realized through a controller, so that the pressure stabilizing effect can be realized, and the urea overflow amount can be reduced to the maximum extent to achieve the effect of reducing energy consumption. However, this design requires an additional electrically controlled valve, which increases the cost and also increases the burden on the controller, reducing the reliability of the system.

By proper design, a mechanical check valve (overflow valve) can also achieve the similar effect of the electric control valve: when the nozzle is opened and urea loses pressure, the one-way valve is immediately closed or the overflow quantity is reduced; when the pressure of the urea is increased when the nozzle is closed, the one-way valve is opened by the increased pressure, and the overflow quantity is increased; thus, the function of stabilizing voltage can be achieved.

However, when the urea pump is started, air in the urea pump and the pipeline needs to be exhausted first, and urea can be sucked into the urea pump after the air is exhausted. For most pumps, pump air is much less efficient than pump fluid and air pressure often does not reach sufficient pressure to open the relief valve. At this time, the exhaust gas can only be discharged by opening the nozzle, so that the emptying efficiency is extremely low, and the actual use requirement cannot be met, namely the exhaust gas is emptied in a short time and is ready for urea delivery.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a urea injection system for diesel engine aftertreatment system does not need automatically controlled pure mechanical device for one kind, can reach and play the steady voltage effect and also can high-efficient evacuation when the urea pump starts.

To achieve these objects and other advantages in accordance with the purpose of the invention, there is provided a urea injection system for a diesel engine after-treatment system, comprising: and the valve has the functions of exhausting and stabilizing pressure, and is arranged on the return pipe.

Preferably, the valve comprises a normally open exhaust valve and a normally closed overflow valve arranged in parallel via two return lines.

Preferably, the valve is an integrated relief valve that integrates two check valves that open at low pressure but close at high pressure and close at low pressure but open at high pressure.

Preferably, the method further comprises the following steps: the urea pump is communicated with the urea box through a liquid inlet pipe and is also communicated with the nozzle through an injection pipe; a return pipe which is respectively communicated with the injection pipe and the urea box; and the filter is arranged on the liquid inlet pipe or the injection pipe or in the urea pump.

Preferably, the integrated relief valve includes: the first shell is hollow, an inlet and an outlet which penetrate through the first shell are formed in the first shell from top to bottom, the first shell is divided into an external groove and an internal channel through a cylindrical partition plate with openings at the top and the bottom, the lower end of the cylindrical partition plate is integrally formed with the first shell, the upper end of the cylindrical partition plate is spaced from the inlet, and the internal channel is communicated with the outlet to form a stepped channel with a large upper part and a small lower part; the first exhaust valve core is just attached to the inner wall of the first shell and arranged in the first shell, a vertical first through hole is formed in the first exhaust valve core, the first exhaust valve core is supported by a first spring, the lower end of the first spring is fixed to the bottom of the external groove, and the upper end of the first spring is fixed to the bottom end of the first exhaust valve core; the first overflow valve core is just tightly attached to the inner channel wall, a plurality of vertical second through holes are formed in the first overflow valve core along the circumferential direction of the first overflow valve core, the first overflow valve core is supported by a second spring, the lower end of the second spring is fixed on a step of the step channel, and the upper end of the second spring is fixed at the bottom end of the first overflow valve core; the first through hole is not vertically communicated with the second through hole, the second through hole is not vertically communicated with the outlet, and the first through hole is vertically communicated with the outlet.

Preferably, the integrated relief valve includes: the second shell is hollow, an inlet and an outlet which penetrate through the second shell are formed in the upper part and the lower part of the second shell respectively, the interior of the second shell is divided into an external groove and an internal channel through a cylindrical partition plate with openings at the upper part and the lower part, the lower end of the cylindrical partition plate and the second shell are integrally formed, the upper end of the cylindrical partition plate is spaced from the inlet, and the internal channel is communicated with the outlet to form a stepped channel with a large upper part and a small lower part; the second exhaust valve core is just tightly attached to the inner wall of the second shell and arranged inside the second shell, a plurality of vertical third through holes and a plurality of vertical fourth through holes are formed in the second exhaust valve core along different circumferential directions of the second exhaust valve core, the second exhaust valve core is supported by a first spring, the lower end of the first spring is fixed at the bottom of an external groove, the upper end of the first spring is fixed at the bottom end of the second exhaust valve core, the bottom end of the second exhaust valve core is also upwards sunken to form a concave hole, the fourth through holes are communicated with the concave hole, and the third through holes are formed in the outer side of the concave hole; the second overflow valve core is positioned in the concave hole and is just tightly attached to the wall of the concave hole, the second overflow valve core can freely move up and down in the internal channel, the second overflow valve core is provided with a vertical fifth through hole, the second overflow valve core is also supported by a second spring, the lower end of the second spring is fixed on a step of the stepped channel, and the upper end of the second spring is fixed at the bottom end of the second overflow valve core; the third through hole is not vertically communicated with the internal channel, the fifth through hole is not vertically communicated with the fourth through hole, and the fifth through hole is vertically communicated with the outlet.

Preferably, the integrated relief valve includes: the third shell is hollow and is provided with an inlet and an outlet which penetrate through the inside from top to bottom, and an annular partition plate is fixed on the inner wall of the third shell; the third overflow valve core is just tightly attached to the inner wall of the third shell, arranged in the third shell and positioned below the annular partition plate, a plurality of vertical sixth through holes are formed in the third overflow valve core along the circumferential direction of the third overflow valve core, a vertical seventh through hole is further formed in the third overflow valve core on the inner side of the sixth through hole and is in a step shape with a large upper part and a small lower part, the third overflow valve core is supported by a second spring, the lower end of the second spring is fixed in the third shell, and the upper end of the second spring is fixed at the bottom end of the third overflow valve core; the third exhaust valve core is supported in the annular partition plate through a first spring, an annular eighth through hole is formed between the third exhaust valve core and the annular partition plate, the lower end of the first spring is fixed on a step of the seventh through hole, and the upper end of the first spring is fixed at the bottom end of the third exhaust valve core; the sixth through hole is not vertically communicated with the eighth through hole, the eighth through hole is not vertically communicated with the seventh through hole, and the sixth through hole is vertically communicated with the outlet.

Preferably, the valve is located in the urea box and is immersed in the urea solution, so as to prevent the valve from losing effectiveness due to drying urea crystals inside the valve.

The utility model discloses at least, include following beneficial effect:

the utility model discloses a urea injection system can realize the steady voltage effect through setting up the valve, can realize high-efficient evacuation effect again, and is with low costs, and the system operation is reliable and stable.

The utility model discloses the integrated form overflow valve that sets up can furthest reduces the overflow volume to also reduced the liquid total output volume of urea pump, reduced the energy consumption, prolonged the life of urea pump.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.

Drawings

FIG. 1 is a schematic diagram of a urea injection system commonly used in the prior art of the present invention;

fig. 2 is a schematic diagram of one of the urea injection systems of the present invention: an integrated overflow valve is adopted;

fig. 3 is used for the utility model discloses the first structure schematic diagram of integrated form overflow valve: an empty state;

fig. 4 is used for the first structural schematic diagram of integrated overflow valve of the utility model: no overflow state;

fig. 5 is used for the first structure schematic diagram of integrated form overflow valve of the utility model: an overflow state;

FIG. 6 is a schematic view of another urea injection system of the present invention: two independent check valves are adopted;

fig. 7 the utility model discloses a second kind of schematic structure of integrated form urea pump overflow valve: an empty state;

fig. 8 the utility model discloses a second kind of schematic structure of integrated form urea pump overflow valve: no overflow state;

fig. 9 the utility model discloses a second kind of schematic structure of integrated form urea pump overflow valve: an overflow state;

fig. 10 the utility model discloses the third kind of schematic structure of integrated form urea pump overflow valve: an empty state;

fig. 11 the utility model discloses the third kind of schematic structure of integrated form urea pump overflow valve: no overflow state;

fig. 12 the utility model discloses the third kind of schematic structure of integrated form urea pump overflow valve: and (4) an overflow state.

Description of reference numerals:

100. the device comprises a urea pump, 200 parts of a liquid inlet pipe, 300 parts of a filter, 400 parts of an injection pipe, 500 parts of a nozzle, 600 parts of a return pipe, 700 parts of an integrated overflow valve, 800 parts of a normally open exhaust valve, 900 parts of a normally closed overflow valve, 10 parts of a first shell, 11 parts of a second shell, 12 parts of a third shell, 15 parts of an outlet, 20 parts of a first exhaust valve core, 21 parts of a second exhaust valve core, 22 parts of a third exhaust valve core, 25 parts of a first through hole, 26 parts of a third through hole, 27 parts of a fourth through hole, 28 parts of an eighth through hole, 30 parts of a first spring, 40 parts of a first overflow valve core, 41 parts of a second overflow valve core, 42 parts of a third overflow valve core, 45 parts of a second through hole, 46 parts of a fifth through hole, 47 parts of a sixth through hole, 48 parts of a seventh through hole.

Detailed Description

The present invention is further described in detail below with reference to the drawings so that those skilled in the art can implement the invention with reference to the description.

It is to be noted that the experimental methods described in the following embodiments are all conventional methods unless otherwise specified, and the reagents and materials, if not otherwise specified, are commercially available; in the description of the present invention, the terms "lateral", "longitudinal", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore, should not be construed as limiting the present invention.

The utility model provides a urea injection system for diesel engine aftertreatment system, include: and the valve has the functions of exhausting and stabilizing pressure, and is arranged on the return pipe. The return pipe is provided with a valve, and the valve is realized through an exhaust function when the air in the pipeline needs to be exhausted, and is realized through a pressure stabilizing function when the pressure is required to be stabilized.

The utility model discloses an injection system main characterized in that utilizes one to open but the valve of closing under the high pressure under the low pressure, this valve can be for one can open the normal open discharge valve that lets the air discharge smoothly when this urea injection system evacuation, the valve of opening under a collocation low pressure is closed but under the high pressure, this valve is a normal close overflow valve that can adjust urea liquid pressure through control overflow volume, realize evacuation and pressurization, thereby make this pump can keep urea supply pressure's stability better, reduce the urea nozzle and open and close the injection liquid pressure fluctuation that causes, reduce the energy consumption, also can empty when the pump starts rapidly simultaneously. The utility model discloses an injection system also can be integrated into an integrated form overflow valve with two valves, and evacuation and steady voltage function are realized simultaneously to a valve.

Example 1

As shown in fig. 2, a urea return passage is also provided between the urea pump 100 and the nozzle 500, so that a part of the urea pumped by the urea pump 100 is returned to the urea tank (not shown) via a return pipe 600 and an integrated relief valve 700.

The integrated overflow valve can be opened under lower pressure, so that the urea pump can discharge air through the integrated overflow valve 700 in the emptying stage; when the gas is discharged, the urea pump 100, the liquid inlet pipe 200, the injection pipe 400 and the return pipe 600 are filled with liquid, the hydraulic pressure continuously rises, and the integrated overflow valve 700 is closed before the pressure reaches the required working pressure; however, when the hydraulic pressure exceeds a predetermined level, integrated spill valve 700 may open again, allowing fluid to return to the urea tank (not shown) through integrated spill valve 700.

Thus, whenever the pressure in the injection pipe 400 and the return pipe 600 fluctuates due to the opening and closing of the nozzle 500, the integrated relief valve 700 is opened to relieve the pressure when the pressure is higher than a certain value, and the valve relief amount (relief amount) is proportional to the pressure, and the integrated relief valve 700 is closed when the pressure is lower than a certain value, so that the pressure of the urea delivered to the nozzle 500 tends to be stable.

Example 2

As shown in fig. 6, the same effect can be achieved by using two different check valves, i.e., a normally open exhaust valve 800 and a normally closed relief valve 900, instead of relief valve 700. The return pipe is divided into a return channel and an exhaust channel between the outlet of the urea pump 100 and the inlet of the nozzle 500, for convenience of writing, the return pipes 600 are generally called as return pipes, each return pipe is connected with a valve, the return channel is composed of a return pipe and a normally closed overflow valve 900, and part of urea can return to a urea tank (not shown in the figure) through the return channel; the exhaust channel is composed of an exhaust pipe and a normally open exhaust valve 800, and air can be exhausted through the exhaust pipe and the normally open exhaust valve 800 when the urea pump 100 is emptied;

the normally open exhaust valve 800 is opened at a low pressure to allow air to be smoothly discharged, and is closed at a high liquid pressure after the air is discharged; in contrast, the normally closed overflow valve 900 remains closed at low pressures, opens to allow some of the liquid to overflow back into the urea tank when the hydraulic pressure is above a certain level (e.g., injection pressure), and the amount of overflow is proportional to the excess pressure level.

The normally open exhaust valve 800 opens when the pressure is below a certain value, allowing the pump 100 to smoothly exhaust air through the valve when it is emptying. When the emptying is finished, the liquid enters the urea pump 100, the liquid inlet pipe 200, the injection pipe 400 and the return pipe 600, and the pressure rises, so that the normally open exhaust valve 800 is closed.

The normally closed relief valve 900 is opened when the liquid is above a certain value and closed when the liquid is below a certain value, thereby reducing pressure fluctuations caused by the opening and closing of the nozzle 500.

The utility model discloses a complete system of urea injection system includes: a urea pump 100 connected to the urea tank through a liquid inlet pipe 200, and further connected to the nozzle 500 through an injection pipe 400; a return pipe 600 that communicates the injection pipe 400 and the urea tank, respectively; and a filter 300 disposed on the liquid inlet pipe 200 or the injection pipe 400 or in the urea pump 100.

As shown in fig. 1, a urea pump 100 is connected to a urea filter 300 through a liquid inlet pipe 200 to draw urea from a urea tank (not shown), and is connected to a urea nozzle 500 through a urea injection pipe 400 to deliver urea under pressure to the urea nozzle 500; between the outlet of the urea pump 100 and the inlet of the nozzle 500 there is a return channel, through which excess urea can be returned to the urea tank (not shown in the figure) via a return conduit 600.

If necessary, a filter (not shown) is added between the urea pump 100 and the nozzle 500 to further filter the urea. In some applications, filter 300 may also be disposed within urea pump 100, or filter 300 may be provided as a primary filter, followed by a fine filter (not shown) between filter 300 and urea pump 100.

The utility model provides a three kinds of concrete forms of integrated form overflow valve 700.

Example 3

As shown in fig. 3 to 5, the integrated relief valve includes: the structure comprises a first shell 10, a second shell and a third shell, wherein the first shell 10 is hollow, an inlet and an outlet 15 which penetrate through the first shell are respectively arranged at the upper part and the lower part of the first shell, the interior of the first shell 10 is divided into an external groove and an internal channel through a cylindrical partition plate with openings at the upper part and the lower part, the lower end of the cylindrical partition plate is integrally formed with the first shell 10, the upper end of the cylindrical partition plate is spaced from the inlet, and the internal channel penetrates through the outlet 15 and; the first exhaust valve core 20 is just attached to the inner wall of the first shell 10 and arranged inside the first shell 10, the first exhaust valve core 20 is provided with a vertical first through hole 25, the first exhaust valve core 20 is supported by a first spring 30, the lower end of the first spring 30 is fixed at the bottom of an external groove, and the upper end of the first spring 30 is fixed at the bottom end of the first exhaust valve core 20; the first overflow valve core 40 is just tightly attached to the inner channel wall, a plurality of vertical second through holes 45 are formed in the first overflow valve core 40 along the circumferential direction of the first overflow valve core, the first overflow valve core 40 is supported by a second spring 50, the lower end of the second spring 50 is fixed on a step of a step channel, and the upper end of the second spring 50 is fixed at the bottom end of the first overflow valve core 40; the first through hole 25 and the second through hole 45 are not vertically communicated, the second through hole 45 and the outlet 15 are not vertically communicated, the first through hole 25 and the outlet 15 are vertically communicated, and the second through hole 45 is communicated with the outlet 15.

As shown in fig. 3 to 5, in the integrated overflow valve 700, a first exhaust valve element 20 capable of sliding up and down is installed inside a first housing 10, and a first through hole 25 is formed in the middle of the first exhaust valve element 20, so that air or urea solution can pass through the first exhaust valve element 20. The first exhaust spool 20 may be operated downwardly under the pressure from above and upwardly under the urging of the first spring 30. Under the first exhaust valve core 20, another first overflow valve core 40 that can slide up and down is disposed at the bottom of the first housing 10, and a plurality of second through holes 45 are formed around the first overflow valve core 40 to allow air or urea solution to pass through the first overflow valve core 40. The first spill valve spool 40 may operate downward under the pressure of urea liquid from above and may operate upward under the drive of the second spring 50. When the first exhaust valve spool 20 moves to the bottom dead center and comes into close contact with the first spill valve spool 40 (as shown in fig. 4), the integrated spill valve 700 is in a fully closed state and any gas or liquid will not be able to pass through the integrated spill valve 700. At any time when there is a clearance between the first exhaust valve spool 20 and the first relief valve spool 40 (as shown in fig. 3 and 5), the integrated relief valve 700 is in an open state and gas or liquid may pass through the integrated relief valve 700.

The first spring 30 that drives the upward movement of the first exhaust valve spool 20 may be designed such that: when the pressure born above the first exhaust valve core 20 is smaller than a certain value, the first exhaust valve core 20 is kept at the highest position (shown in fig. 3), namely the valve is opened, and after air or liquid passes through the first exhaust valve core 20 and the first overflow valve core 40 below, the air or liquid finally passes through the outlet 15 from the bottom of the integrated overflow valve 700 and is discharged into a urea tank (not shown in the figure); when the pressure applied to the upper side of the first exhaust valve core 20 is greater than a certain value, the resistance of the first spring 30 is overcome, and the first exhaust valve core 20 is driven to move downwards to the lowest (bottom dead center) position. At this time, if the pressure experienced by the first relief valve spool 40 is insufficient to travel downward against the second spring 50, the lower surface of the first exhaust valve spool 20 is in intimate contact with the upper surface of the first relief valve spool 40 (as shown in fig. 4), i.e., the valve is closed and neither air nor liquid can pass through the integrated relief valve 700.

The second spring 50 that drives the upward movement of the first spill valve core 40 may be designed such that: maintaining the first spill valve member 40 in the uppermost position (as shown in FIG. 3 or FIG. 4) when the pressure experienced above the first spill valve member 40 is less than a certain value; at this time, when the first exhaust valve spool 20 is also at the uppermost position, both air and urea may pass through the first exhaust valve spool 20 and the first spill valve spool 40 (as shown in fig. 3), whereas when the first exhaust valve spool 20 is at the lowermost position, i.e., the valve is closed, neither air nor liquid may pass through the valve (as shown in fig. 4); when the pressure applied above the first relief valve spool 40 is greater than a certain value, the first relief valve spool 40 is driven downward against the resistance of the second spring 50, so that even when the first exhaust valve spool 20 is at the lowest position, the valve is opened (as shown in fig. 5), and the liquid can pass through the first exhaust valve spool 20 and the first relief valve spool 40, pass through the outlet 15 from the bottom of the relief valve, and return to the urea tank (not shown).

With the above arrangement, when the urea pump 100 is started, the liquid inlet pipe 200, the injection pipe 400 and the return pipe 600 are all air. At this time, the urea pump needs to discharge the air in the device as soon as possible to draw in the urea solution. For most liquid pumps, the efficiency and pressure of pumping air is much lower than that of pumping liquid. Thus, the air pressure will be kept in a very low range throughout the evacuation process before liquid is drawn in. If the first spring 30 is designed to drive the first exhaust valve spool 20 upward with a force greater than the downward force caused by air pressure, the valve will remain open (as shown in FIG. 3), so that air can smoothly pass through the first exhaust valve spool 20 and the first spill valve spool 40, and finally be discharged out of the urea pump.

During the above-described evacuation process, if the urea nozzle 500 is opened, a portion of the air is also simultaneously discharged from the nozzle 500, which helps to shorten the evacuation time.

When the air is evacuated, liquid enters the urea pump, enters the return pipe 600 and the injection pipe 400, and finally reaches the urea nozzle 500 and the integrated relief valve 700. As the pressure of the fluid continues to rise, the first exhaust valve spool 20 will move downward until it is fully closed (as shown in fig. 4) when the pressure of the fluid against the first exhaust valve spool 20 is sufficient to overcome the resistance of the first spring 30. At this point, the urea nozzle 500 may also be closed and all liquid outlets blocked. So that the pressure inside the urea pump 100 and the liquid inlet pipe 200, the injection pipe 400, and the return pipe 600 will all rise rapidly. When the hydraulic pressure reaches the injection pressure required by the nozzle 500, the urea injection system is ready to enter a normal operating state.

At this point, if the hydraulic pressure continues to rise, and when the fluid exceeds a certain value, sufficient to drive the first spill valve element 40 downward against the second spring 50, the entire integrated spill valve 700 will again be in an open state (as shown in FIG. 5), and fluid will return to the urea tank (not shown) through the spill valve. The greater the hydraulic pressure, the further the first spill valve member 40 moves downward, the larger the opening, and the greater the amount of spill. As the amount of relief increases, the fluid pressure decreases and the first relief valve spool 40 moves upward under the force of the second spring 50, with a consequent decrease in the amount of relief. Thus, the capacity of the integrated overflow valve 700 for adjusting the overflow volume according to the pressure can play a role in stabilizing the pressure.

It is clear that the above-mentioned amount of overflow is in direct proportion to the liquid pressure and in inverse proportion to the spring constant K of the second spring 50, the softer the spring, the greater the amount of overflow and, conversely, the smaller the amount of overflow. Thus, the relief opening pressure and the amount of relief can be adjusted by selecting the spring constant of the second spring 50.

Especially at the instant when the urea nozzle 500 is opened causing the liquid pressure to drop, the integrated relief valve 700 responds quickly to close or reduce the amount of relief; at the instant that the urea nozzle 500 is closed causing the hydraulic pressure to rise, the integrated spill valve 700 responds quickly to open or increase the amount of spill. Thus, the pressure regulation of integrated relief valve 700 greatly reduces the hydraulic fluctuations associated with the opening and closing of urea nozzle 500. Ideally, when the relief valve 700 is properly designed, the amount of flow can be adjusted just enough to compensate (follow) the variation of the amount of liquid ejected due to the opening and closing of the nozzle 500, so as to achieve a very desirable pressure stabilizing effect.

The response time of the relief valve (follow-up nozzle switch) is determined by the elastic coefficient K of the second spring 50, the mass of the relief valve core, the viscosity of the fluid medium and other factors. The design of the valve therefore also requires care to be taken for the proper natural frequency.

Finally, the overflow amount can be reduced to the maximum extent due to the throttling effect of the integrated overflow valve 700, so that the total liquid output amount of the urea pump is reduced, the energy consumption is reduced, and the service life of the urea pump is prolonged.

Example 4

As shown in fig. 7 to 9, the integrated relief valve includes: the second shell 11 is hollow, an inlet and an outlet 15 which penetrate through the second shell are formed in the second shell, the second shell 11 is divided into an external groove and an internal channel through a cylindrical partition plate with openings at the upper part and the lower part, the lower end of the cylindrical partition plate and the second shell 11 are integrally formed, the upper end of the cylindrical partition plate is spaced from the inlet, and the internal channel is communicated with the outlet 15 to form a stepped channel with a large upper part and a small lower part; the second exhaust valve core 21 is just tightly attached to the inner wall of the second shell 11 and arranged inside the second shell 11, a plurality of vertical third through holes 26 and a plurality of vertical fourth through holes 27 are formed in the second exhaust valve core 21 along different circumferential directions of the second exhaust valve core, the second exhaust valve core 21 is supported by a first spring 30, the lower end of the first spring 30 is fixed to the bottom of an external groove, the upper end of the first spring 30 is fixed to the bottom end of the second exhaust valve core 21, the bottom end of the second exhaust valve core 21 is further upwards sunken to form a concave hole, the fourth through holes 27 are communicated with the concave hole, and the third through holes 26 are located on the outer side of the concave hole; the second overflow valve core 41 is positioned in the concave hole and is just tightly attached to the wall of the concave hole, the second overflow valve core 41 is arranged to freely move up and down in the internal channel, the second overflow valve core 41 is provided with a vertical fifth through hole 46, the second overflow valve core 41 is also supported by a second spring 50, the lower end of the second spring 50 is fixed on a step of the stepped channel, and the upper end of the second spring 50 is fixed at the bottom end of the second overflow valve core 41; the third through hole 26 is not vertically communicated with the internal channel, the fifth through hole 46 is not vertically communicated with the fourth through hole 27, the fifth through hole 46 is vertically communicated with the outlet 15, and the third through hole 26 is communicated with the outlet 15 only when a gap exists between the second exhaust valve core 21 and the top end of the cylindrical partition plate.

The structure of the integrated relief valve 700 shown in embodiment 4 is similar to that shown in embodiment 3, except that the positions of the openings in the relief valve core and the vent valve core are different, and there are some differences in the relative mounting positions and the mounting positions of the springs, and actually, the relief valve core is embedded in the vent valve core, and the specific positional relationship is shown in the attached drawings. The first spring 30 and the second spring 50 are designed to achieve the same function as that of embodiment 3, and the whole device is ensured to have three different working states under different conditions, so that the functions of emptying and stabilizing pressure are realized.

Example 5

As shown in fig. 10 to 12, the integrated relief valve includes: the third shell 12 is hollow and is provided with an inlet and an outlet 15 which penetrate through the interior from top to bottom, and an annular partition plate is fixed on the inner wall of the third shell 12; the third overflow valve core 42 is just tightly attached to the inner wall of the third shell 12, is arranged in the third shell 12 and is positioned below the annular partition plate, a plurality of vertical sixth through holes 47 are formed in the third overflow valve core 42 along the circumferential direction of the third overflow valve core, a vertical seventh through hole 48 is further formed in the third overflow valve core 42 and is in a step shape with a large upper part and a small lower part, the third overflow valve core 42 is supported by a second spring 50, the lower end of the second spring 50 is fixed in the third shell 12, and the upper end of the second spring 50 is fixed at the bottom end of the third overflow valve core 42; the third exhaust valve core 22 is supported in the annular partition plate through a first spring 30, an annular eighth through hole 28 is formed between the first spring 30 and the annular partition plate, the lower end of the first spring 30 is fixed on the step of the seventh through hole 48, and the upper end of the first spring 30 is fixed at the bottom end of the third exhaust valve core 22; the sixth through hole 47 and the eighth through hole 28 do not vertically penetrate, the eighth through hole 28 and the seventh through hole 48 do not vertically penetrate, and the sixth through hole 47 and the outlet 15 vertically penetrate.

The structure of the integrated relief valve 700 according to embodiment 5 is different from those according to embodiments 3 and 4. In this embodiment, the vent spool is mounted on top of the spill spool and its driving first spring 30 is embedded in the spill spool, the specific positional relationship being shown with reference to the drawings. The first spring 30 and the second spring 50 are designed to achieve the same function as that of embodiment 3, and the whole device is ensured to have three different working states under different conditions, so that the functions of emptying and stabilizing pressure are realized.

In fact, the interior of the integrated relief valve 700 is not limited to the three types of structures listed above, and may have a variety of different structures, which are not listed herein.

In the above description, since urea is easily crystallized in a dehydrated state or in a cold weather, so that the valve is disabled, the normally open exhaust valve 800, the normally closed overflow valve 900 and the two-in-one integrated overflow valve 700 are preferably immersed in the urea tank for use, thereby avoiding the failure due to the crystallization of urea.

Obviously, an integrated relief valve is preferred, whether for reliability or manufacturing cost and space layout considerations.

While the embodiments of the invention have been described above, it is not intended to be limited to the details shown, or described, but rather to cover all modifications, which would come within the scope of the appended claims, and all changes which come within the meaning and range of equivalency of the art are therefore intended to be embraced therein.

Claims (7)

1. A urea injection system for a diesel aftertreatment system, comprising:

the urea pump is communicated with the urea box through a liquid inlet pipe and is also communicated with the nozzle through an injection pipe;

a return pipe which is respectively communicated with the injection pipe and the urea box;

the filter is arranged on the liquid inlet pipe or the injection pipe or in the urea pump;

and the valve has the functions of exhausting and stabilizing pressure, and is arranged on the return pipe.

2. The urea injection system for a diesel aftertreatment system of claim 1, wherein the valve comprises a normally open exhaust valve and a normally closed spill valve arranged in parallel via two return lines.

3. The urea injection system for a diesel aftertreatment system of claim 1, wherein the valve is an integrated spill valve that integrates two check valves that open at low pressure but close at high pressure and close at low pressure but open at high pressure.

4. The urea injection system for a diesel aftertreatment system of claim 3, wherein the integrated relief valve comprises:

the first shell is hollow, an inlet and an outlet which penetrate through the first shell are formed in the first shell from top to bottom, the first shell is divided into an external groove and an internal channel through a cylindrical partition plate with openings at the top and the bottom, the lower end of the cylindrical partition plate is integrally formed with the first shell, the upper end of the cylindrical partition plate is spaced from the inlet, and the internal channel is communicated with the outlet to form a stepped channel with a large upper part and a small lower part;

the first exhaust valve core is just attached to the inner wall of the first shell and arranged in the first shell, a vertical first through hole is formed in the first exhaust valve core, the first exhaust valve core is supported by a first spring, the lower end of the first spring is fixed to the bottom of the external groove, and the upper end of the first spring is fixed to the bottom end of the first exhaust valve core;

the first overflow valve core is just tightly attached to the inner channel wall, a plurality of vertical second through holes are formed in the first overflow valve core along the circumferential direction of the first overflow valve core, the first overflow valve core is supported by a second spring, the lower end of the second spring is fixed on a step of the step channel, and the upper end of the second spring is fixed at the bottom end of the first overflow valve core;

the first through hole is not vertically communicated with the second through hole, the second through hole is not vertically communicated with the outlet, and the first through hole is vertically communicated with the outlet.

5. The urea injection system for a diesel aftertreatment system of claim 3, wherein the integrated relief valve comprises:

the second shell is hollow, an inlet and an outlet which penetrate through the second shell are formed in the upper part and the lower part of the second shell respectively, the interior of the second shell is divided into an external groove and an internal channel through a cylindrical partition plate with openings at the upper part and the lower part, the lower end of the cylindrical partition plate and the second shell are integrally formed, the upper end of the cylindrical partition plate is spaced from the inlet, and the internal channel is communicated with the outlet to form a stepped channel with a large upper part and a small lower part;

the second exhaust valve core is just tightly attached to the inner wall of the second shell and arranged inside the second shell, a plurality of vertical third through holes and a plurality of vertical fourth through holes are formed in the second exhaust valve core along different circumferential directions of the second exhaust valve core, the second exhaust valve core is supported by a first spring, the lower end of the first spring is fixed at the bottom of an external groove, the upper end of the first spring is fixed at the bottom end of the second exhaust valve core, the bottom end of the second exhaust valve core is also upwards sunken to form a concave hole, the fourth through holes are communicated with the concave hole, and the third through holes are formed in the outer side of the concave hole;

the second overflow valve core is positioned in the concave hole and is just tightly attached to the wall of the concave hole, the second overflow valve core can freely move up and down in the internal channel, the second overflow valve core is provided with a vertical fifth through hole, the second overflow valve core is also supported by a second spring, the lower end of the second spring is fixed on a step of the stepped channel, and the upper end of the second spring is fixed at the bottom end of the second overflow valve core;

the third through hole is not vertically communicated with the internal channel, the fifth through hole is not vertically communicated with the fourth through hole, and the fifth through hole is vertically communicated with the outlet.

6. The urea injection system for a diesel aftertreatment system of claim 3, wherein the integrated relief valve comprises:

the third shell is hollow and is provided with an inlet and an outlet which penetrate through the inside from top to bottom, and an annular partition plate is fixed on the inner wall of the third shell;

the third overflow valve core is just tightly attached to the inner wall of the third shell, arranged in the third shell and positioned below the annular partition plate, a plurality of vertical sixth through holes are formed in the third overflow valve core along the circumferential direction of the third overflow valve core, a vertical seventh through hole is further formed in the third overflow valve core on the inner side of the sixth through hole and is in a step shape with a large upper part and a small lower part, the third overflow valve core is supported by a second spring, the lower end of the second spring is fixed in the third shell, and the upper end of the second spring is fixed at the bottom end of the third overflow valve core;

the third exhaust valve core is supported in the annular partition plate through a first spring, an annular eighth through hole is formed between the third exhaust valve core and the annular partition plate, the lower end of the first spring is fixed on a step of the seventh through hole, and the upper end of the first spring is fixed at the bottom end of the third exhaust valve core;

the sixth through hole is not vertically communicated with the eighth through hole, the eighth through hole is not vertically communicated with the seventh through hole, and the sixth through hole is vertically communicated with the outlet.

7. The urea injection system for a diesel aftertreatment system of claim 1, wherein the valve is located in a urea tank immersed in a urea solution.

Images