CN104819072B - A kind of cooler for recycled exhaust gas gas alarm method and device - Google Patents

Abstract

The invention provides a gas alarm method and device for an EGR cooler, including a pressure limiting valve assembly, a one-way valve assembly and an alarm trigger assembly. In the initial stage of EGR cooler use, the pressure difference between the inlet pipe and the outlet pipe is small, and the pressure difference is less than Preset pressure difference, so the spool of the one-way valve assembly is far away from the trigger switch at this time, and the alarm module is not activated. When the pressure difference between the inlet pipe and outlet pipe of the EGR cooler is greater than the preset pressure difference, the pressure limiting valve assembly will The air inlet and the overflow hole will be connected, so that the gas in the intake pipe enters the one-way valve body, and the valve core of the one-way valve assembly is driven to move to the trigger switch, so that the trigger switch is closed, thereby activating the alarm module to give an alarm. The gas alarm device of the present invention only needs to be connected in parallel with the inlet pipe and the outlet pipe of the original EGR cooler, and the original EGR cooler has less changes and does not affect its normal use, and the gas alarm device can be realized relatively simply and conveniently Real-time and effective monitoring and early warning of EGR cooler.

Description

A gas alarm method and device for an EGR cooler

technical field

The invention relates to the mechanical field, in particular to a gas alarm method and device for an EGR cooler.

Background technique

With the increasing application of exhaust gas recirculation technology in diesel engines, various exhaust gas recirculation (Exhaust Gas Recycling, EGR) coolers have emerged at the historic moment. Most of the existing EGR coolers directly use the coolant of the diesel engine itself. As a medium to cool the exhaust gas, when the diesel engine is recirculating the exhaust gas, the incomplete combustion products HC and soot in the exhaust gas, as well as the sulfide and water vapor produced after the exhaust gas is cooled, are easily attached to the wall of the EGR cooler , with the increase of diesel engine service time, a thick layer of carbon deposits will gradually be formed on the inner surface of the EGR cooler.

The most direct impact of the appearance of carbon deposits on the EGR cooler is the reduction of the exhaust gas flow area of the cooler and the increase of channel pressure. In terms of diesel engine emissions, the EGR rate continues to decrease and the emissions continue to deteriorate. For the carbon deposition of the diesel engine EGR cooler, the existing technology adopts a bypass EGR cooler or installs an oxidation device before the EGR cooler, so as to reduce the erosion of the exhaust gas on the EGR cooler during the operation of the diesel engine.

The above technologies can only prolong the service life of the EGR cooler to a certain extent, but the current state of the EGR cooler cannot be known, for example, the flow capacity of the EGR cooler and the pressure difference between the intake pipe and the outlet pipe cannot be evaluated. For this reason, it is necessary to provide a device capable of evaluating the current state of the EGR cooler, so as to remind the user to clean or replace the EGR cooler when necessary.

Contents of the invention

The invention provides a gas alarm method and device for an EGR cooler, which can evaluate the current state of the EGR cooler and remind users to clean or replace the EGR cooler when necessary.

In order to achieve the above object, the present invention provides the following technical means:

A gas alarm device for an EGR cooler, comprising:

A pressure limiting valve assembly (7), a check valve assembly (8) and an alarm trigger assembly (9) connected in parallel with the EGR cooler inlet pipe (33) and the EGR cooler outlet pipe (32);

Wherein, the pressure limiting valve assembly (7) includes a first air inlet (1) and an overflow hole (12) communicated with the EGR cooler intake pipe (33), and the pressure limiting valve assembly (7) is used for The first air inlet (1) and the overflow hole (12) are connected only when the pressure difference between the first air inlet (1) and the overflow hole (12) is greater than a preset pressure difference ;

The one-way valve assembly (8) includes a one-way valve body (14) whose first end communicates with the overflow hole (12) and whose second end is sealed. The trigger switch of the alarm triggering assembly (9) passes through the one-way The second end of the valve body (14) enters the inside of the one-way valve body (14), and the one-way valve body (14) is provided with a second air inlet (2) communicated with the outlet pipe (32) of the EGR cooler , and the spool (15) slidably arranged in the one-way valve body (14), the one-way valve assembly (8) is used to connect the first air inlet (1) and the overflow hole (12) When the pressure difference between them is greater than the preset pressure difference, the control spool (15) slides in the direction of the trigger switch to close the trigger switch, and the valve between the first air inlet (1) and the overflow hole (12) When the pressure difference is less than the preset pressure difference, the control spool (15) slides in the direction of the first air inlet (1) of the trigger switch to disconnect the trigger switch;

The alarm triggering component (9) includes a trigger switch and an alarm module connected to the trigger switch. When the trigger switch is closed, the alarm module is activated to prompt that the EGR cooler needs to be cleaned or replaced.

Preferably, the pressure-limiting valve assembly (7) comprises a first stepped hole, a ball (3) arranged in a larger hole of the first stepped hole, an adjustment handle (11), and the ball (3) and the adjustment The spring (10) between the handles (11) can be adjusted by rotating the adjustment handle (11) to the preload of the spring (10).

Preferably, the pressure limiting valve assembly (7) also includes:

A limit block (13) connected to the adjustment handle (11), the spring (10) runs through the limit block (13), and is stuck between the sphere (3) and the adjustment handle (11), the sphere (3 ) is limited between the larger hole of the first stepped hole and the limiting block (13).

Preferably, the one-way valve assembly (8) includes a second stepped hole, the diameter of the smaller hole of the second stepped hole is consistent with the diameter of the valve core (15), and the second air inlet (2) is connected to the stepped hole The larger hole is communicated, and spool (15) becomes piston shape at the larger hole one end of the second stepped hole, and its external diameter is greater than the diameter of the smaller hole of the second stepped hole.

Preferably, the one-way valve assembly 8 also includes:

A limit bolt (16) connected to one end of the spool (15) adjacent to the trigger switch, and a second spring (17) outside the limit bolt (16).

Preferably, the trigger switch of the alarm trigger assembly 9 is a static contact piece (19) and a moving contact piece (18). When the static contact piece (19) and the moving contact piece (18) are in contact, the trigger switch is closed. The trigger switch is disconnected when the sheet (19) and the movable contact piece (18) are not in contact.

Preferably, the alarm module includes a warning light (21) connected in series with the trigger switch, and/or a buzzer (22) connected in series with the trigger switch.

A gas alarm method for an EGR cooler, applied to the gas alarm device for an EGR cooler as claimed in claim 1, comprising:

Obtain the pressure difference between the intake pipe of the EGR cooler and the outlet pipe of the EGR cooler;

judging whether the pressure difference is greater than a preset pressure difference;

When the pressure difference is greater than the preset pressure difference, an alarm is given.

Preferably, it also includes:

Obtain the preset differential pressure of the EGR cooler in advance.

Preferably, it also includes:

When the pressure difference is less than the preset pressure difference, no processing is performed.

The invention provides a gas alarm device for an EGR cooler. The gas alarm device is connected in parallel with the inlet pipe and the outlet pipe of the EGR cooler. The gas alarm device includes a pressure limiting valve assembly, a one-way valve assembly and an alarm trigger assembly. EGR cooling In the initial stage of the use of the cooler, the pressure difference between the intake pipe and the outlet pipe is small, and the pressure difference is less than the preset pressure difference, so the spool of the check valve assembly is far away from the trigger switch at this time, and the alarm module is not activated. When the intake pipe of the EGR cooler When the pressure difference between the outlet pipe and the outlet pipe is greater than the preset pressure difference, the pressure limiting valve assembly will guide the air inlet and the overflow hole, so that the gas in the air inlet pipe enters the check valve body, driving the valve core of the check valve assembly to The trigger switch moves to close the trigger switch, thereby activating the alarm module for alarming.

The gas alarm device provided by the present invention only needs to be connected in parallel with the inlet pipe and the outlet pipe of the original EGR cooler, and the original EGR cooler is less modified and has no influence on its normal use, and the gas alarm device can be relatively simple, It is convenient to realize real-time and effective monitoring and early warning of the EGR cooler.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. Those skilled in the art can also obtain other drawings based on these drawings without creative work.

Fig. 1 is the structural diagram of a kind of EGR cooler gas warning device disclosed by the embodiment of the present invention;

Fig. 2 is the structural diagram of another kind of EGR cooler gas warning device disclosed by the embodiment of the present invention;

3 is a structural diagram of another EGR cooler gas alarm device disclosed in an embodiment of the present invention;

4 is a structural diagram of another EGR cooler gas alarm device disclosed in an embodiment of the present invention;

5 is a structural diagram of another EGR cooler gas alarm device disclosed in an embodiment of the present invention;

6 is a structural diagram of another EGR cooler gas alarm device disclosed in an embodiment of the present invention;

Fig. 7 is a flow chart of an EGR cooler gas alarm method disclosed in an embodiment of the present invention.

detailed description

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

As shown in Figure 1, the original EGR cooler includes an EGR cooler body 31, an EGR cooler inlet pipe 33, an EGR cooler outlet pipe 32, an EGR cooler water inlet pipe 34, an EGR cooler outlet pipe 35, and an exhaust gas flow regulating valve. , the high-temperature exhaust gas enters the body of the EGR cooler 31 from the EGR cooler inlet pipe 33, and after being cooled by the cooling water in the EGR cooler inlet pipe 34 and the EGR cooler outlet pipe 35, the temperature coming out of the EGR cooler outlet pipe 32 is relatively low. exhaust gas.

As shown in Figure 1, the present invention provides a kind of EGR cooler gas warning device, and this gas warning device 36 is arranged on the EGR cooler inlet pipe 33 and the EGR cooler outlet pipe 32 in parallel, when EGR cooler inlet pipe 33 and When the pressure difference of the outlet pipe 32 of the EGR cooler reaches a certain value, the emission result of the diesel engine is close to the limit value of the emission regulations. At this time, the alarm module is activated to remind the user that the EGR cooler of the diesel engine has reached the limit of use. If the diesel engine continues to use the emission, the emission will exceed the regulation. Limit value, it is necessary to take certain physical or chemical measures to clean the EGR cooler, or replace the EGR cooler with a new one.

The gas alarm device 36 is described in detail below, as shown in Figure 2, the gas alarm device includes a pressure limiting valve assembly 7 connected in parallel with the EGR cooler inlet pipe 33 and the EGR cooler outlet pipe 32, a one-way valve assembly 8 and an alarm Trigger component 9.

This gas alarm device 36 is installed in parallel with the inlet and outlet pipes of the diesel engine EGR cooler, and is mainly composed of three major parts. Among them, the pressure limiting valve assembly 7 is connected with the inlet pipe 33 of the EGR cooler. The pressure limiting valve will not open until the pressure difference at the end reaches the preset pressure difference; the check valve assembly 8, this part is connected with the outlet pipe 32 of the EGR cooler, and its function is to ensure that the uncooled Exhaust gas will not directly enter the engine cylinder through the gas alarm device 36; the alarm trigger component 9, when the circuit of the alarm trigger component 9 is closed, then sends a warning reminder, or as an input condition of another trigger device of the diesel engine.

As shown in Figures 3-5, the pressure limiting valve assembly 7 includes the first air inlet 1 and the overflow hole 12 communicated with the EGR cooler intake pipe 33, and the pressure limiting valve assembly 7 is used only in the first When the pressure difference between the air inlet 1 and the overflow hole 12 is greater than the preset pressure difference, the first air inlet 1 and the overflow hole 12 are connected;

The one-way valve assembly 8 includes a one-way valve body 14, the first end of the one-way valve body 14 communicates with the overflow hole 12, and the second end is sealed, and the trigger switch of the alarm trigger assembly 9 passes through the one-way valve body The second end of 14 goes deep into the inside of the one-way valve body 14, and the one-way valve body 14 is provided with the second air inlet 2 communicated with the outlet pipe 32 of the EGR cooler, and is slidably arranged in the one-way valve body 14 The spool 15, the one-way valve assembly 8 is used to control the flow of the spool 15 to the trigger switch when the pressure difference between the first air inlet 1 and the overflow hole 12 is greater than the preset pressure difference. Sliding in the direction to close the trigger switch, when the pressure between the first air inlet 1 and the overflow hole 12 is less than the preset pressure difference, the control valve core 15 slides and disconnects in the direction of the first air inlet 1 of the trigger switch trigger switch;

The alarm triggering component 9 includes a trigger switch and an alarm module connected to the trigger switch. When the trigger switch is closed, the alarm module is activated to prompt that the EGR cooler needs to be cleaned or replaced.

The invention provides a gas alarm device for an EGR cooler. The gas alarm device is connected in parallel with the inlet pipe and the outlet pipe of the EGR cooler. The gas alarm device includes a pressure limiting valve assembly, a one-way valve assembly and an alarm trigger assembly. EGR cooling In the initial stage of the use of the cooler, the pressure difference between the intake pipe and the outlet pipe is small, and the pressure difference is less than the preset pressure difference, so the spool of the check valve assembly is far away from the trigger switch at this time, and the alarm module is not activated. When the intake pipe of the EGR cooler When the pressure difference between the air outlet pipe and the outlet pipe is greater than the preset pressure difference, the pressure limiting valve assembly will connect the first air inlet and the overflow hole, so that the gas in the air inlet pipe enters the check valve body, driving the valve of the check valve assembly The core moves toward the trigger switch, so that the trigger switch is closed, thereby activating the alarm module to give an alarm.

The gas alarm device provided by the present invention only needs to be connected in parallel with the inlet pipe and the outlet pipe of the original EGR cooler, and the original EGR cooler is less modified and has no influence on its normal use, and the gas alarm device can be relatively simple, It is convenient to realize real-time and effective monitoring and early warning of the EGR cooler.

As shown in FIG. 3 , in order to realize that the pressure limiting valve assembly 7 conducts the air inlet 1 and the overflow hole 12 only when the pressure difference between the first air inlet 1 and the overflow hole 12 is greater than the preset pressure difference; The structure of the pressure-limiting valve assembly is: the pressure-limiting valve assembly 7 includes a first stepped hole, a ball 3 arranged in a larger hole of the first stepped hole, an adjustment handle 11, and an adjustment handle between the ball 3 and the adjustment handle 11. Between the spring 10, the preload of the spring 10 can be adjusted by rotating the adjustment handle. The limit block 13 connected with the adjustment handle 11, the spring 10 runs through the limit block 13, and is stuck between the sphere 3 and the adjustment handle 11, the sphere 3 is limited between the larger hole of the first stepped hole and the Between the limit block 13.

The function of the adjustment handle 11 is to adjust the pre-tightening force of the spring 10, so as to be suitable for different pressure differences of different models of diesel engines. 10 service life.

As shown in Figure 4, the one-way valve assembly 8 includes a second stepped hole, the smaller hole of the second stepped hole is consistent with the size of the valve core 15, and the second air inlet 2 communicates with the larger hole of the stepped hole , the spool (15) becomes a piston shape at one end of the larger hole of the second stepped hole, and its outer diameter is greater than the diameter of the smaller hole of the second stepped hole. The one-way valve assembly 8 further includes: a limit bolt 16 connected to the end of the valve core 15 adjacent to the trigger switch, and a second spring 17 outside the limit bolt 16 .

At the initial moment, since a part of the spool 15 is at the larger hole of the second stepped hole, the second air inlet 2 communicates with the larger hole of the second stepped hole, so the gas in the outlet pipe of the EGR cooler is connected to the second stepped hole. The larger hole of the hole is connected, driven by the gas from the outlet pipe 32 of the EGR cooler, the valve core 15 moves toward the first air inlet 1, and the end of the valve core 15 is limited by the limit bolt 16, when the limit When the bolt 16 moves to the larger hole of the stepped hole, it will stop moving due to the stop bolt 16 .

After the EGR cooler has been used for a period of time, the pressure difference between the EGR cooler inlet pipe 32 and the EGR cooler outlet pipe is greater than the sealing preload of the spring 10, and the preload of the spring 10 is not enough to bear the pressure and gradually shrink, so that the first The air inlet 1 and the overflow hole 12 are connected, and the gas in the EGR cooler inlet pipe 32 enters the inside of the check valve body 14. Since the pressure of the EGR cooler inlet pipe 33 is greater than the pressure of the EGR outlet pipe 32, the one-way The spool 15 in the valve assembly 8 gradually moves towards the trigger switch under the action of pressure, and the piston sealing end of the spool 15 moves to the larger hole of the second stepped hole and will be stuck, because the edge of the piston is larger than the second stepped hole. The diameter of the hole is larger, so the one-way valve body can be sealed to prevent uncooled gas in the EGR cooler inlet pipe 33 from entering the EGR cooler outlet pipe 32 .

As shown in Figure 5, the trigger switch of the alarm trigger assembly 9 is a static contact piece 19 and a moving contact piece 18, when the static contact piece 19 and the moving contact piece 18 are in contact, the trigger switch is closed, when the static contact piece 19 and the moving contact piece The trigger switch is disconnected when sheet 18 is non-contact. As shown in FIG. 5 , the alarm module includes a warning light 21 connected in series with the trigger switch, and/or a buzzer 22 connected in series with the trigger switch.

The trigger switch in the alarm trigger assembly 9 is a static contact piece 19 and a moving contact piece 18. Under normal circumstances, the moving contact piece 18 is separated from the static contact piece 19. When the valve core 15 gives a certain pressure to the moving contact piece 18 under the pressure difference , it will drive the moving contact piece 18 to contact the static contact piece 19, thereby activating the alarm module. The alarm module can prompt the user with the flashing or constant bright mode of the prompt lamp 21 or prompt the user with the buzzer sounding that the current EGR cooler has reached the limit, and the EGR cooler needs to be cleaned or replaced.

The working process of the diesel engine is described in detail below: at the beginning, the pressure difference between the inlet and outlet pipes of the EGR cooler is lower than the pretightening force of the spring 10 in the pressure limiting valve assembly 7, and the pressure limiting valve assembly 7 is in a closed state, and the exhaust gas cannot pass through. . At one end of the outlet pipe 32 of the EGR cooler, the spool 15 in the check valve assembly 8 is in an open state due to the action of the exhaust gas in the outlet pipe 32 of the EGR cooler. To the valve body and the pressure limiting valve chamber. And the limit bolt 16 that originally pressed the moving contact piece 18 is separated from the moving contact piece 18 under the linkage of the spool 15, causing the moving contact piece 18 to separate from the static contact piece 19, and the alarm trigger circuit is in a disconnected state, as shown in Figure 2 .

When the pressure loss of the air path of the EGR cooler increases, and the pressure difference between the inlet and outlet pipes of the EGR cooler is sufficient to overcome the pre-tightening force of the spring 10 in the pressure limiting valve assembly 7, the exhaust gas pushes the ball 3 of the pressure limiting valve to press against the spring 10 direction, and flow into the one-way valve body 14 from the overflow hole 12. Because the exhaust gas pressure of the EGR cooler inlet pipe is higher than the exhaust gas pressure of the EGR cooler outlet pipe 32, once the exhaust gas flows through the overflow hole 12, the valve core 15 returns to its position under the action of the exhaust pressure difference on both sides, and is gradually pressed into the In the one-way valve body 14, the exhaust gas cannot directly flow into the cylinder of the diesel engine through the one-way valve. With the return of the spool 15, the limit bolt 16 presses the movable contact piece 18 to make it contact with the static contact piece 19, the alarm trigger circuit is connected, and the alarm module starts to function. It can be judged by the flickering of the warning light that the pressure loss of the EGR cooler is large at this time, and corresponding measures need to be taken.

The opening pressure of the pressure-limiting valve assembly 7 is different according to the different supporting purposes of the diesel engine. The present invention can be realized by rotating the adjustment handle 11 to obtain different spring preloads, and the specific value of the opening pressure can be obtained through experiments. .

As shown in FIG. 6 , an exhaust gas flow regulating valve 24 and an EGR cooler inlet pipe pressure sensor 23 are installed on the EGR cooler inlet pipe, and an EGR cooler outlet pipe pressure sensor 25 is installed on the EGR cooler outlet pipe 32 .

On the basis of Fig. 6, firstly, the exhaust gas flow regulating valve 24 is fully opened to carry out the emission test of the diesel engine. The universal test of the pressure difference of the outlet pipe measures and calculates the maximum pressure difference and the minimum pressure difference of the pressure sensors 23 and 25 under the normal working conditions of the diesel engine at this time. The maximum pressure difference will be used as a minimum pressure limit valve assembly spring preload input to ensure that the opening pressure of the pressure limiting valve assembly is greater than the maximum pressure difference measured at this time.

Then adjust the opening degree of the exhaust gas flow regulating valve 24, and carry out the exhaustion test of the diesel engine. When the discharge of the diesel engine obtained from the test is close to the legal limit value, carry out the universal test of the pressure difference between the inlet and outlet pipes of the EGR cooler of the diesel engine, measure and calculate the maximum pressure difference and the minimum pressure difference of the pressure sensors 23 and 25 under the normal working conditions of the diesel engine at this time, This maximum pressure differential will act as the immediate input for the cracking pressure of the pressure limiting valve assembly. After multiple tests and certain corrections, the cracking pressures of the pressure limiting valve assemblies corresponding to diesel engines for different purposes can be determined.

As shown in Fig. 7, the present invention also provides a kind of EGR cooler gas warning method, is applied to the EGR cooler gas warning device described in Fig. 2, and described method comprises:

Step S101: Obtain the pressure difference between the EGR cooler inlet pipe and the EGR cooler outlet pipe;

Before the implementation of the present invention, the preset pressure difference of the EGR cooler is obtained in advance.

Step S102: judging whether the pressure difference is greater than a preset pressure difference;

Step S103: when the pressure difference is greater than the preset pressure difference, an alarm is issued.

Step S104: When the pressure difference is less than the preset pressure difference, no processing is performed.

The invention provides a gas alarm method for an EGR cooler. The gas alarm device is connected in parallel with the intake pipe and outlet pipe of the EGR cooler. The gas alarm device includes a pressure limiting valve assembly, a one-way valve assembly and an alarm trigger assembly. EGR cooler In the initial stage of use, the pressure difference between the inlet pipe and the outlet pipe is small, and the pressure difference is less than the preset pressure difference, so the spool of the one-way valve assembly is far away from the trigger switch at this time, and the alarm module is not activated. When the inlet pipe of the EGR cooler and When the pressure difference of the outlet pipe is greater than the preset pressure difference, the pressure limiting valve assembly will guide the air inlet and the overflow hole, so that the gas in the inlet pipe enters the one-way valve body, driving the valve core of the one-way valve assembly to trigger The switch moves to close the trigger switch, thereby activating the alarm module to alarm.

The gas alarm device provided by the present invention only needs to be connected in parallel with the inlet pipe and the outlet pipe of the original EGR cooler, and the original EGR cooler is less modified and has no influence on its normal use, and the gas alarm device can be relatively simple, It is convenient to realize real-time and effective monitoring and early warning of the EGR cooler.

Each embodiment in this specification is described in a progressive manner, each embodiment focuses on the difference from other embodiments, and the same or similar parts of each embodiment can be referred to each other.

The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention will not be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (7)

1. A kind of 1. cooler for recycled exhaust gas gas warning system, it is characterised in that including：

   The pressure limiting valve module (7) in parallel with cooler for recycled exhaust gas air inlet pipe (33) and cooler for recycled exhaust gas escape pipe (32), check valve assembly (8) and alarm trigger assembly (9)；

   Wherein, the pressure limiting valve module (7) include the first air inlet (1) for being connected with the cooler for recycled exhaust gas air inlet pipe (33) with And spout hole (12), the pressure difference that pressure limiting valve module (7) is used for only between the first air inlet (1) and spout hole (12) are more than default During pressure difference, first air inlet (1) and the spout hole (12) are turned on；

   The check valve assembly (8) includes the check valve body (14) that first end connects with spout hole (12), the second end seals, described The trigger switch of alarm trigger assembly (9) enters check valve body (14) inside, check valve through the second end of check valve body (14) Body (14) is provided with the second air inlet (2) connected with the cooler for recycled exhaust gas escape pipe (32), and is slidably arranged on unidirectional Valve element (15) in valve body (14), check valve assembly (8) are used between first air inlet (1) and the spout hole (12) Pressure difference when being more than preset pressure, control valve element (15) slides to the direction of the trigger switch, closure trigger switch, first When pressure difference between air inlet (1) and spout hole (12) is less than preset pressure, control valve element (15) enters to the first of trigger switch The direction of gas port (1) is slided, break trigger switch；

   Alarm trigger assembly (9) includes trigger switch and the alarm module being connected with the trigger switch, when the triggering is opened Close and activate alarm module when closing, prompt the need of cooler for recycled exhaust gas to clean or change.
2. 2. device as claimed in claim 1, it is characterised in that the pressure limiting valve module (7) includes the first shoulder hole, is arranged at Spheroid (3) in the large hole of first shoulder hole, adjustment handle (11) and in spheroid (3) and adjust between handle (11) Spring (10), rotation adjustment handle (11) pretightning force of spring (10) can be adjusted.
3. 3. device as claimed in claim 2, it is characterised in that the pressure limiting valve module (7) also includes：

   The limited block (13) being connected with adjustment handle (11), the spring (10) runs through the limited block (13), and is positioned in ball Between body (3) and adjustment handle (11), spheroid (3) is limited between the large hole of first shoulder hole and limited block (13).
4. 4. device as claimed in claim 1, it is characterised in that the check valve assembly (8) includes the second shoulder hole, second-order The diameter of terraced hole smaller hole is consistent with valve element (15) diameter, and second air inlet (2) connects with the large hole of shoulder hole, Valve element (15) is more than the diameter of the second shoulder hole smaller hole in second shoulder hole large hole one end into piston-like, its external diameter.
5. 5. device as claimed in claim 4, it is characterised in that the check valve assembly 8 also includes：

   The caging bolt (16) being connected with the valve element (15) close to trigger switch one end, and on the outside of caging bolt (16) Second spring (17).
6. 6. device as claimed in claim 1, it is characterised in that the trigger switch of the alarm trigger assembly 9 is static contact (19) and movable contact spring (18), when static contact (19) and movable contact spring (18) contact, trigger switch closes, and when static contact (19) and moves Trigger switch disconnects when contact (18) is non-contact.
7. 7. device as claimed in claim 1, it is characterised in that the alarm module includes the police to be connected with the trigger switch Show lamp (21), and/or the buzzer (22) connected with the trigger switch.