CN214330773U

CN214330773U - Evaporation diagnostic unit using gas positive pressure diaphragm pump

Info

Publication number: CN214330773U
Application number: CN202023305394.1U
Authority: CN
Inventors: 岳海云; 樊林
Original assignee: Beijing Innovitch Technology Co ltd
Current assignee: Beijing Innovitch Technology Co ltd
Priority date: 2020-12-31
Filing date: 2020-12-31
Publication date: 2021-10-01
Anticipated expiration: 2030-12-31

Abstract

An evaporation diagnosis unit using a gas positive pressure diaphragm pump comprises a shell, the gas positive pressure diaphragm pump and an electromagnetic valve sealing assembly, wherein the gas positive pressure diaphragm pump is columnar; the bracket assembly comprises a bracket and an electromagnetic valve, and a piston head of the sealing piston is formed at the head end of the piston rod through injection molding; the bracket comprises an upper ring, a lower ring and a plurality of connecting arms, a gap is arranged between the connecting arms, the connecting arms are connected between the upper ring and the lower ring to form a frame, and the bracket is formed on the secondary plate in an injection molding mode; the lower ring of the bracket is provided with a central hole for a piston rod to pass through the bracket and enter the electromagnetic valve; the sealing disc of the piston head is provided with a piston sealing surface which is matched with the sealing surface of the bracket assembly of the upper ring, so that air can not pass through the electromagnetic valve sealing assembly through the bracket; the spring is used for enabling the piston head to keep a gap between the piston sealing surface and the bracket assembly sealing surface under the condition that the electromagnetic valve is powered off. The utility model discloses optimize the performance of evaporation diagnostic unit, improved manufacturing and installation.

Description

Evaporation diagnostic unit using gas positive pressure diaphragm pump

Technical Field

The utility model relates to an automobile especially relates to the evaporation diagnostic unit of car.

Background

According to the requirements of the national six regulations GB 18352.6-2016 j.4.4.1, the OBD system should monitor the integrity of the entire vaporization system except for the piping and connections between the carbon canister valve and the intake manifold, preventing fuel vapor from leaking into the atmosphere. The national six regulation GB 18352.6-2016 j.4.4.2.2(B) requires that an OBD system should detect a failure in an evaporative system when there are one or more leaks throughout the evaporative system that are greater than or equal to the amount of leakage produced by a 1mm diameter orifice. There are three major classes of OBD diagnostic strategies that meet this requirement, the first being negative pressure (DTESK) based detection strategies; the second is a positive pressure based detection strategy. The third is a natural vacuum based detection strategy.

The evaporation diagnosis unit is a key part in a positive pressure detection strategy and is arranged between the carbon tank and the atmosphere channel. For example, the Bosey and Shanghai automobile groups use evaporative diagnostic units for detection.

In the prior art, as a key part, the evaporation diagnosis unit has defects in manufacturing, installation, operation and the like, for example, the evaporation diagnosis unit adopts a vane rotor pump for inflation, and therefore, further improvement of the evaporation diagnosis unit is needed.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide an evaporation diagnostic unit to optimize evaporation diagnostic unit's performance, improve evaporation diagnostic unit's manufacturing and installation.

In order to achieve the above object, the present invention provides an evaporation diagnosis unit using a gas positive pressure diaphragm pump, which is characterized in that the evaporation diagnosis unit comprises a housing, a gas positive pressure diaphragm pump and a solenoid valve seal assembly, wherein the gas positive pressure diaphragm pump and the solenoid valve seal assembly are both installed in the housing, and the gas positive pressure diaphragm pump is columnar; the electromagnetic valve sealing assembly comprises a sealing piston, a spring and a bracket assembly, and the bracket assembly comprises a bracket and an electromagnetic valve; the sealing piston comprises a piston head and a piston rod, the piston head comprises a sealing disc, and the piston head is formed at the head end of the piston rod through injection molding; the electromagnetic valve is used for driving the sealing piston and comprises a secondary plate and a guide pipe; the bracket of the bracket assembly comprises an upper ring, a lower ring and a plurality of connecting arms, wherein gaps are formed among the connecting arms, the connecting arms are connected between the upper ring and the lower ring to form a frame-type bracket, and the bracket is an injection molding piece formed on a secondary plate of the electromagnetic valve through injection molding; the lower ring of the bracket is provided with a central hole which is aligned with the secondary plate and the guide pipe and used for enabling the piston rod to penetrate through the bracket and enter the electromagnetic valve along the guide pipe; the bottom end of the sealing disc of the piston head is provided with a piston sealing surface which is matched with a bracket assembly sealing surface of the upper ring of the bracket, which is positioned at the top end of the upper ring, and when the piston sealing surface is jointed with the bracket assembly sealing surface, a seal is formed, so that air cannot pass through the electromagnetic valve sealing assembly through the bracket; the spring is used for enabling the piston head to keep a gap between the piston sealing surface and the bracket assembly sealing surface under the condition that the electromagnetic valve is powered off.

Preferably, the piston head is encapsulated with a sealant at least on the seal disk by an encapsulation process.

Preferably, the secondary plate and the guide pipe are formed as one body through a spin riveting process.

Preferably, an upper edge of the lower ring of the holder abuts against an engagement portion of a housing of the evaporation diagnostic unit to mount the holder assembly in the housing.

Preferably, the central hole of the lower ring of the bracket is provided with a tubular positioning flange along the periphery of the center for mounting and positioning the spring.

Preferably, one end of the spring is supported on the holder, and the piston rod passes through the spring so that the other end of the spring abuts against the lower surface of the seal plate.

Preferably, the head end of the piston rod is transversely provided with a through hole, and the through hole is filled with the injection molding material of the piston head.

Preferably, the guide tube and the piston rod are in clearance fit.

Preferably, the central hole of the lower ring has a positioning flange having a tubular shape along the circumference of the central hole to mount and position the spring.

Preferably, the outer circumference of the upper ring of the bracket has a groove for mounting a sealing ring to seal between the upper ring and the inner surface of the housing of the evaporation diagnostic unit.

The evaporation diagnosis unit in the prior art comprises a vane rotor pump, positive pressure gas is generated by the vane rotor pump, and although the vane rotor pump is stable in operation and uniform in output flow, the vane rotor pump is large in size, high in price and high in requirement on assembly precision. Particularly, the large volume of the vane rotor pump easily causes that the evaporation diagnosis unit is not easy to be arranged on the whole vehicle; the pump body part of the vane rotor pump is machined, so that the machining precision is high, and the overall manufacturing cost is high. When the vane rotor pump works, the rotor and the vanes do friction rotation motion in the stator, and the mutual positions of the rotor and the stator have great influence on the performance of the pump, so that the assembly precision of the rotor and the stator is high in the assembly process, and the vanes, the rotor and the stator also need to have high wear resistance.

Compared with the prior art, the utility model discloses a gaseous malleation diaphragm pump is small, makes the evaporation diagnostic unit arrange on whole car easily. The pump body part of the diaphragm pump is an injection molding part, so that the diaphragm pump can be produced in batch, and is low in manufacturing cost and low in price. A leather cup in the air positive pressure diaphragm pump does reciprocating motion, is not easy to wear and is simple to assemble. Therefore, through set up gaseous malleation diaphragm pump in evaporation diagnostic unit, the utility model discloses reduced evaporation diagnostic unit's selling price, made evaporation diagnostic unit have stronger market competition. And the air positive pressure diaphragm pump does not have friction motion when working, and the service life is long.

On the other hand, in the prior art, the structures and the mutual connection relationship of the sealing piston, the bracket and the electromagnetic valve are loose and fine, the installation and the manufacture are inconvenient, the sealing and centering performance needs to be improved, and the firmness and the durability of the structures need to be enhanced.

Compared with the prior art, the utility model discloses an evaporation diagnostic unit can optimize evaporation diagnostic unit's performance, improves evaporation diagnostic unit's manufacturing and installation.

Particularly, the utility model discloses a structure has guaranteed that support assembly and sealed piston mutual position are correct, makes sealed face of sealed piston and the sealed face of support assembly laminate completely under the electromagnetic force effect, has better leakproofness, makes the evaporation diagnostic unit performance more superior, market competition reinforcing.

Moreover, the utility model discloses a structure makes the assembly process of evaporation diagnostic unit simple, has reduced the leakproofness defective rate of evaporation diagnostic unit assembly line to, it is more advantageous to make the product sell the price.

In addition, the utility model discloses a sound construction, durable.

Drawings

FIG. 1 is a schematic diagram of pump current measurement of a reference hole inside an evaporation diagnostic unit.

FIG. 2 is a schematic view of a vapor control system seal detection.

Fig. 3 shows the state of the solenoid valve seal assembly when measuring the pump current of the reference hole inside the evaporation diagnostic unit.

FIG. 4 illustrates the state of the solenoid valve seal assembly upon detection of the evaporative control system seal.

Fig. 5 is a perspective view showing an installation state of the carrier assembly and the sealing piston.

Fig. 6 is a perspective view showing another perspective view of the mounting state of the carrier assembly and the sealing piston.

Fig. 7 is a cross-sectional view of the integrated support, sub-plate and guide tube.

Fig. 8 is a perspective view of a sub-plate and guide tube integrated piece.

Fig. 9 is an axial view of the sub-plate and guide tube integral piece.

Fig. 10 is a view of fig. 8 taken along B-B.

Figure 11 is a cross-sectional view of the piston rod after injection molding of the piston head thereon.

Fig. 12 is a front view of the piston rod.

Fig. 13 is a cross-sectional view of the sealing piston.

FIG. 14 is an elevation view of the seal piston mounted on the carriage assembly with the solenoid valve removed except for the sub-plate and guide tube.

Fig. 15 is a view of fig. 14 taken along a-a with the solenoid valve removed except for the sub-plate and guide tube.

Fig. 16 is a perspective view of the gas diaphragm pump of the present invention.

Fig. 17 is a right side view of the gas diaphragm pump of the present invention.

Fig. 18 is a front view of the gas diaphragm pump of the present invention.

Fig. 19 is a plan view of the gas diaphragm pump of the present invention.

Detailed Description

Hereinafter, an embodiment of an evaporation diagnosis unit using a positive pressure gas diaphragm pump according to the present invention will be described with reference to the accompanying drawings.

The embodiments described herein are specific embodiments of the present invention, and are intended to be illustrative of the concepts of the present invention, which are intended to be illustrative and exemplary, and should not be construed as limiting the scope of the embodiments and the invention. In addition to the embodiments described herein, those skilled in the art will be able to employ other technical solutions which are obvious based on the disclosure of the claims and the specification of the present application, and these technical solutions include technical solutions which employ any obvious replacement or modification of the embodiments described herein.

The drawings in the present specification are schematic views to assist in explaining the concept of the present invention, and schematically show the shapes of the respective portions and the mutual relationships thereof. It should be noted that the drawings are not necessarily drawn to the same scale in order to clearly illustrate the structures of the various components of the embodiments of the present invention. The same reference numerals are used to designate the same or similar parts. Further, when the description is made with reference to the drawings, directional words such as "upper", "lower", etc. are employed for convenience of description, and they do not constitute specific limitations on the structure of the features.

The operation of the evaporation diagnostic unit will first be described with reference to fig. 1 and 2.

Fig. 1 is a schematic diagram of pump current measurement of a reference hole inside an evaporation diagnosis unit, and fig. 2 is a schematic diagram of evaporation control system seal detection.

Fig. 1 and 2 are schematic diagrams of leak detection of a fuel evaporative emissions Control system, illustrating the operation of an evaporative diagnostic Unit, including an intake manifold a, a throttle valve B, a canister solenoid valve C, a canister D, a fuel tank E, an evaporative diagnostic Unit G including a solenoid valve K, a gas positive pressure diaphragm pump P, and a reference hole 101, an air filter H, fresh air J, and an ECU (Electronic Control Unit).

The evaporation diagnosis unit comprises a shell 1, and a positive pressure gas diaphragm pump and an electromagnetic valve sealing assembly which are contained in the shell 1, wherein the electromagnetic valve sealing assembly comprises a sealing piston 2, a spring 10 and a bracket assembly, and the bracket assembly comprises an electromagnetic valve, a bracket, a secondary plate and a guide pipe integrated piece. Referring to fig. 1 and 2, a portion enclosed by a dotted line represents an evaporation diagnostic unit that inflates a closed evaporation control system with a positive air pressure diaphragm pump and generates a pressure of not more than 6.5kPa in the evaporation control system, and a pump current required for this is measured by an ECU. The higher the pressure in the evaporative control system at a given time during pump charging indicates a smaller system leakage, and the system pressure value and the system leakage are inversely proportional. The pump current is proportional to the pressure in the evaporation control system, and the pump current value is used as an indirect value of the leakage amount of the evaporation control system. The diagnostic process is divided into three stages.

A first stage: the pump current of the reference hole inside the evaporation diagnosis unit is measured.

Referring to fig. 1, the pump current measurement of the reference hole inside the evaporation diagnosis unit is performed in three steps.

1. As shown in fig. 1, the solenoid valve in the evaporation diagnostic unit is in a de-energized state.

2. The pump is operated and positive pressure gas generated by the pump leaks only through the reference hole, and the gas flow direction is shown by the hollow arrows in fig. 1.

3. The ECU continuously detects the pump current, and when the pump current is stable, the ECU records the pump current value I_{Reference to}As a subsequent calculation Ratio ═ I (I)_Measuring-I_{No load})/(I_{Reference to}-I_{No load}) The basis of (1).

And a second stage: and carrying out sealing detection on the evaporation control system.

Referring to fig. 2, the sealing detection of the evaporation control system is performed in three steps.

1. As shown in fig. 2, the solenoid valve in the evaporation diagnostic unit is in an energized state. The carbon tank is closed by the atmosphere channel 3, and the evaporation diagnosis unit, the carbon tank, the oil tank and the carbon tank electromagnetic valve form a closed space. With respect to the canister vent to atmosphere 3, please refer to the structure formed by the support 12 in fig. 3 and 4.

2. And when the pump works, positive pressure gas generated by the pump enters a closed space formed by the evaporation diagnosis unit, the carbon tank, the oil tank and the carbon tank electromagnetic valve. The gas flow direction is shown by the hollow arrows in fig. 2.

3. The ECU continuously detects the pump current, and the ECU records the minimum value I of the pump current_{No load}(ii) a When the pump current is stable, the ECU records the pump current value I_Measuring，I_{No load}And I_MeasuringAs the subsequent calculation Ratio (I) ═ I_Measuring-I_{No load})/(I _{Reference to}-I_{No load}) The basis of (1).

And a third stage: the ECU calculates the Ratio (I)_Measuring-I_{No load})/(I_{Reference to}-I_{No load}) And whether the leakage quantity of the evaporation control system meets the requirements of the national six-law is judged.

When the evaporation control system performs sealing detection, the electromagnetic valve is in a power-on state, and the carbon tank is in a closed state through the atmosphere channel 3. The sealing surface on the sealing piston 2 and the sealing surface on the bracket 12 are in a joint state under the action of electromagnetic force. The utility model discloses a special structural design can guarantee that support 12 and sealing piston 2 mutual position are correct when making the solenoid valve be in the on state, and assembly process is simple, and the sound construction is durable.

The utility model discloses a sealed assembly of pump and solenoid valve to evaporation diagnostic unit improves, can adopt prior art's design concept to other parts of evaporation diagnostic unit, consequently is in the utility model discloses in do not do detailed explanation to evaporation diagnostic unit's casing 1's structure, with outstanding the utility model discloses the key of explanation. Nevertheless, although the utility model discloses the structure to the sealed assembly of pump and solenoid valve improves, but does not change the utility model discloses a function of pump and the sealed assembly of solenoid valve in evaporation diagnostic unit, promptly, gaseous malleation diaphragm pump also provides malleation gas for evaporation diagnostic unit, also is through solenoid valve drive piston, and the sealed assembly of solenoid valve also is through solenoid valve drive piston, realizes the transformation of air gas circuit.

The utility model discloses in, adopt the gaseous diaphragm pump to fill malleation gas for evaporation diagnosis unit, it is a miniature direct current has brush diaphragm air pump. Referring to fig. 16-19, the gas diaphragm pump of the present invention is cylindrical, and is designed according to the principle of a positive displacement pump, and is powered by a motor, and through an eccentric wheel on the motor shaft, drives rubber to circulate and reciprocate, and forms suction and discharge actions inside the cavity, and through closing and opening of a check valve, suction and discharge of gas are realized.

Prior art adopts the impeller rotor pump to aerify, compares with it, the utility model discloses a gaseous diaphragm pump is aerifyd and is possessed following advantage:

1. the small volume of the air positive pressure diaphragm pump enables the evaporation diagnosis unit to be easily arranged on the whole vehicle.

2. The pump body part of the diaphragm pump is an injection molding part, so that the diaphragm pump can be produced in batch, and is low in manufacturing cost and low in price.

3. A leather cup in the air positive pressure diaphragm pump does reciprocating motion, is not easy to wear and is simple to assemble.

The utility model discloses use gaseous malleation diaphragm pump to aerify, reduced the volume of evaporation diagnostic unit, reduced the selling price of evaporation diagnostic unit, make evaporation diagnostic unit have stronger market competition. And the air positive pressure diaphragm pump does not have friction motion when working, and the service life is long.

As mentioned above, the evaporation diagnostic unit comprises a housing 1, a positive air pressure diaphragm pump, and a solenoid valve seal assembly, the housing 1 is generally designed as an upper housing and a lower housing, which are sealingly joined and have an air interface and a canister interface. The gas positive pressure diaphragm pump and the electromagnetic valve sealing assembly are accommodated in the shell 1, a sealing joint part exists between the electromagnetic valve sealing assembly and the shell 1, the electromagnetic valve drives the piston to move, and the sealing joint part between the electromagnetic valve sealing assembly and the shell 1 is closed and separated, so that the air pumped by the gas positive pressure diaphragm pump returns to an air interface or enters the carbon tank. The flow paths of the air in the evaporative diagnostic unit in these two states are shown in fig. 1 and 2, respectively.

The operation and structure of the solenoid valve seal assembly will be described with reference to fig. 3 and 4, in which fig. 3 shows the state of the solenoid valve seal assembly when measuring the pump current of the reference hole inside the evaporation diagnostic unit, and fig. 4 shows the state of the solenoid valve seal assembly when detecting the sealing of the evaporation control system.

As shown in fig. 3 and 4, the solenoid valve seal assembly is installed in the housing 1 and cooperates with the engagement portion of the housing 1. In fig. 3 and 4, the lower housing of the housing 1 is removed and only the upper housing is shown for ease of illustration and to make the illustration clearer. The electromagnetic valve sealing assembly comprises a sealing piston 2, a spring 10 and a bracket assembly, wherein the bracket assembly comprises an electromagnetic valve, a bracket, a secondary plate and a guide pipe integrated piece. The lower part of the bracket 12 of the bracket assembly abuts against the engagement part of the groove of the housing 1, while the upper part of the bracket 12 of the bracket assembly carries a sealing ring 11 which engages with the cavity surface of the upper housing such that air cannot pass between the sealing ring 11 and the cavity surface of the upper housing.

As shown in fig. 3, when the pump current of the reference hole inside the evaporation diagnosis unit is measured, the solenoid valve is in a power-off state. At this time, the direction of the gas flow is shown by an arrow F in the figure, and the canister vent atmosphere passage 3 is in an open state. Under the action of the elastic force of the spring 10, the piston rises, and the sealing piston top sealing surface 2012 on the sealing disc of the piston abuts against the shell inner air outlet hole 102 of the upper shell, so that the shell inner air outlet hole 102 is sealed, and air cannot enter the shell inner air outlet hole 102; on the other hand, at this time, there is a gap between the seal piston lower seal surface 2013 and the poppet assembly seal surface 1204, and there is no abutment, so that air enters the air port via this gap. The housing interior exit aperture 102 of the housing 1 may be constructed using prior art designs of housing for evaporative diagnostic units, where the diameter of the housing interior exit aperture 102 is typically 2 mm.

Referring to fig. 4 again, when the evaporation control system performs sealing detection, the electromagnetic valve is energized, and the sealing piston 2 overcomes the force of the spring 10 and moves downward along the inner hole of the guide tube 13 in the bracket assembly under the action of electromagnetic force until the sealing piston lower sealing surface 2013 and the bracket assembly sealing surface 1204 are in a fit state under the action of electromagnetic force. More specifically, when the solenoid valve is energized, the solenoid valve applies a downward force on the piston rod 202, the piston is moved downward against the spring force of the spring 10, the lower sealing surface 2013 of the sealing piston at the bottom of the sealing disk of the piston abuts against the sealing surface 1204 of the bracket assembly at the top edge of the bracket assembly, the lower sealing surface 2013 of the sealing piston and the sealing surface 1204 of the bracket assembly are in contact, and the sealing ring 11 engages the cavity surface of the upper housing such that air cannot pass between the sealing ring 11 and the cavity surface of the upper housing, and thus air cannot pass through the sealing assembly of the solenoid valve into the air port, and the carbon canister is in a closed state through the air passage 3.

As shown in fig. 3 and 4, the solenoid valve includes a primary plate 6, a secondary plate 9, a bobbin 4, a coil 8, a stopper 5, and a sleeve 7.

Reference is again made to fig. 5 to 7 for explaining the structure of the bracket assembly of the present invention, wherein fig. 5 and 6 are perspective views showing different view angles of the installation state of the bracket assembly and the sealing piston 2, and fig. 7 is a sectional view of the bracket, the secondary plate and the guide pipe integrated piece. The utility model discloses a support assembly includes support 12 and solenoid valve, wherein the secondary board 9 and the stand pipe 13 of solenoid valve form integrative piece through moulding plastics with support 12 the utility model discloses well stand pipe 13 is used for giving piston rod 202 direction, preferably adopts the copper, can call as the copper pipe. The support 12 comprises an upper ring 1201, a lower ring 1203 and connecting arms 1202, the connecting arms 1202 are used for connecting the upper ring 1201 and the lower ring 1203, so that the support 12 is a frame formed by linear materials, in the utility model, the connecting arms 1202 are preferably linear, the number is preferably three, so that the frame structure is simple and convenient, and air passes through the frame through the space between the connecting arms 1202.

The following five aspects are used to explain how to realize the correct mutual position of the bracket assembly and the sealing piston 2, the assembly process is simple, and the structure is firm and durable.

In a first aspect: referring to fig. 8 to 10, the secondary plate 9 and the guide tube 13 are spin-riveted together by a spin-riveting process. Fig. 9 and 10 show the spin rivet 14. Because of the good ductility of copper, the guide tube 13 is made of copper tube, which is beneficial to spin riveting. In the spin riveting process, the spin riveting tool ensures the position relationship between the secondary plate 9 and the guide pipe 13, and the position relationship between the secondary plate 9 and the guide pipe 13 is an important position relationship for the whole electromagnetic valve sealing assembly. Compared with the prior art, the secondary plate 9 and the guide pipe 13 are connected by adopting the spin riveting process, so that the position relation between the secondary plate 9 and the guide pipe 13 is firstly ensured, and the manufacture is simple and rapid.

In a second aspect: referring to fig. 7, a bracket portion is injection molded on the secondary plate 9 and the guide tube 13 subassembly by an injection molding process to form the bracket subassembly. In the injection molding process, the injection mold ensures the position relationship between the support sealing surface and the inner hole of the guide tube 13.

In a third aspect: referring to fig. 11-12, a piston head 201 is injection molded onto a piston rod 202 using an injection molding process to form a piston. During the injection molding process, the positional relationship between the piston head 201 and the outside diameter of the piston rod is ensured by the mold.

As shown in fig. 11-12, the piston rod 202 includes a head end 2021 and a tail end 2024, the head end 2021 is injection-molded with the piston head 201, and, in order to ensure the injection-molding firmness, a through hole 2022 is opened along the transverse direction of the head end, and after the injection-molding, the plastic of the piston head 201 fills the through hole 2022 and is firmly combined with the head end 2021.

A step 2023 may be formed between the leading end 2021 and the trailing end 2024 of the piston rod 202 to reduce the diameter of this portion of the piston rod 202, thereby reducing the weight of the piston rod 202. The tail 2024 of the tail end 2024 of the piston rod 202 is tapered to cooperate with the stop block 5 of the solenoid valve to facilitate centering and ensure positional relationship.

In a fourth aspect: referring to fig. 13, a sealing paste 2011 is added to the piston sealing disk of the piston head 201 to form the sealing piston 2 by an encapsulation process. In the encapsulating process, the positional relationship between the lower sealing surface 2013 of the sealing piston on the sealing glue 2011 and the outer diameter of the piston is ensured by a mold.

Referring to fig. 11 and 13, the piston seal disk of the piston head 201 is provided with a seal piston top seal surface 2012 and a seal piston lower seal surface 2013, which are respectively matched with the housing interior vent hole 102 and the assembly seal surface 1204 to realize the bidirectional sealing function of the seal piston 2. The packing piston top seal surface 2012 and the packing piston bottom seal surface 2013 are actually formed by a raised annular structure on the piston packing disk, which is triangular in cross-section as shown in fig. 13. As can be seen from the sealing surface configurations shown in fig. 11 and 13, the lower sealing surface 2013 includes a portion of the lower sealing surface 2013 formed by injection molding as shown in fig. 11, and another portion of the lower sealing surface 2013 formed by the sealant 2011 covering the sealing disk of the piston as shown in fig. 13, which are each a raised annular configuration. In contrast, a part of the lower sealing surface 2013 of the sealing piston formed by injection molding is harder, and the other part of the lower sealing surface 2013 of the sealing piston formed by the sealant 2011 is softer, so that the two parts are matched, and the effectiveness and the reliability of sealing the carbon tank to the atmosphere channel 3 are ensured from the two aspects of structure and hardness.

In a fifth aspect: referring to fig. 14-15, the spring 10 is first mounted on the sealing piston 2, and the sealing piston 2 and carrier assembly is assembled. The piston rod 202 in the assembled 3-seal piston 2 is inserted into the guide tube 13 in the stent assembly, and the outer diameter of the piston and the inner diameter of the guide tube are in clearance fit.

As shown in figures 3, 4, 7 and 15, the lower ring 1203 of the support 12 has a central hole, which is aligned with the secondary plate 9 and with the guide tube 13, for the passage of the piston rod 202 through the support 12 into the solenoid valve; preferably, the central hole of the lower ring 1203 of the bracket 12 has a positioning flange along the circumference of the central hole, and is tubular for mounting and positioning the spring 10.

The structural design described in these five aspects makes it easy to achieve correct mutual positions of the bracket assembly and the sealing piston 2, and the assembly process is simple.

The above five aspects are all technical means for ensuring the correct mutual positions of the bracket assembly and the sealing piston 2.

Through improving the structure of the sealed assembly of solenoid valve, the utility model discloses guaranteed that support assembly and sealed piston 2 mutual position are correct, made sealed face of sealed piston 2 and the sealed face of support assembly laminate completely under the electromagnetic force effect, have better leakproofness, make the evaporation diagnostic unit performance more superior, market competition reinforcing.

Additionally, the utility model discloses make the assembly process of evaporation diagnostic unit simple, reduced the leakproofness defective rate of evaporation diagnostic unit assembly line to, make the product sale price more have an advantage.

Moreover, the structure of the utility model is firm and durable.

Claims

1. An evaporation diagnosis unit using a gas positive pressure diaphragm pump, comprising a housing, a gas positive pressure diaphragm pump, and a solenoid valve seal assembly, both of which are installed in the housing, wherein,

the gas positive pressure diaphragm pump is columnar;

the electromagnetic valve sealing assembly comprises a sealing piston, a spring and a bracket assembly, and the bracket assembly comprises a bracket and an electromagnetic valve;

the sealing piston comprises a piston head and a piston rod, the piston head comprises a sealing disc, and the piston head is formed at the head end of the piston rod through injection molding;

the electromagnetic valve is used for driving the sealing piston and comprises a secondary plate and a guide pipe;

the bracket of the bracket assembly comprises an upper ring, a lower ring and a plurality of connecting arms, wherein gaps are formed among the connecting arms, the connecting arms are connected between the upper ring and the lower ring to form a frame-type bracket, and the bracket is an injection molding piece formed on a secondary plate of the electromagnetic valve through injection molding;

the lower ring of the bracket is provided with a central hole which is aligned with the secondary plate and the guide pipe and used for enabling the piston rod to penetrate through the bracket and enter the electromagnetic valve along the guide pipe;

the bottom end of the sealing disc of the piston head is provided with a piston sealing surface which is matched with a bracket assembly sealing surface of the upper ring of the bracket, which is positioned at the top end of the upper ring, and when the piston sealing surface is jointed with the bracket assembly sealing surface, a seal is formed, so that air cannot pass through the electromagnetic valve sealing assembly through the bracket;

the spring is used for enabling the piston head to keep a gap between the piston sealing surface and the bracket assembly sealing surface under the condition that the electromagnetic valve is powered off.

2. The evaporative diagnostic unit of claim 1, wherein the piston head is coated with a sealant at least on the sealing disk by an encapsulation process.

3. The evaporative diagnostic unit of claim 1, wherein the secondary plate and the guide tube are formed as one body by a spin riveting process.

4. The evaporative diagnostic unit of claim 1, wherein an upper edge of the lower ring of the cradle abuts an engagement portion of a housing of the evaporative diagnostic unit to mount the cradle assembly in the housing.

5. The evaporative diagnostic unit as defined in claim 1, wherein the central hole of the lower ring of the bracket has a tubular positioning flange along the periphery of the center for mounting and positioning of the spring.

6. The evaporative diagnostic unit as defined in claim 1, wherein one end of the spring is supported on the bracket, and the piston rod passes through the spring so that the other end of the spring abuts against the lower surface of the sealing disk.

7. The evaporative diagnostic unit as defined in claim 1, wherein the head end of the piston rod is transversely perforated with a through hole that is filled with the injection molding material of the piston head.

8. The evaporative diagnostic unit of claim 1, wherein the guide tube is a clearance fit with the piston rod.

9. The evaporative diagnostic unit of claim 1, wherein the central aperture of the lower ring has a tubular locating flange around the central aperture to mount and locate the spring.

10. The evaporative diagnostic unit as defined in claim 1, wherein the outer periphery of the upper ring of the bracket has a groove for mounting a sealing ring to seal between the upper ring and the inner surface of the housing of the evaporative diagnostic unit.