DE102020100967A1 - Combined check and shut-off valve for an internal combustion engine - Google Patents

Abstract

There are combined check and shut-off valves for internal combustion engines with an actuator (10), a flow housing (20) with an inlet (22) and an outlet (24), a valve rod (12) which can be moved by means of the actuator (10), a shut-off element (26) which is attached to the valve rod (12) and which can be lowered onto and lifted from a first valve seat (28), a non-return plate (34) which is mounted on the valve rod (12) and which is dependent on a pressure difference is movable against a second valve seat (32) which is arranged radially inside the first valve seat (28) and a spring (36) which is clamped between the shut-off element (26) and the non-return plate (34) and the non-return plate (34 ) loaded in the direction of the second valve seat (32), known. In order to simplify the assembly and manufacture of the valve while maintaining the same tightness, it is proposed according to the invention that the flow housing (20) integrally is square and the second valve seat (32) is formed directly by the flow housing (20) and at least one sealing lip (42, 44) is formed on the non-return plate (34), which extends from the non-return plate (34) in the direction of the valve seat ( 32) and with which the non-return plate (34) rests against the second valve seat (32) when the non-return plate (34) closes the flow opening (30).

Description

The invention relates to a combined check and shut-off valve for an internal combustion engine with an actuator, a flow housing with an inlet and an outlet, a valve rod which can be moved by means of the actuator, a shut-off element which is attached to the valve rod and which is mounted on a first valve seat can be lowered and lifted from this, a non-return plate which is mounted on the valve rod and which is movable as a function of a pressure difference against a second valve seat which is arranged radially inside the first valve seat and which has a throughflow opening which is arranged between the inlet and the outlet is limited radially inward and radially outward, and a spring which is clamped between the shut-off element and the check plate and loads the check plate in the direction of the second valve seat.

Combined check and shut-off valves of this type are used in secondary air systems or Otto particle filter regeneration units of internal combustion engines. Secondary air systems consist of a secondary air pump and a secondary air valve and are used to reduce pollutants when the internal combustion engine is cold started. During a cold start, gasoline engines are run with excess fuel, while at the same time the catalytic converter has not yet reached its working temperature. This is why large amounts of carbon monoxide (CO) and unburned hydrocarbons (HC) are produced between a cold start and the onset of the lambda control. In order to reduce these emissions, secondary air is blown into the exhaust system in front of the catalytic converter by means of the secondary air pump. The oxygen in the secondary air oxidizes the pollutants carbon monoxide (CO) and hydrocarbons (HC) to carbon dioxide (CO ₂ ) and water (H ₂ O). During this exothermic afterburning, thermal energy is generated, which additionally heats up the catalytic converter and thus brings it up to operating temperature more quickly.

The secondary air valve, which is arranged between the secondary air pump and the exhaust system, serves on the one hand as a non-return valve, which prevents exhaust gas from flowing in the direction of the secondary air pump due to the exhaust gas pulsations and damages it and, on the other hand, as a shut-off valve, via which the period of air supply into the exhaust system is regulated can.

Various secondary air valves which are pneumatically or electromagnetically actuated are known from the prior art. So is from the DE 10 2006 024 728 A1 a combined shut-off and check valve is known in which the valve seats for both valve bodies are formed on a valve plate in which flow openings are formed. To improve the seal, the valve plate has an elastomer coating which is designed as a sealing lip in the area of the valve seat.

In the known designs, however, there is the disadvantage that the construction of the valves to achieve sufficient tightness is relatively complex and too much space is required. Accordingly, the manufacturing costs and the assembly effort of the known shut-off and check valves are too great.

The object is therefore to create a combined check and shut-off valve for an internal combustion engine, in which a good sealing effect is achieved with reduced component assembly and manufacturing costs. In addition, manufacturing costs should be lowered and the space required should be reduced.

This object is achieved by a combined check and shut-off valve for an internal combustion engine with the features of main claim 1.

The fact that the flow housing is formed in one piece and the second valve seat is formed directly by the flow housing and at least one sealing lip is formed on the non-return plate, which extends from the non-return plate in the direction of the valve seat, and with which the non-return plate in the state that closes the flow opening Check plate rests against the second valve seat, the valve plate, which otherwise serves as a valve seat, can be completely dispensed with. There is also no need for a separate ring as a valve seat. This reduces the assembly effort and the number of components. In addition, the required axial installation space is reduced. The valve seat is correspondingly formed on the housing part in which a flow channel is formed and to which the actuator is attached.

The at least one sealing lip is preferably designed to be inclined with its free end in the direction of a side on which a higher pressure is applied when the non-return plate rests on the second valve seat. The sealing effect between the valve seat and the sealing lip is improved due to the greater flexibility of the sealing lip. The inclination of the sealing lip takes place correspondingly to the side on which the inlet pressure is applied during normal operation of the valve device. The check plate is used to prevent backflow to the inlet in the event of pressure pulsations. At this moment the non-return plate rests on the valve seat, so that at this point in time the pressure is on The outlet of the valve is larger than the inlet. A free end of the sealing lip is thus inclined towards the side on which a higher pressure is applied at this point in time, that is to say towards the outlet. This means that the existing pressure differences are used to increase the contact pressure of the check plate on the valve seat, which increases the tightness. When the non-return plate rests on the second valve seat, an undercut is formed on the side of the sealing lip facing the higher pressure. A sealing lip with such an undercut is easy to manufacture by means of a corresponding geometry in the shaping tool. Furthermore, such an undercut makes a contribution to the improved sealing effect by utilizing the higher exhaust gas pressure compared to the pressure of the secondary air. With a given sealing lip geometry, the higher exhaust gas pressure tends to press the sealing lip radially inward and thus also to load it axially in the direction of the valve seat, which results in an improved sealing of the valve.

In an advantageous embodiment, a radially inner sealing lip and a radially outer sealing lip are formed on the check plate, wherein the radially outer sealing lip has an axial and a radially outward component and is formed radially outside the flow opening and the radially inner sealing lip has an axial and a having radially inwardly directed component and is formed radially inside the throughflow opening. This sealing lip geometry, using the existing pressure conditions on the inner and outer circumference of the sealing lip, creates an improved contact pressure on the non-return plate and thus a better seal.

The non-return plate is advantageously made of an elastic plastic, which enables a compensation of manufacturing tolerances or unevenness on the valve seat, since a sealing effect is achieved by the deformation even on uneven surfaces. In addition, the elastic deformability described is implemented to improve the seal due to the pressure differences that are present. In particular, the sealing lip is thus elastically deformable in order to increase the sealing effect.

In an alternative embodiment, the non-return plate is made from a metal or a stable plastic and coated with an elastic plastic that forms the sealing lip. Thus, given a good seal, due to the flexibility of the sealing lip, a high level of stability and rigidity of the non-return plate can be ensured in order to prevent undesired deformations.

In a further development of the invention, the first valve seat is designed in one piece with the flow housing, so that no additional component has to be manufactured and assembled for the first valve seat either and the space requirement and the number of components are correspondingly low.

As a result, the shut-off element has an elastic plastic coating with which the shut-off element can be moved against the first valve seat in order to ensure a reliable seal, since tolerances and unevenness that may be present on the first valve seat can be compensated for by the deformability of the plastic coating.

In order to additionally prevent the non-return plate or the shut-off element from sticking to the valve seat, a PTFE coating is applied to the first valve seat and / or second valve seat formed on the flow housing, which ensures that the valve bodies can be easily released from their seats.

In order to be able to ensure the largest possible volume flows with the valves open with a small installation space, the flow opening extends in a ring shape over a circumference of 360 °. Accordingly, large cross-sections are available.

A combined check and shut-off valve for an internal combustion engine is thus created, which ensures a high level of tightness despite the fact that no additional components forming the valve seats are used. In this way, the installation space required axially can be reduced, the number of components required can be reduced, and thus the costs during manufacture and assembly can be reduced.

• 1 zeigt eine Seitenansicht eines erfindungsgemäßen Rückschlag- und Absperrventils in geschnittener Darstellung.

An embodiment of a combined check and shut-off valve according to the invention is shown in the figures and is described below.

• 1 shows a side view of a check and shut-off valve according to the invention in a sectional illustration.

The valve device according to the invention consists of a pneumatically or electrically operated actuator 10 over which a valve rod 12th can be operated. The valve stem 12th is in an actuator housing 14th mounted and protrudes axially through a bore 16 a flow housing 20th , which has an inlet 22nd and an outlet 24 having, which has a flow space 18th in the flow housing 20th are fluidically connected.

On to the actuator 10 opposite end of the valve rod 12th is a shut-off element 26th attached, which with a first valve seat 28 cooperates directly on a surface of the flow housing 20th is trained. On the flow housing 20th is an annular flow opening 30th formed, which serves as a flow cross-section through which the inlet 22nd with the outlet 24 by lifting the shut-off element 26th from the first valve seat 28 is connectable. This through-flow opening 30th extends in the circumferential direction to the axis of movement of the valve rod 12th viewed over a circle, i.e. over 360 °, between an interior of the flow housing 20th through which the valve stem 12th penetrates, and a radial exterior.

Immediately on a surface of the flow housing 20th is also a second valve seat 32 formed with a check plate 34 cooperates which on the valve rod 12th is mounted and axially between the second valve seat 32 and the shut-off element 26th is arranged and radially inside the first valve seat 28 is arranged. The checkback plate 34 is from a spring 36 towards the second valve seat 32 loaded, the opposite end against the shut-off element 26th rests so that the spring 36 between the check plate 34 and the shut-off element 26th is biased, and is radial just like the check plate 34 from the shut-off element 26th surround. The checkback plate 34 is accordingly when the shut-off element is closed 26th and thus in an unloaded normal position of the actuator 10 , by the spring 36 towards the second valve seat 32 burdened.

This checkback plate 34 consists of an inner support element 38 , which with an elastic plastic layer 40 , in particular made of an elastomer. This plastic layer 40 can for example by spraying onto the carrier element 38 be formed, which in turn can be made either from a metal or a stable plastic. The elastic plastic layer 40 has a radially inner sealing lip 42 and a radially outer sealing lip 44 with which the non-return plate 34 against the second valve seat 32 is moved, which according to a circular support surface radially inside the flow opening 30th and a circular bearing surface radially outside of the throughflow opening 30th of the flow housing 20th is formed, the sealing lips 42 , 44 axially opposite to the bearing surfaces of the second valve seat 32 on the non-return plate 34 are trained. On the second valve seat 32 a PTFE coating is preferred 45 applied to catching the check plate 34 on the second valve seat 32 , especially after slower shutter speeds.

If a secondary air flow is to be fed into the exhaust manifold of the engine during operation, the actuator 10 controlled and the shut-off element 26th from the first valve seat 28 lifted. In this operating state, the non-return plate takes 34 their normal function as a check valve, which opens and closes depending on the pressure in the exhaust manifold.

In the event of pressure peaks in the exhaust tract, a corresponding flow is generated from the outlet 24 to the inlet 22nd through the check plate 34 prevented when at the outlet 24 there is a higher pressure than at the inlet 22nd . The non-return plate is in this state 34 thus with their sealing lips 42 , 44 on the second valve seat 32 on, so that the through-flow openings 30th flow cross-sections formed are closed. The sealing lips 42 , 44 have at the same time an axial and a radial extension, with radial extension in the sense of the application being understood to mean that a component is at a 90 ° angle to the axial direction of the throughflow openings 30th is pioneering. This therefore means that the radially inner sealing lip 42 compared to the axial direction to the valve rod 12th is inclined and the radially outer sealing lip 44 is inclined radially outward and thus both sealing lips 42 , 44 are inclined towards the side on which the non-return plate is placed 34 on the second valve seat 32 the higher pressure is applied, namely to the outlet 24 . This is how it occurs on the second valve seat 32 one each from the non-return plate 34 protruding lip geometry with an undercut.

The alignment and position of the sealing lips 42 , 44 uses the prevailing pressure gradient to create the seal between the sealing lips in this state 42 , 44 and the second valve seat 32 to increase. This occurs because when the shut-off element is open 26th when pressure peaks occur in the exhaust tract and thus at the undercut, a higher pressure than in the flow openings 30th is present, through which the sealing lips 42 , 44 towards the second valve seat 32 be bent and thereby with an increased contact pressure against the second valve seat 32 be pressed.

If no more air is to be conveyed or if the combustion engine is switched off, the actuator is activated 10 and with it the valve stem 12th in their starting position, in which the shut-off element 26th on the first valve seat 28 rests. To prevent the shut-off element from getting stuck in this position 26th on the first valve seat 28 to be avoided is the flow housing 20th in the area of the first valve seat 28 with a PTFE (polytetrafluoroethene) coating 46 Mistake. In addition, the shut-off element is used to improve the tightness 26th with an elastic plastic coating 48 , in particular made of elastomer, provided with which the shut-off element 26th in the closed state against the first valve seat 28 is present. Due to the deformability of this elastic plastic coating 48 this can change the shape of the valve seat 28 adjust and compensate for unevenness accordingly.

For example, the non-return plate with the sealing lips creates a tight seal for the flow openings without the need to produce or install additional valve seats. Instead, the valve seats can be formed directly on the flow housing due to the design of the non-return plate and also of the shut-off element, so that additional components are not required. The axial installation space can also be reduced accordingly. A tight seal is produced even if there are unevenness on the valve seats, as these can be compensated for by the elastic plastics used. A backflow of exhaust gases into the secondary air tract is reliably prevented.

It should be clear that the scope of protection of the present main claim is not limited to the exemplary embodiment described. Changes to the structure of the various parts of the combined check and shut-off valve are conceivable. In particular, various actuators, such as pneumatic or electromagnetic actuators, can be used. Additional spacer elements can also be formed on the valve, which lift the non-return plate from the valve seat when the shut-off element is closed. The sealing lip can also have different shapes.

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 102006024728 A1 [0004]

Claims (10)

Combined check and shut-off valve for an internal combustion engine with an actuator (10), a flow housing (20) with an inlet (22) and an outlet (24), a valve rod (12) which can be moved by means of the actuator (10), a Shut-off element (26) which is attached to the valve rod (12) and which can be lowered onto and lifted from a first valve seat (28), a non-return plate (34) which is mounted on the valve rod (12) and which is dependent on a Pressure difference is movable against a second valve seat (32) which is arranged radially inside the first valve seat (28) and which has a throughflow opening (30), which is arranged between the inlet (22) and the outlet (24), radially inward and limited radially outward, and a spring (36) which is clamped between the shut-off element (26) and the non-return plate (34) and loads the non-return plate (34) in the direction of the second valve seat (32), thereby marked It is ensured that the flow housing (20) is formed in one piece and the second valve seat (32) is formed directly by the flow housing (20) and at least one sealing lip (42, 44) is formed on the non-return plate (34) and extends from the non-return plate (34) extends in the direction of the second valve seat (32), and with which the non-return plate (34) rests against the second valve seat (32) when the non-return plate (34) closes the flow opening (30). Combined check and shut-off valve for an internal combustion engine according to Claim 1 , characterized in that the at least one sealing lip (42, 44) is inclined with its free end in the direction of a side on which a higher pressure is applied when the non-return plate (34) rests on the second valve seat (32). Combined check and shut-off valve for an internal combustion engine according to Claim 1 or 2 , characterized in that a radially inner sealing lip (42) and a radially outer sealing lip (44) are formed on the check plate (34), the radially outer sealing lip (44) having an axial and a radially outward component and radially outside the throughflow opening (30) is formed and the radially inner sealing lip (42) has an axial and a radially inwardly directed component and is formed radially inside the throughflow opening (30). Combined non-return and shut-off valve for an internal combustion engine according to one of the preceding claims, characterized in that the non-return plate (34) is made from an elastic plastic. Combined non-return and shut-off valve for an internal combustion engine according to one of the preceding claims, characterized in that the non-return plate (34) has a carrier element (38) made of a metal or a stable plastic, on which an elastic plastic layer (40) is formed, which the Sealing lip (42, 44) forms. Combined check and shut-off valve for an internal combustion engine according to one of the preceding claims, characterized in that the sealing lip (42, 44) is elastically deformable. Combined check and shut-off valve for an internal combustion engine according to one of the preceding claims, characterized in that the first valve seat (28) is formed in one piece with the flow housing (20). Combined check and shut-off valve for an internal combustion engine according to one of the preceding claims, characterized in that the shut-off element (26) has an elastic plastic coating (48) with which the shut-off element (26) can be moved against the first valve seat (28). Combined check and shut-off valve for an internal combustion engine according to one of the preceding claims, characterized in that a PTFE coating is applied to the first valve seat (28) and / or second valve seat (32) formed on the flow housing (20). Combined check and shut-off valve for an internal combustion engine according to one of the preceding claims, characterized in that the throughflow opening (30) extends annularly over a circumference of 360 °.

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