WO2022048742A1

WO2022048742A1 - Flap device for an internal combustion engine

Info

Publication number: WO2022048742A1
Application number: PCT/EP2020/074468
Authority: WO
Inventors: Stefan Rothgang; Hendrik Ferner; Thomas DITGES; Frank Bürger; Christoph RÜBERG
Original assignee: Pierburg Gmbh
Priority date: 2020-09-02
Filing date: 2020-09-02
Publication date: 2022-03-10
Also published as: EP4208635A1

Abstract

Flap devices are known which comprise: a flow housing (14) having an adjustable flow cross-section (18); an actuator (12); a flap body (36); a shaft (34) on which the flap body (36) is fastened and which can be rotated by the actuator (12); and a separate sealing ring (20) which is fastened in the flow housing (14) and surrounds the adjustable flow cross-section (18) and against which the flap body (36) abuts in order to close the flow cross-section (18). According to the invention, in order to prevent freezing in frosty conditions, the sealing ring (20) has an at least partially annular contact surface (50) to a heating element (48).

Description

DESCRIPTION

Valve device for an internal combustion engine

The invention relates to a valve device with a flow housing with an adjustable flow cross section, an actuator, a valve body, a shaft on which the valve body is attached and which can be rotated via the actuator, a separate sealing ring attached in the flow housing, which surrounds the adjustable flow cross section and against which the flap body rests to close the flow cross section.

Such flap devices are used in particular in motor vehicles to regulate air or exhaust gas flows. In particular, these are particularly tight flaps that are suitable both for being attached to internal combustion engines and in the air or hydrogen circuits of a fuel cell drive.

Irrespective of the respective application, condensates often form in the drive train due to moisture in the air, in the exhaust gas or the water content required in the fuel cell. At low temperatures, these condensates cause problems, especially when starting a vehicle from cold, since they often collect between the movable control body and the valve seat and freeze there. Forcibly detaching the control body from the valve seat by actuating the actuator with great force, damage may occur due to cracks or contractions in the sealing rings that form the valve seat, which is particularly to be feared when an elastic plastic sealing ring is used as the valve seat , which is often necessary for a sufficient tightness of the flap device. Such a flap device with a separate elastic sealing ring is known, for example, from DE 92 17 697 U1, but this flap device is highly sensitive to the flap body freezing to the sealing ring. Accordingly, in order to generate sufficiently large breakaway torques, strong and large actuators must also be used in order to ensure that the flap functions during a cold start.

Another way of avoiding such large actuators is known for lift valves, for example from DE 198 01 387 A1. This discloses an exhaust gas recirculation valve designed as a lift valve, in the flow housing of which PTC heating elements are arranged in the area of the valve seats, which are intended to prevent the control body of the exhaust gas recirculation valve from sticking to the valve seat after a cold start. The heating elements are either located within the housing walls or the metal heating element itself forms the valve seat surface.

So while in the first case no reliable protection against freezing of the flap body is guaranteed, in the second case the sealing effect when the valve body is in contact is not sufficient, for example for use in a fuel cell circuit, and the achievable volume flows are also limited. Sufficient flow cross sections are not made available with such a lifting valve. Furthermore, in the event of damage in the area of the heating element, the entire housing must be replaced, which results in undesired additional costs.

The task is therefore to provide a flap device with which very good tightness is ensured when the flow cross section is closed, i.e. when the flap body rests on the seat surface, and a sufficiently large volume flow can be guaranteed when the valve is open. In addition, protection against freezing of the flap body to the seat a cold start and ambient temperatures below freezing. Furthermore, an optional installation as well as an exchange of the heating element and, if possible, also of the valve seat should be able to be implemented without the entire housing of the flap device having to be removed and exchanged.

This object is achieved by a flap device having the features of claim 1.

The flap device according to the invention has a flow housing with an inlet, an outlet and a duct section through which flow can take place. Furthermore, the flap device consists of an actuator, which can be designed in particular as an electric motor with a gearbox connected to it. This actuator actuates, for example via the gear, a shaft that protrudes into the duct section and on which a flap body is attached, so that when the actuator is actuated, its rotational movement is transmitted to this flap body in a reduced manner via the gear, causing it to move between an open position in which it largely releases an adjustable flow cross-section in the channel section and a position which closes the flow cross-section and in which the flap body rests on a sealing ring which surrounds the adjustable flow cross-section can be moved. The sealing ring serves as a seat for the flap body. According to the invention, this sealing ring has an at least partially ring-shaped contact surface with a heating element, so that it can have a direct heating effect on it. Thus, when using the flap device in a motor vehicle that is parked at temperatures below freezing, a frozen flap body can be released before the cold start by energizing the heating element. The heating element acts directly on the seat, resulting in a high level of efficiency and the ice can be dissolved in a short time. The sealing ring and the flap body can be protected in this way from damage caused by sticking, which is particularly the case Use of elastic contact surfaces between valve body and sealing ring would be feared without using the heating element. Furthermore, smaller actuators can be used since no breakaway torques have to be generated. This also reduces the energy consumption of the actuator during operation. The sealing ring and heating element can also be removed from the flow housing and replaced if damage occurs.

Preferably, the heating element is a heating wire with at least one connection line, which when energized generates heat due to its resistance, which heat is emitted directly to the sealing ring. The use of a heating wire also has the advantage that it is easy to install and requires little additional space. Incidentally, such electrical heating reacts very quickly. The connecting cable must be at least indirectly connected to a power source.

The heating wire advantageously surrounds the sealing ring directly. The sealing ring and the heating wire can either be attached to one another before installation in the flow housing, or the heating wire is first inserted separately into the flow housing. In both cases, the result is a construction in which disassembly from the flow housing of the heating wire and the sealing ring is possible.

It when the sealing ring is an elastic sealing ring made of plastic is particularly advantageous. This plastic can in particular be silicone, ethylene propylene diene (monomer) rubber, fluorine rubber (FKM) or a hydrogenated acrylonitrile butadiene rubber. With such a sealing ring, a high degree of tightness can also be achieved with flap valves when the flap body rests on the sealing ring, which adapts itself to the shape of the flap body due to its elasticity and thus compensates for existing tolerances and unevenness. The otherwise existing sensitivity to damage when the valve body sticks to the valve seat is significantly reduced by the heating element, so that by this Combination a very long durability of such a tight flap device is achieved.

In an alternative embodiment, the heating element is a heating wire that is injected into the sealing ring. This eliminates the need for individual disassembly and replacement, but assembly is simplified and the heating wire is protected from damage by the surrounding material of the sealing ring. Furthermore, in this way the heat source is shifted even closer to the support surface, whereby the heating rate and thus the dissolution of existing ice particles is additionally accelerated.

Furthermore, the sealing ring can advantageously be designed as a lip sealing ring. Such a lip sealing ring leads to very good sealing properties, so that the flap device is almost leak-free when the flap body rests on the sealing ring.

In a further embodiment of this, the heating element can be arranged in an axial annular groove of the sealing ring. When using a lip sealing ring, the heating wire can be arranged in the groove between the two legs. This simplifies assembly, while individual disassembly and thus individual replacement of the components can nevertheless take place. In addition, this creates a direct proximity to the seat with the advantage of faster heating.

In a further advantageous embodiment, the heating element is encapsulated with a plastic, with two connection contacts protruding from the plastic, with the encapsulated heating element having a contact surface with the sealing ring. Accordingly, there is direct heat conduction to the lip seal ring. Nevertheless, the optionality remains, so that the valve can be built with or without a heating element without having to change the design or individual components. The contact can be made directly via the two connection contacts protruding from the plastic take place, which can then be pressed against corresponding stamping comb spring ends in the housing.

Furthermore, it is advantageous if the flow housing has an inlet connection piece and an outlet connection piece, with either the inlet connection piece or the outlet connection piece bearing axially against the sealing ring, as a result of which it is fastened. Correspondingly, a shoulder is to be provided on the flow housing, against which the sealing ring is pushed in order to be fixed in its position on the stop by subsequently pushing in the inlet connector or outlet connector against the sealing ring. A particularly simple interchangeability can be realized in this way.

The heating element can also be fixed in a corresponding manner, in that the flow housing has an inlet connection or outlet connection which rests axially against the heating element after the inlet connection or the outlet connection has been pushed against the heating element, which can rest on a shoulder or axially on the sealing ring.

In order to achieve automatic control of the heating wire, a bimetallic element can be arranged in the connecting line of the heating element, which establishes an electrical connection to the heating element when the temperature falls below a limit and interrupts it when the limit temperature is exceeded, so that only at temperatures actually occurring at which freezing occurs of the condensate on the seat surface is to be feared, heating also takes place. Unnecessary energy consumption is avoided in this way.

In an alternative embodiment to this, a PTC element is arranged in the connection line of the heating element, the conductivity of which increases with falling temperature, so that the current flow and thus the heating effect are increased with falling temperature. In this way, icing can be broken up even at extreme sub-zero temperatures, while the current is lower at temperatures around freezing point because the ice can be dissolved much more easily. When using the PCT element as well as the bimetallic element, additional switches can be provided in the control unit to end the current flow.

In a further alternative or further development, the flap device has a position sensor which generates an output voltage which is dependent on the position of the flap body and which is at a maximum when the flap body rests on the sealing ring, and which is connected to a gate terminal of a mosfet which is in the connecting line of the heating element is arranged. It can thus be automatically ensured that the sealing ring and thus the seat surface are only heated when the flap body is actually resting on the sealing ring or is in its vicinity. This can be done in addition to the temperature-dependent control or individually.

The flap body preferably rests on the sealing ring during a cold start of an internal combustion engine or a fuel cell system. This ensures that no larger ice bridges form that require a longer period of dissolution. Furthermore, when using the circuit via the Mosfet, it is ensured that current is supplied. Alternatively, an open flap can also be provided when the device is switched off, which reduces the formation of ice bridges when the device is switched off. In the case of fuel cell systems in particular, however, it is often necessary to prevent condensate from flowing to the fuel cell when it is switched off.

In order to further ensure that there is no unnecessary energy consumption after the ice has dissolved, a maximum energization time for the heating element is stored in a control unit of the flap device. Accordingly, there is no current flow after a cold start during operation. The flap device according to the invention is accordingly characterized by a long service life while maintaining a high degree of tightness in the closed state, ie when the flap body is placed on the sealing ring. This is achieved by breaking up ice bridging in good time, while reducing the necessary power consumption to a minimum. The heating element and the sealing ring are easy to assemble and disassemble.

An embodiment of a flap device according to the invention is shown in the figures and is described below.

FIG. 1 shows a side view of a flap device according to the invention in a partially sectioned illustration.

FIG. 2 shows a view of the flap device according to FIG. 1 rotated by 90°.

FIG. 3 shows a top view of the flap device from FIGS. 2 and 3 with the gear cover open.

Figure 4 shows an enlarged detail A from Figure 1.

The valve device shown in the figures consists of an actuator housing 10 in which an actuator 12 is arranged and a flow housing 14 through which a gas flow to be regulated can flow. A first housing part 16 forms the actuator housing 10 and a section 17 of the flow housing 14 in which a controllable flow cross section 18 is formed, which is surrounded by a sealing ring 20 forming a valve seat. The first housing part 16 has a receptacle 22 for an electric motor 24 and a gear receptacle 26 for a gear 28 designed as a spur gear. The transmission mount 26 is closed by a cover 30 . Extends parallel to the axis of rotation of the electric motor 24 through the first housing part 16 a bore 32, through which a shaft 34, which forms the output member of the gear 28, projects into the section 17 of the flow housing 14. A flap body 36 is fastened to this shaft 34 and is rotated accordingly when the actuator 12 is actuated in the channel 38 formed through the flow housing 14 .

In the present exemplary embodiment, the flow housing 14 also has an inlet connector 40 and an outlet connector 42 which axially lengthen the channel 38 on both sides of the section 17 of the flow housing 14 . During assembly of the inlet connection piece 40 , this is pushed into the section 17 and with a second sealing ring 44 lying axially on the inlet connection piece 40 against the sealing ring 20 . In the present exemplary embodiment, the sealing ring 20 is designed as an elastic lip sealing ring made of plastic, so that when the flap body 36 rotates it is pushed against the sealing ring 20, which is slightly compressible, so that when the flap body 36 makes contact, a tight closure of the channel 38 is achieved.

According to the invention, a heating element 48 designed as a heating wire is arranged between the sealing rings 20, 44, which in the present exemplary embodiment has two essentially ring-shaped contact surfaces 50 for the sealing ring 20, since the heating element 48 has two windings. Alternatively, however, it would also be possible to arrange the heating element 48 in a radially outer annular groove or in a groove between the legs of the sealing ring 20 or just to let it rest directly against the sealing ring 20 from the outside. It is also possible to overmould the heating element 48 during the production of the sealing ring 20 .

A non-visible electrical connection line extends from the heating element 48 to a plug 54 of the flap device, via which the heating element 48 can be supplied with current. A bimetallic element (also not shown) or a PTC element is arranged in the connection line. When using the bimetallic element, this switches the Power supply from falling below a defined limit temperature of about 5 ° C, for example. At higher temperatures, the power supply is interrupted so that no heating takes place. If a PTC element is used instead of the bimetallic element, the flow of current and thus the heating effect of the heating element 48 increases as the temperature falls.

In addition, a mosfet with its drain connection and its source connection is arranged in the connection line. A gate connection of the mosfet is connected to an output connection of a position sensor 68 or switch, which generates an increasing output voltage as the distance between the flap body 36 and the sealing ring 20 decreases, or switches when the flap body 36 rests on the sealing ring 20, whereby the mosfet only then switched through and thus the heating element 48 is energized when the flap body 36 actually rests on the sealing ring 20 or is at least in its vicinity.

Furthermore, a maximum energization time is set via a time switch in a control unit 70 of the flap device in order to prevent the heating element 48 from continuing to be energized when the ambient temperatures are low and the flap body 36 is closed. Of course, this can also be done via an external control unit.

If a fuel cell or an internal combustion engine, in which the flap device is arranged in order to regulate a gas flow containing condensates, is now stopped, the flap body 36 is rotated into its closed position. During a subsequent cold start, at low temperatures around freezing point, the condensates in the gas flow to be regulated can cause a layer of ice to form between the sealing ring 20 and the flap body 36, through which the flap body 36 would no longer be able to rotate freely. With the present invention, this is automatically achieved at correspondingly low temperatures Heating element 48 is connected to a voltage source, so that its electrical resistance generates heat, which is transferred directly to the sealing ring 20 by thermal conduction through the contact surface thereof. As a result, the layer of ice is broken up and the flap body 36 can move freely. This is particularly desirable in the case of flap devices which, like the described flap device, have an elastic sealing ring 20 made of plastic as the valve seat, since otherwise damage to the sealing ring 20 would have to be expected with such sealing rings 20 due to a violent detachment of the flap body 36 from the sealing ring 20. Accordingly, a highly sealed valve is created which is at the same time insensitive to ice formation and thus has a long service life.

It should be clear that the scope of protection of the main claim is not limited to the embodiment described, but various modifications are possible. In particular, the housing can be designed with different partitions or differently shaped flap bodies and sealing seats can be used. These also do not have to be made of plastic, but can also be made of a metal that conducts heat as well as possible. The heating element can rest against the metal sealing ring or, alternatively, be encapsulated. The valve body and the housing can also be made of metal or plastic, depending on use. The power supply can be carried out directly via the plug or in series with the power supply of the electric motor.

Claims

Pierburg GmbH, 41460 Neuss PATENT CLAIMS

1. Flap device with a flow housing (14) with an adjustable flow cross section (18), an actuator (12), a flap body (36), a shaft (34) on which the flap body (36) is attached and which is connected via the actuator (12 ) is rotatable, a separate sealing ring (20) fixed in the flow housing (14), which surrounds the controllable flow cross section (18) and against which the flap body (36) rests to close the flow cross section (18), characterized in that the sealing ring ( 20) has an at least partially ring-shaped contact surface (50) with a heating element (48).

2. Flap device according to claim 1, characterized in that the heating element (48) is a heating wire with at least one connecting line.

3. Flap device according to claim 1 or 2, characterized in that the heating element (48) surrounds the sealing ring (20) directly.

4. Flap device according to one of the preceding claims, characterized in that the sealing ring (20) is an elastic sealing ring made of plastic.

5. Flap device according to claim 4, characterized in that the heating element (48) is a heating wire which is injected into the sealing ring (20). Flap device according to one of the preceding claims, characterized in that the sealing ring (20) is a lip sealing ring. Flap device according to one of the preceding claims, characterized in that the heating element (48) is arranged in an annular groove of the sealing ring (20). Flap device according to one of Claims 6 or 7, characterized in that the heating element (48) is encapsulated in plastic, with two connection contacts protruding from the plastic, the encapsulated heating element (48) having a contact surface with the sealing ring (20). Flap device according to one of the preceding claims, characterized in that the flow housing (14) has an inlet connection (40) or outlet connection (42) which abuts axially against the sealing ring (20). Flap device according to one of the preceding claims, characterized in that the flow housing (14) has an inlet connection (40) or outlet connection (42) which abuts axially against the heating element (48). Flap device according to one of claims 2 to 10, characterized in that 14 in the connection line (52) of the heating element (48), a bimetallic element is arranged, which produces an electrical connection to the heating element (48) when the temperature falls below a limit and interrupts it when the temperature exceeds the limit. Flap device according to one of Claims 2 to 10, characterized in that a PTC element is arranged in the connecting line (52) of the heating element (48), the conductivity of which increases as the temperature falls. Flap device according to one of Claims 2 to 12, characterized in that the flap device has a position sensor (68) which generates an output voltage which is dependent on the position of the flap body (36) and which when the flap body (36) rests on the sealing ring (20) is maximum, and which is connected to a gate connection of a MOSFET, which is arranged in the connection line (52) of the heating element (48). Flap device according to one of the preceding claims, characterized in that the flap body (36) during a cold start

Internal combustion engine or a fuel cell system on the sealing ring (20) rests. Flap device according to one of the preceding claims, characterized in that a maximum energization time for the heating element (48) is stored in a control unit (70) of the flap device.