WO2018149635A1

WO2018149635A1 - Magnetic armature and method for producing a magnetic armature

Info

Publication number: WO2018149635A1
Application number: PCT/EP2018/052323
Authority: WO
Inventors: Bernhard Hager; Florian Pickl; Karl-Otto Englert; Ralf Gragen
Original assignee: Robert Bosch Gmbh
Priority date: 2017-02-14
Filing date: 2018-01-31
Publication date: 2018-08-23
Also published as: DE102017202300A1

Abstract

The invention relates to a method for producing a magnetic armature (36), in particular a magnetic armature (36) for a switching valve (15), comprising: applying a corrosion protection layer (46) onto a base material (44) of the magnetic armature (36), the corrosion protection layer (46) having pores (50); and applying a sliding material (48) onto the corrosion protection layer (46) without closing the pores (50) in the corrosion protection layer (46) prior to the application of the sliding material (48).

Description

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title

Magnetic armature and method for producing a magnet armature The invention relates to a magnet armature and a method for producing a magnet armature

Magnetic anchor, in particular a magnet armature for an electromagnetic switching valve, which in an apparatus for injecting a fluid

Reducing agent is used in an exhaust line of an internal combustion engine.

State of the art

The SCR technology ("selective catalytic reduction") has proved its worth for de-icing the exhaust gases of internal combustion engines, especially diesel engines, for which systems have been developed which ensure compliance with the required exhaust gas limit values by a defined addition of an aqueous urea solution C, AdBlue ") as a reducing agent in the exhaust system of

Allow internal combustion engine and the reduction of nitrogen oxides in a subsequent S CR catalyst. These systems essentially comprise a reducing agent tank for storing the reducing agent, a metering module arranged at the exhaust gas line of the internal combustion engine, a pumping device designed to convey the reducing agent from the reducing agent tank to the metering module, and an electronic control unit. Aqueous urea solution freezes at temperatures below -11 ° C. Of the

Freezing point can not be reduced further without impairing the functionality as a reducing agent. In order not to be damaged by the resulting ice pressure when freezing the reducing agent, the metering module of such a system must be completely emptied when parked. For this purpose, in particular, a switching valve can be provided, which makes it possible to operate the pumping device as a suction pump to promote the reducing agent from the dosing back into the reducing agent tank. Such a switching valve usually has a magnetic armature, which is movable by switchable on and off electromagnetic field. - -

It is an object of the invention to improve such a switching valve and in particular such a gas tanker and to simplify its manufacturing process. Disclosure of the invention

According to one exemplary embodiment of the invention, a method for producing a magnet armature, in particular a magnet armature for a switching valve, comprises applying a corrosion protection layer to a base material such that pores are formed at least on the surface of the anticorrosion layer and applying a sliding material to the anticorrosive layer, without the pores , which are formed in the anticorrosion layer, to close before applying a sliding material.

A magnet armature, in particular for a switching valve, according to an embodiment of the invention comprises a base material, one on the

Base material applied corrosion protection layer containing pores; and a lubricant applied to the anticorrosion layer. The pores of the anticorrosion layer have not been sealed before the application of the sliding material.

The invention also includes an electromagnetic switching valve with a magnetic armature according to an embodiment of the invention and an apparatus for injecting a fluid reducing agent into a

Exhaust line of an internal combustion engine, with a reducing agent tank, which is designed to store the fluid reducing agent; a metering module, which is attached to the exhaust line and is adapted to inject the reducing agent metered into the exhaust gas line; a pumping device, which is designed to promote reductant from the reducing agent tank to the dosing in a conveying operation and to promote in a Rücksaugbetrieb reducing agent from the dosing into the reducing agent tank. Also, the lines that connect the dosing with the pumping device and the pumping device itself can be emptied. The device also comprises an electromagnetic switching valve, which makes it possible to switch the operation of the device between the conveying operation and the Rücksaugbetrieb, wherein the electromagnetic switching valve is a magnet armature according to a

Embodiment of the invention has. - -

The invention provides a process- and cost-optimized magnet armature which is protected against corrosion by a corrosion protection layer and permanently dry-lubricated by a sliding layer.

In one embodiment, the application of the corrosion protection layer by gas nitrocarburizing takes place. Gas nitrocarburizing has proven to be an advantageous method of forming a corrosion protection layer.

In one embodiment, the sliding layer is a plastic-polymer layer, in particular a PTFE layer with embedded molybdenum disulfide (M0S2). In one embodiment, the sliding layer is a polyamideimide layer, in particular a polyamideimide layer, which additionally contains PTFE and / or molybdenum disulphide. Such compounds provide particularly durable surfaces with a low coefficient of friction.

In one embodiment, the base material is not roughened prior to the application of the anti-corrosion layer. In particular, it is not necessary to roughen the base material because the pores in the anticorrosive layer provide a sufficiently large surface area to which the slip layer adheres well. The additional step of roughening the surface can therefore be dispensed with.

The invention will be explained in more detail below with reference to the attached figures.

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Brief description of the drawings

Figure 1 shows schematically an embodiment of a reducing agent injection device with a switching valve, which is designed according to an embodiment of the invention.

Figure 2 shows a simplified schematic view of a switching valve according to an embodiment of the invention.

FIG. 3 shows a schematic view of a section through the surface of the magnet armature, which is designed according to an exemplary embodiment of the invention.

Description of the drawings

Figure 1 shows in a schematic view an embodiment of a reducing agent injection device 2 with a switching valve 15 which is formed according to an embodiment of the invention.

The reducing agent injection device 2 comprises a metering device 10, which is attached to an exhaust line 4 of an internal combustion engine 6. The metering device 10 is designed to inject fluid reducing agent 9 into the exhaust gas line 4 upstream of an S CR catalytic converter 5 arranged in the exhaust gas line 4.

The reducing agent 9 to be injected into the exhaust gas line 4 is stored in a reducing agent tank 8.

A pumping device 12 is provided, reducing agent 9 by a

Remove fluid intake line 20 from the reducing agent tank 8 and supply the metering device 10 through a pressure line 22 under increased pressure.

The pumping device 12 includes a motor 14, a piston 13 driven by the motor 14, and two one-way valves 16, 18, one of which is disposed upstream and downstream of the piston 13, respectively. - -

The reducing agent injection device 2 may comprise at least one filter, not shown in the figure, which prevents the dirt particles from penetrating the reducing agent tank 8 into the pumping device 12 and / or the metering device 10 and clogging and / or damaging them.

The pumping device 12 is shown schematically in FIG

Reductant tanks 8 shown. The pumping device 12 can, for example in the form of an integrated filter and pump unit, also within the

Reductant tanks 8, in particular be arranged at the bottom of the reducing agent tank 8.

It is also a return line 23 is provided to excess, promoted by the pumping device 12 reducing agent 9, not from the

Dosing module 10 is injected into the exhaust line 4, through a throttle 24 and / or not shown in the figure 1 one-way valve in the

Reductant tank 8 due.

The reducing agent injection device 2 comprises a control device 28, in particular an electronic control device 28, which is designed to control the motor 14 of the pump device 12 and the metering device 10 so that a desired amount of reducing agent 9 is injected into the exhaust line 4 of the internal combustion engine 6.

Provided on the pressure line 22 is a pressure sensor 26 which allows the control device 28 to monitor the fluid pressure in the pressure line 22 and set it to a predetermined value by activating the motor 14 of the pump device 12.

Between the pumping device 12, the suction line 20 and the pressure line 22, a switching valve 15 is arranged, which makes it possible to operate the

Reductant injector 2 to switch between an injection mode and a suction mode.

In injection mode, the pumping device 12 promotes reducing agent 9 from the reducing agent tank 8 to the metering device 10. In the suction operation is the

Reduction agent 9 sucked from the pumping device 12 from the metering device 10 and fed back into the reducing agent tank 8 to

prevent the reducing agent 9 at low ambient temperatures - - Freezes within the metering device 10 and damaged the metering device 10 by its spatial extent. In the suction mode, the

Reducing agent 9 are also removed from the pressure line 22 and the pumping device 12. The switching valve 15 is driven by the control device 28.

Figure 2 shows a simplified schematic view of a switching valve 15 according to an embodiment of the invention.

The switching valve 15 comprises a valve chamber 30 with three fluid ports 32a, 32b, 32c. By moving a closure member 34 disposed in the valve chamber 30, a first fluid port 32a may be selectively connected to a second fluid port 32b or to a third fluid port 32c while the other of the two fluid ports 32b, 32c is closed by the closure member 34 , In the simplified schematic view of Figure 2, a single closure element 34 is shown. The switching valve 15 may also have a plurality of closure elements 34 which can be moved together or independently.

The closure element 34 is moved by a magnet armature 36, which is movably mounted in an electromagnet 38 with at least one coil 40. By energizing the coil 40, the armature 36 and the closure member 34 connected to it can be moved to selectively a

Allow fluid flow between the first fluid port 32a and the second fluid port 32b or between the first fluid port 32a and the third fluid port 32c.

In order to minimize friction losses and wear of the magnet armature 36 during its movement, the magnet armature 36 should be guided in its guide 42 with as little friction as possible.

The armature 36, which consists of a metallic magnetic base material 44 (see Figure 3), in particular a nitriding steel such as

HSMnPb30 is made, therefore, with a layer of sliding material

CGIeitschicht ") 48 provided. - -

In order to prevent corrosion of the metallic material 44, a corrosion protection layer 46 is previously applied to the base material 44.

The corrosion protection layer 46, which is produced in particular by gas-nitrocarburizing of the base material, has in particular at its from the

Base material facing away from pores 50, which are not closed, before in a subsequent step, the sliding layer 48, for example

Polyamide-imide, PTFE and / or molybdenum disulfide comprises, on the

Corrosion protection layer 46 is applied.

According to a basic concept of the invention, the post-oxidation of the corrosion protection layer C, GNC layer ") 46, which is known from the prior art, is dispensed with, in particular, by the post-oxidation of the gas by nitrocarburizing.

By leaving the pores 50 open in accordance with one aspect of the invention, they provide a sufficiently large surface area to ensure adhesion of the subsequently applied slip layer 48.

In particular, it is possible to dispense with additional roughening of the corrosion protection layer 46 formed by gas nitrocarburizing, for example by sandblasting. During the manufacture of the magnet armature 36, at least one working step can thus be saved.

Figure 3 shows in a schematic view a section through the surface of the magnet armature 36 with the metallic base material 44, which has a non-roughened surface. On the surface of the base material 44, a GNC layer 46 is formed, at least on its of the

Base material 44 opposite side pores 50 has. On the GNC layer 46, the sliding layer 48 is formed.

The result is a process- and cost-optimized magnet armature 36, which is well protected by the GNC layer 46 against corrosion and permanently dry-lubricated by the sliding layer 48 applied to the GNC layer 46.

Claims

claims

A method of manufacturing a magnet armature (36), in particular a magnet armature (36) for a switching valve (15), the method comprising:

Applying a corrosion protection layer (46) to a base material (44), the corrosion protection layer (46) having pores (50); and

Applying a slip material (48) to the anticorrosive layer (46) without the pores (50) in the anticorrosive layer (46) prior to

Applying the sliding material (48) to close.

2. The method of claim 1, wherein the method comprises, in particular, the sliding material (48) on the anti-corrosion layer (46).

without oxidizing the anticorrosion layer (46) beforehand.

3. The method according to claim 1 or 2, wherein applying the

Corrosion protection layer (46) in particular gas nitrocarburizing comprises.

4. The method according to any one of the preceding claims, wherein the sliding material (48) comprises a plastic-polymer layer containing in particular polyamide-imide, PTFE and / or molybdenum disulfide.

5. The method according to any one of the preceding claims, wherein the base material (44) before applying the corrosion protection layer (46) is not roughened.

6. magnet armature (36), in particular for a switching valve (15) which has been produced in a method according to one of claims 1 to 5.

7. magnet armature (36), in particular for a switching valve (15), with

a base material (44);

a corrosion protection layer (46) applied to the base material (44) and having pores (50); and

a lubricant applied to the anticorrosion layer (46)

(48);

wherein the pores (50) of the anticorrosion layer (46) have not been sealed prior to the application of a slip material (48).

8. An armature (36) according to claim 7, wherein the corrosion protection layer (46) comprises a layer applied by gas nitrocarburizing, and / or wherein the sliding material (48) comprises a plastic layer containing in particular polyamide-imide, PTFE and / or molybdenum disulfide.

9. Electromagnetic switching valve (15) having a magnet armature (36) according to one of claims 6 to 8.

10. Device (2) for injecting a fluid reducing agent (9) in an exhaust line (4) of an internal combustion engine (6), with

a reducing agent tank (8) adapted to store the fluid reducing agent (9);

a metering module (10), which is attached to the exhaust line (4) and designed to inject the reducing agent (9) metered into the exhaust line (4);

a pumping device (12), which is designed to promote reductant (9) from the reducing agent tank (8) to the metering module (10) in a conveying operation and in a suckback operation, reducing agent (9) from the

Dosing module (10) in the reducing agent tank (8) to promote; and

an electromagnetic switching valve (15) according to claim 9, which makes it possible to switch the operation of the device (2) between the conveying operation and the Rücksaugbetrieb.