WO2021110307A1

WO2021110307A1 - Solenoid valve for a fluid-conveying device and method for operating a solenoid valve

Info

Publication number: WO2021110307A1
Application number: PCT/EP2020/078848
Authority: WO
Inventors: Andreas Kellner; Peter Boehland; Romain CHASSAGNE; Ralf Gragen
Original assignee: Robert Bosch Gmbh
Priority date: 2019-12-03
Filing date: 2020-10-14
Publication date: 2021-06-10
Also published as: DE102019218742A1

Abstract

The invention relates to a solenoid valve (1) for a fluid-conveying device (2), comprising an armature (3) that can be moved in a stroke motion, a spring (4) for preloading the armature (3), and an annular magnet coil (5) for generating a magnetic force that counteracts the spring force of the spring (4), wherein a yoke core (6) is inserted in the annular magnet coil (5) and, together with the armature (3), delimits a working air gap (7). According to the invention, the armature (3) and the yoke core (6) comprise mirror-inverted stepped contours (8, 9) which engage in one another during a stroke of the armature (3) and result in the formation of at least one radial gap (10) between the armature (3) and the yoke core (6). The invention also relates to a fluid-conveying device (2) comprising such a solenoid valve (1) and to a method for operating such a solenoid valve (1).

Description

description

Title:

Solenoid valve for a fluid delivery device and a method for operating a

Solenoid valve

The invention relates to a solenoid valve for a fluid delivery device with the features of the preamble of claim 1. Furthermore, the invention relates to a fluid delivery device with a solenoid valve according to the invention, the fluid delivery device in particular for delivering an operating or auxiliary material, for example an aqueous urea solution for the aftertreatment of exhaust gases from an internal combustion engine , can be used. The invention also relates to a method for operating a solenoid valve according to the invention.

State of the art

Solenoid valves are known from the prior art which have a solenoid coil and a liftable armature for actuating the valve. By energizing the magnetic coil, a magnetic field can be built up, the magnetic force of which acts on the armature in such a way that the armature moves towards or away from the magnetic coil - usually against the spring force of a spring pretensioning the armature. If the armature is coupled to a valve element or forms the valve element itself, the solenoid valve can be opened or closed in this way, depending on whether the solenoid valve is designed as a normally closed or normally open valve.

The stroke of the armature is usually limited by a stroke stop. For example, a yoke core, which is part of the magnetic circuit and lies opposite the armature at a working air gap, can be inserted into the magnetic coil. The working air gap thus defines the maximum stroke of the armature. When the attack on Stroke stop generates noises which, depending on the ambient conditions, can reach a disruptive or no longer acceptable level.

The present invention is therefore based on the object of specifying a solenoid valve of the type mentioned above which can be operated with particularly little noise.

To solve the problem, the solenoid valve with the features of claim 1 is proposed. Advantageous further developments of the invention can be found in the subclaims. Furthermore, a fluid delivery device with such a solenoid valve and a method for operating such a solenoid valve are specified.

Disclosure of the invention

The proposed solenoid valve comprises a liftable armature, a spring for preloading the armature and an annular magnetic coil for generating a magnetic force which counteracts the spring force of the spring. A yoke core is inserted into the ring-shaped magnet coil, which, together with the armature, delimits a working air gap. According to the invention, the armature and the yoke core have oppositely stepped contours which interlock when the armature is lifted and lead to the formation of at least one radial gap between the armature and the yoke core.

The armature and the yoke core accordingly each have a stepped contour, with contours of the same opposite being formed. This means that the contours essentially complement one another. A first contour creates a positive shape, for example, which essentially corresponds to a negative shape of the respective other contour. Thus, the contours can interlock when the armature approaches the yoke core.

The interlocking of the contours during a stroke of the armature has the result that at least one radial gap is formed between the armature and the yoke core. This forms a secondary air gap that is opposite the working air gap is significantly smaller and thus leads to a targeted loss of magnetic force in the working air gap. This means that the magnetic force causing the armature stroke does not increase as the armature approaches the stroke stop - as is usual - but decreases. At the same time, the spring force of the spring can be selected so that a force equilibrium is established between the magnetic force and the spring force in a certain position of the armature and the armature stops moving before it reaches the stroke stop. The movement of the armature thus ends completely silently. The balance of forces keeps the armature in a state of suspension as long as the magnet coil is energized.

Alternatively, the spring force of the spring can be selected so that there is no equilibrium of forces and the armature strikes the stroke stop, but at a significantly reduced speed or with a significantly reduced force. In this way, the movement of the armature does not end noiselessly, but at least it ends with significantly less noise.

A preferred area of application of the solenoid valve according to the invention is a fluid delivery device. In this application, the proposed solenoid valve can be used as an inlet and / or outlet valve.

According to a preferred embodiment of the invention, the contours of the armature and the yoke core, which are stepped in opposite directions, are stepped at least once. This means that at least one radial gap or secondary air gap is formed when the armature approaches the yoke core. In this way, the above-described effect can be further enhanced. Multiple grading, each comprising two or more stages, is also conceivable.

The oppositely stepped contours of the armature and the yoke core each lead to annular shoulders, which are preferably arranged concentrically to one another and coaxially with respect to a common longitudinal axis of the armature and the yoke core. The exact angular position of the armature with respect to the yoke core is therefore irrelevant. The armature preferably has a stepped contour which is formed on the outer circumference. In this case, the yoke core has a stepped contour which is formed on the inner circumference or extends inward. At When the magnet coil is energized, the armature dips into the yoke core. In principle, however, it can also be the other way round.

A residual air gap disk is advantageously arranged in the working air gap. The residual air gap disc is particularly advantageous when the armature does not remain in a floating state, but rather ends its stroke at a stop. The stop is then ended by the residual air gap disc. The residual air gap disc counteracts magnetic and / or hydraulic sticking of the armature to the stop. If a residual air gap disc is provided in the working air gap, this can be made of an elastomer material at least in some areas. Since this is flexible, a “soft” stop can be created with the help of the residual air gap disc, which also has a noise-reducing effect. As an alternative or in addition, the remaining air gap disc can be manufactured from a metal, at least in some areas.

It is also proposed that the armature have an end-face annular surface, which is delimited by the stepped contour, as a stop surface. The stop surface formed on the armature can replace a residual air gap disc.

If the energization of the solenoid is terminated, the spring force of the spring returns the armature to its starting position. This can be defined by a further stop or by a sealing seat with which the armature or a valve element coupled to the armature interacts. When the armature is reset, noises which are perceived as annoying can thus also arise.

In order to suppress these noises, it is proposed that the armature have a sealing element which interacts with a sealing seat and which is made of an elastomer material. Due to its material properties, the sealing element ensures that the anchor falls “softly” back into the sealing seat. The resulting noise is significantly lower compared to two metal bodies hitting one another.

As an alternative or in addition, it is proposed that the sealing seat be a sealing element made from an elastomer material. Through this measure, a "Soft" stop for the armature can be formed when it is returned to its original position.

In a further development of the invention, it is proposed that the armature be guided over a sleeve. The sleeve can be made from a magnetically conductive material or from a magnetically non-conductive material.

As an alternative or in addition, it is proposed that the armature be guided over a non-magnetic film which is arranged between it and a guide, for example the aforementioned sleeve. The non-magnetic film reduces the transverse forces acting on the armature and thus the friction in the area of the guide, so that this measure also has a noise-reducing effect. The non-magnetic film can be made of polytetrafluoroethylene, for example.

In addition, the radial play in the area of the guide of the armature can be minimized, so that hydraulic damping of the armature movement is achieved. Since the solenoid valve is preferably used in a fluid delivery device, the medium to be delivered can also be used to dampen the armature movement.

According to a further preferred embodiment of the invention, a flow channel is formed in the armature, which connects pressure spaces on both sides of the armature. The flow channel serves to equalize pressure when the armature moves. The flow channel preferably forms a throttle in at least one section. Hydraulic damping of the armature movement can also be achieved by this measure, so that it moves more slowly when opening and closing.

The fluid delivery device also proposed to achieve the object mentioned at the beginning has an inlet valve and an outlet valve, the inlet valve and / or the outlet valve being a solenoid valve according to the invention. In this way, a valve circuit can be generated which is favorable for the predominant conveying direction of the fluid conveying device, for example opens into the fluid conveying device on the inlet side and opens out of the fluid conveying device on the outlet side. In addition, a method for operating a solenoid valve according to the invention is proposed. In the method, a magnet coil is energized to act on a lifting armature which is pretensioned by means of the spring force of a spring, and an extinguishing voltage is not applied when the magnet coil is de-energized. By not applying an extinguishing voltage, the magnetic force is reduced less quickly, so that the speed of the armature when it is reset is lower. The reduced speed in turn reduces the noise generated when the armature strikes, so that the noise level is further reduced.

If the solenoid valve is used in a fluid delivery device, the method is particularly suitable at low speeds of the delivery device. Because in this case it is usually not a question of fast switching of the solenoid valve. At higher speeds, in turn, a quenching voltage can be applied to ensure rapid resetting of the armature. This is accompanied by loud switching noises, but since the ambient noise is usually also much louder at high speeds, the switching noises are drowned out.

Preferred embodiments of the invention are described in more detail below with reference to the drawings. These show:

1 shows a schematic longitudinal section through a first solenoid valve according to the invention,

FIG. 2 is a diagram showing the magnetic and spring characteristics of the solenoid valve of FIG. 1,

3 shows a schematic longitudinal section through a yoke core and an armature for a solenoid valve according to the invention, showing the air gaps,

FIG. 4 shows the diagram of FIG. 2 with explanations, 5 a) and b) each show a schematic longitudinal section through a second solenoid valve according to the invention in different switching positions,

6 a) and b) each show a schematic longitudinal section through a third solenoid valve according to the invention in different switching positions,

7 shows a schematic longitudinal section through a fourth solenoid valve according to the invention; FIG. 8 shows a schematic longitudinal section through a fifth according to the invention

Magnetic valve,

9 shows a schematic longitudinal section through a sixth solenoid valve according to the invention,

10 shows a schematic longitudinal section through a fluid delivery device according to the invention,

11 shows a schematic longitudinal section through a known solenoid valve and

FIG. 12 is a diagram showing the magnetic and spring characteristics of the magnetic valve of FIG. 11.

Detailed description of the drawings

1 shows a first solenoid valve 1 according to the invention for a fluid delivery device 2. The illustrated solenoid valve 1 comprises a liftable armature 3 and a yoke core 6, which lie opposite one another at a working air gap 7. The armature 3 and the yoke core 6 are surrounded by an annular magnetic coil 5. A spring 4 is arranged between the armature 3 and the yoke core 6. If the magnetic coil 5 is energized, a magnetic field builds up, the magnetic force of which moves the armature 3 against the spring force of the spring 4 in the direction of the yoke core 6. The armature 3 dips into the yoke core 6 in sections, since the armature 3 and the yoke core 6 have contours 8, 9 stepped in opposite directions to limit the working air gap 7.

As shown by way of example in FIG. 3, when the armature 3 and the yoke core 6 are immersed, at least one radial gap 10 is formed which is smaller than the working air gap 7 and thus leads to a reduction in the magnetic force in the working air gap 7. In FIG. 3, the contours 8, 9 are stepped twice, so that two radial gaps 10 are formed. In FIG. 1, the contours 8, 9 are even stepped three times, so that three radial gaps 10 are formed here when the armature 3 dips into the yoke core 6 (not shown).

The effect of the radial gaps 10 can be seen in FIG. 2, the characteristic M representing the magnetic characteristic and the characteristic F representing the spring characteristic. The spring force decreases continuously as the working air gap 7 increases, while the magnetic force also decreases at times and increases at times. This leads to a curve-shaped magnetic characteristic curve M, which intersects the spring characteristic.

In comparison, the magnetic characteristic M ‘and the spring characteristic F‘ of a conventional solenoid valve are shown in FIG. 12 (see FIG. 11). In the conventional solenoid valve, the armature 3 'and the yoke core 6' do not have contours that are stepped in opposite directions, so that a radial gap is not formed between the armature 3 'and the yoke core 6' when the armature 3 'is against the yoke core 6'. approaching. The magnetic force of the magnet coil 5 ‘accordingly increases and not decreases with a decreasing working air gap 7‘ (see characteristic line M ‘in FIG. 12).

As shown by way of example with reference to FIG. 4, which in turn shows the characteristic curve of a solenoid valve 1 according to the invention, the magnetic force and the spring force are in an equilibrium of forces when the magnetic characteristic M intersects the spring characteristic F. The result of the equilibrium of forces is that the armature 3 remains in its position after a stroke h and does not reach the stroke stop on the yoke core 6. This means that a residual air gap (ah) remains between the armature 3 and the yoke core 6, which corresponds to the original air gap a minus the stroke h. The armature 3 does not strike the yoke core 6, so that the armature 3 ends its working stroke completely silently. In order to reset the armature 3 to its starting position with as little noise as possible, a sealing element 14 (15) made of an elastomer material can be arranged in the area of a sealing seat 13, which allows a “soft” fall back into the sealing seat 13.

As shown by way of example in FIG. 5, the armature 3 can be connected to a valve element 25 or form a valve element 25 and have an annular sealing element 14 in a section of the valve element 25 that interacts with a sealing seat 13. Alternatively, the annular sealing element 15 (see reference symbols in brackets) can also form the sealing seat 13 when it is attached to the yoke core 6. In the present case, however, the sealing element 14 is attached to the valve element 25, so that it lifts off the sealing seat 13 when the armature 3 lifts. The stroke of the armature 3 is slowed down by the contours 8, 9 of the armature 3 and the yoke core 6, which are stepped in opposite directions, so that a residual air gap remains between the armature 3 and the yoke core 6 without the armature 3 reaching a stroke stop. Fig. 5a) shows the armature 3 in its starting position and Fig. 5b) shows the armature 3 in an open position.

6 shows an alternative embodiment with a sealing element 14 in the area of a sealing seat 13. The sealing element 14 is here attached directly to the armature 3 and lifts off the sealing seat 13 with the armature 3 when it is opened. Fig. 6a) shows the armature 3 in its starting position. Fig. 6b) shows the armature 3 when opening.

Another preferred embodiment of a solenoid valve 1 according to the invention is shown in FIG. The armature 3 is guided here by a sleeve 16 which surrounds the armature 3. The sleeve 16 is preferably made of a magnetically conductive material, but can also consist of a magnetically non-conductive material.

8 shows a further preferred embodiment of a solenoid valve 1 according to the invention. Here, the armature 3 is guided by a film 17 which surrounds the armature 3. The film 17 is made of a material which reduces the friction between the guide and the armature 3, for example polytetrafluoroethylene. The reduced friction caused by the film 17 leads to a reduction in the noise based on friction.

In the embodiment of FIG. 8, a residual air gap disk 11 is also arranged in the working air gap 7, which is made of a material, for example an elastomer material, that is intended to prevent the armature 3 from hitting the yoke core 6 hard. Furthermore, the radial play in the area of the guide 18 is designed so tight that a type of throttle 22 is formed, which effects hydraulic damping of the movement of the armature 3 so that it moves more slowly and strikes the remaining air gap disc 11 at a reduced speed. A further throttle 12 is formed in the present case in the area of a flow channel 19 which connects an upper pressure chamber 20 with a lower pressure chamber 21. The flow channel 19 thus enables pressure equalization when the armature moves up or down. Hydraulic damping of the armature movement can also be achieved via the throttle 22 formed in the flow channel 19.

In FIG. 9, a modification of the embodiment of FIG. 8 is shown. Instead of the residual air gap disk 11, the armature 3 has an annular surface 12, which is significantly reduced compared to the diameter of the armature 3, as a stop surface.

10 shows a fluid delivery device 2 according to the invention with two magnetic valves 1 according to the invention, which are constructed differently and form an inlet valve 23 and an outlet valve 24. The inlet valve 23 is used to fill a compression chamber 28 with a fluid which is compressed with the aid of a membrane 27 delimiting the compression chamber 28 and, after compression, is discharged from the compression chamber 28 via the outlet valve 24.

The inlet valve 23 is designed analogously to the solenoid valve 1 in FIG. 7 and also has a sealing element 14 according to FIG. 5. Reference is therefore made to the description of FIGS. 5 and 7 in order to avoid repetitions. The outlet valve 24 is designed analogously to the solenoid valve 1 of FIG. 1 and additionally has a sealing element 14 according to FIG. 6, so that reference is made to the description of FIGS. 1 and 6. The measures for noise reduction and / or avoidance described above in connection with the individual figures can each be implemented or implemented individually or in different combinations. The invention is therefore not limited to the exemplary embodiments shown in the figures. Other embodiments are possible.

Claims

Expectations

1. Solenoid valve (1) for a fluid delivery device (2), comprising a lifting armature (3), a spring (4) for preloading the armature (3) and an annular magnetic coil (5) for generating a magnetic force that corresponds to the spring force of the spring (4) counteracts, with a yoke core (6) being inserted into the ring-shaped magnet coil (5) which, together with the armature (3), delimits a working air gap (7), characterized in that the armature (3) and the yoke core (6 ) have contours (8, 9) which are stepped in opposite directions and which interlock when the armature (3) is lifted and lead to the formation of at least one radial gap (10) between the armature (3) and the yoke core (6).

2. Solenoid valve (1) according to claim 1, characterized in that the contours (8, 9) stepped in opposite directions are stepped at least once.

3. Solenoid valve (1) according to claim 1 or 2, characterized in that a residual air gap disc (11) is arranged in the working air gap (7), preferably the residual air gap disc (11) is made at least in some areas from an elastomer material and / or from a metal.

4. Solenoid valve (1) according to one of the preceding claims, characterized in that the armature (3) has an end-face annular surface (12) delimited by the stepped contour (8) as a stop surface.

5. Solenoid valve (1) according to one of the preceding claims, characterized in that the armature (3) has a sealing element (14) which interacts with a sealing seat (13) and is made of an elastomer material, and / or the sealing seat (13) is a sealing element (15) made of an elastomer material.

6. Solenoid valve (1) according to one of the preceding claims, characterized in that the armature (3) is guided via a sleeve (16).

7. Solenoid valve (1) according to one of the preceding claims, characterized in that the armature (3) is guided over a non-magnetic film (17) which is between it and a guide (18), for example the sleeve (16), is arranged.

8. Solenoid valve (1) according to one of the preceding claims, characterized in that a flow channel (19) is formed in the armature (3) which connects pressure spaces (20, 21) lying on both sides of the armature (3), wherein preferably the flow channel ( 19) forms a throttle (22) in at least one section.

9. Fluid delivery device (2) with an inlet valve (23) and an outlet valve (24), wherein the inlet valve (23) and / or the outlet valve (24) is a solenoid valve (1) according to one of the preceding claims.

10. The method for operating a solenoid valve (1) according to any one of claims 1 to 8, in which a solenoid (5) is energized to act on a lifting armature (3) which is biased by means of the spring force of a spring (4) and when the magnet coil (5) is de-energized, an erasing voltage is applied or an erasing voltage is not applied.