WO2015052280A1

WO2015052280A1 - Blow-out unit for a vacuum pump

Info

Publication number: WO2015052280A1
Application number: PCT/EP2014/071637
Authority: WO
Inventors: Stefan Imhof
Original assignee: Continental Teves Ag & Co. Ohg
Priority date: 2013-10-11
Filing date: 2014-10-09
Publication date: 2015-04-16
Also published as: DE102013220594A1

Abstract

Disclosed is a blow-out unit (76) for a vacuum pump (28) for generating negative pressure in a negative pressure chamber (40), more particularly in a brake booster (24), by extracting air (30) from the negative pressure chamber (40), comprising a housing (88) with an air inlet (96) for introducing the extracted air (30) and an air outlet (94) for expelling the air (30) introduced into the housing (88), and, disposed in the housing (30) between the air inlet (96) and the air outlet (94), a filter element (84) through which the air (30) is guided, the filter element (84) containing a porous chain polymer material.

Description

Blow-out unit for a vacuum pump

The invention relates to a blow-out unit for a vacuum pump, the vacuum pump and a brake booster with the vacuum pump.

From DE 10 2009 054 499 AI a vacuum pump for a brake booster is known. The vacuum pump has an air intake area, by means of which air is sucked out of a vacuum chamber. The aspirated air is thereby ejected for sound attenuation and to prevent water intrusion into the interior of the vacuum pump through a blow-out unit to the environment. This blow-out unit comprises two filter elements separated by a partition, through which the air to be ejected is directed in a labyrinth-like manner. The complex structure and installation costs and space requirements are considered to be in need of improvement.

It is an object of the invention to improve the known Ausblaseinheit for the vacuum pump.

The object is solved by the features of the independent claims. Preferred further developments are subject of the dependent claims from ^¬.

According to one aspect of the invention, a blow-out unit for a vacuum pump for generating a negative pressure in a vacuum chamber, in particular a brake booster by sucking air from the vacuum chamber comprises a housing having an air inlet opening for introducing the sucked air and an air outlet opening for discharging the air introduced into the housing a filter element disposed in the housing between the air inlet opening and the air outlet opening, through which the air is guided, wherein the filter element contains a porous chain polymer material.

The specified blow-out unit is based on the consideration that the vacuum pump has a high operating noise level, which is caused by the suction and the ejection of the sucked air. The exhaust unit therefore comprises Fil ^¬ terelement through which the sucked air is passed during blowing, which should lead to a significant attenuation of the high Betriebsge- räuschpegels.

To ensure this significant attenuation of the operating noise level, the filter element could be made of a foamed polyurethane material, since such a material is inexpensive to manufacture and temperature resistant. However, the attached ^¬ passed exhaust unit is based on the insight that ejected, blown out air must be passed through a very thick Po ^¬ lyurethan filter layer for a sufficient attenuation of the operating noise level, resulting in a significant increase of necessary space for the exhaust unit and the associated Vacuum pump leads.

Although the installation space could be reduced when using polyurethane as a filter material, if the air is filtered like a labyrinth in the exhaust unit, the basic problem of high space requirements can not be counteracted by the labyrinth shape in the filtering in the blow-out of the above-mentioned vacuum pump at least two filter elements are necessary, which are separated by the partition of ^¬ each other.

Here, the specified blow-out attacks, in the context of which a porous chain polymer material is used as the filter material instead of the relatively inexpensive polyurethane. Under a chain polymer material is intended to a

Polymer material to be understood, which is produced by chemical Re ^¬ actions, in which like or schiedliche under ^¬ monomers via a chain growth to the

React polymer material. The polymer material may contain linear chain molecules and / or crosslinked chain molecules as a chain polymer material. Opposite the polyurethane is a porous one

Kettenpolymerwerkstoffes initially cost-intensive. However, the porous chain polymer material makes it possible to suppress the above-mentioned operating noise level of the vacuum pump against the polyurethane by using a smaller amount of material with the same effect. In particular, it is no longer necessary to guide the ejected air to be exhausted in a labyrinth-like manner through the blow-out unit. Rather, the air can pass through a comparatively thin layer of the porous

Chain polymer material can be performed, wherein the same operating noise level-reducing effect is achieved, as in the use of a blow-out unit with polyurethane as a filter material in the vacuum pump mentioned above. Consequently, the specified exhaust unit can be built to save space. Surprisingly, it is even possible to save costs with the specified blow-out unit, since one of the two filter elements and the dividing wall in the blow-off unit mentioned at the beginning can be dispensed with, which compensates for the increased cost of use for the porous chain polymer material and moreover reduces the production costs leads .

The filter element could be next to the porous one

Chain polymer material also contain other materials, more preferably, however, the filter element consists entirely of the porous chain polymer material, so that an efficient filtering effect is given. In a further development of the specified blow-out unit, the porous chain polymer material is a thermoplastic, preferably a polyolefin, and particularly preferably a polyethylene, where as polyethylene, for example, an "ultra high molecular

i ^ eight "polyethylene, PE-UHMW, which can most effectively achieve the aforementioned noise reduction effect in a reasonable cost range. In another development of the specified blow-out unit, the porous chain polymer material has a porosity between 35% and 55%, preferably between 37% and 42% and particularly preferably between 40% and 44%. The porosity of a

Material is known to be a dimensionless measurand and represents the ratio of void volume to total volume of the material. It may be defined, for example, as a percentage size, which is calculated based on one minus quotient of gross density of the material and true density of the material. Within these specified ranges for the

Porosity of the porous chain polymer material, the porous chain polymer material is optimally permeable to air, wherein

at the same time penetration of spray water from the outside into the interior of the blow-out and thus the vacuum pump can be largely avoided.

The penetration of spray water could be prevented in an additional development of the specified blow-out by a seal and / or a coating on the porous chain polymer material. The seal and / or the coating to particularly useful ^¬ advantageously comprises a water repellent material.

In an alternative development of the specified blow-out unit, the filter element is designed as a lid closing the outlet opening. In this way, the filter element serves at the same time as part of the specified ^¬ blow unit delimiting housing, which leads to a further saving of space with the specified blow-out. In this case, the part of the housing could be formed without the filter element as a filter holder, wherein the filter element, which could be formed for example in the form of a filter plate, may be inserted into this filter holder. The filter holder could be formed with or without Schmutzabweiser as additional protection of the filter element.

According to a further aspect of the invention comprises a Vaku ^¬ cuum a working chamber having a suction port for sucking air from the vacuum chamber and an outlet port for discharging the sucked air and one of the indicated Ausblaseinheiten, wherein the outlet opening of the working chamber as seen in the flow direction of the air is arranged in series in front of the air inlet opening of the blow-out.

In a development of the specified vacuum pump, the outlet opening of the working chamber and the air inlet opening of the blow-out unit are connected directly to one another. This development is based on the consideration that the sucked from the Un ^¬ terdruckkammer air will not be passed directly from the working ^¬ chamber into the exhaust unit but via a gap in the exhaust unit, in the example, a motor and / or a gear for driving the vacuum pump is ordered to ^¬ . However, direct introduction of the air sucked from the vacuum chamber into the blow-out unit would prevent accumulation of heat accumulating in this intermediate space, which would stress the engine and / or the transmission, so that the engine and / or the transmission could be designed more favorably in this respect.

Particularly preferably, the housing Ausblaseinheit could also be integrally formed on the outside of a housing of the vacuum pump, wherein the outlet opening of the working chamber leads directly into the air inlet opening of the blow-out. In this way, a separate blow-out completely eliminated, whereby the space of the specified vacuum pump can be further reduced.

According to a further aspect of the invention, a brake booster comprises a container, a movable wall separating the container into a first working space and a second working space, which is connectable to a brake pedal controlling an air pressure in the first working space, and one of the indicated vacuum pumps for generating a negative pressure in the second workspace.

The features, features and benefits described above This invention, as well as the manner in which these are attained, will become clearer and more clearly understood in connection with the following description of the embodiments which will be described in connection with the drawings, in which:

1 is a schematic view of a vehicle with a device for controlling a service brake,

2 shows a schematic view of the device for actuating the service brake in the vehicle of FIG. 1 with a vacuum pump, FIG.

3 is a schematic sectional view of the vacuum pump of FIG. 2,

Fig. 4 is a schematic view of an alternative From ^¬ blowing unit for the vacuum pump of Fig. 3,

Fig. 5 is a schematic view of another alternative Ausblaseinheit for the vacuum pump of Fig. 3, and

FIGS. 6 is a schematic view of yet another al ^¬ ternatives exhaust unit for the vacuum pump of FIG. 3.

In the figures, the same technical elements are provided with the same reference numerals and described only once.

Reference is made to FIG. 1, which shows a schematic view of a vehicle 2 with a device 4 for activating a service brake of the vehicle 2 which is not further referenced.

The vehicle 2 has a chassis 8 which can be driven on a road, not shown, on four wheels 10 via a vehicle engine (not shown). At the individual wheels 10 brake discs 12 are rotatably mounted in the present embodiment, in which rotatably to Chassis 8 fixed brake effectors 14 can attack to block the wheels 10 in a conventional manner and decelerate the vehicle 2 out of the drive. This Bremsef ^¬ fektoren 14 are of a tandem master cylinder 16 via hydraulic lines 18 based on one with a

Brake pedal 20 predetermined braking request 22 driven.

In this case, the device 4 for controlling the service brake on a brake booster 24 which amplifies the braking request 22 of the brake pedal 20, so that on the Tandemhauptzy ^¬ linder 16 an increased brake request 26 is applied. In this case, 28 air is sucked out of the brake booster 24 via a vacuum pump 28, so that in the brake booster 24, a vacuum is built up.

Reference is made to Fig. 2, which is a schematic view of the device 4 for actuating the service brake in the vehicle 2 of FIG. 1 with the vacuum pump 28 in a first state a), in which the brake pedal 20 is unconfirmed, and a second state b), in the context of which the brake pedal 20 is operated for example by a driver of the vehicle 2, shows.

In the device 4 shown in FIG. 2, the brake request 22 and the amplified brake request 26 are transmitted by means of a piston rod 32. In this case, the piston rod 32 is guided by the brake booster 24.

The brake booster 24 has a container 34 which is fixed by means of a fixed to the piston rod 32

Partition 36 is divided into a first working space 38 and a second working space 40. In the first working space 38, the brake booster 24 has an air inlet opening 42, which can be closed by a closure 44 fastened fixedly to the piston rod 32. In the partition wall itself, a passage opening 46 is formed through which air from between the working chambers 38, 40 can flow. Further, the partition wall 36 via a return element 48, such as a spring in Container 34 supported.

In the unactuated state a) of the brake pedal 20, also called the rest position of the brake pedal 20 closes the closure 44, the air inlet opening 42, wherein the passage opening 46 between the two working chambers 38, 40 is opened and between the two working chambers 38, 40 takes place a pressure equalization. This pressure compensation is influenced by the vacuum pump 28, which sucks the air 30 from the second working space 40.

If the brake pedal 20 is actuated in the context of the state b), the air inlet opening 42 is opened, so that air can flow from the outside into the first working chamber 38. At the same time, the passage opening 46 is closed by the closure 44, whereby no further pressure equalization between the two working spaces 38, 40 is possible. In this way, a pressure difference arises between the two working chambers 38, 40, as a result of which the dividing wall 36 and thus the piston rod 32 fixedly attached thereto are pulled in the direction of the second working chamber 40. In this way, the Bremsanfor ^¬ tion 22 is amplified and applied to the tandem master cylinder 16, the increased braking request 26.

In Fig. 3 is a schematic sectional view of the vacuum pump 28 of FIG. 2 is shown.

The vacuum pump 28 has a first working chamber 50 and a second working chamber 52, which are correspondingly compressible via a first diaphragm 54 and a second diaphragm 56. In this case 60 from ^¬ the two working chambers 50, 52 respectively from the two diaphragms 54, 56 and a respective lower cover 58, bordered. The two membranes 54, 56 are elastic, designed preferably formed of an elastomer material. On the lower covers 58, 60 are each an upper cover 62, 64 are arranged, wherein between the lower covers 58, 60 and the upper covers 62, 64 each have an inlet channel 66 and an outlet channel ^¬ 68 is formed. 3, on the upper cover 62 on the upper side of the vacuum pump 28, the inlet Lasskanal 66 and on the upper cover 64 of the underside of the vacuum pump 28 of the outlet channel 68 watch. The inlet channel 66 and the outlet channel 68 are respectively connected to the corresponding working chambers 50, 52 via openings, not shown further, in the lower lids 62, 64, or opened into them. The inlet channels are also 66 connected to the second Ar ^¬ beitsraum 40 of the brake booster 24th The outlet channels 68 lead in a manner not shown in a gap 70 of the vacuum pump 28, in which a additionally driven by a motor 72 gear 74 is arranged, by means of which the membranes 54, 56 can be moved in a manner to be described. Since it comes to understanding ahead ^¬ invention, neither the motor 72 still on the gear 74, is not to be discussed further on these two items for brevity.

At this intermediate space 70 is a blowoff unit 76 is connected via at least one not shown further in Fig. 3 ^¬ air inlet passage opening at the exhaust unit 76, which is hereinafter simply called inlet opening.

During operation of the vacuum pump 28, the engine 72 compresses and expands the working chambers 50, 52 periodically. With each expansion of the working chambers 50, 52, the air 30 is discharged from the second working chamber 40 via the inlet channels 66

Brake booster 24 sucked. In each compression of the working chambers 50, 52 from the second working chamber 40 of the brake booster 24 is ^¬ sucked air is discharged into the intermediate chamber 30 through the outlet channels 70 68th This ejected air 30 then passes through the aforementioned A ^¬ outlet opening into the exhaust unit 76, passes this and exits via at least one non-illustrated air outlet port ^¬ outwards from which is hereinafter simply called the outlet opening.

In the present embodiment, the blowout unit 76 is secured to a wall 82 surrounding the gap 74 via bolts 80 passing through mounting holes 78. AI ternatively could be the exhaust unit 76 but also by hot gas ^¬ rivets be fixed by Baj onettverschluss, by gluing or by clipping by means of pins to the wall 82 of the vacuum pump 28th

In FIG. 3, the blow-out unit 76 has a filter element in the form of a filter plate 84. This filter plate 84 is received in the present embodiment in a housing of a substructure 88 and a superstructure 90, wherein the Filterplat- te 84 is clamped between the base 88 and the superstructure 90. The air 30 expelled from the working chambers 50, 52, entering the blow-out unit 76 from the gap 74, passes through the filter plate 84. Operating noise from the vacuum pump 28 is filtered, i. steamed, the u.a. when compressing and expanding the working chambers 50, 52 arise.

For a particularly good sound-absorbing effect, the filter plate 84 could be made of porous polyethylene with a porosity of 40%. In this way, the filter plate 84 on the one hand form a particularly thin with a sufficiently high permeability to the air 30, but still achieve a high noise-canceling effect. The superstructure 90 serves primarily as a dirt deflector and could, as shown in the perspective view of Fig. 4, also be omitted in order to save further space. In this case, the filter plate 84 closes the blowout ^¬ unit 76, wherein one side of the filter plate 84 is directed to the above-mentioned outlet opening, which is provided in FIG. 4 by the reference numeral 94.

In order to protect the filter plate 84 in front of the outlet opening 94 penetrating moisture, it may be coated with a water-repellent coating 92. These

Coating 92 is of course applied within the pores of the porous filter plate 84 to ensure air permeability to the air 30. Such a coating could be realized for example by nano-layers. The protection against penetrating moisture is supported by the choice of the above-mentioned porosity, in which the Fil ^¬ terplatte 84 offers a high resistance to flow of moisture.

Also, as shown in FIG. 3, the coating 92 may be installed together with the superstructure 90 as needed. Further, as shown in FIG. 5, are covered with a valve plate 98, the above-mentioned A ^¬ outlet opening which is provided in Fig. 5 by the numeral 96, that as

Check valve acts and the air 30 can only enter from the intermediate ^¬ space 70 in the blow-out unit 76 but not vice versa. In this way, it can be avoided that any moisture entering via the outlet opening 94 passes into the intermediate space 70 and damages the gear 72 there, for example due to corrosion. In order to further improve the protection against the ingress of moisture, the valve plate 98 can also be covered with a cover 102 via a holding rivet 100. Alternatively or in addition to this valve plate 98, the filter plate 84 may be coated again with the coating 92.

Alternatively, however, the blower unit 76 described above may also be formed on the upper cover 62 and / or on the lower cover 64, as shown in FIG. 5. For this purpose, the above-mentioned outlet channel 68 via holes which simultaneously form the above-mentioned inlet openings 96 open to the outside. Around these inlet openings 96, a wall is formed around which forms the above-mentioned substructure 88. In this substructure 88, the filter plate 84 is held. To protect against the ingress of moisture, valve plates 98 can again be arranged as check valves in the outlet channel 68. Alternatively or additionally, the filter plate may also be coated with the coating 92.

Claims

1. blow unit (76) for a vacuum pump (28) for generating a negative pressure in a vacuum chamber (40), in particular a brake booster (24) by sucking air (30) from the vacuum chamber (40) comprising

a housing (88) having an air inlet opening (96) for introducing the sucked air (30) and an air outlet opening (94) for discharging the air (30) introduced into the housing (88) and

a filter element (84) arranged in the housing (30) between the air inlet ^opening (96) and the air outlet opening (94), through which the air (30) is guided,

wherein the filter element (84) is porous

Contains chain polymer material.

2. blowout unit (76) according to claim 1, wherein the filter element (84) consists of the porous chain polymer material.

3. blowout unit (76) according to claim 1 or 2, wherein the porous chain polymer material is a thermoplastic, preferably a

Polyolefin, and particularly preferably is a polyethylene.

4. blow out unit (76) according to any one of the preceding claims, wherein the porous chain polymer material has a porosity between 35% and 55%, preferably between 37% and 42% and particularly preferably between 40% and 44%.

A blower unit (76) according to any one of the preceding claims comprising a seal and / or a coating (92) on the porous chain polymeric material.

The blower unit (76) of claim 5, wherein the seal and / or coating (92) comprises a water repellent material.

7. blow-out unit (76) according to any one of the preceding claims, wherein the filter element (84) as a the outlet opening (94) occlusive cover is formed.

8. Vacuum pump (28) comprising at least one Arbeitskam ^¬ mer (50) with at least one suction port (66) for sucking air (30) from the vacuum chamber (40) and at least one outlet opening (68) for ejecting the sucked air (30). and an exhaust unit according to one of the preceding claims, wherein the outlet opening (68) of the working chamber is arranged in series in the flow direction of the air (30) in front of the air inlet opening (96) of the blow-out unit (76).

A vacuum pump according to claim 8, wherein the discharge port (68) of the working chamber (50) and the air inlet port (96) of the blow-out unit (76) are directly connected to each other.

10. Vacuum pump according to claim 8, wherein the working chamber (50) by an elastic membrane (54) is limited.

11. Brake booster (24) comprising a container (34), at least one container (34) in a first working space (38) and a second working space (40) separating, movable wall (36) controlled by a brake pedal (20) is and a vacuum pump (28) according to any one of the preceding claims for generating a negative pressure in the second working space (40).