DE8801464U1 - Pneumatic power amplifier in tandem design, especially for hydraulic vehicle braking systems - Google Patents

Description

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PIPI.-ING. GEXHARP FULS (l9JI'IJ70 EUROPEAN PATENT ATTORNEYS pipu-cbe*. &rgr;&kgr;. &bgr;. fxeiherr von «c h mann PlU-ING. PIETEX SEHKENS DIPU-INC. DIPL.-WIRTSCH.-ING. KUPEKT COETZ DIPl.-PHTS. PX. AXEL VON NELLFELP Lucas Industries D-8000 MUNICH 90 SCHWEIGERSTRASSE 2

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telephone: (0S9) 6£ 20 51

05 . 02 · 1988 TELEGRAM: PKOTECTPATENT

TELEX: { X4O7O

fax: (089)6639 36 (UT)

Pneumatic power amplifier in tandem installation, especially for hydraulic vehicle braking systems

The invention relates to a pneumatic power amplifier in tandem design, in particular for hydraulic vehicle braking systems , with

- an amplifier housing with two end walls and a fixed partition wall,

- two movable inner walls that divide the interior of the amplifier housing into two chambers on either side of the fixed partition wall, which can be connected to sources of different pressure,

- Flow connections between two chambers, which are separated from each other by another chamber,

- connecting rods extending from one end wall through the intermediate wall and the two inner walls to the other end wall, and

- tubular bellows arranged around the connecting rods and forming part of at least one of the flow connections.

In a known power amplifier of this type (GB 2070173 B), the front inner wall, relative to the direction of travel of the associated vehicle, is connected to the front bulkhead by two bellows, through which a connecting line extends.

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The bellows only have the task of maintaining the separation required during operation between the chambers arranged on either side of the front partition wall. In a corresponding way, the rear inner wall is connected to the partition wall by a pair of bellows, through which one of the connecting rods also extends. In addition to the task of separating the chambers on either side of the rear inner wall from one another, these rear bellows have the further task of establishing a permanent flow connection between the chamber arranged behind the rear inner wall and the chamber arranged behind the front inner wall, but in front of the stationary partition wall. A further flow connection exists between the two chambers, which are arranged immediately in front of each of the two movable inner walls; this further flow connection is established by a central pipe which is axially movable together with the two inner walls and is sealed against the stationary partition wall by a mechanical seal.

In this known brake booster, the axial distance of the rear inner wall from the stationary intermediate wall, as well as the axial distance of the front inner wall from the front bulkhead, must be considerably greater than the greatest required path of the inner walls, since the bellows in the front end division of the inner walls form bellows packages that still require considerable space in the axial direction and must not be compressed too much in order to avoid being damaged.

In another known power amplifier in tandem construction (GB 2034429 A), connecting pipes are arranged between the two end walls instead of continuous connecting rods, at the ends of which there are "in through di"

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These connecting pipes are provided with cross holes within the two chambers _, which are located directly in front of each of the two intermediate walls, so that the pipe forms a permanent flow connection between these two chambers. In a corresponding manner, a further connecting pipe is provided with cross holes within the two chambers, which are located directly behind each of the two inner walls, so that there is also a permanent flow connection between these two chambers. A rolling bellows extends from the front inner wall around each of the connecting pipes, which ends approximately halfway to the front end wall and is there fastened to the associated connecting pipe. In a corresponding manner, a rolling bellows extends from the rear inner wall around each connecting pipe, which ends approximately halfway to the stationary intermediate wall and is there fastened so that it cannot move to the associated connecting pipe.

The forward movements of the two inner walls that occur when this known brake booster is activated mean that the rolling bellows are turned over more or less and therefore do not form a fold package, which would require space. This brake booster can therefore be built shorter than the known brake booster described above. The two assemblies, each consisting of a connecting pipe and two threaded bolts, which connect the two end walls to the brake at a certain distance, are, however, much more complex than the simple connecting rods in the first described booster. On the one hand, the separate production and subsequent fastening of the two threaded bolts on the connecting pipe and

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Others include the production of cross holes, the edges of which must be rounded very carefully so that they cannot damage the rolling bellows.

The invention is therefore based on the object of designing a pneumatic power amplifier in tandem construction in such a way that the required flow connections between associated chambers require little construction effort and little space in the axial direction.

The object is achieved according to the invention with a power amplifier of the type described at the outset, in which at least one of the connecting rods extends through a piece of pipe which is tightly connected to the intermediate wall, projects from there in the direction of one of the end walls, ends in front of this and is sealingly connected to the inner wall which is adjacent to this end wall by a hose-like bellows, together with which the piece of pipe forms one of the flow connections.

The space between two walls that are movable relative to one another and that serves as a flow connection and surrounds a connecting rod in a ring shape is thus formed according to the invention by the juxtaposition of a bellows and a piece of pipe. This means that the hose-like bellows can be correspondingly shorter and can be turned inside out during operation in the event of larger movements of the movable wall associated with it. The arrangement according to the invention of a reference element and a connecting rod extending through it is considerably easier to manufacture than the known arrangement with a bellow that extends from one end wall to the other, has a threaded bolt at each of its ends and is provided with cross holes in between.

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The pipe section according to the invention can be completely smooth, so that 96 cannot damage the associated bellows"

In a preferred embodiment of the invention, the pipe section is formed as one piece with the stationary partition wall. If the partition wall is made of sheet metal, for example, the or each pipe section formed on it can be produced by deep drawing. However, the pipe section and partition wall can also be a one-piece injection-molded part made of plastic.

In an expedient embodiment of the invention, the pipe section ends on the way to the associated inner wall, relative to its rest position, which is the position of the respective inner wall furthest away from the intermediate wall.

line alternative to this is that the pipe section extends through the corresponding inner wall and, relative to its rest position, ends at least approximately halfway to the adjacent end wall"

An embodiment of the invention is described below

explained in further detail using chemical drawings. It shows:

Fig. 1 is an axial section through an actuating device of a vehicle braking system and

Fig. 2 is a detail also drawn in axial section as a variant or addition to the features shown in Fig. 1.

The actuating device shown is intended for a hydraulic dual-circuit braking system and consists essentially of a pneumatic power amplifier

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12, into . **ttttr*«ntil 14 for diets, eleventh hydraulic master brake cylinder 16 and a reservoir 18 for brake fluid attached to it.

The power amplifier 12 has an amplifier housing 20, which is composed of a front end wall 22, a rear end wall 24, a casing 26 and an intermediate wall 28.

&PSgr; In the example shown, all of the above

&zgr; Examples of sheet metal parts. The amplifier housing can

J ₁ also made of corresponding plastic injection-molded parts I; in this case the partition wall 28

'< Bpractically manufactured in one piece with the jacket 26

presents.

I The interior spaces between the front bulkhead 22 and the

■s Partition wall 28 on the one hand and between this and the

I^ rear bulkhead 24 on the other hand are each connected by a I inner wall 30 or 32 into a front vacuum chamber 34 and I a front air chamber 36 or a rear vacuum chamber

?: chamber 38 and a rear air chamber 40.

The terms "front" and "back" used here

, correspond to the usual arrangement of the force tamper&bgr;

'; in the engine compartment of a motor vehicle; this arrangement is

i but not necessarily. Especially if the power amplifier

I 12 with the control valve 14 and the master brake cylinder 16

I not combined into one assembly, but installed separately. I, the power amplifier 12 can have any J ₂ Place the associated vehicle ingesta. Ice such

The separate arrangement is the subject of the German utility model application G 8801182.8 of the same applicant.

¹ The two end walls 22 and 24 are connected to each other by a

Pair of connecting rods 42, which are parallel

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to the axis A of the power amplifier 12 through the front inner wall 30, the intermediate wall 28 and the rear inner wall 32. The two connecting rods 42 lie in a common plane containing the axis A; for the sake of clarity of the illustration, only one connecting rod 42 is shown in Fig. 1, which will be discussed in more detail below.

The connecting rod 42 has a front end piece 44 which is tightly secured to the front bulkhead 22, protrudes forwards therefrom and serves to secure the master brake cylinder 16, and a rear end piece 46 which is secured to the rear bulkhead 24, protrudes rearwards therefrom and serves to secure the entire assembly consisting of the power booster 12, control valve 14, master brake cylinder and reservoir 18 to a body part, for example a bulkhead, of a motor vehicle.

According to Fig. 1, a pipe section 48 extends rearward from the intermediate wall 28, which encloses a section of the connecting rod 42 shown with a radial gap and ends at least halfway between the intermediate wall 28 and the rear inner wall 32, which is in its rest position in the drawing. In the example shown, the pipe section 48 is deep-drawn from sheet metal in one piece with the intermediate wall 28.

The connecting rod 42 is enclosed by a front bellows 50 and a rear bellows 52. The front bellows 50 is fastened with its rear end to the front inner wall 30. In a corresponding manner, the rear bellows 52 is tightly fastened with its rear end to the rear inner wall 32. The front

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Bellows 50 is guided with its front end directly on the connecting rod 42 in a sealing manner but still slidably. As a result, together with the front inner wall 30, it separates the front vacuum chamber 34 from the front air chamber 36. The rear bellows 52 is guided with its front end on the pipe section 48 in a sealing manner but still slidably and thus serves to separate the rear vacuum chamber 38 from the rear air chamber 40.

The control valve 14 is of conventional design and in the example shown has a valve housing 54 which is arranged coaxially with the power booster 12 and partially within the booster housing 20. The rear part of the valve housing S1 protrudes rearwards from the booster housing 20. In a corresponding manner, the master brake cylinder 16 has a cylinder housing 56 which is arranged coaxially with the power booster 12 and partially within the booster housing 20 and protrudes forwards from it. The valve housing 54 is axially displaceable, while the cylinder housing 56 is firmly screwed to the booster housing 20.

Between the valve housing 54 and the cylinder housing 56, completely inside the amplifier housing 20, a tubular intermediate piece 58 is arranged, which can be moved in the axial direction with a small axial play relative to the valve housing 54 together with the latter. The stationary intermediate wall 28 is sealed against the intermediate piece 58 by a mechanical seal 60. The front inner wall 30 is tightly attached to the front end of the intermediate piece 58, while the rear inner wall 32 is tightly attached to the valve housing 54.

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The described arrangement and sealing of the individual walls means that a flow connection between the rear vacuum chamber 38 and the rear air chamber 40 can only be established via the control valve 14. The front vacuum chamber 34 is constantly connected to the rear vacuum chamber 38 - and only to this - through the tubular intermediate stack 58. The front air chamber 36 is constantly connected to the rear air chamber 40 - and only to this - through the pipe section 48 and the bellows 52 attached to it.

One of the two vacuum chambers 34 and 38 is permanently connected to a vacuum source, for example to the intake line of an internal combustion engine. The rear air chamber 40 can be connected to the outside environment via a filter 62 by operating the control valve 14. In its rest position, the control valve 14 blocks this connection, but connects the rear air chamber 40 to the rear vacuum chamber 38. As a result, the vacuum is effective in all chambers 34, 36, 38 and 40 as long as the control valve 14 is not operated. When the control valve 14 is operated, ambient air enters the rear air chamber 40 and from there also into the front air chamber 36; the connection between the rear air chamber 40 and the rear vacuum chamber 38 is interrupted, so that ambient air cannot flow into any of the vacuum chambers 34 and 38.

A more detailed description of the control valve 14, the master brake cylinder 16 and the reservoir 18 can be omitted, since they are all of known design.

With the flow connection shown in Fig. 2, the central connection shown in Fig. 1 between

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see the two vacuum chambers 34 and 38 if additional space is to be gained in the central area of the power booster 12, for example in order to assemble the control valve 14 and the master brake cylinder 16 even closer together and thus save on the overall axial length of the assembly.

Claims (6)

&bull;I ti H ·· '! ! .*'**"·*"* &bgr;».·&Iacgr;&Ngr;&Ogr;. «ANt «UMf MO»» WüESTHOFP.v.PECHMAliiN.feEHtöWi'-OdfeTt' "."""UMWiWmWdWiMfl 0&Igr;&EEgr;.&Iacgr;&Ngr;&Ogr;. OlftHAftO »ULI (if fl'ltfl) BUROPBAN PATiNT ATTORNEYS BiH ₁ -CHiM. &ogr;«, &igr;. »aiiHik« by mo &eegr; man n DI.MNO.0llfI« MHIIINI BI»L.*INO. Dt»L.'«IATIOH,MNO, *&ugr;&Mgr;&lgr;&Tgr; OOItl OtH.'tHii. Dft. AXIl VON HILLMLD Luoas Industries D-8000 MUNICH 90 10-62 327 iCMWBlOBRiTRASSfil fILIfONi (t$f)Un $t OS «02 « 1988 TIUÖftAMMt »»OtlOtiAtlNT TItIIl mW ttutA%\(0*9) Protection claims 1. Pneumatic power amplifier in tandem installation, especially for hydraulic vehicle braking systems, with - an amplifier housing (20) having two front winches (22, 24) and a stationary partition wall (28), - two movable inner walls (32, 34) which divide the interior of the amplifier housing (20) on both sides of the stationary partition wall (28) into two chambers (34, 36 or 38, 40) each, which can be connected to sources of different pressure, - Flow connections between two chambers (34, 38 and 36, 40), which are separated from each other by another of the chambers (36 or 38), - connecting rods (42) which extend from one end wall (22) through the intermediate wall (28) and the two inner walls (30, 32) to the other end wall (24), and - hose-like bellows (50, 52) which are arranged around the connecting rods (42) and are components of at least one of the flow connections, characterized in that at least one of the connecting rods (42) extends through a piece of pipe (48) which is connected to the intermediate wall (28), from there protrudes in the direction of one of the end walls (22, 24), ends in front of it and is connected to the 05.02.1988 - 2 - 10-62 327 Inner wall (30, 32) which is adjacent to this end wall (22 or 24) and is sealingly connected by a bellows (50 or 32), with which the pipe element (48) together forms one of the flow connections. 2. Power amplifier according to claim 1, characterized in that the pipe section (48) is formed in one piece on the stationary intermediate wall (28). 3. Power amplifier according to claim 1 or 2, characterized in that the bellows (52) is designed as a folding bellows and is guided displaceably with one end on the pipe section (48). 4. Power amplifier according to claim 1 or 2, characterized in that the bellows (52) is designed as a rolling bellows and is attached at one end to the pipe piece (48). 5. Power amplifier according to one of claims 1 to 4, characterized in that the pipe section (48) ends on the edge of the associated inner wall (32), relative to its rest position, which is the position of the respective inner wall (32) furthest away from the intermediate wall (28). 6. Power amplifier according to one of claims 1 to 4, characterized in that the pipe section (48) extends backwards over the corresponding inner wall {30} and, in its rest position, ends at least approximately halfway to the adjacent end wall (22). ·■ ti ·· tf ·· · ·
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