DE2015611C3 - Tandem master cylinder for a hydraulic vehicle brake system - Google Patents

Description

Isa

Braking power

^st

the

Driver spurts

in the floating Kob ()

Seals (33) formed annulus (32)

to

a complete failure of the braking system

40 is coming.

A tandem master cylinder is already known (German Ausiegeschrift 1 174 633), in which the connection opening to the refill age for

The invention relates to a tandem master cylinder assigned to the pedal-operated master piston a hydraulic vehicle brake system with two, 45 th pressure chambers in one separated by a narrow chamber Brake circuits associated pressure evacuated intermediate space opens, the opposite of both men, which is sealed with a refill in connection pressure chambers, wöbe, the seal stand and one of which is between a pe- between the annular space and the main piston dalbetätigbaren main piston and a floating pressure chamber associated as a lip seal mimicking the second piston and the other between 50 forms, which in one of the annular space to the Druckdem floating piston and the pressure drop for brake fluid falling from the main chamber The end of the cylinder facing away from the piston is formed, is designed to be permeable. This well-known main and with a cylinder at said end of the cylinder, however, does not belong to the initially specified Valve that the other pressure chamber NEN genus, since it has a backlash connection to connects to the refill container and from the 55 limiting the relative axial movement of the two floating piston can be actuated, and a piston is not provided. If the dem

di d Bk t dh

Backlash connection between the two pistons, the relative movement of the two pistons on one Limited distance that is less than the maximum KoI-benhub.

Such a designed tandem master cylinder is the subject of an older, not previously published Proposal (German Offenlegungsschrift 1 803 614). With the help of the lost motion connection between the two Klb id d ih dß bi Dkfll

60

The brake circuit associated with the master piston is therefore a comparatively in this known master cylinder large pedal travel required.

In a preferred embodiment of the invention, the space is a floating piston between its seals formed ring

An embodiment of the invention is in the fol-

the piston is achieved there that in the event of a pressure failure 65 lowing explained in more detail on hand cfer drawing.

in one of the two brake circuits with a low The drawing shows a tandem master cylinder

additional pedal movement of the other brake circuit according to the invention in longitudinal section.

can be pressurized. In this older, the tandem master cylinder 10 shown has an ab-

gated hole, in the larger section VDn a pedal operated main piston Π works. A floating piston 12 operates in the narrower portion of the bore. The space between the two pistons forms a pressure chamber 13, while the other Druckreum 14 of the space between the other end of the piston 12 and the adjacent end of the cylinder. That the Main piston facing end of floating piston 12 has an axially extending piston Shank IS formed, which ends in a head 16, which is received in an axial recess 17 in the front end of the main piston. The recess 17 goes forward into an extension 18 with a larger diameter, in which one is attached the shank 15 attached washer 19 can move axially. The extent of this is axial Movement is limited by a stop formed by a bushing 20 in the front end of the extension 18 is inserted into the recess and has a central opening 21, which the shaft 15 with Game surrounds.

A compression spring 22 disposed between the washer 19 and the bushing 20 normally holds the washer in contact with the inner lid of the extension 18. Another compression spring 23 is on the shaft 15 between the washer 19 and the rear end of the floating Piston 12 is attached and normally holds head 16 in abutment with the washer, as shown in the drawing.

Hitting the head 16 at the inner end of the recess 17 limits the mutual approach of the two pistons, while separating the pistons by compressing the spring 22 is limited.

Ce two pistons are loaded axially in the usual way by return springs 24 and 25, which the Push the piston into its rest position.

The two brake circuits can be connected to outlets 26 and 27 which lead out of the corresponding pressure chambers. Furthermore, the two brake circuits can be connected to a refill container via openings 28 and 29. The opening 29 is controlled by a valve 31 in a known design, which is open when the swimming pool

ben 12 is in a fully retracted position and closes when this piston is applied the brakes are moved forward. The opening 28 is connected to an annular space 32 in the piston 12, the one space between the two

ίο forms the pressure chambers 13, 14 and from the brake fluid can flow past a seal 33 on the piston into the pressure chamber 13 if there is negative pressure prevails.

If when the main piston 11

unequal volume requirements for applying the brakes Herrseben in the two brake circuits, the floating piston 12 can move within the Gienzen that determine the axial length of the recess 17 and the possible axial movement of the washer

Determine ao disk 19 in the extension 18, move axially with respect to the main piston 11,. ^r , o that the pressure in space 13 and 14 and thus also the pressure exerted on the brakes of the two brake circuits is equalized.

If the brake circuit supplied from the pressure chamber 13 should fail, the main piston 11 becomes moved forward until the inner end of the recess 17 rests against the head 16, the spring 22 opposed to this movement resistance. then

takes the main piston with the floating piston 12 and displaces brake fluid from the pressure chamber 14 supplying the other circuit.

If the brake circuit supplied from the pressure chamber 14 should fail, the floating coil is

ben 12 axially moved away from the main piston 11 and thereby takes the washer 19 with it, as far as it is the Spring 22 allowed. The main piston then generates pressure in the pressure chamber 13, whereby the on the pedal force exerted over a surface on the pressure

Space 13 located brake fluid is applied, the difference between the surfaces of the corresponds to both pistons.

1 sheet of drawings

Claims (1)

Proposal, however, the two DnickrSumc are only separated from each other by a single seal, gun. " _Dic | _{If it} fails once, it can Liquid from a pressure chamber in the ande-BrembftussigKeii ren ι "« «". _Breniskre j _{sc are} intact , the j> ° 'feels ^at S * ^D. ' _broken n seal nothing. If any one of the _{brake circuits} fails, this is the cause " ^üCn J;" J: 'r); _chtl , _ne also in the other.-n Bremsdie deteue uu ξ _{that it then mc] nm} kre s men ^ g * 'Brake system _{failure * m stepped on} the pedal without a major de ^ _through ^B. Patent claims: I. Tandem main cylinder for a hydraulic one
Vehicle brake system with two separate s
Brake circuits associated pressure chambers, the
are in communication with a refill container
and one of which is between a pedal-operated main piston and a floating second piston and the other between «
the floating piston and the from
Main piston facing away from the end of the cylinder
is formed, and with one on said
End of the cylinder arranged valve that the
other printing space with the container x _S
connects and from the floating piston
can be actuated, as well as with a lost motion connection
between the two pistons which de the relative movement. two pistons to a route loading by g, _g ^g complements re ⁸ is smaller than the maximum piston stroke * o NachfüUbeha Herfur is the ^ dcm, characterized in daßd.e Neten Dnickraum in a su connecting opening (28) for a refill container relative to the be the for the main piston (11) assigned th gap between pressure chamber (13) opens in a known manner in and that ^the one opposite to the two pressure chambers (13 * ₅ mes compared to ^the and 14) sealed gap (annulus pressure chamber at e .nem ™ 32) opens between these pressure chambers and pressure chamber sloping that the seal (33) of the intermediate space sigke.t permeable (annular space 32) with respect to the main piston falls in the 11) associated pressure chamber (13) with a 30 main cylinder one of the from the intermediate space south, it falls off one of the be.den pressure space lumbar pressure vessel for brake fluid through- ff according to claim 1, that SSr ^ te defective characterized in that the intermediate space receives a 35 container e.ne connection. In the floating piston (12) between its sen defect immediately there is a slightly larger Pcdalweg Resistance you » ^we ™ ^en . , \ _ο ,, ": _P ; _npm
The levy, ta «nem Failure """* ^ 2 £ ^ Sn ^ m pressure erwegung ™" ^ JS ^ J £ Zw "* M dazeugen, ^d ^ ^e ^% _{erhindu ngs} ö _f f _voltage wtfd _for by solved, aaü do ν & ° _d Herfur dendcm H £ g ^^ g »?