DE2221074C3 - Control device for the brake circuit, assigned to the rear wheels and containing a pressure reducer, of a hydraulic dual-circuit brake system for motor vehicles - Google Patents

Description

a) is housed in a cylindrical housing (17), which with a stepped Hole is provided,

b) the - first - bore section (18) with the larger diameter with a plug (19) is closed and the - second - bore section (20) with the smaller one The diameter of the end wall (21) of the bore is limited,

c) a stepped piston (26) can be displaced in the bore against the force of the pretensioning spring 36) is guided, which is on its end face opposite the end wall (21) (34) carries a sealing washer (35),

d) the piston part (33) of smaller diameter in the second bore section (20) bounded by the end wall (21) a first chamber (37) into which a first, centrally in the end wall (21) located passage (23) and a second passage (3 (1) opens, wherein the first passage (23) with the pressure source for the rear wheel brakes and with the pressure reducer (13) and the second passage (38) in connection with the line (16) bypassing the pressure reducer (13) stands.

e) the piston part (25) of larger diameter in the first Bohningsabschnitt (18) with the stopper (19) a second chamber (40) delimits the at least inen third Passage (43) is connected to the front red brake circuit,

f) the effective surfaces on the piston (26) are designed so that the piston can be displaced by the front brake pressure against the action of the pretensioning spring (36) and closes the most passage (23) in the end wall (U) with its sealing washer (35).

3. Control device according to claim 2. dadi.iuh 6ο characterized in that the sealing washer (35) is carried on an axial extension of the piston part [33) of smaller diameter. which 5ich extends in the direction of the end wall (21).

4. Control device according to claim '?. or 3, characterized in that the Dichtangsicheibe (35) in a truncated cone: n hollow

35

45

55 space is held in the end face of the piston part (33) of smaller diameter.

5. Control device according to one of claims 2 to 4, characterized in that the Pre-tensioning spring (36) pushes the piston against a stop formed by an axial skirt (41) biased, the skirt from the top of the plug (19), which is opposite the piston (26), protrudes and the skirt (41) has a number of radial slots (42), the one Connection between the third passage (43), which acts as an axial flow channel in the plug (19) is formed, and produce a fourth passage (45) formed in the housing (17).

6. Control device according to one of claims 2 to 5, characterized in that the two parts (25, 33) of the piston (26) with sealing rings (51, 52) which are in annular circumferential grooves in respective intermediate positions over the lengths of the two parts (25, 33) are provided are, and that these two parts (25, 33) of the piston (26) are designed as separate elements which can be inserted separately into the bore of the cylinder (17).

7. Control device according to one of claims 2 to 6, characterized in that the Housing of the cylinder (17) is provided with a fifth passage (50) to which the for Pressure reducer leading line (12) is connected and that with the first passage (23) in the flow direction before its confluence in the first chamber (37) in connection, stands.

40 The invention relates to a control device for the rear wheels associated with, a pressure reducer containing Bremskrc's a hydraulic dual-circuit brake system for motor vehicles, comprising a acted upon by the pressure in the front wheel brake circuit, a pressure reducer prompt line valve controlling that the Druckmitteldurchfluß releases through this bypass line upon failure of the Vordcrradbrcmskrcises .

In a known control device of this type (US Pat. No. 3,448,230), the valve a Ventilk.'irper, one face of which is from Pressure in the front brake circuit and its other end face acted upon by the pressure in the rear brake circuit is. If the pressure is the same in both brake circuits, the valve body is in one position held in which the flow through the bypass line is blocked. If, on the other hand, the pressure falls in the Front brake circuit off, the pressure in the rear brake circuit moves the valve body into one of the Flow through the bypass line releasing position, so that the pressure reducer short-circuited and braking of the vehicle becomes possible, without the driver having to exert excessive pressure on the brake pedal in order to achieve an effective To get braking.

However, this star has the disadvantage that the Valve which, when open, reduces the pressure

3 4

less short-circuits, only very rarely in those A further advantageous embodiment of the invention

is operated in cases when the pressure in the manure is that the preload spring

Front brake circuit fails. Since there is therefore very piston against an axial skirt

it is probable that the valve biases during long th stop, the skirt of the

Time periods are not operated at all, there is 5 top of the plug, which is opposite the piston

the danger of the formation of deposits and thus lies, protrudes and the apron a number of ra-

of clogging, so that the movable part has diaischlitzen which connect between

"Eat" and thus possibly a defor- the third passage, which acts as an axial flow channel

tion of the threads occurs and the valve is formed externally in the plug, and a fourth

Treme cases just becomes ineffective when io establish a passage formed in the housing,

a satisfactory operation is most important. Furthermore, it is advantageous if the two parts of the

is required, d. H. in the event of a failure of the brake circuit of the pistons with sealing rings, which are

Front wheels. ten in respective intermediate positions over the lengths

The object of the invention is, therefore, a control of the two parts are housed, are provided, of the type described above so trainees device i ₅ and that these two parts separately as that their function even warranty-made elements are of the piston then formed, which is separated in making when a bridging the Dnickminde- leave the bore of the cylinder insert, and not needed if the housing of the cylinder _was RERS for a longer time with a fifth. Passage is provided, to which the for Druckminde-

According to the invention, this task is thereby connected to the leading line and to the

solves that the valve by the force of a spring in the first passage in the direction of flow before the

its open position and is biased when sen Anstci- opening into the first chamber in communication

the pressure in the front brake circuit is closed,

will sen. Examples of implementation

An advantageous development of the invention is 25 forms of the invention on the basis of schcmatic drawings

characterized in that the valve is explained in more detail. In the drawings shows

a) in a cylindrical housing under Fig. 1 the schematic representation of a hydraulic installation is, which with a graduated Bihlischen dual-circuit brake system for motor vehicles with tion is provided, two separate circles and a pressure reducer

b) the - first - bore section with the larger one in a circle for the rear wheels, the one with one after one formed with a plug ver the first embodiment of the invention is closed and the - second - Bohrungsab- control device is provided,

Cut with the smaller diameter of FIG. 2, a longitudinal section in relation to FIG. End wall of the bore is limited, enlarged scale by filling this first in the bore a stepped piston against the 35 approximate shape of the invention and

The force of the pretensioning spring is displaceably guided. FIG. 3 shows a longitudinal section likewise in gcgenübei

is, which is opposite to the front wall on its F i g. 1 enlarged scale for a second Aus

Low end face carries a sealing washer, guide form of the invention.

d) the piston part of smaller diameter in which the hydraulic, in F i g. 1 illustrated Brcmsan second bore section with the end wall 40 order comprises a pressure cylinder 1, which is of | a first chamber limited, controlled in which a first, a brake pedal 2 and secreted with the two ge centrally of the end wall passage in-circuits via lines 3 and 4, pressure and a second passage opens, said liquid is fed.

the first passage with the pressure source for the lines 3 and 4 are both with a control

Rear wheel brakes and connected to the pressure reducing device 5, their structure and work

rer and the second passage with which the pressure will be explained in more detail below

less bypassing line in connection The device 5 in turn is connected to the front wheel

_stc ] _lti "bremszyliiidcin 6 or 7 via lines 8 and 9 vcr-

e) the piston part of larger diameter in the collar; it is also 10 µm with the brake cylinders first bore section with the plug 50 11 for the rear wheels via an arrangement of lei a second chamber delimits, which is connected by a few slopes, which a line 12 between at least a third passage with the front of the facility? and a pressure reducer 13. unites wheel brake circuit is in communication, line 14 / wipe the outlet of the Druckminde,

f) the effective areas on the piston so designed rers 13 and a line 15, which you are that the piston from the front brake 55 connection to the brake cylinders IO and 11 here pressure against the action of the biasing spring and finally a line 16 between de is displaceable and has "its sealing device 5 and the line 14, disk the first passage in the end wall. The pressure reducer 13 is like the pressure cylinder locks. ve. ··, of a known type and designed in such a way that there

In this connection, a reduction in the brake pressure in the Hmtci can be avoided in particular.

It would be an advantage if the Dichlunus disc on a wheel brake / .vlindem 10 and 11 with respect to the same

axial extension of the piston-part genncm-n becomes possible, which in the front wheel cylinder

Diameter t'.etrai! E; i is. they look up in RiclKUiiu and 7 according to a predetermined Kedukj

to extend the front wall, and if after a wc- tion relation comes into effect,

Another embodiment of the invention is shown in FIG

Disk in a conical cavity in and comprises a housing 17 with a bore m

of the end face d,. Knlbenlcils cerinueren Du.vhmes- a first section 18 larger diameter:

ore "..!,., it, ..! ; .i '' which is closed by a plug 19 and cinc |

second section of smaller diameter, which serves as a stop element and is limited by skirt 41 an end wall 21 is closed. The end wall 21 the movement of the piston against the plug 19. has a central raised portion 22, one of which the chamber 40 protrudes through an axial passage axial opening forms a passage 23, the 43 of the plug 19 with a thread for a binding with a screw connection 24 is to 5 screw connection 44 in the outer surface of the plug a connection for the to the printing cylinder 1 19 in connection, which via the line 3 with the rende line 4 take up. Inside the Boh pressure cylinder 1 is connected. Chamber 40 tion of the housing 17 is a piston 26 with a is also via a radial passage 45 with a first part 25 of larger diameter stored, the thread for a screw connection 46 in Verbinfrei io slide in the first section 18 of the bore in a side eye 47 on the housing can, and which is also formed a second part of a 17 and the one with the front brake diameter cylinder 6 or 7 connected by means of a line smaller than that of the first part which becomes free in the second section 20 of the bore.

can slide. The seal between the first housing 17 also has a thread for part 25 of the piston and the associated portion 15 a screw connection 48 in a lateral eye section 18 of the bore of the housing 17 is through 49, in which there is also the thread for the an annular sealing ring with an opposing screw terminal 39; the screw connection brought about the lip 71 facing the plug 19. 48 is via a radial passage 50 with the This sealing ring is housed in an annular circumferential passage 23 between the chamber 37 and the catch groove 28 in the piston, which is close to the 20 screw connection 24 in connection. The connection end of the first part 25 is provided and one 48 is arranged in such a way that it has shoulder 29 with the line 12, the outer diameter of which can be bonded, the connection to the inlet of the slightly smaller than that of the remaining part of the first pressure reducer 13 manufactures.

Part 25 of the piston is. The in F i g. 3 shown embodiment under Similarly, the seal between 25 differs from that of FIG. 2 in that the the second part 33 of the piston and in the associated seal between the parts 25 and 23 of the KoI-th Section 20 of the bore by means of a similar bens 26 and the respective parts 18 and 20 dei formed sealing ring with a lip 30, the bore in the housing 17 duieh sealing ringc the end wall 21 is opposite and formed in a circumferential 51 or 52 of O-shaped cross-section Fenden annular groove 31 is housed, which are close to 30. These sealing rings 51 and 52 are in Ringdem The end of the second part 33 of the piston is arranged in the piston part 25 or 33 approximately in the latter net and housed on the opposite center of the front wall 21. In this case, to the unified Page is formed by an annular shoulder 32 to facilitate the construction of the control device are the whose diameter is slightly smaller than that of the parts 25 and 33 of the piston as two separate ones Remainder of the second part 33 of the piston 26 is. 35 components are made and are made by the effect

The end face 34 of the part 33 of the piston 26, the spring 36 held together.

which is opposite the end wall 21 has a back The piston 26 and the spring 36 are proporterschnitten frustoconical cavity, in lioniert that with intact brake circuits the Resullie which a resilient sealing washer 35 below the counteracting hydraulic is brought, which is coaxial with the passage 23. A part 40 acting on the piston during the breaking the resilient washer 35 stands from the side 34 of the forces is able to push the piston against the forehead part 33 of the piston and has a through wall 21 to move against the action of the spring 36 This is slightly larger than that of the passage 23 gene, so that the connection between the passage and slightly less than that of the raised part 23 and the chamber 37 by means of the sealing washer « 22 of the end wall 21 is. 45 35 is closed, and in this way the conn-inter the shoulder 32 of the second part 33 of the manure between the lines 4 and 16 interrupted Piston and the end wall 21 is a screw spring and thereby a normal operation of the pressure the 36 interposed, which ensures the piston 26 in reducer 13.

Direction of the plug 19 biases and thereby The operation of the in Figs. 2 and 3 Darge

the sealing washer normally placed at a distance of 50 bodies is as follows: Before the hy

The central raised part 22 of the end wall 21 keeps hydraulic lines in FIG. 1 illustrated Bremsanordnuni

And leaves the passage 23 open. is operated, the elements are in the Ge

One between the part 33 of the piston 26 and the housing 17 in the FIG. 2 and 3 position shown,
the wall of the bore formed in the housing 17. When braking begins, hydraulic pressure is applied

Chamber 37 is via a lateral opening 38 with 55 from the pressure cylinder 1 to the chamber 40 or 37 ii

a thread for a screw connection 39 in the housing 17 through the lines 3 and 4 respectively

Connection through line 16 with the line, so that the hydraulic thrust on each side

treatment 14 can be connected, which is given between that of the piston 26; the resulting «

Pressure reducer 13 and line 15 between the thrust on piston 26 moves it from the stop

«Is held and continues with the brake cylinders 10 and 11 60 fen 19 and pushes it in the direction of the forehead

of the rear brake circuit is connected. wall 21 against the resistance of spring 36.
f Between the plug 19 and the shoulder 29 of the After a brief flow of the liquid from

Piston 26 is a chamber 40 formed in flow 23 to the opening 38, which during de

which takes place an annular axial skirt 41 of the period of time during which the piston fell

jJ stopper 19 extends, the outer diameter of which approaches 65 the end wall 21 and the friction elements de

fingers as the diameter of the first section 18 front and rear brakes are applied, win

Jler bore in the housing 17 is and one is the connection between the passage 23 and the comb

Having a plurality of radial slots 42. The 37 blocked by the sealing washer 35. Of the

At the point, the pressure medium can only reach the cylinders 10 and 11 reach the rear brakes via the passage 50 of the screw connection 48, which is connected to the Line 12 is in communication, which establishes the connection with the input of the pressure reducing device 13.

When the brake pedal is released, the spring 36 returns the piston 2.5, 26 to its starting position, in which he rests against the skirt 41 of the piston 19 and thus establishes the connection between the passage 23 and chamber 37.

The braking process of cylinders 6 and 7 of the front wheel brakes is not affected, as the pressure medium continuously from the line 3 to the line 8 through the screw connection 44 of the plug 19, the axial passage 43, the radial slots 42 of the skirt 41,

the passage 45 and the screw connection 46 can flow.

Should it occur during the brake application of the brake assembly as a result of a fault in the front wheel brake circuit lead to a loss of brake pressure in this circuit, then the movement of the piston 26 iii direction of the end wall 21 does not take place or the piston is from this position under the Effect of the spring 36 returned so that the

ίο Pressure from line 4 on the one with the cylinders 10 and 11 of the Hinierradbremscn connected branch lines 14 and 15 via the line 16 transmitted is soft bypasses the pressure reducer 13 in the bypass, so that the full brake pressure on the Rear brakes is applied.

For this purpose 3 sheets of drawings

Claims (2)

Patent claims: 1. Control device for the one assigned to the rear wheels, containing a pressure reducer Brake circuit of a hydraulic dual-circuit brake system for motor vehicles, which is dependent on the pressure in the Front brake circuit acted upon, a line that bypasses the pressure reducer Includes valve that, if the front brake circuit fails, the pressure medium flow through releases this bypass, thereby characterized in that the valve (23, 26. 3S) is biased into its open position by the force of a conveyor (36) and when rising of the pressure in the front brake circuit is closed. 2. Control device according to claim 1, characterized in that the valve