DE3233313A1 - Antilock brake system - Google Patents

Abstract

Antilock brake system for an air-operated hydraulic wheel brake, the brake unit provided for normal braking and with a control compressed air/hydraulic pressure medium changeover being followed downstream by a compressed-air modulator unit, by which the direct hydraulic line connection from the master brake cylinder of the brake unit to the individual wheel brake cylinders is monitored by means of a compressed-air control unit under the effect of ABS. <IMAGE>

Description

R. 18036 He
1632 / ot / wl
July 19, 1982

ROBERT BOSCH GMBH, TOQO Stuttgart 1 Brake blocking protection device State of the art

The invention is based on a brake lock protection device according to the preamble of the main claim. Anti-lock devices are known (DE-OS 2 212 566; DE-OS 2 753 992); however, this can affect asymmetrical road surfaces. or even with unsyirmetric vehicle brake turfs, depending on the control logic, problems arise due to under-braking or over-braking of individual wheels. The brake lock protection device z. P according to DE-OS 2753992 is constructed so that the braking modulation hydraulic wheel brakes is compressed air side is controlled, wherein each single wheel brake cylinders respectively associated converting units are provided, these are located immediately upstream and implements an air-pressure-controlled impingement in a hydraulic pressure corresponding effect. In detail is

/ 2

16 32 / ot / wi v

July 19, 1982 - X - R. 18036

the well-known brake protection blocking device constructed so that in the brake line to two brake cylinders of a vehicle first a common 3/2-way valve is used and then behind this valve via a branch in each line A further 2/2-way valve is arranged leading to each brake cylinder; all of these valves are controlled by compressed air and cause the brake pressure modulation of the hydraulic wheel brake, this also has the advantage that the same ABS components can be used for the valves, as they are also used for a pure air brake.

This known anti-lock device could be disadvantageous However, it should be considered that for each control channel a separate Bremsdruckaggre.gat for the implementation of the pressurized air must be used in a hydraulic pressure value, each consisting of a main cylinder and a preload cylinder. This means that compared to standard standard braking equipment practically a doubling of the braking units alone; Another problem is that through the inclusion of the respective Brake pressure unit in the ABS control (anti-lock braking system) this naturally a significantly higher number of load changes must represent than with a normal brake and therefore the need may arise through correspondingly early Exchange to prevent a failure.

Finally, the interlocking coupling of normal braking and ABS components it is impossible, for example with

/ 3

3/33313

1632 / ot / Vl T

July 19, 1982 -Ji- _{R> 18C36}

for motor vehicles with ABS as special equipment to leave the normal normal braking system of the series vehicle unchanged and only add an additional ABS equipment to be provided, what with the possibly only smaller number of such vehicles equipped with an anti-lock braking system is desirable. Except for the interlocking of the individual brake and ABS components, however, ABS special equipment also requires brake units, so that for this reason, too, the demand for a mere ABS supplement while maintaining the normal braking system cannot be met.

There is therefore a need for a brake anti-lock device for motor vehicles, which is a compressed air operated, hydraulic Includes wheel brake and is designed so that while avoiding additional load changes caused by the ABS effect of the brake pressure unit, the normal brake can be left essentially unchanged.

Advantages of the invention

The brake lock protection device according to the invention with the characterizing features of the main claim has on the other hand the advantage that the brake pressure unit, as it is already present in the normal brake, from the ABS control caused, much higher load cycle effects can be kept out, so that its wear is decisive

/ 4

16 32 / ot / wl £

July 19, 1982 - Λ - R. 1 8036

is reduced and one is relieved of the need to prevent a possible failure through an early exchange.

It is also advantageous that the invention makes it possible to use the normal brake system to keep unchanged for example a series vehicle and, as special equipment, this normal braking system can be supplemented with an anti-lock braking system as required. Additional braking units are not required in this case; there is only the need to connect the hydraulic connecting lines from the brake unit to the Normal brake cylinders arranged in the wheel area lead to separate at a suitable point and a pressure modulator unit to insert.

The brake lock protection device according to the invention can thereby Build largely from the same ABS components as they are for an anti-lock braking system with a pure air brake exist anyway; since the normal braking system is retained in its structure and in its effect, are also no problems to fear in the event of a failure of the ABS system; it can be braked in the usual way and the vehicle operate.

The measures listed in the subclaims are advantageous developments and improvements of the main claim specified anti-lock device possible.

/ 5

3? 33 3

1632 / ot / wl $

July 19, 1982 - # - R. 18036

It is particularly advantageous to act on the compressed air control unit and the brake unit, which mediate the ABS effect the same control air from the service brake valve and the ability to monitor each wheel brake cylinder individually and to steer. It is also advantageous that pressure maintenance functions are implemented by appropriate electrical control can be initiated, with a pressure increase or a pressure reduction can be initiated by a pressure holding function corresponding clocking with correspondingly desired pressure gradients.

drawing

Embodiments of the invention are shown in the drawing and are explained in more detail in the description below. It shows Figure 1 in a schematic representation Arrangement of the additional work components required for anti-lock protection in the case of a hydraulically braked one Axle and compressed air-controlled brake unit, Figure 2 in details, he te r he illustration of the structure of the additional ABS work components according to Figure 1, each in section, the respective vehicle components and the already existing Normal brake system are only shown in a highly schematic manner, FIG. 3 also in a sectional illustration integrated solution of the ABS components and Figure 4 shows the design of the pressure control unit in the single-channel version Use of two solenoid valves per channel.

/ 6

1632 / ot / wl

July 19, 1982 -jiT- R. 18036

Description of the exemplary embodiments

The basic idea of the present invention consists in the ABS control in a compressed air-actuated, hydraulic vehicle brake to realize that the brake unit, which is required anyway for the normal brake system At the same time, the implementation of compressed air control / hydraulic pressure effect is also implemented, a compressed air modulator unit is downstream, with which the direct line connections from Master brake cylinder of the brake unit to the individual wheel brake cylinders Monitored in terms of ABS regulation and controlled by a compressed air control unit in the pressure curve can also be influenced.

In FIG. 1, only two vehicle wheels 6a, 6b assigned to a common vehicle axle 7 with their respective wheel brake cylinders are shown 5a, 5b shown. The service brake valve is denoted by 1; to him via lines la, Ib from one not Compressed air source illustrated, which is ultimately responsible for the actuation of the

Wheel brake cylinder 5a, 5b supplied amounts of compressed air required and get directly to the brake unit 2, which has a master brake cylinder at 2 'and so at the same time the Transition from compressed air control to the hydraulic area realized. The hydraulic master cylinder 2 'does this hydraulic pressure medium via a pressure modulator unit 3 belonging to the ABS control to the wheel brake cylinders 5a, 5b. To that extent is the pressure modulator unit 3 in the course of the hydraulic

July 19, 1982 - - = Γ - R. 18036

1632 / ot / wl ^ ^Λ

Line connections behind the hydraulic master brake cylinder 2 'of the brake unit 2 in series with the wheel brake cylinders and works under the control effect of a pressure control unit 4, the from a branch point 8 in front of the brake unit 2 and behind the service brake valve 1 is supplied with control air; the pressure control unit are, as indicated by the arrow 9, then also the corresponding ABS control commands supplied by the ABS components 3 and 4 ir. A corresponding pressure curve with the desired gradients of the hydraulic pressure medium to the Wheel brake cylinders are implemented. It can be seen that the anti-lock device according to the invention for a compressed air operated, hydraulic normal brake system leaves this practically unchanged and bypasses its brake pressure unit.

In Figure 2, pressure modulator unit 3 and pressure control unit 4 are shown in detail; the pressure control unit 4 comprises in the illustrated embodiment three pilot solenoid valves 11, 12, 13, each having a line connection 11a, 12a and 13a to an associated compressed air main valve 14, 15 and 16 monitor. The middle main valve 15 is directly to the Compressed air inlet line 17 connected; it is therefore in direct Connection to the brake valve 1 and is available as a 3/2-way valve educated. The two valve outputs of the central main valve 15 are connected to the valve inputs via lines 18a, 18b of the other two main valves 14 and 16, which in this respect then only represent 2/2-way valves.

/8th

ΛΖ

1632 / ot / wl

July 19, 1982 - # - R. 18Ο36

It can be seen that with the interposition of the two outer main valves 14 and 16, the lines 18a, 18b of the central Main valve 15 are led in two channels to the pressure modulator unit 3, the outputs of which then each to one of the wheel brake cylinders 5a, 5b are connected, as will be explained.

The three before control solenoid valves 11, 12, 13 are with the three main valves 14, 15, 16 combined in a common housing to form the pressure control unit 4; the pressure control unit therefore comprises four in the illustrated embodiment Valve seats 20 (with respect to the main valve 14), 21 and 22 (with respect to the central main valve 15) and 23 (with respect to the main valve 16) for compressed air; the passages of the valve sets are monitored by membrane members as valve closing members. The central one Main valve 15 has a valve closing body 24, which optionally connects the compressed air inlet of line 17 with the lines 18a, 18b connects or the lines 18a, 18b to one Outlet A vented. The pilot solenoid valves 11, 12, 13 contain control magnets 25, 26, 27. It can be seen that by the optional activation of the solenoid valves 11 and / or 12 and / or 13, in any case with corresponding timing Let the desired pressure control curves of the ABS control be achieved, including pressure maintenance, pressure increase or pressure reduction, which will be explained further below.

In the illustrated, non-activated closing body position the pre-control valves 11, 12, 13 prevent the compressed air

/ 9

1632 / ot / wl ^Λ ^

July 19, 1982 -Jd- R. 13C36

supply from input 17 via the line connections Ha, 12a, I "3a to the rear of the main valve diaphragm members so that they are in the position shown and the supply of Release compressed air from the brake valve 1 via the respectively open seats 20, 22 and 23 to the pressure modulator unit 3.

The pressure modulator unit 3 is designed with two channels, so that the brake pressure in the wheel brake cylinders 5a, 5b can be regulated individually, depending on the desired ABS function, with the Branch of the hydraulic pressure output line 28 from the brake unit 2 to the wheel brake cylinders 5a, 5b within the Pressure modulator unit takes place with appropriate connecting lines 28a and 28b to the wheel brake cylinders. The pressure modulator unit includes a compressed air control section 29a, 29b, respectively and a hydraulic monitoring valve area 30a, 30b; each channel of the pressure modulator unit therefore consists of one Air part and a hydraulic part together, so that the pressure modulator unit represents the interface in the transition from compressed air control to hydraulic pressure medium control.

In detail, the pressure modulator unit is constructed so that it - in symmetrical design per channel, so that only the structure of a channel needs to be discussed in more detail -, has an air piston 31, which is enclosed in a Pneumatic cylinder 32 is slidably mounted under the action of a bias spring 33; the compressed air inlet is with 34 designated. The air cylinder housing

/ 10

3 7 3 3

1632 / ot / wl

July 19, 1982 -WT- R. 18O3Ö

passes into a central, tapering part 35, in which a hydraulic piston 36 also slidably mounted with a connection between the air piston 31

and the hydraulic piston 36 through a piston rod 37 connecting both pistons. The hydraulic piston 36 has a pressure pin 38 that opens a valve seat 39 interspersed with a distance and a valve member 40 (valve ball) drives. The valve balls 40 (both channels) experience a Guiding of the tapered hydraulic cylinder body 35 or in one immovably mounted therein, at the same time the valve seats ring-like or hat-like retaining means 41 with a central passage opening, arranged in a slidably displaceable manner, The holding or guiding means 41 for the valve balls 4 0 are in the direction of the respective hydraulic piston 36 by one here double-acting preload spring 42 is preloaded and thus hold the valve balls 40 in contact with the piston tappets 38.

The size dimensions of the air piston 31 with its cup-shaped Air cylinder housing 32 and the hydraulic piston 36 in its cylindrical hydraulic cylinder housing 35 are deliberately chosen so different that a suitable transmission ratio results in the pressure modulator unit 3 from the air to the hydraulic part, which is greater than or at least equal to the of the brake unit 2, so that the monitoring valves during normal braking 39, 40 in the pressure modulator unit in both channels always open and the direct line connection from Brake unit 2 to the wheel brake cylinders 5a, 5b is free. this

/ 11

3 ') 3 3

1632 / ot / wl ^

July 19, 1982 - yC - R. 18036

is also ensured by the same (air) control pressure in the brake unit 2 and in the pressure modulator unit 3.

Finally, the return spring acting on the air piston 31 has the effect 33 of the pressure modulator unit in each channel that the monitoring s valves remain open even without braking. Through this it is ensured that the braking process can be displayed in the usual way at any time. .

The following overall function then results: Normal braking runs as just described; ABS components 3 and 4 do not intervene and the hydraulic line connection to the brake cylinder lines 28a, 28b is open.

In the event of overbraking, there is a risk of locking of the electronics (not shown) on the respective wheel rotation behavior recognized and there are corresponding, the brake pressure correcting commands to the electromagnetic pilot control valves 11, 12, 13 of the pressure control unit 4 given.

Accordingly, a pressure reduction by the electrical Activation of the outlet magnet of the pre-control valve 12 initiated, whereby the control pressure in the air chambers and connection Lines of the pressure modulator unit are vented via the central main valve 15 piloted by this outlet magnet by lifting the valve member from seat 21 and releasing it to outlet A. The equality of forces between the hydraulic

'12

3 7 3 3

1632 / ot / wl

Jul. 19, 1982 - WC - K. 18036

likteil and the air part is canceled and the pressure in the wheel brake cylinders 5a, 5b can be increased by the volume receding hydraulic piston 36 are dismantled. At the same time, the respective monitoring valve 39, 40 approaches it Closing function and interrupts the hydraulic pressure medium supply from the brake unit.

The selective application of only one wheel brake cylinder then if the current overbraking is only given on one wheel and the pressure reduction is therefore only required on this wheel, takes place in that, as just explained, the outlet magnet of the control valve 12 is activated, but at the same time the electrical control of the respective holding magnet of the opposite wheel, i.e. the magnet in the pilot valve 11 or 13 is made. This reduces the pressure in this channel (in the wheel that is not over-braked) for the duration of the pressure reduction stored in the other channel, i.e. set to pressure hold.

The pressure holding function in general is performed by the electrical control of the respective holding magnet in the pilot valve 11 or 13 achieved, pressure holding can take place from a pressure increase or pressure reduction phase, depending on the type of electronic Control.

Furthermore, the holding phase can be changed into flat pressure increase or flat pressure decrease phases by means of a clocked control will; by different clocking can in the individual

/ 13

^? Q Q ^ 1 Q

1632 / ot / wl

July 19, 1982 - yS - R. 18036

Channels can also be controlled at different pressure levels.

When the central main valve 15 is closed with respect to the outlet, the pressure builds up either by clocking the holding magnets valves in the front control valves 11 and 13 with flat pressure gradients or with steep pressure gradients when the holding valve is open.

Since the monitoring valves 39, 40 in the pressure modulator unit are designed as check valves, as can be easily seen, the driver can release the brakes in any phase be performed; even if the print control unit is controlled by the ABS control prescribes holding functions.

The function just described results in the same way at the other exemplary embodiments of FIGS. 3 and 4, where parts identical to those in FIG. 2 are provided with the same reference numerals

In the embodiment of Figure 3, the pressure control unit 4 'is modified to the effect that the in Figure 2 as pilot valves designated electromagnetic action units H ', 12' and 13 'the control compressed air directly through its closing functions the air chambers of the unchanged pressure modulator unit 3 supply. The valve functions are therefore in the idle state through anchor 25 ', 26', 27 'in opposite Direction preloaded by respective preload s springs, which in the normal starting position has no effect

/ 14

3 7 3 3

1632 / ot / wl ^Λ &

July 19, 1982 - -W - R. 18036

the ABS control open monitoring valves in the pressure modulator unit result. The illustration in FIG. 3 shows a compact device in which the compressed air control unit 4 ', which in this case only consist of the three solenoid valves 11', 12 ', 13 'is integrated in the pressure modulator housing.

With the same mode of operation as previously explained, the pressure control unit 4 ″ in FIG. 4 comprises two solenoid valves per channel 48a, 48b and 49a, 49b, which are each 2/2 way valves. In the position shown in Figure 4 of the solenoid valve is for the implementation of normal braking the line connection from the master cylinder 2 'to the wheel cylinders 5, 5a, 5b open; The hold function for .bei the wheel cylinder is activated by the the two inner solenoid valves 48b, 49b switched over; a Pressure reduction occurs when switching over the two outer solenoid valves 48a, 49a, in which position the air chambers of the Pressure modulator unit 3 are vented.

Furthermore, it is within the scope of the invention to replace the two-channel pressure modulator unit 3 with two separate, single-channel pressure modulators. This requirement can, for example, be given in individual cases due to cramped installation conditions. The branching of the line connection 28 from the brake unit 2, 2 ^J to the individual wheel brake cylinders 5a, 5b takes place in this case upstream of the respective single-channel pressure modulators, for example by means of a line T-piece. The mode of operation is identical to the two-channel pressure modulator unit 2, 2 ', but without the compact design there.

Blank page

Claims (1)

R. 18036 Ke
1632 / ot / wl July 19, 1982 ROBERT BOSCH GMBH, 70Q0 Stuttgart 1 Claims 11. yBrake lock protection device for the wheel brakes of a Motor vehicle, with common control of the brake pressure in at least two brake cylinders of the vehicle and one, The compressed air control unit imparting the ABS effect, characterized in that a pressure modulator unit (3) is provided is, which is in the direct hydraulic line connection from the brake unit (2, 2 ') to the wheel brake cylinders (5a, 5b; is switched on and controlled by the compressed air control unit in such a way that the pressure modulator unit itself as a transfer unit Compressed air / hydraulic pressure medium is working. 2. Device according to claim 1, characterized in that the pressure modulator unit is designed with two channels one monitoring valve (39, 40) in the hydraulic connection line to each wheel brake cylinder (5a, S / 2 1632 / ot / wl July 19, 1982 - 2 - R- 18036 3. Device according to claim 1 or 2, characterized in that the translation of compressed air / hydraulic pressure medium in the pressure modulator unit (3) is designed so that the respective line connection (28; 28a, 28b) during normal braking from the hydraulic master cylinder (2 ') to the wheel brake cylinders (5a, 5b) is open. 4. Device according to one or more of claims 1 to 3, characterized in that the monitoring valves (39, 40) are designed as check valves in the pressure modulator unit (3). 5. Device according to one or more of claims 1 to 4, characterized in that the branching of the line connection (28) from the brake unit (2, 2 ') to the individual wheel brake cylinders (5a, 5b) within the pressure modulator unit (3) is arranged with one monitoring valve each (39, 40) in the hydraulic part. 6. Device according to one or more of claims 1 to 5, characterized in that the pressure modulator unit (3) in a common housing and preferably arranged symmetrically opposite to the inside, the hydraulic Monitoring valves (39, 40) and outward in diameter expands in each case the compressed air control part (29a, 29b), formed from air chamber (32) and air piston (31), contains. / 3 l632 / ot / wl July 19, 1982 - 3 - R. 18036 7. Device according to claim 6, characterized in that the closing member (valve ball 40) of the hydraulic monitoring sventile is driven by the piston tappet (38) of a hydraulic piston (36) which via a piston rod (37) with the air piston (31) of the pressure modulator unit (3) is connected. 8. Device according to claim 6 or 7, characterized in that the pressure modulator forming two channels in each case unit in a tapered central part on both sides hydraulic guide cylinders (35) for the hydraulic pistons (36) that are slidably displaceable mounted holding means (41) for each valve member (valve ball 40) inwards and opposite one another are provided under bias of a common bias spring (42) and that in the hydraulic cylinder area a bearing sleeve is provided which at its outer ends is inwardly directed and the seat (39) for the valve balls (40) has annular flanges (39) forming. 9. Device according to one or more of claims 1 to 8, characterized in that the compressed air control unit (4) is formed by the control valves for a pure compressed air brake and connected separately to the pressure modulator unit (3) is (Figure 2). / 4 1632 / ot / wl July 19, 1982 - 4 - _{R. i8o36} 10. Device according to one or more of claims 1 to 8, characterized in that the compressed air control unit (4 ") is shared with the pressure modulator unit (3) Housing is integrated and comprises three solenoid valves (H ', 12', 13 '), the air chambers of the pressure. modulator unit supply the control air directly (Figure 3). 11. Device according to one or more of claims 1 to 8, characterized in that the compressed air control unit (4 ") comprises two solenoid valves (4.8a, 48b; 49a, 49b) per channel, which are arranged separately from the pressure modulator unit (Fig. 4), 12. Device according to one or more of claims 1 to 11, characterized in that the compressed air control for the compressed air control unit (4, 4 ', 4 ") is a parallel branch behind the brake valve (1) and in front of the normal brake unit (2, 2 ') common to at least two brake cylinders is arranged in such a way that the compressed air control unit (4, 4 ', 4 ") and the brake unit (2) from the service brake valve (1) are supplied with the same control air. 13. Device according to one or more of claims 1 to 12, characterized in that the pressure modulator unit consists of consists of two separate, single-channel pressure modulators.