DE2459775A1 - Vehicle brake anti-skid arrangement - has normally open control valve between pressure producer and associated dual circuit brakes (SW170576) - Google Patents

Abstract

The anti-skid arrangement consists of a pressure producer acting via a brake pressure controller producing a variation of the brake pressure, when blocking tendency occurs. The brake pressure producer acts in the first line onto a selected first brake circuit, but subsequently action in the second brake circuit follows due to the series-connection of the control unit and a throttle, to which a pressure reducing valve is connected in parallel. A normally open control valve is fitted between the brake pressure producer and associated wheel brakes. The brake pressure control unit enables maintainance of constant pressure in one brake circuit even when the brake pressure drops in the other brake circuit.

Description

Anti-lock control system (addition to P 24 50 749.1) The decision concerns an anti-lock control system according to patent ..................... (patent application P 2-4 50 749.1), in which a first brake pressure @ rz @ uger via a brake pressure control unit influences a first brake circuit to vary the brake pressure when there is a tendency to lock and in which this first brake pressure generator was connected in series from the brake pressure regulating unit and a throttle connected in parallel to a one-way valve serving to reduce the pressure is also influenced the brake pressure in a second brake circuit.

The throttle with the unidirectional valve connected in parallel can here be replaced by any other equivalent arrangement, e.g. a piston, which is exposed to the pressure prevailing in front of and behind the throttle and its Position a throttle cross-section in its size so that with higher Pressure in the wheel brake cylinders such a change in cross-section takes place, o.ass a more quickly Pressure reduction is going on and that with lower pressure in the wheel brake cylinder has a smaller throttle cross-section and thus a slower one Pressure build-up comes about. You can vary the throttle opening so that the pressure changes are independent of the pressure, i.e. the pressure changes over linearize over time.

In the main patent are various forms of the invention of the Main patent mentioned, so for example that the first brake pressure source is a main brake cylinder and that the pressure generated therewith, which can be regulated by means of the control device, is on the one hand serves as brake pressure in the first circuit and on the other hand via the throttle and the parallel-connected Unidirectional valve for influencing a control piston, which serves as the master brake cylinder of the second circle is effective.

According to the present invention is to solve the problem of the main patent another embodiment proposed, although under claim 1 of the main patent falls, but is not expressly mentioned there.

According to the invention it is proposed on the basis of claim 1 of the main patent, that between a brake pressure generator assigned to the second brake circuit and the associated wheel brakes, a normally open control valve is switched on is and that a stear piston is provided, on the one hand one of the brake pressure PR on the wheel brakes. In the second circle dependent pressure P (PR) and on the other hand over the parallel connection of the throttle and the one-way valve one of the one of the Brake pressure regulating device influenced pressure PSt dependent pressure P (is) exposed is, and that the control valve and the control piston are arranged in such a way to one another are and the control piston is designed such that from reaching a certain Size of the ratio P of the piston pressures at the control piston <n emigrates and first the control valve closes and then an enlargement of the Brake fluid available between the control valve and the wheel brake causes.

In the invention, a common pressure generator can be used for both brake circuits may be provided, but preferably two pressure generators, e.g. two brake master cylinders known type or two brake pressure control valves provided for full-power brakes.

A whole series of further training proposals in the main patent mentioned can also be used in the present invention; so can the brake pressure regulating device can be designed so that it is kept constant in a circle of the pressure is possible if pressure is reduced in the other circuit. This is done preferably a three-position valve is used as a control valve, which is designed in this way is that it is in its first position the output of the first pressure generator, in particular Master brake cylinder, with the first brake circuit and via the throttle with the control chamber the control piston connects, in a second position, the connection to the first The pressure generator is interrupted and a connection between the said control chamber is established and a return line and in a third position additionally the first brake circuit with the return line connects. The anchor preferably has of the three-position valve on two closure bodies, at least one of which is relative is displaceable to the armature and one of which is the return line in the starting position completes and the other in the second and third position the connection to the first pressure generator interrupts and also the first brake circuit is on connected a pressure build-up in it permitting unidirectional valve, which is in the third position of the anchor is lifted from its seat.

When using the three-stage valve described, an between unidirectional valve switched on for the first circuit and the first brake master cylinder provided that causes the pressure reduction in the first circuit at the end of the brake. To one too Maintaining constant pressure in the second circuit when the pressure is reduced in the first circuit (position three) To achieve this, the control chamber of the second circuit is attached to the three-position valve connected through a valve that is normally open, but in the third Position of the armature is closed.

Similar to the main patent, you can also use a Provide a parallel channel with a normally open bypass valve, this Channel in the present case a connection between the first pressure generator and forms the first brake circuit; As with the main patent, the bypass valve should only be closed during the scheme to get through here when scheme with a smaller Pressure gradient to work. This bypass valve can as in the main patent a Be a hydraulic valve and brake fluid flowing out during the control this valve can be closed.

The essence of the invention can also be used in systems where a hydraulic energy supply (e.g.

Pump and storage chamber) is used for brake actuation. here there is a hydraulic one in the connections of the two pressure generators with the brakes The control valve is switched on and the control pistons of these two control valves are switched on on the one hand a pressure dependent on the pressure in the associated brake circuit and on the other hand exposed to a pressure that is determined by the pressure regulated by means of the regulating device the hydraulic energy supply is dependent, this pressure on the control piston of the first circuit directly and in the second circuit via a throttle with a parallel-connected Unidirectional valve is effective.

Both in the above solution and in the solution with a control valve (at least) one safety piston can be provided which the pressure of the hydraulic energy supply or the pressure of the first brake circuit is exposed and migrates when this pressure disappears and thereby over a mechanical connection that keeps the control valve or valves open.

The regulation of the pressure in the second circle can be carried out as with the main patent can also be achieved by a second, ui'.-dependent control valve, which is between Pressure source and throttle are switched on.

You can use the invention in vehicles in which the wheel brakes Diagonally opposite wheels or brakes combined in axles lie in a circle. In the case of an axis-wise division, you can use both the front wheels as also assign the rear wheels to the first circle. In all of these cases preferably two front wheels transducers for the derivation of signals to Brake pressure control assigned. In the case of an axis-wise grouping, a third transducer is preferably provided on the differential and the two front wheel sensors are used for regulation in accordance with selectlow operation.

There can also be a temporary switchover to select-high operation Application.

When using the aforementioned three-position valve or a second Control valve are the sensors assigned to the individual brake circuits derived control signals for controlling the associated control elements or control positions used.

The transducers are preferably one after the other in a predetermined rhythm connected to a single-channel evaluation circuit that generates the control signals. When using the three-position valve or two control valves, the output of the channel an assignment of the successive signals to the brake circuit, from which they were derived.

With reference to Figures 1 and 2 of the drawing, exemplary embodiments of the invention are described and explained.

Vehicles are assumed to have the brakes on individual axes are combined to form brake circuits.

It is in Fig. 1 of the drawing a tandem master cylinder -l provided, which is actuated via the brake pedal 3 and a brake booster 2 will. The brake circuit connected at 4 contains the brakes of the front wheels 6, 7 of the vehicle. A three-position solenoid valve 8 is provided here as a control valve, that the pressure at its outlet rise or fall depending on the position or can keep constant. This valve 8 is in the one to the brakes of the front wheels 6, 7 leading brake lines switched on; it regulates the brake pressure accordingly the signals obtained from the transducers. The second output of the valve is connected to the return pump 9. The first output of the valve 8 is via a Throttle and a parallel unidirectional valve that provides a quick Pressure reduction in the cylinder chamber 12 allowed, connected to this cylinder chamber. In order to is the control piston 13 to the pressure building up via the throttle 10 at the outlet of the valve 8 exposed.

The line 5 is connected to the second output 5 of the master brake cylinder switched on, which fillirt to the brakes of the two rear wheels 14 and 15. In these Line 5 is connected to the valve 16, which is in the position shown of the piston 13 is kept open by this. The piston is on its left side the pressure exposed to the brakes of the wheels 14 and 15.

The two front wheels 6 and 7 are transducers 6 'and 7' and the A transducer 14 'is assigned to the differential of the rear wheels. These deliver Signals to the evaluation circuit 17, which is to be constructed with a single channel, and to which the transducers are switched on alternately. The signals from the front wheel sensors should by means of select-low operation with temporary switching to select-high operation be evaluated. The pressure at the output of the Valve 8 varies. If necessary, the longitudinal and transverse acceleration of the Vehicle to be included in the scheme.

A pressure in the valve chamber that is lower than the pressure at 16 12 due to the regulation causes the piston 13 to move to the right. This becomes a valve 16 closed and takes place because of the further migration of the piston 13 to the right also a pressure drop in brake circuit two. If the pressure builds up afterwards At the outlet of valve 8, pressure builds up in chamber 12 and thus in the brake circuit two because of the throttle 10 only langssni. A downward gradient is obtained here, which corresponds approximately to the pressure curve of FIG. 5a of the main patent, with the pressure curve the front wheels can still hold constant phases. The piston 18 is a Safety piston that closes (permanently) if brake circuit 4 fails of the valve 16 prevented. The valve 19, which is biased, should be at a certain large pressure difference trigger a pressure build-up on the brakes of the wheels 14/15.

Instead of valve 8, a valve corresponding to the three-stage valve can be used Use 25 of Fig. 2 of the main patent in the various configurations and then has the advantage that - with full design according to Fig. 2 of the main patent - the pressures in the two circles with constant hold in the other circle can be lowered separately.

In the embodiment of the invention shown in FIG. 2, the two Master brake cylinder for the two brake circuits 4 and 5 with the help of one at 20 and 21 (return) connected hydraulic energy supply actuated. In this In this case, the master brake cylinder 1 'can be controlled by means of the brake pedal 3' Shifted pressure. In the connections between the master cylinders and the axially combined brakes of the wheels 6 ', 7' and 14 ', 15' are control valves 22 and 23 switched on, their control spools ^ 4 and 25, which are normally the valves 22 and 23 keep open, on the one hand the pressures on the combined wheel brakes are exposed. In the control chambers 26 and 27 of the piston 24 and the piston 25, respectively the pressure prevails, which is normally the pressure of the hydraulic energy supply corresponds, but during the brake pressure control by means of the three-stage valve 28 corresponds to the regulated pressure with four connections at least in the control chamber 26. In the connection to the control chamber 27 there is also a throttle and non-return valve unit 29, corresponding to 10/11 of FIG. 1, or an equivalent member (see above) switched on. The valve 28 thus regulates the pressure in space 26 directly and temporarily over in space 27 the delay throttle, which usually results in independent closing the valves 22 and 23 and to reduce the pressure in the brake circuits by moving the piston 24 and 25 comes. The three-stage valve 28 releases the pressure in both chambers rise in one position connects space 27 in its second position with a return line and in its third position the space 26 with this Return line, so that separate pressure reduction occurs.

The safety piston 30 are the pressure of the hydraulic energy supply and are held in this position as long as pressure is applied. Falls lie F. allergy supply off, so keep them going by emigrating The valves open via the tappet 31 so that emergency braking is possible.

- patent claims -

Claims (1)

Claims / 1. Anti-lock control system according to patent .................. (Patent application 24 50 749.1), in which a first brake pressure generator Via a brake pressure control unit to vary the brake pressure when there is a tendency to lock influences a first brake circuit and in which this first brake pressure generator has the series connection of the brake pressure control unit and a throttle, which is a dem Pressure reduction serving unidirectional valve is connected in parallel, also the brake pressure influenced in a second brake circuit, characterized in that between one the brake pressure regulator assigned to the second brake circuit and the assigned wheel brakes a normally open hydraulic control valve is switched on and that a control piston is provided, on the one hand one of the brake pressure PR on the wheel brakes in the second circuit dependent pressure P (PR) and on the other hand via the parallel connection from the throttle and the unidirectional valve one of that from the brake pressure regulating device influenced pressure P5t dependent pressure P (post) is exposed and that the control valve and the control piston are arranged in relation to one another and the control piston in such a manner is designed that from reaching a certain size of the ratio P (Px) / P (PSt) of the piston pressures at the control piston migrates, and first the control valve closes and then an increase in the brake fluid causes the volume available between the control valve and the wheel brake. 2. Anti-lock control system according to claim 1, characterized in that that the brake pressure control unit is designed in such a way that it also maintains a constant value of the Claims apply pressure in at least one circle in the event of a pressure reduction in the other circuit. 3. Anti-lock control system according to claim 2, characterized in that that a three-position solenoid valve is provided. 4. Anti-lock control system according to claim 3, characterized in that that the three-position solenoid valve is designed such that it is in its first Position the output of the first pressure generator, in particular the master brake cylinder, with the first brake circuit and via the throttle with the control chamber of the control piston connects, in a second position interrupts the connection to the first pressure generator and a connection between said control chamber and a return line and in a third position additionally the first brake circuit with the Return line connects. 5. Anti-lock control system according to claim 4, characterized in that that the armature of the three-position valve has two closure bodies, one of which at least one is displaceable relative to the anchor, and one of which is in the The exit point closes the return line and the other in the second and third position the connection to the first pressure generator below: cbreak and also the first brake circuit via a one-way valve that allows a pressure build-up in it is connected, which is lifted from its seat in the third position of the armature is. 6. Anti-lock control system according to claim 5, characterized in that that the connecting line of the three-position valve with the first pressure generator, in particular the master cylinder and the first brake circuit via a pressure reduction unidirectional valve permitting in the first circuit are connected to one another. 7. anti-lock control system according to claim 5 or 6, characterized -characterized, that means are provided which in the third position of the armature the connection interrupt between said control chamber and the return line. 8. Anti-lock control system according to claim 7, characterized in that that in the connecting line leading to said control chamber a normally open valve is switched on, which due to the displacement of the Äiikers in the third position is locked. 9. Anti-lock control system according to one of claims 1 to 8, characterized characterized in that a normally open, but from the beginning of the brake pressure control closed bypass valve in a parallel channel between the first brake pressure generator and the first brake circuit is switched on, which has a faster pressure increase with open bypass valve]. permitted. 10. Anti-lock control system according to claim 9, characterized in that that the bypass valve is a hydraulically controlled valve and that the control chamber of the 3 control piston, this valve is connected to the return line in such a way that by the pressure medium flowing out during the regulation, a piston displacement and so that the bypass valve closes, which then remains closed, until the pressure of the first pressure generator drops. 11. Anti-lock control system according to one of claims 1 to 10, at the brakes using a hydraulic energy supply (e.g. pump with storage chamber), characterized in that the pressure generator for both brake circuits via a hydraulic control valve iJ each. with the associated Brake circuits are connected that the control piston of the first brake circuit assigned Control valve on the one hand a pressure dependent on the brake pressure of this circuit and on the other hand is exposed to a pressure which is determined by the means of the brake pressure control unit regulated Pressure of the hydraulic E energy supply is dependent and that. the other control piston on the one hand is exposed to a pressure dependent on the pressure in the other brake circuit and on the other hand, a pressure is applied which is determined by the means of the brake pressure regulating unit regulated pressure of the hydraulic energy supply and due to the activation the throttle and the unidirectional valve connected in parallel into the feed at times depends on the throttle. 19. Anti-lock control system according to one of claims 1 to 10, characterized characterized in that a safety piston is provided, the pressure of the first Brake circuit is exposed and a mechanical connection with the hydraulic Has control valve, such that the control valve is opened when the piston migrates due to failure of the pressure in the first brake circuit. 13. Anti-lock control system according to claim ii, characterized in that that for the two control valves at least one of the pressure of the hydraulic energy supply exposed piston is provided, and that this is a mechanical connection with the control valves, such that the control valves are opened when the pressure of the energy supply fails. 14. Anti-lock control system according to claim 1, characterized in that that a second brake pressure regulating device for the separate variation of the pressure in the control chamber connected to the control device via the throttle the first pressure generator, in particular the master cylinder, and the throttle switched on is. 15. Antiblock control system according to one of claims 1 to 14, characterized characterized in that in each case the brakes of diagonally opposite vehicle wheels are included in the brake circuits. Claims 16. Anti-lock control system according to one of the claims 1 to 14, characterized in that each of the brakes of the wheels of an axle are included in the brake circuits. 17. Anti-lock control system according to claim 16, characterized in that that the brakes of the rear wheels are included in the first brake circuit. 18. Anti-lock control system according to nspruch 16, characterized in that that the brakes of the front wheels are included in the first brake circuit. 19. Anti-lock control system according to one of claims 15 to 18, characterized characterized in that the two front wheels are transducers for brake pressure control assigned. 20. Anti-lock control system according to claim 19, characterized in that the control takes place when one of the two front wheels shows a tendency to lock (select-low). 21. Anti-lock control system according to claim 20, characterized in that that it is also temporarily switched to select-high operation. 22. Anti-lock control system according to claim 16 and 19, characterized in that that a Qleßwertgeber is also available on the rear axle when there is a tendency to lock the scheme triggers. 23. Anti-lock control system according to one of claims 19 to 22, characterized characterized in that the transducers assigned to the individual brake circuits derived signals can be used to regulate the pressure in the associated brake circuit. Claims 24. Anti-lock control system according to one of the claims 19 to 23, characterized in that the transducers in a manner known per se be switched one after the other to a single-channel evaluation circuit. 25. Anti-lock control system according to claim 24, characterized in that that switching means are provided which are derived from the individual transducers Distribute control signals to the control circuits of the associated control device.