DE2164094A1 - BRAKE LOCK PROTECTION SYSTEM - Google Patents

Description

Annex to the patent and utility model application for the brake lock protection system The invention relates to a brake lock seat system with a wheel sensor, one with its valves in the brake valve unit and one electronic control unit, with the aid of which a brake pressure curve can be achieved is, which is quickly lowered after reaching the blocking pressure and then is quickly increased again.

Such a brake anti-lock system is known (D-OS 1 926 544). When you hit the brake cylinder again after the first blocking and release process, the renewed, reduced brake pressure in each case by a certain percentage lower than the previous blocking pressure. This Percentage is determined by the difference in area of a tax body. That has but the disadvantage that the highest possible brake pressure is not always achieved. This is especially true for vehicles with a large hysteresis of the brake pressure, such as I; KW's that require long brake lines.

It is also already known (CH 475 117) for anti-lock Brake systems control the brake pressure with the help of two separately electrically operated This makes it possible to use electronic Controls the pressure level after a brake pressure reduction for a specific e To keep time constant, -wherein the outlet and inlet valves are closed. "Constant'l" is also to be understood as meaning the case in which the pressure is very slow increases because the inlet valve is bridged by a throttle point. With plants with a large hysteresis of the braking pressures, however, the known device has disadvantages. Due to the large hysteresis, the brake pressure in the brake cylinder is reduced too far. This means that the wheel is accelerated strongly after the reduced phase and that within The switching point from "unthrottled" to "throttled" is reached in the shortest possible time. This starts the throttled pressure increase from a level that is too low. The result is a longer braking distance.

The invention is based on the object of avoiding these disadvantages uAd to create a brake anti-lock system which, after the first reaching of the Brake lock-up pressure works with the highest possible brake pressure and at which the Hysteresis of the brake pressure is overridden by the system.

This object is achieved according to the invention in that the blocking pressure can be stored in the electronic control unit, and that to determine a possible high, new pressure peak when the brake pressure rises again in each case brake pressure reached again with the stored locking pressure in the electronic Control unit is comparable, with the brake pressure achieved again at least in the order of magnitude of the hysteresis of the brake. This shortens the braking distance, because the mean brake pressure is very high.

An advantageous embodiment of the invention is according to a further Feature achieved in that zanlage with an el Electromagnetically operated double valve unit and an electronic control unit The two solenoid valves monitor the locking pressure in the wheel brake cylinder of the double valve unit can be actuated and readjusted separately, and furthermore the second electro-magnetic valve is preceded by a throttle valve that follows the first blocking protection process by closing the first solenoid valve is at least temporarily switched on and that the double valve unit with a known inductive pressure transducer is combined with a sensing element is subject to the pressure in the wheel brake cylinder.

An Ausführungsbeispie] - the invention is shown in the drawing namely show: FIG. 1 the double valve unit in section, FIG. 2 a diagram via the pressure curve in the case of anti-lock protection, Fig. 3 another version of the double valve unit, in which this is assembled with a safety valve.

An anti-lock braking system has a double valve unit 1, the into that of a brake valve 2 or - in the case of a hydraulic brake system - of a hydraulic master brake cylinder to a wheel brake cylinder in the 3 leading brake line 4.5 is inserted. The Dorjpelventil unit 1 is controlled electromagnetically with the aid of a vehicle wheel sensor 2 'and an electronic control unit 3'.

The electromagnetically controlled double valve unit 1 has two Pilot valves 6 and 7 with electro-magnets 6 'and 7', which are connected to the electronic Control unit 3 'are electrically connected and their armatures 8 and 9 each have a locking piece Actuate 10 or 11 of the pilot valves 6 and 7. -Each locking piece 10 resp. 11 monitors the connection of a main valve working space 12 or 13 either with a supply line connection 14 or 15 or with an outside air connection 16 or 17.

Each main valve 18 or 19 has a movable valve body 20 or 21, which is in a bore 22 or 23 against the force of a spring 24 or 25 is movable. Each valve piston 20 or 21 carries approximately in the middle of its length a valve closing body 26 or 27 and at his both ends Thickenings 28 or 29 and 30 or 31, which act as pistons. The two Pistons 28 and 30 facing the pilot valves 6 and 7 delimit the working spaces 12 and 13 as movable walls, and the pistons 29 and 31 have on their end face Outside air connection and are subject to the pressure of the ring surface 29 'and 31' Brake valve via a channel 32. This channel 32 leads to the first main valve 18 immediately, but it only reaches the second main valve 19 via a throttle point 33.

The first main valve is a 2/2 \ Jege valve. It only has one valve seat 34, which its valve closing body 26 can open or close to a brake line 5 leading channel to connect to the brake line 4 or to disconnect from it.

The second main valve is a 3/2-way valve. It has two valve seats 36 and 37, which are each arranged on one side of the valve closing body 27. Together with the valve closing body 27, one valve seat 36 monitors a connection the channels 35 and 38 with an annular space 23 'and the other valve seat 37 an outside air connection 39 of channel 38.

The valve seat 34 and the valve seats 36 and 37 each lie in one Annular space 40 and 41, in which the valve closing members 26 and 27 are movable. The annular spaces 40 and 41 are connected to one another via the connecting channel 38. The annular space 41 of the second main valve 19 is via a constriction 42 with a Working chamber 43 of an inductive pressure transducer 44 connected to the side the housing of the main valve 19 is attached and the one designed as a membrane Feeler member 43 'has.

The two main valves 18 and 19 are relieved of pressure by a combination of floating piston seals 45 and 46 or 45 'and 46' with insert sleeves 47 and 48, the Imit openings 49 and 50 for the Pressure medium passage are provided. The two main valves 18 and 19 of the double valve unit 1 are arranged one behind the other in the flow direction, so that the throttle point 33 is only connected upstream of the second main valve 19.

The anti-lock system described works as follows: im The driving condition of the vehicle is assumed by all parts of the double valve unit 1 in the position shown in FIG. If the brake valve 2 is actuated, pressure medium flows from the brake line 4 via the open main valve 18 into the brake line 5. It is braked.

If the braking is so strong that the braked vehicle wheel blocks, then get the magnets 6 'and 71 of the two solenoid valves 6 and 7 over the sensor 2 'and the electronic control unit 3' current, so that their armature 8 and 9 bring the valve closing bodies 10 and 11 into their other end position. The brake pressure, which had just led to the blockage is via the annular space 40, the channel 38 and the annular space 41 and via the constriction 42 into the working chamber 43 of the inductive Pressure sensor 44 arrives and was via this in the electronic control unit 3 'saved. In the diagram according to FIG. 2, point 1 has been reached.

Silver the switched solenoid pilot valves 6 and 7 arrive the working spaces 12 and 17 of the main valves 18 and 19 under supply pressure, and the Pistons 28 and 30 go down. Close valves 26 / yt- and 27/36. The valve 26/34 seals off the passage of the brake line 4/5, so that no further increase in pressure in the brake cylinder of 7 can take place Brake line 5 is via the channel 38, the annular space 41 and the open valve seat 37 connected to the outside air connection 39. Now the brake pressure is in the brake cylinder 3 lowered so far that the wheel is accelerated again; Point 2 of the diagram.

The sensor 2 'switches the electromagnets via the electronic control device 3r 6 'and 7' from, so that the pilot valves 6 and 7 and also the main valves 18 and 19 back to its original position. go back. via the now free formation connection the Breus line 4 and 5, a brake pressure builds up again quickly in the brake cylinder 3, which is, however, slightly lower than the blocking pressure previously achieved, period 3 of the diagram. By storing the blocking pressure with the help of the pressure transducer 44 in the electronic control unit 3 'and by comparing the stored blocking pressure With the pressure just reached it is possible to move point 3 close to the blocking pressure to move. In point 3, the solenoid of the pilot valve 6 is now switched on again, and the valve 2G / 34 is closed again. The only way to increase pressure is via that Valve 27/36 to which the throttle. 33 is connected upstream. That's why -the Pressure from point 3 on is less steep. Due to the position of point 3 near the blocking pressure the throttled pressure increase occurs from a relatively high level .. As a result, the wheel will be braked harder and the braking distance will be shortened, and it will the hysteresis is covered.

If within a with the electronic control unit 3 by a Timing device 60 predetermined time of the Blocking pressure not yet is reached, the magnet 6 'of the pilot valve 6 is switched off at point 4.

Now there is a rapid increase in pressure up to the blocking pressure When the time has expired, the pilot valves 6 and 7 are switched on. The brake is released again. The pressure curve then corresponds to the curve from point 1 at.

Fig. 3 shows a double valve unit 51, which largely just as is constructed like that according to FIG. 1. The same reference numbers have therefore also been used used. However, a safety valve 51 'is also provided here.

-This safety valve 51 'has a valve closing body 52t and a valve seat 53 in the outer air connection 39. A switching piston 54 is on the valve closing body 52 and has two piston surfaces of equal size. The top of the piston 54 is via a supply line 55 to the pilot valve 7 and the bottom of the piston 54 is connected to the pilot valve 6 via a supply line 56.

The safety valve is opened by a spring 57 arranged under the piston 54 51 common. held in open position.

When the brake pressure rises again from point 2 of the diagram (Fig. 2) and the armature of the magnet 7 'gets stuck, then the 2nd main valve 19 would always are in the open position, i.e. the brake cylinder 3 would be connected to outside air and the wheel could not be braked. This danger is according to the invention thereby avoided that in the event of failure of the magnet 7 'the supply pressure on the power 55 acts on the top of the piston 54. The safety valve 51 closes the outside air connection 39 from. In the brake cylinder 3 takes place despite the failure of the Magnet 7 'pressure build-up instead of when the Pun1X4; 3 reached in the diagram of FIG the magnet switches 6 ' one, so that the pressure build-up in itself would only take place in a throttled manner. 1Due, however, via the pilot valve 6 on the underside of the switching piston 54 is also pressure built up, the safety valve goes 51 in the open position, and the brake pressure can escape into the open again. The point 3 is fallen below again, the magnet 6! is switched off again. The bottom of the switching piston 54 is relieved. The piston 54 goes down again.

This switching sequence takes place in rapid alternation. In the approximate Pressure level of point 3. The rapid switching impulses can be in the electronic control unit 5 'sur - actuation of one of a Buhler 61 and a' warning ...

- lamp 62 existing warning device can be used.

The use of an inductive pressure transducer 44 in the braking system a motor vehicle also has the advantage that when diagnosing the motor vehicle the brake pressure can be recorded electronically.

Claims (8)

Expectations 1. Anti-lock protection system with one wheel sensor, one with its valves -in the brake engaging valve unit and an electronic control unit, with the help of the same a curve of the brake pressure can be achieved, which after reaching the blocking pressure is quickly reduced and then quickly increased again is characterized in that the blocking pressure in the electronic control unit can be stored, and that for determining a new pressure peak that is as high as possible when the brake pressure rises again, the brake pressure that has just been reached again comparable to the locking pressure stored in the electronic control unit is, the brake pressure achieved again at least in the order of magnitude of the hysteresis the brake is on. 2. Brake anti-lock system according to claim 1, characterized in that, that of the new, relatively high pressure peak at the brake pressure in itself is known to be delayed further increased by a throttle and that it is after a certain time predetermined by a timer by switching off the throttle can be increased quickly up to the new blocking pressure. 3. Brake blocker protection system with an electromagnetically actuated Double valve unit and an electronic control unit to monitor the blocking pressure in the wheel brake cylinder according to claim 1 or 2, characterized in that the two Solenoid valves (6,6 ', 7,7') of the double valve unit (1,51) can be operated separately and can be readjusted that the second --Elektro-solenoid valve (7 (7 ') a Throttle point (33) is connected upstream after the first anti-lock operation Can be switched on at least temporarily by closing the first electric flag valve (6, 6 ') is and that the double valve unit (1.51) with a known, inductive Pressure sensor (44) is combined, which with a sensing element (43 ') the pressure in the wheel brake cylinder (2) is subject. 4. Brake anti-lock system according to claim 3, characterized in that that the brake pressure reached during the first anti-lock process with the help of the inductive Pressure sensor (44) can be stored in the electronic control unit (3 '). 5. Brake anti-lock system according to claim 4, characterized in that that the duration of the storage of the brake pressure by a time measuring device (60) is limited. - 6. Brake anti-lock system according to one of the claims 3 to 5 with solenoid valves, each consisting of a pilot control and a pilot control and a main valve, characterized in that the actuation the main valves (18,19) required switching forces are reduced by a Combination of known, floating Schaitkolb endi chtringen (45,45 ', 46,46') with a well-known pressure relief, which is achieved by breakthroughs (49.50) in insert sleeves (47.48) of the valve bores is reached. 7. Brake anti-lock system according to claim 6, characterized in that that in an outside air connection of the second main valve (19) a safety valve (51 ') is arranged, which is provided with a switching piston (54), both of which Piston areas under the influence of supply pressure via one of each of the pilot solenoid valves (6,6 ', 7,7') connected supply line connection (55,56) are, and that the supply pressure Via the supply line connection (55) of the second pilot solenoid valve (7.7 ') acts on the safety valve (51) in the closing direction. 8. Braking protection layer according to claim 6, characterized in that that a warning display (61,62) is present, which in the safety switching case of the Safety valve (51 ') occurring, fast switching impulses over the electronic control unit (3 ') can be actuated.