DE1780667A1 - ANTI-LOCK CONTROL SYSTEM FOR A PISTON CONTROLLED HYDRAULIC BRAKING SYSTEM - Google Patents

Description

'JMS LDIX GmbH
69 Heidelberg
/ · ÖWnah ^ f er Weg 56

Heidelberg, June 28, 1972 E / Pt-Ka / Ba E-255-

Anti-lock control system for a piston-controlled (|

hydraulic braking system

The invention relates to an anti-lock control system for a piston-controlled hydraulic brake system for vehicles, in which in the connecting line: between the master brake cylinder and wheel brake cylinder (main pressure line) a valve arrangement is switched on, by means of which at Blocking tendency the braking force is temporarily reduced.

Brake systems are called piston-controlled brake systems understood, in which the brake actuation is effected by moving the Kolbens.des master brake cylinder, wherein it does not matter whether the shift is caused by the ™ Brake pedal takes place directly or via a brake booster. In the case of these brake systems, on the other hand, there is a so-called pump brakes, in which the braking medium is in a constant cycle, the difficulty that after a limited number of pressure drops the entire stroke volume of one of the pistons of the master cylinder has flowed out and the brake becomes ineffective. Even when using modulators to influence the braking force (e.g. from the magazine "Automobil Engineer", August 1965, pages J64 - 365 is known) the mentioned occurs Problem of the need for return conveyance of braking

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liquid does not open. In these systems, an auxiliary piston is used depending on the rotational movement behavior of the wheel moves, which in turn, if there is a tendency to block, first enters the connecting line between the master cylinder and wheel brake cylinder switched on, normally open, valve closes and then by moving one Modulator piston varies and the volume for the pressure medium enclosed between the valve and the wheel brake cylinder so that the pressure changes.

The earlier patent 1,555-472 has an anti-lock control system with the features mentioned above to the subject. For the return of the flowing out during the braking force control Pressure medium is there in the return line, a variable-volume storage chamber switched on, which the absorbs outflowing pressure medium during the control process and after the end of the braking process - i.e. after Disappearance of the brake pressure - the pressure medium via eiij. Check valve in the section of the connecting line located between the master brake cylinder and the valve arrangement promotes back. The storage chamber preferably has a movable one Wall that is under spring force.

This ensures that when you take the brake pedal back the amount of fluid that has flowed out into the brake circuit is funded back. But since the supply of brake fluid is already exhausted during a control process can be, one cannot depend on such a withdrawal and the resulting refilling of the printing cylinder permit. Usually the driver is frightened as a result of the sudden lack of braking action causes, in fact, unable to take the brake pedal back quickly enough.

The invention is based on this IJachteil to avoid and a device for automatic refilling of brake fluid in the main pressure line system to create during the regulated braking process.

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According to the invention, this task is carried out by those in the characteristic of claim 1 specified features achieved.

The dependence of the amount of brake fluid that is topped up or pressed in on the fluid content of the main pressure system and thus on the fluid requirement can be designed very differently. Essentially, there are two possibilities of measuring the amount drained or the amount still present (discharge or residual stock measurement). This will be discussed in more detail below. The best way to realize the invention is usually heavily influenced by the type of% braking system and the control system.

If the brake system has a brake booster and the anti-lock control system has separately controllable outlet and inlet valves as well as a so-called storage chamber, whose viand is movable and is under spring force and the one for the temporary reception of those drained during regulation Brake fluid is determined, then the invention can be realized that the connections of the two Chambers of the pneumatic cylinder of the brake booster depending on the degree of filling of the storage tank are interchangeable with simultaneous closing of the inlet valve. So for the purpose of refilling the " Pressures reversed on both sides of the pneumatic piston, whereby the one contained in the brake booster, Pneumatic control valve operated by the driver inoperative is set. The secondary piston consequently moves back automatically and and the storage chamber can move empty. Since the inlet valve is closed with priority during this time is held, the pressure drop on the brake has no effect.

For the refill device according to the invention, a snap mechanism for switching over at least one auxiliary pressure valve is proposed. "This snap mechanism is

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of one depending on the brake fluid content of the main pressure line system moving component can be actuated in such a way that a valve rod when falling below a certain minimum amount moves into one end position and when a certain target amount is exceeded in the other end position moves.

Under the main pressure line system, the cylinder of the Main or secondary piston and the connected main pressure line understood with all of its branches, up to those involved in the anti-lock control Valves. The moving component can after the first ™ mentioned method of discharge measurement the movable storage chamber wall be. However, it can also be done just as well by the method of measuring the remaining stock of the main pressure piston or an upstream joint member, e.g. the brake lever.

In the case of the aforementioned refill device, in particular, three-way valves coupled to one another can be used for Plan to swap the chamber connections and couple with the snap mechanism. The movable storage chamber wall activates the snap mechanism before the storage chamber is completely filled and thus initiates the return movement

»Of the secondary piston. Just before the storage chamber wall ■
When it reaches the empty position, the snap mechanism switches the two three-way valves over again suddenly and thus ends the refilling process. With an electrical differential pressure switch arranged between the two chambers, the contact of which is connected to the excitation winding of the inlet valve, the pneumatic pressure change can be detected and the inlet valve can be kept closed during the piston return movement.

An electrical snap switch, such as a toggle switch, can also be provided, similar to the snap mechanism at the end points of a certain idle path

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can be actuated by a component whose position is from Brake fluid content of the main pressure line system depends. This results in a particularly advantageous development the refill device described above, but the electromagnetically actuated three-way valves presupposes. Then, for example, the movable storage chamber wall is left operate the snap switch and switch it electrically so that the inlet valve has priority is as long as the pneumatic pressures are reversed. The differential pressure switch is saved.

Individual embodiments of the invention are explained in more detail below with reference to the drawing. For quick Orientation should be noted in advance that with all figures simple lines represent electrical lines, thick lines represent mechanical linkages or electrical ones Switching contacts, double lines with a small spacing are hydraulic and double lines with larger spacing are pneumatic Drilling lines. ;

Fig. 1 shows a refill device in a brake system ι with brake booster, whose pneumatic connections are reversed. The intended . Valves can be operated electromagnetically,

Fig. 2 shows a similar system with a purely mechanical Actuation of the switching valves by means of a snap mechanism.

In FIG. 1, a pneumatic brake booster directly controlled by a brake pedal 1 is designated as a whole by 2. Such a brake booster is, for example, the T $ Λ brake device from Alfred Teves KG, Frankfurt. This device contains a secondary piston 3 with a flexible sleeve acting as a valve and a suction air piston 4, which are rigidly connected to one another by a piston rod 5. The return spring is not specifically designated above the secondary pressure cylinder, which is through a line 7 the

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When the wheel brake is applied, there is a brake fluid reservoir 6, The wheel brake and the wheel brake cylinder are installed in the brake shield of a! vehicle wheel es 8 and nods specially shown «The well-known brake booster normally works so that connector 9 is on the left of the pneumatic piston with the intake manifold of the engine • Is connected, while the outside air via a connection 10 to the control valve built into a rubber sleeve 11 and through this has access to the right side of the pneumatic piston.

The anti-block control system exists in this brake system from an electromagnetically actuated inlet valve 12, which is built into the main pressure line 7, and one just such an outlet valve 13, which is one on the wheel brake cylinder connected outlet line 14 closes. If the outlet valve is open, brake fluid passes through a Line 15 enters a storage chamber 16 and pushes one Piston 17 'which closes one side of this chamber, against a spring 18, upwards. The piston represents the movable one Storage chamber wall. On the other hand, the storage chamber 16 is provided with a check valve 19 the main pressure line 7 connected.

The drive shaft 21 of a motion status transmitter 20 is gear connected to the wheel 8 and switches when it occurs of rotational accelerations and / or delays the inlet valve 12 and the outlet valve 13 so that when Braking achieves a wheel slip that is as constant as possible For the embodiments of Figs. 1 and 2 it is It is important that the two aforementioned valves are separated are controllable.

According to the invention, two three-way valves 22 and 'are shown in FIG. 23 provided. In the switching position shown, the upper connections are connected to the 'left outputs, while the right outlets are closed by plate-shaped valve bodies. A hose line 24 connects

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the upper connection of the valve 22 with the intake manifold a motor, not shown, while the upper terminal of the right three-way valve 23 "under atmospheric Air pressure. The two valve bodies are connected to one another by a valve rod 25, the left and protrudes from the valve housing on the right. On the left the rod carries a magnet armature 26 and. right-grips a tension spring 27 at. The storage chamber piston 17 carries a double cranked switch rod 28 for actuating a total of with 29 designated toggle switch, whose switching element is rotates about a pivot point 30. '

Provided the driver brakes and the anti-lock control system works for a particularly long time, so much brake fluid is transferred into the reservoir chamber 16 that the secondary piston 3 approaches its end position in which no further brake pressure generation is possible. Then the storage chamber piston 17 has risen so far that the bend 28a of the switching rod lets the toggle switch snap upwards. In this way, the current source labeled + is applied to the inlet valve 12 and to a switching magnet winding 31 at the same time . The inlet valve closes and the armature 26 is tightened. The switch at the three-way valves 22 and 23 so that the suction air connection is connected to the line 9 of the brake booster. As a result, the double piston moves to the right regardless of the position of the brake control valve, the brake pressure in the line 7 drops, but this does not affect the brake due to the closed inlet valve 12, and the. Storage chamber 16 is emptied via the check valve 19. As a result of the backward movement of the storage chamber piston 17, the bend 28b of the switching rod moves the toggle switch 29 down again. The three-way valves 22 and 23 switch back and restore the original mode of operation of the brake booster Inlet valve 12 is thus again

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subject exclusively to the controlling influence of the motion state generator 20. _{; s} ;

To further increase operational safety, a pressure switch 32 connected to line 15 is indicated, then operate the starter of the vehicle engine should when the storage chamber 16 is completely filled and, as a result, the brake pressure prevails in it. This condition normally does not occur, but is possible if the engine is not running on an incline is braked or the engine stops during emergency braking. There is then no vacuum for fast Return of the brake booster double piston.

The embodiment according to FIG. 2 differs from JTig, 1- by a purely mechanical unit 53 which contains the "two three-way valves 22 and 23", the storage chamber i'6 and a snap mechanism 3 ² ^ only indicated schematically for actuating the three-way valves. A switching lever 35 on the snap mechanism is moved, like the toggle switch 29 from Pig .. The Schnappmeehanismus then works so that when the lever 35 is moved upward, the ¥ entilstange 25 of the three-way valves is suddenly moved to the left, while.

to also here as in lig. 1 uring the polarity reversal of the brake booster 2 to keep the inlet valve 12 closed * a differential pressure switch 3 & is provided. This consists of a membrane 37 »which when moving downwards a switch for the inlet valve 12 closes. The hem _ -over the membrane. 37 is with the connecting line 9 and the ftaum connected to the connecting line 10 of the brake booster under the membrane. So if in the connection

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line 10 is negative, this switch closes.

Claims -

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Claims (4)

s * 0 claims 1. Anti-lock system for a piston-controlled hydraulic brake system for vehicles, in which in the connecting line between the master brake cylinder and. Wheel brake cylinder (main pressure line) a valve arrangement is switched on, by means of which the braking force can be temporarily reduced if there is a tendency to block, characterized in that for the return of the brake fluid to the main pressure line system, ft rend of the controlled braking process on for amplification the primary force provided brake booster whose connections depend on the ßreuisfluid content are interchangeable. 2. Anti-lock control system according to claim 1, wherein the valve arrangement is normally the master cylinder connects with the wheel brake cylinder, but temporarily this connection in the case of the braking force control locks and for Vermindex'iing the braking force the wheel brake cylinder vex'bindet with a liquid return line, which is connected to the outlet via a non-return valve of the master cylinder is in connection, where- W with a variable-volume storage chamber between the valve arrangement and the non-return valve for the temporary reception of released liquid ■ is switched on, characterized in that the connections of the two chambers of the pneumatic cylinder of a pneumatically operated brake booster are interchangeable .unct ^v that switching means are provided which when reached address a certain degree of filling of the Speichererkamsier and cause the exchange and the interruption of the connection of the master brake cylinder to the wheel brake cylinder. BATH ORIGiMAL 309829/0528 / Patent claims E-255 / 3 anti-blocking control system according to claim i, characterized in that that switching means are seen that make the interchange effective when the fluid present in the master cylinder is a minimum falls below. . _. 4. Anti-lock control system according to claim 3 _5, characterized in that, that a snap switch "is provided" which leaves the connections unaffected in a first position ^ on the other hand, makes the interchange effective in a second position and that this snap switch is in engagement with the brake pressure source that it is brought into its second position when the piston of the master cylinder is displaced beyond a predetermined position, which characterizes a minimum amount of brake fluid, and is switched back again when the piston is in another position, which characterizes a target amount. 5 »anti-lock control system according to claim 4, characterized., that the snap switch has an "electrical" contact for disabling the reversal actuated. Heidelberg, June 28, 1972
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