DE3118164A1 - BRAKE LOCK PROTECTION DEVICE - Google Patents

Description

ROBERT BOSCH GMBH, 7OOO Stuttgart 1

Brake blocking device

State of the art

The invention is based on a brake lock protection device according to the preamble of the main claim. Such a one Brake lock protection device is known (DE-OS 26 56 983). However, this known device requires a special type of preload cylinder. In addition, with the directly controlled hydraulic 2/2 solenoid valves, only relatively small valve cross-sections need to be monitored. When applied Such small valve cross-sections are not sufficient in commercial vehicle brake systems.

Advantages of the invention

The anti-lock device with the characterizing features of the main claim has the advantages that such conventional series production can be used as a prestressing cylinder. Since the 2/2 valves are pilot operated, they can be made larger and monitor larger valve cross-sections. After all, it is with a vehicle with hydraulic brake on the front axle and with pneumatic brake on the rear axle the electrical control

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The same for both axes because the pilot solenoid valves required for controlling are the same. Other advantages of the invention emerge from the subclaims and from the description drawing

An exemplary embodiment of the invention is shown in the drawing and explained in more detail in the description below. They show: FIG. 1 a schematic diagram of a brake

in section} anti-lock device with a valve unit / i Figure 2 a modification of the detail of the valve unit and figure another detail of the valve unit ·

Description of the embodiment

A hydropneumatic brake device has a brake valve 1 which feeds compressed air from a container 2 into a control line or vents the latter to the outside air. The control line 3 leads to a housing h of a valve assembly 5 in which a 3/2 valve 6 and two 2/2 valves 7 and 8 are arranged next to one another.

The 3/2 valve 6 has two valve seats 9 and 10, an inlet valve seat 9 and an outlet valve seat 10, between which a closing element 11 is arranged, which alternately one of the two valve seats 9 and 10 can cover. Daa valve 6 has an inlet connection 12 from which a control channel 13 is branched off, the one inlet valve seat 1 ^, 15, 16 of three electromagnetically operable Pilot valves 17, 18 and 19 leads. One outlet seat each these pilot valves 17, 18, 19 bears the reference number 20, 21 or 22.

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The three valves 6, 7 and 8 each have a control chamber 23 »2k, 25, which are closed by a respective membrane 26, 27> 28 · and connected to the respective inlet-Ventilistz lh, 15 _S 16th The membrane 26 carries a plunger 29 for actuating the closing body 11, and the two diaphragms 27 and 28 of the 2/2 valves 7 and 8 also carry plungers 30 and 31, which are intended for actuating a ball as closing body 32 and 33. On the other hand, a spring-loaded plunger 3k or 35 is placed on each ball closing body 32 or 33, which endeavors to keep the ball closing body 32 or 33 away from a valve seat 36 or 37. It can be seen that the two valves 7 and 8 have relatively large valve cross-sections. In a modification of the design shown, the two valves 7 and 8 can also be designed as slide valves.

The control line 3 continues behind the 3/2-way valve 6 in a line 3 ′, which leads to an air side 38 of a prestressing cylinder 39. This pretensioning cylinder 39 is of a type that is customary for brake systems, ie no special production is required. A hydraulic side ko of the prestressing cylinder 39 supplies a hydraulic brake line kl with brake fluid, which comes from a refill container k2. The brake line kl is routed to the two valves 7 and 8 in the valve unit 5 and is divided there into two brake line branches k 1 'and kl ", which lead to wheel brake cylinders k3 and kk arranged on vehicle wheels.

The rotation of the vehicle wheels is monitored by sensors U 5 and k6, which are connected to an electronic control unit ^ 7. Electrical connection lines for the electromagnets kö, k9 and 50 of the pilot valves 17, 18 and 19 are also routed to this.

The device described works as follows: As the drawing shows, in the anti-lock device according to the invention, the brake pressure modulation takes place on the compressed air side through the 3/2 valve 6 and on the hydraulic side with the aid of the two 2/2 valves 7 and thereby the two 2/2 hydraulic valves T and 8, as well as the air valve 6, are pilot-controlled by compressed air fed into the control chambers 23 »2k and 25 via the pilot valves 17» and 19. This has the advantage that the two hydraulic valves 7 and 8 can be designed as simple, problem-free ball valves and that the cross-sections in the valves 7 and 8 can be relatively large, because the valves 7 and 8 - each provided with a pilot control also under switch over larger forces safely. In this way, valve cross-sections up to h mm in diameter can be used.

In addition, the brake valve 1, the valve unit 5 and the preload cylinder 39 are separate components, the Brake valve 1 and the preload cylinder 39 are common series products. All parts 1, 5 and 39 are through pipes connected with each other. With such a design, the installation of a conventional load-dependent brake force regulator is necessary simply possible by inserting it either into the air control line 3, .3 'or ... into the hydraulic brake line 1 * 1, U1 ', lH "begins.

Finally, it can be seen that due to the special type of air control of the hydraulic valves 7 and 8, the creation a brake concept is possible for a vehicle, whose front axle is hydraulic and whose rear axle is hydraulic braked with compressed air. The front axle brakes were there to monitor with a valve unit 5 according to the present invention and the rear axle with a valve

aggregate, 'as it is for example door operator BE-OS 27 53 992 (Pressure control valve 22) is treated. The electronic control for both valve units could be the same and be carried out by the same electronic control unit.

The following is to be said about the operation of the valve unit 5:

A brake pressure reduction in the case of anti-lock protection is carried out by the central 3/2 valve 6, and a pressure holding function is carried out with the two downstream, hydraulic 2/2 valves 7 and 8; 'It takes place a brake pressure V _-, reduction via air pressure reduction in the control line 3 ¹ and by volume uptake by the retreating master cylinder piston in the opening cylinder 39 · And a brake pressure maintenance is carried out alone in the hydraulic circuit. Two-channel control is provided by the possibility of blocking the respective wheel brake cylinder pressure from that in the other brake cylinder. However, since a hydraulic fluid is incompressible in principle, the same opening times of the two valves 7 and 8 must be prevented in order to avoid pressure equalization of the two brake cylinders k3 and kh. This is made possible by the fact that the two valves are clocked shifted during pressure build-up phases. There is no functional disadvantage because the pressure build-up phase (hold valve open) is approximately 1: 6 in relation to the pressure hold phase (hold valve closed) and asynchronization can therefore be achieved very easily. With this simple measure, different braking pressures can be achieved in the two Brqmszylindern i + 3 and hk even when using hydraulics as the pressure medium.

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On the other hand, however, there are also vehicle states in which only a certain one is used to limit the yaw moment Differential pressure in the two brake cylinders are allowed allowed. This can be achieved by allowing a time-limited synchronous Venitlan control in this case will.

There is thus the possibility of controlling the valves 7 and 8 synchronously to control the pressure difference in the two To eliminate brake cylinders, to control a maximum pressure difference by asynchronous control of valves 7 and 8, or, depending on the ratio of the temporally synchronous to asynchronous control, only a certain one To control differential pressure.

For example ^ LSt executable that with a pulsed, flat pressure build-up with an opening duration of the valves 7 and 8 of e.g. 10 msec, the ratio of synchronous to asynchronous control of k: 6 is selected and thus the brake cylinder with the higher pressure level in relation to the lower pressure level of the other brake cylinder can only take a certain pressure difference.

It is also conceivable that the valve control during the regulated braking process is time-dependent or vehicle speed depending on the ability to change from synchronous to asynchronous modulation. At "beginning of braking or at high vehicle speed the greatest limitation of the yaw moment is given by the synchronous valve control, towards the end of the braking a greater yaw moment is then permitted by a more asynchronous control.

This measure relieves the driver significantly in the mostly critical braking phase, but towards the end of the braking process, the driver is relieved the greater differential pressure also achieves greater braking

In order to optimize the time behavior of the pressure rise and also the pressure drop, as can be seen from FIG. 2, an additional throttle adjustment can be made with the aid of a throttle 51 in the brake line K ^- I ^1.

For these circuitry measures, it may be necessary, when using simple master brake cylinders for the anti-lock regulation additional measures are required. With these simple and therefore also cheap A sniffer hole control is used in a known manner for master brake cylinders when not braked to connect the piston chamber to the refill container.

With such sniffing hole controlled master cylinders there is the risk that the piston sleeve due to the dynamic pressure in the sniffer hole in the event of rapid braking is pressed in and can be damaged in the process. Therefore, master cylinders with a tilt valve are better suited can achieve high braking pressures even with very small piston strokes. In order to still use the sniffing hole controlled To be able to use the master cylinder for the anti-lock control, the following additional measures are according to the invention conceivable.

1.-As the figure 2 shows, is in the brake line

^ 1 + 1 between the prestressing cylinder 39 and the valve unit 5, a pressure accumulator 52 connected with a small storage volume (approx. 2 to 5 cm), the storage pressure of which is below the brake pad application pressure lies.

This pressure accumulator 52 prevents the piston cuff is pressed into the sniffer hole when the master brake cylinder is actuated quickly, resulting in a malfunction can come.

The pressure accumulator '52 can of course be installed in the valve unit 5 be integrated.

2. Another way to protect the piston machine from damage to protect is given by the fact that in the case of blockage protection regulation driving over the sniffer hole the piston sleeve is prevented from returning the piston.

This is made possible by the fact that in the brake pressure control unit in the line connection of the 3/2-way valve 6 to the Outside air, as can be seen in Figure 3, a retaining valve 53 is arranged, the closing pressure of which is below the brake shoe application pressure lies. As a result, as a rule, there remains a residual pressure in the prestressing cylinder 39, which means that it is completely released allows the wheel brake, but does not allow the piston sleeve to pass over the sniffer hole.

For normal braking, on the other hand, the pre-tensioning cylinder is completely vented directly via the brake valve.

Claims (12)

■ · Λ 2.1+. 1981 He / Wl ROBERT BOSCH GMBH, 7000 Stuttgart 1 Expectations 1.jBrake anti-lock device for the wheels of a motor vehicle with joint control of the brake pressure in at least two brake cylinders, in which a common 3/2 valve is used for the brake cylinder and a separate 2/2 valve is used for each brake cylinder, hciJ * f? erner a hydropneumatic brake system is used in which the 3/2 valve is inserted into an air line leading from a brake valve to a prestressing cylinder and the 2/2 valves are inserted into a hydraulic brake line leading from the prestressing cylinder to the brake cylinders, characterized in that the 2/2-way valves (7, 8) are designed as pressure medium-actuated valves and that the actuating pressure medium is branched off from a pressure medium line (control line 3) which is pressurized during braking. 2. Brake lock protection device according to claim 1, characterized characterized that both the 3/2 valve (6) and the two 2/2 valves (7, 8) Main valves piloted via pilot valves (17s 18, 19) are. - 2 - 3 3. Brake lock protection device according to claim 1 or 2, characterized in that the pilot-controlled pressure medium is the same for all three valves (6, 7, 8). k. Brake lock protection device according to one of "Claims 1 to 3j, characterized in that the 2/2 valves (7 and 8) each have a ball (32, 33) as a closing body and that each ball (32, 33) is supported on both sides by a tappet ( 30, 31; 3 ^, "$ [>) can be actuated. 5. Brake lock protection device according to one of claims 1 to 3, characterized in that the 2/2 valves as Slide valves are formed. 6. Brake lock protection device according to one of claims h or 5β, characterized in that a pressure accumulator (52) is connected to the brake line (U)) between the prestressing cylinder (39) and 2/2 valve (7) (Figure 2). 7 · Brake lock protection device according to one of the claims 1 to 6, characterized in that the pressure medium for actuating the valves (6, 7, 8) is compressed air and that the by the two 2/2 valves (7, 8) controlled pressure medium is hydraulic. 69 5 8. brake lock protection device according to claim 7 j thereby characterized in that during the anti-lock control process, a brake pressure reduction primarily by lowering the pressure in the compressed air circuit and a holding function is carried out in the hydraulic circuit. 9. Anti-lock device according to claim 8, characterized in that for different brake pressure control in the two brake cylinders (k3, hk) the pressure build-up phases with the two valves (7, 8) are clocked out of phase. 10. according to 9 » characterized in that the phase shift of the pressure build-up phase during the controlled braking can be changed as a function of time or speed. 11. Brembsbloekierschutzeinrichtung according to any one of claims 8 to 10, characterized in that to optimize the Time behavior when the pressure rises or falls, a throttle (51) is used, which is inserted into the brake line (Ui ') is. 12. Bremsbloekierschutzeinrichtung according to any one of claims 8 to 11, characterized in that there is a retaining valve in the line connection of the 3/2-way valve (67) to the outside air (53) is inserted (Figure 3)