DE2548973C2 - Dual-circuit brake system with load-dependent control for motor vehicles - Google Patents

Description

first

since

this one

vom urucKucr ei »« »-» »- -τ ·.-.-, _", - _it _ nruck- ast autgruna um * · «-» - -

circle the second piston

with the

mark, uau uci ^ v..v.

62) in addition to the area (52; 72) has a partial effective surface (53; 71) in a control chamber (47; 71a) in the actuating direction for the second piston from the regulated brake pressure controlled by the brake pressure regulator (11, 111) of the rear axle brake circuit is applied

2. Brake system according to claim 1, wherein the pressure medium is compressed air and the pressure transmitter Two-circuit motor vehicle brake valve with a relay piston as a second Koiben, the Relay piston in a (further) control chamber is acted upon by the pressure in the first pressure chamber characterized in that the two control chambers assigned to the relay piston (43, 44) (46, 47) by means of a ring (56) which is concentric to the relay piston and fixed to the housing in a pressure-tight manner from one another are separated.

3. Brake system according to claim 2, characterized in that between the ring fixed to the housing (56) and the relay piston (43,44) an intermediate ring (45) is arranged and that the ring and the Interchangeable ring to change the area ratio.

4. Brake system according to claim 3, characterized in that the annular surface of the intermediate ring (45) is acted upon by the pressure of the first pressure chamber and together with an active surface (52) of the Relay pistons (43, 44) form the active surface acted upon by the pressure of the first pressure chamber (33a).

5. Brake system according to claim t, wherein the pressure medium is hydraulic and the pressure transducer is a Tandem master cylinder is characterized in that the second piston with a shaft (62a) sealed by an exchangeable ring (119) fixed to the housing and protruding into the first pressure chamber (65) the partial effective area (71a) of the second piston of the Gradation between the piston (62) and the shaft (62a) is formed.

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necessary mitzuregeln the front axle to de decreed by regulations regarding BreSsdmmung between tractor and Appen ^dix% erM.iregelung the front axle gives a _f ew _r e% r? e7da ^g by that the brake pad wear? n the brakes of the motor vehicle in all partial brake

O'B ¹ -. . .

To Mitregelung oes Vorderachsbremskreises have since become known Äsungen where for dTvorderachse a special Mittelvent .. which be.n by the brake pressure of the rear axle lußt w.rd. m Finsatz comes ^J ". These valves represent a" eTeblfchen iusSchen effort. Moreover revealed Säfprobiem. that if the rear axle brake circuit fails, only a very low brake pressure is available for the brake circuit of the front axle

In order to remedy this problem, the aforementioned control valve is known with an additional hvo en - · ■ _{n and} failure-prone control mechants- • see the control valve of the front axle brake circuit in the event of a pressure failure in the rear axle

The invention relates to a braking force regulator that is controlled by an automatic load-dependent braking force controller Dual-circuit brake system in motor vehicles according to the preamble of claim 1.

Automatically load-dependent brake force regulators become

DT-OS 22 48 923 describes such a rear axle brake circuit control device, which is described as complex known, in which a special, a constant one for the co-regulation of the front axle brake circuit Transmission ratio having control valve is assigned, which is controlled by the pressure in the Rear axle brake circuit is acted upon in such a way that the transmission ratio is in the same direction as the control pressure in Rear axle brake circuit is changeable. At the same time, this control valve is equipped with an additional control device, a switchover valve, which, depending on the pressure in the rear axle brake circuit either with the regulated pressure of the rear axle brake circuit or with the unregulated pressure of the Front axle brake circuit is acted upon in such a way that when there is pressure in the rear axle brake circuit, the control pressure the same and when the rear axle brake circuit is depressurized, the pressure in the front axle brake circuit is effective, d. H. if the rear brakes fail, the front brakes are fully effective.

By the US-PS 3904253 is a load-dependent Control device for the rear axle brake circuit, its pressure transmitter as a tandem master cylinder In this control system, however, the front axle brake circuit is not also controlled; there the braking force control effect of the pressure transducer only in the event of failure of the front axle brake circuit In the rear axle brake circuit fully or partially canceled by controlling the full or at least higher brake pressure in the rear axle brake «© circle to achieve a greater braking effect of the rear brakes.

Based on the prior art known from DT-OS 22 48 923, the invention is based on The task is based on a load-dependent influence of the front axle brake pressure without an additional control valve for the front axle brake circuit.

The object is achieved according to the invention by the features listed in the characterizing part of claim I. Appropriate refinements of the invention can be found in the subclaims.

Embodiments of the invention are explained in more detail below with reference to the drawing. Show it

F i g. 1 functional diagram of the brake system according to the invention with pneumatic tandem brake valve,

2 functional diagram of the brake system according to the invention with hydraulic tandem master brake cylinder,

F1 g. 3 the principle diagram of a pneumatic tandem brake valve with the arrangement characterizing the invention,

F i g. 4 the principle diagram of a hydraulic tandem master cylinder with the arrangement characterizing the invention.

As shown in Fig. 1, lead from compressed air storage tanks 1 and 2 lines 3 and 4 to the Voriratsanschluen 5 and 6 of a two-circuit motor vehicle brake valve 7. The brake circuit I of the brake valve 7 is with its connection 8a via a line 9 with the connection 10 of an automatic load-dependent brake force regulator 11 in connection, the control connection 12 of which is connected to the pneumatic wheel brake cylinders 13 of the rear axle via a line 14 . The control connection 12 of the brake force regulator U is also connected via a line 15 to a connection 8 /> provided on the brake valve 7. The brake circuit II of the brake valve 7 is connected with its connection 16 via a line 17 directly to the pneumatic wheel brake cylinders 18 of the front axle.

In the case of the brake system according to FIG. 2 is a pneumatically operated hydraulic system in which a hydraulic tandem master cylinder is operated by a known pneumatic tandem pre-tensioning cylinder or by a known pneumatic tandem amplifier . Only the hydraulic part of the system is described below.

The brake circuit 1 of the tandem master brake cylinder 107 is connected with its connection 108a via the line 109 to the connection 110 of an automatic load-dependent hydraulic brake controller 111 , the control connection H2 of which is connected to the hydraulic wheel brake cylinders 113 of the rear axle via a line 114 . The control connection 112 of the brake force regulator 111 is also connected via a line 115 to a connection 108b provided on the tandem master brake cylinder 107 . The brake circuit II of the tandem master brake cylinder 107 is connected with its connection 116 via a line 117 directly to the hydraulic wheel brake cylinders 118 of the front axle.

The descriptions given with reference to the functional diagrams in FIGS. 1 and 2 only extend to the circuit of the system. Before the function of these systems is described, first of all - for a better understanding - on the basis of the schematic diagrams F i g. 3 and F i g. 4 went into more detail on the structure of the two-circuit motor vehicle brake valve 7 and the tandem master brake cylinder 107 and their devices will.

The two-circuit motor vehicle brake valve shown in FIG. 3 in tandem design, in which two inlet and outlet valves assigned to a brake circuit are actuated by adjusting the operating lever with the aid of a graduated piston and a relay piston, consists mainly of a mechanical one operable brake valve (1st circuit), and a controlled braking pressure from the 1st circuit relay valve (2nd circuit), which can also be actuated mechanically upon failure of the circuit by means of I. drag clutch.

The following description illustrates the structure of the brake valve and its function Necessary facilities within the system:

A valve housing 31, the interior of which is divided into an upper part (1st brake circuit) and a lower part (2nd brake circuit), contains valve elements in each part for regulating the pressure medium flow between the corresponding inlet and outlet openings. The upper part of the housing 31 is divided into an inlet chamber 32 and two brake air chambers 33a and 336, the chamber 33a being separated from chamber 32 by a valve seat 34a which is closed by a combined inlet and outlet valve element 35 when the brake is not actuated. This valve element is received by the retaining ring 36 at the upper end of a valve sleeve 37, which is arranged displaceably in an annular seal 38. The lower end of a spring 39 is supported on the web of the guide of the sealing ring, the upper end of which is in engagement with the retaining ring 36 of the valve sleeve 37 in order to press the valve element 35 into sealing engagement with the valve seat 34a.

A stepping piston 41, which is arranged displaceably in the brake air chamber 33a, has a non-positive connection via a spring element 40 with a brake pedal (not shown). When the brake is not applied, this piston 41 is held in the upper position by a spring 42 which is arranged between the bottom of the chamber 33a and the lower surface of the piston 41. During a downward movement of the graduated piston 41 , it comes into sealing engagement with the valve element 35 and opens the connection between the inlet chamber 32 and the brake air chamber 33a, which is connected to the VorratsanschluQ 5 - not shown here - so that there; Pressure medium via the outlet opening Fig. 1 Pos. 8a zi the brake force regulator and on to the Bremszylin which the 1st circle can flow.

In the lower part of the valve housing 31, a relay piston consisting of a piston 43 and a piston 44 separates two by an intermediate ring 4! separate control chambers 46 and 47 from a second brake air chamber 48. The two pistons 43 and 44 are mutually displaceable, whereby the piston 44 is spring-loaded when the brake is not actuated

49, which is in engagement with an annular surface of the piston 44, is pushed upward, so that when the control chambers 46 and 47 pressure medium from the brake air chambers 33a and 336 through bores 50 and 51 flow in, the active surfaces 52 and 53 acted upon and the pistons 43 and 44 move downward as a unit. When the bottom of the Piston 44 comes into engagement with a combined inlet and outlet valve element 54, that is Inlet valve 55a opened to the supply line 4 via supply connection 6 with the brake line 17 via To connect outlet connection 16. When the pressure builds up in the brake air chamber 48, it takes effect against the faces of the pistons 43 and 44 and moves them upwardly as a unit until the inlet valve port 55a and the exhaust valve opening 556 overlap. Thus, this valve works essentially like that at the beginning described valve of the 1st circuit.

After the overall structure of the two-circuit motor vehicle brake valve is described below, for a better understanding of the invention in detail to those with the invention in Related changes to the brake valve are included.

In the current two-circuit motor vehicle brake valve, the 1st circuit is mechanically operated Piston provided, while a pneumatically controlled valve for the normal function of the valve of the 2nd circuit Relay piston, which is controlled by the brake pressure of the first circuit, is provided. For controlling of the relay piston is its control chamber via a bore with the brake pressure chamber of the 1st circuit connected. It is essential that if the brake pressure fails in the 1st circuit due to mechanical actuation, by fully depressing the brake pedal, a modulation of the brake pressure to full Function of the 2nd circuit and thus to achieve the prescribed auxiliary braking effect is possible.

The invention solves the problem of co-regulation of the front axle as follows:

A division of the active area of the Rclaiskolbens acted upon by the braking pressure into two active areas

52 and 53 result in a division of the control chamber into sections separated from one another by the intermediate ring 45 Chambers 46 and 47.

The active area 53 is acted upon by the regulated brake pressure of the rear axle brake cylinder, while the active surface 52 is subject to the unregulated brake pressure.

An optional change in the situation » Brake force control of the front axle for brake force control of the rear axle is through a size change of the two working axes 52 and S3 of the relay piston can be influenced by the intermediate ring 45 on whose ring area is also affected by the unregulated brake pressure of the 1st brake circuit and with the active area

53 forms a common surface, can be exchanged together with the ring 56. Any desired Relationship of a braking force control between the two axles by installing a corresponding one Intermediate ring 43 and ring 56 with the corresponding Dimensions can be achieved. The valve is designed in such a way that a subsequent one can also be used Exchange of the intermediate ring 45 and accordingly the ring 56 is possible. So it is only through the Replacing these two parts changes the ratio of the effective areas 32 and 53, which means that the Dimensions of the relaunch piston 43.44 for all coming under different conditions to be installed Brake valves are always the same, which is a large production series and a simple subsequent Exchange benefits

If the rear axle brake circuit fails for any reason and with it the entire application of the corresponding active areas of the relay piston of the front axle brake circuit, remains at one Emergency braking - as already described - via the

to mechanical actuation to get the control of the full brake pressure in the front axle brake circuit. This also applies in the event that if the mechanical control of the load-dependent brake force regulator breaks, the regulator goes into the idle position, despite a full vehicle load and under normal braking conditions with a heavily loaded vehicle and regulator position empty, the prescribed auxiliary braking effect cannot be achieved.
The function of the two-circuit motor vehicle brake valve

jo tils is used below in connection with Fig.! and F i g. 3 described:

When the brake pedal is depressed, the graduated piston 41 moves downwards, closing the outlet 346 and opens inlet 34a. As a result, the water flows from the container 1 via line 3 and connection 5 - in FIG. 3 not - Coming compressed air from chamber 32 in chamber 33a via connection 8a and line 9 to Brake force regulator U and further, regulated according to the axle load, via line 14 into the brake cylinder 13 of the rear axle. In the process, a pressure builds up in chamber 33a under the graduation piston 4t at the same time via bore 50 in space 46 on active surface 52 of relay piston 43, 44. The second The effective area 53 of the Rclaiskolbens is with the regulated pressure for the rear axle via line 15. Connection 86 and chamber 336 acted upon. Under the influence of the two active surfaces 52 and 53 acting pressures moves the piston 43 and 44 existing Rclaiskolben against the force of the Spring 49 down: outlet 556 is closed and inlet 55 'is opened. Compressed air flows from the connection 6 ilbcr connection 16 in the brake cylinder 18 of the Front axle, which are ventilated in chambers 46 and 47 according to the controlling pressure.

The pressure building up in chamber 33a acts on the underside of the graduation piston 41, which thereby is moved upwards against the force of the spring element 40, up to both sides of the piston 41 In this position there are inlet 34a

jo and outlet 346 closed (final position).

In a corresponding manner move under the effect of the increasing pressure in chamber 48, the acts together with spring 49 from below on the pistons 43 and 44, this upwards until the

SS final position is reached, ie until inlet SSe and outlet SSb are closed.

If circuit II fails, circuit 1 continues to operate as described. In case of failure of the circle I control the relay piston falls away: Circle It

βο is activated mechanically - as follows:

When the brake is applied, piston 41 is pressed down. As soon as he touches the insert 57, which is firmly connected to the piston 44, further Downstroke also moves piston 44 downward. Outlet

"S SS6 closes, and inlet 55" opens. Circuit Ii is fully effective despite the failure of circuit I.

The above in connection with a two-circuit motor vehicle brake valve in a two-circuit pressure

air braking system described well in a similar manner also for a two-circuit or tandem master cylinder in a hydraulic two-circuit brake system.

The in Fig. 2 shows the functional diagram that the same circuit is used as in the functional diagram of a compressed air brake system shown in FIG. 1.

The normal function of the dual circuit or tandem master cylinder is as follows:

If the push rod piston 61 is actuated in the direction of the working piston 62, 62a, the Primary sleeve 63 pass over the compensating bore 64a and pressure chamber 65 of the 1st circle is closed; the brake fluid is under the pressure transmitted to it. As a pressurized liquid passes this on evenly on all sides, the pressure chamber 66 of the 2nd circle receives via the working piston 62, 62a and after passing over the compensating bore 67a through the primary sleeve 68 the same Pressure ratios. At the same time, the amount of liquid displaced in the pressure chamber 65 passes through the Bottom valve 69 and connection 108a in the 1st brake circuit and the amount of fluid displaced in pressure chamber 66 Via the bottom valve 70 and connection 116 into the 2nd brake circuit.

The expansion tanks, which serve as the storage chamber for the brake fluid, are connected to the tandem master cylinder via connection 64 of the first brake circuit and via connection 67 of the second brake circuit connected.

The working piston 62,62a, which consists of two parts, is provided with an annular piston surface 71, which via connection 1086 to connection 112 of the brake force regulator, which modulates the regulated brake pressure 111 is connected. Both the unregulated one thus act jointly on the working piston 62, 62a Pressure across piston surface 72 as well as the regulated pressure across piston surface 71. One optional Change in the ratio of braking force control of the front axle to braking force control of the rear axle is also here by changing the size of the two piston surfaces 71 and 72 or by replacing the The piston skirt (62a) and the ring (119) can be influenced.

In this master cylinder too, if one fails of the two circuits, the other brake circuit is maintained and thus the one prescribed by law Auxiliary braking effect achieved.

If, for example, a leak occurs in the 1st brake circuit, when the The brake pedal does not form any pressure in the pressure chamber 65, since the brake fluid escapes through the leakage point. In In this case, the surface 73 meets the surface 72 and mechanically transmits the pressure force via the working piston 62 to the pressure chamber 66. The 2nd brake circuit thus remains effective.

If a leak occurs in the 2nd brake circuit, it can no pressure occurs in the pressure chamber 66. The working piston 62 moves forward without resistance until the Surface 74 abuts surface 75. The 1st brake circuit thus remains effective.

For this purpose 3 sheets of drawings

Claims (1)

Patent claims: , Brake pressure in the brake cylinders adjusted ^ M ...-. ^! _d ^^ _{Fahrz s} dom respective ^ Bey ^"sz _hjeht automatically. adapt. This ^An P ^a _d ⁸ _e ⁵ _r ^u _A ⁸ _ch | _load dependent j from the / "*" "'" "