DE3042125A1 - PRESSURE PRESSURE CONTROL VALVE FOR A TWO-CIRCUIT BRAKE SYSTEM - Google Patents

Description

-. 304212b

Description:

The invention relates generally to an anti-skid brake system, i.e. a so-called anti-lock braking system, for a motor vehicle and in particular a pressure control valve for a so-called dual-circuit brake system, which has the task of the increase from the input-side to the output-side pressure medium pressure in such a dual-circuit brake system to regulate.

A dual-circuit brake system with two brake circuits is used in motor vehicles as a result of the better reliability commonly used. Such a dual-circuit brake system has two basic designs: (1) with one In the first basic design, the brake system is designed in such a way that the pressure medium pressure from one of the outlets a tandem pressure cylinder or a tandem master brake cylinder to the right front brake cylinder and the left rear brake cylinder and the pressure from the other inlet to the left front brake cylinder and applying the right rear brake cylinder; (2) with another basic design there are two Brake cylinders are provided on each front wheel and the brake system is designed in such a way that the pressure medium pressure from one of the outlets of the master brake cylinder to one of the associated right and left front brake cylinders and the left rear brake cylinder and the pressure from the other outlet to the other of the respective right and left front brake cylinders and the right rear brake cylinder is applied.

3Q42125

The first basic design is an X-dual-circuit brake system and the second is called the J-J dual circuit braking system. With every brake system it is necessary to have a pressure control valve, like a limiting valve ... or a metering valve in the respective pressure medium pressure supply lines to the rear brake cylinders to provide the actual weight shift to compensate for the motor vehicle during the braking process. Therefore, common dual-circuit brake systems require two pressure medium pressure control valves. Through this difficulties arise with regard to the installation space and the design of the vehicle.

There is also a single valve arrangement for a two-circuit brake system has been proposed in which a pair of Zumeßventi! arrangements each have the pressure medium pressure control functions takes over for the front brake systems, these metering valve assemblies being arranged in parallel in a common housing. The respective piston elements of the valve assemblies are preloaded by means of a common spring, the applied to a common spring seat. In such metering valve arrangements, however, the pressure medium pressure at the beginning of the weakening of the increase in the rear wheel brake pressure, i.e. the critical pressure, constant, so that the distribution of the front and rear braking forces is constant.

As is known per se in this field, the braking force distribution must change with the change in vehicle weight change when you achieve such an ideal distribution of the front and rear braking forces which enables even braking of the front and rear wheels, and the aforementioned critical

. -. 3 U 4 ^ Ί ^ b

The hydraulic pressure should increase as the vehicle weight increases. That is why the pressure medium pressure control valve is unsuitable of the type described above for heavy goods vehicles and the like, their Weight changes greatly depending on whether they are empty or loaded.

To solve this problem, a so-called delay-sensitive valve has been proposed, which is provided in a single valve assembly having two metering valves. By providing the delay sensitive Valve, the characteristic values of the rear wheel brake pressure are dependent on the vehicle weight regulated.

The invention aims to create a pressure medium pressure control valve for a dual-circuit brake system, that is not only the aforementioned delay sensitive valve, but also a safety device which is such that if one brake circuit fails, the other brake circuit works in such a way that a front brake cylinder and a rear brake cylinder be actuated to brake the vehicle.

The invention accordingly provides a pressure medium pressure control valve for a dual-circuit brake system of a wheeled vehicle at. The valve has two parallel metering valve assemblies on, which are each provided with pistons, which are axially in a direction opposite to a common Spring as a function of the pressure medium pressure applied to the respective inlet connections are movable to the strength of the pressure medium pressure

to regulate the respective outlet connections, a ver- Delay-sensitive valve device that increases the strength of the on during normal operation of both brake circuits regulates the load acting on the common spring as a function of the degree of deceleration of the vehicle and a safety device which is designed such that when the first brake circuit fails a bypass passage between the inlet and outlet ports associated with the second brake circuit is formed to the pressure in the second brake circuit inlet port directly to the second brake circuit outlet port and which blocks and allows the bypass passage if the second brake circuit fails, that the pressure in the first brake circuit compresses the common spring to the critical pressure in the first brake circuit in accordance with the change in the rate of increase of the outlet port pressure of the first brake circuit to increase the inlet port pressure of the same.

A preferred idea of the invention lies in a pressure medium pressure control valve for a two-circuit brake system, which has two parallel metering valve assemblies with a common spring through which the respective Piston to regulate the strength of the pressure medium pressure at the respective outlet ports: i.n? - ".) Dependency preloaded by the pressure medium pressure applied to the respective inlet connections and a delay-sensitive one Has valve assembly of the ball type, through which the strength of the joint Spring acting load is regulated depending on the degree of deceleration of the vehicle, and that also has a safety valve device which is designed such that if a first one fails Brake circuit the pressure in the second brake circuit

BATH ORIGINAL

304212b

is applied directly to the outlet connection associated with the second brake circuit, and that if the second brake circuit, the pressure in the first brake circuit can compress the common spring to the critical pressure in the first brake circuit corresponding to the change in the rate of increase of the outlet connection pressure of the first brake circuit to increase the inlet connection pressure of the same.

Further details, features and advantages of the invention emerge from the description below of preferred embodiments with reference to the accompanying drawings. It shows:

Figure 1 is a vertical sectional view of a pressure medium pressure control valve according to the invention, which in a valve design a Dual-circuit brake system of a motor vehicle is shown,

FIG. 2 shows a diagram to illustrate the relationship between the printing cylinder pressure (Master cylinder pressure) and the rear wheel brake pressure,

FIG. 3 shows a diagram to illustrate the relationship between the vehicle weight and critical pressure, and

FIG. 4 is an enlarged sectional view of a main section an alternative embodiment according to the invention.

ORIGINAL _INSPECTED

In FIG. 1, a pressure medium pressure regulating valve according to the invention is shown, which is designated by 10 as a whole is. The valve 10 has a housing 12 in which a first valve piston chamber 14 and a second Valve piston chamber 16 are formed. These valve piston chambers 14 and 16 are parallel and open to an end surface 12a of the housing 12. Inside the housing 12 are also formed a first inlet port 18 and a first outlet port 20, which to the first Lead valve piston chamber 14, as well as a second inlet connection 22 and a second outlet connection 24, which lead to the second valve piston chamber 16. In the respective Valve piston chambers 14 and 16 are provided first and second control valve assemblies 26 and 28, the have the task of selectively the pressure medium flow between the inlet and outlet ports 18 and 20 and between the inlet and outlet ports 22 and 24 to pass and interrupt.

The control valve assemblies 26 and 28 are metering valve assemblies with matching construction. For reasons for the sake of clarity, only the structure of one of these metering valve assemblies 26 and 28, for example the metering valve assembly 26 will be explained, which is assigned to the first valve piston chamber 14. For a better understanding, however, the corresponding parts of the other valve assembly 28 are added a "'" after the corresponding reference number in the Marked drawing.

A piston 30 is arranged axially movably in the first valve piston chamber 14. The piston 30 has on his left end a blind bore 34 in which a cone valve or poppet valve 32 is received. Through a-

- ίο -

The open end of the blind bore 34 is used to pry a valve seat 36 firmly connected, on which the poppet valve 32 is preloaded by means of a spring 38. When the piston 30 moves to the right in the drawing to a certain position / becomes the valve cone of the poppet valve 32 forced that it is seated on the valve seat 36 by the action of the spring 38. As a result, the passage between the inlet and outlet ports 18 and 20 is blocked. The length of the Shank portion 40 of the poppet valve 32 is determined such that it is on the left side of the valve seat 36 protrudes. Thus, when the piston 30 is in its extreme left position, the front part of the contacts Shaft portion 40 lbenkaxnmer the bottom of the Ventilko lbenkaxnmer 14, whereby the valve body of the poppet valve 32 of the valve seat 36 is withdrawn so that the poppet valve 32 assumes its open position.

The valve seat 36 has openings 42 which are used for production a connection between the outlet connection 20 and the interior of the valve seat 36 and the piston 30 has openings 44 which are used to establish a connection between the inlet connection 18 and the blind bore 34 serve. The valve piston chamber 14 tightly encloses a sleeve 46 which has a small diameter Surrounds portion of the piston 30 leaving a gap. The sleeve 46 has openings 48, which serve to establish a connection between the inlet port 18 and the space. From this it follows that in the open state of the poppet valve a free passage for the pressure medium between the Inlet and outlet ports 18 and 20 is formed.

The piston 30 is from the open end of the valve piston chamber 14 as shown. The right-hand end section of the piston 30 is secured by means of a holding ■ device 50 out, which is inserted into the valve piston chamber 14 and by means of a sealing element 52 is sealed.

The protruding ends 30a and 30a ^{1 of} the pistons 30 and 30 ″ contact a flange section 54a of a cylindrical spring holder 54. The spring holder 54 receives a plastic bushing 56 in a central bore 54b is slidably movable, the rod-shaped guide element being fixed in a housing 12. A spring 60 is arranged between the flange portion 54a of the spring holder 54 and a spring seat 62 and is compressed between them, as will be explained in more detail below. The spring 60 thus presses the pistons 30 and 30 * of the control valve assemblies 26 and 28 in such a way that the poppet valves 32 and 32 ″ remain in their open position. For the reason given in more detail below, the cross-sectional area of the central opening of the bushing 56 at the section on the right gradually increases depending on the distance approximately from the central section of the bushing opening to form a conical space 59 between the section of the rod-shaped guide element 58 on the right and the right-hand section lying portion of the bushing 56 as shown.

The components, such as the spring 60, the spring holder 54, the socket 56, etc. are in a cylindrical hollow part 64a of a housing 64 of a delay-sensitive

Chen valve assembly 56 housed. The housing 64 is connected to that previously described via a sealing plate 68 Housing 12 connected. Another spring 70 is housed in the cylindrical hollow section 64a / which is arranged between the spring seat 62 and the sealing plate 68 and between these components is compressed to bias the seat 62 in a rightward direction. In the housing 64 are a cylindrical chamber 72 opening to the inner space of the cylindrical part 64a and a ball chamber 74 formed. The chambers 72 and 74 are in communication via a passage 76 formed in the housing 64 is formed. A valve seat 78 is attached to the open end of the passage 76 in a location where which is exposed to the chamber 74.

A piston 80, which forms one piece with the spring seat 62 described above, is sealingly and slidably movable arranged in the cylindrical chamber 62, around an expandable or enlargeable working chamber 72a between the piston 80 and the bottom of the chamber. An air vent valve 62 is on the housing attached to establish communication with the working chamber 72a. A ball 84 is in the ball chamber 74 movably arranged. The ball chamber 74 is closed by means of a plug 86. A corresponding Number of grooves 88 is formed in the wall of the ball chamber 74, which serve to the first and to bring second chamber sections 74a and 74b in communication, which are formed in front of and behind the ball 84 are.

In the pressure medium pressure control valve 10 according to the invention a switch valve assembly 90 is also provided.

BATH ORIGINAL

seen, which serves as a safety device, i.e. as a failover. The switching valve assembly 90 has a stepped cylindrical bore which is formed in the housing 64. the Bore includes a large diameter portion 92 and a small diameter portion 94 which are coaxial are aligned. The open end of the bore is closed by means of a plug 96, in which an inlet port 98 is formed which connects to section 92. In the hole a piston 100 is axially and movably arranged. The piston 100 has a projecting circumferential part 100a, which is slidably received tightly in the large-diameter portion 92 around the same to be divided into first and second chambers 92a and 92b. The chambers 92a and 92b stand, respectively with the ball chamber 24 and the environment via respective passages 102 and 104, which in FIG the housing 64 are formed. The end of the piston 100 on the left is tightly closing and sliding movably received in the small-diameter portion 94 of the bore to between the left lying End of the piston 100 and the bottom of the Kammerabschnittε 64 to form an enlargeable or expandable working chamber 94a. The working chamber 94a is with both Inlet and outlet ports 106 and 108 in communication formed in the housing 64. A rubber ring 110 is attached to the leftmost end of the piston 100 such that the piston the connection between the inlet connection 106 and the working chamber 94a closes when the piston 100 occupies its leftmost position. To ensure that the connection is blocked, a Valve seat 112 attached to a portion with the

the rubber ring 110 cooperates. A feather is arranged in the second chamber 92b of the larger-diameter bore portion 92 and this is between the piston 100 and the plug 96 are pressed together to close the piston 100 to block the connection between inlet and outlet ports 106 and 108 preload. As can be seen from the following Description results, in the normal state of the brake system, the piston 100 is located furthest to the left Position held so that only the passage between the inlet port 28 and the ball chamber 24 is open is.

When the pressure medium pressure control valve 10 according to the invention is mounted in a vehicle body, it is mounted in an inclined position that an angle "Θ" is present with respect to the axis "K" of the vehicle body, so that in the normal state of the valve 10 the ball 84 is in contact with the plug 86 by its own gravity, in order to thereby achieve the To open passage 76 between the ball chamber 74 and the enlargeable working chamber 72a.

In the actual application of the valve 10, the inlet ports 98 and 105 are with the outlet ports, respectively 116a and 116b of a tandem printing cylinder (Tandem master cylinder) 116 connected. The inlet port 18 is with the right front brake cylinder and the outlet port 116a of the master cylinder 116, while the outlet port 20 is connected to the left rear wheel brake cylinder 120 is. The inlet port 22 is to the left front brake cylinder 122 and the outlet port 116b of the

BAD ORiGSHAL

Master cylinder 116 connected while the exhaust port 24 is connected to the right rear wheel brake cylinder 124. A brake pedal 126 is applied the tandem brake master cylinder 116 to identical pressure medium pressures at outlet ports 116a and 116b to deliver.

Similar to a conventional metering valve, each piston 30 or 30 'has a section with a diameter b' and a section with a diameter b ", where b _{1 is} greater than b ₂ .

The terms b-, b ₂ and b ₃ are used in the following mathematical equations. Of course, these variables are to be understood as the effective areas of the respective areas b ₁ , b and b, and not as their diameter.

When the brake pedal 26 is depressed while the brake system is working, in order to ensure that the master brake cylinder 116 _{delivers pressure medium pressures P ^ and P M2} to the outlet connections 116a and 116b, these pressures P ₁ and P ₂ (in practice P .. = ^{1 >} m2 ^ ^to ^ ^en right front wheel brake cylinder 118 and the inlet port 18 and the left front wheel brake cylinder 122 and the inlet port 22. These master cylinder pressures P ₁ and P _M2 are also transmitted directly to the assigned rear wheel brake cylinders 120 and 124, respectively, since at the start of work Of the master brake cylinder, the poppet valves 32 and 32 'are kept open

act in this state on the associated pistons 30 and 30 ', results from the following equations, in which the force generated by the spring 60 is denoted by F.

(where P _M1 = P _M2 - P _M )

_{(P M} = P _R1 -P _R2 -P _{R #} applies here, and P _R1 and P ″ denote the pressure medium pressures at the outlet connections 20 and 24, respectively).

If the pressure medium pressure P _{M of} the brake master cylinder rises due to the constant actuation of the brake pedal 126 in such a way that it satisfies the following equation,

P _M xb ₂ > lx F (3)

the pistons 30 and 30 'move against the force the spring 60 to the right and the poppet valves 32 and 32 * are closed, whereby the connection between the respective inlet and outlet ports and 20, 22 and 24 is interrupted. Thus the Pressure transfer to the rear brake cylinders 120 and 124 blocked. In this state, the following equilibrium equation results:

P _M χ (L ₁ - b ₂ ) + j χ F = P _R χ b ₁ (4) ^b 1 " ^b 2 F

If the pressure medium pressure P _{M of} the master cylinder rises further as a result of the constant actuation of the brake pedal 126, the pressure P _M acts on the differential area b ₁ -b and causes the pistons 30 and 30 'to return to their starting positions and the poppet valves 32 and 32' again open, the rear wheel brake pressure increasing with a smaller slope 1 ~ 2 , as shown by the curve ¹ bc in FIG. In this way, the undesired slipping of the rear wheels or the blocking of the same is avoided.

During the procedure described above, b3.eibt the switching valve assembly 30 in the position shown in Figure 1, in which the "connection between the inlet and outlet ports 106 and 108 blocked and the connection between the inlet port 98 and the Ball chamber 24 is made. This is due to the fact that the piston 100 is not only due to the force the spring 114, but also by the force to the left is preloaded, the product of the effective area differences between the protruding in the circumferential direction right-hand end face of the piston opposite chamber 92 and the left-hand end face of the piston opposite the chamber 94 and the master cylinder pressure.

Only the master cylinder pressure is applied to the ball chamber 74 from outlet 116a through inlet port 98 and passage 102 to reduce the delay

to operate sensitive valve assembly 66 in the manner described below.

As is known, when the master cylinder pressure P "increases, the braking force" B "also increases and the deceleration" 00 " 1 obtained by dividing the braking force" B "by the vehicle weight" W "also increases, as can be seen from FIG the following equations yields:

B = C χ P _M (6)

(C is a constant)

OC _ B

~ g - w

"bc"

When the delay ratio is a predetermined Reached a value determined by the inclination angle "θ" of the valve 10 with respect to the vehicle axis "H" is, then it follows

(f (OO: a function of "Θ").

With this deceleration ratio, the ball 84 in FIG. 1 moves against the force component due to its own weight the acceleration of gravity in the direction of the angle of inclination "Θ-" to the left to open the Valve seat 78 to close. Even if the master cylinder pressure P., continues to increase in this state, the pressure acting on the piston 80 at this point in time remains constant at that value when the ball 84 closes the opening of the valve seat 78. The pressure

P_ in the expandable working chamber 72a results G

BAD ORlGfNAL

30 (2125

from the following equation:

P _G = ^ - x W (9)

The force which pushes the piston 80 to the left in FIG. 1, which is determined by the product of the pressure P "and the

Qj

Pressure receiving area b_, of the piston 80 is determined, the sum of the forces F and F ^{1 of} the springs 60 and 70, so that the following equation results:

F + F ¹ = P _r . χ b-, = ± 7 ^ 2. _x b, χ W (10)

Cj j C -J

The force F causes the pistons 30 and 30 'to be pushed to the left in FIG. 1 and the force F ¹ is absorbed by the sealing plate 78, which is arranged between the housing 12 and the housing 64.

The forces F and F "are each obtained by adding the value obtained from the products of the travel of the piston 80 ^ ^ χ and the spring constants k ₁ and k ^ of the springs 60 and 70 to the nominal loads f ₁ and f _{2 of} these springs added at the point in time P = 0. Thus the relationship between F and F 'results in the following way:

= f ₉ + * 2_ (F - f.) (11)

The following results from equations (10) and (11):

(12)

C -3 »- v * 2 K ₁ M ' ^K 1

On the other hand, the critical pressure P results from

of equation (2) as given below:

^P s ⁼ 2bJ

When the equation (12) is put into the equation (13) is set, the following results:

^{1 (f} 2 -

2b ₂ (1

(14)

K ₂

If (f "- - f)> O results, a ratio of the critical "pressure P to the vehicle weight is obtained

W according to FIG. 3. As can be clearly seen from this diagram, the critical pressure P rises as it increases Vehicle weight W on.

If the intersection point b in Figure 2 with increasing vehicle weight is higher, the rear wheel brake pressure P_ also increases. For example, if the vehicle is half loaded the rear wheel brake pressure P increases in accordance with the characteristic curve shown by a-b "-c", which essentially represents an ideal state that is known per se.

If part of the braking system, including the brake cylinder 122 for the left front wheel, fails, remains the piston 100 of the switching valve arrangement 90 in the position shown in Figure 1 and the blocking of the connection between inlet and outlet ports 106 and

ORIGiMAL IiMSPECTED

108 and the connection between the inlet port 98 and the ball chamber 74 are maintained. This is due to / that the switching valve assembly 90 is designed such that it maintains the position shown, whether the inlet port 106 receives pressurized fluid from one brake circuit or not, provided / that the other brake circuit including the brake cylinder 118 for the right front wheel is working normally. Thus, even if such a failure occurs, the delay sensitive valve assembly 66 will operate normally in substantially the same manner previously described. However, the metering valve assembly 28 does not operate. The piston 30 ′ therefore remains in the position shown in FIG. When the pressure medium pressure in the normally operating brake system, which includes the right front wheel brake: cylinder 118, increases, the piston 30 of the metering valve assembly 26 moves against the force of the spring 60 to the right. Thus, the spring retainer 54 gradually tilts to pivot about the point at which it contacts the piston 30 '. This inclination is achieved by the conical space 59 which is formed between the rod-shaped guide element 58 and the bush 56. Then the spring holder 54, ie specifically the flange portion 54a thereof, moves away from the projecting end 30a ^{1 of} the piston 30 'and slides with the bushing 56 on the rod-shaped guide element 58, whereby the poppet valve 32 is closed. At this point in time, the spring 60 only acts on the metering valve arrangement 26. The following equation is therefore obtained;

^b i - ^b 2 F

P _R = - ± —1 xP _H ^ (15)

Thus, one obtains a greater braking force / which is shown in Figure 2 by A-B'-C ¹ and that only in / that only one brake circuit of the brake system operates / contains the right front wheel brake cylinder 118th This compensates for the lack of braking force, which is caused by the failure of the other brake circuit.

From a practical point of view, if you fail of a brake circuit, the brake pedal 126 is depressed with a force twice as large as that of those who is required when both brake circuits are working normally in order to obtain the same braking force, as if both brake circuits are working normally. Therefore, if a brake circuit fails in practice, the one in the expandable working chamber 72a enclosed pressure P when operating the delay-sensitive valve arrangement 66 is twice as large as when both brake circuits are working normally. When pressing down hard of the brake pedal 26 to a rapid deceleration of the vehicle in such a malfunction is achieved dtiher, that the path of movement of the piston 80 due to the increase in the pressure P_ trapped in the chamber 72a (i.e. the compression travel of the spring 60) twice as large as when both brake circuits are working normally, so that the rear wheel brake pressure including the metering valve arrangement corresponding to that designated by a-b '"- c" · in FIG Characteristic increases. Thus, a greater braking force is obtained using only a single brake circuit.

It should be noted here that the rear wheel brake pressure indicated by the intersection point b "'has a value which is greater than the value which in practice of

ORIGINAL

is supplied to the master cylinder. This means that if a brake circuit fails, the left Includes front brake cylinder 122, the left rear brake cylinder 120 receives a pressure medium pressure which is essentially equal to the pressure P 1 of the master brake cylinder is. Thus, sufficient braking force is obtained using only a single brake circuit.

Similar conditions arise if the other brake circuit, which contains the right front wheel brake cylinder 118, fails, the piston 100 of the switching valve arrangement 90 moving into its rightmost position against the force of the spring 114 due to the lack of pressure medium pressure in the chamber 92 whereby communication between inlet and outlet ports 106 and 108 is opened. In this state, the master cylinder _{pressure P M} is thus applied directly to the right rear brake cylinder 124 via the connections and 108, unaffected by the metering valve arrangement 28. Sufficient braking force is also obtained here.

As can be seen from the above description, is in the pressure medium pressure control valve according to the invention the delay-sensitive valve assembly 66 is only present in one of the brake circuits, so that a malfunction Brake circuit is not a malfunction of the other brake circuit brings with it. Furthermore, the switching valve arrangement 90 ensures sufficient braking force even if a brake circuit fails.

FIG. 4 shows a modified embodiment of the aforementioned switching valve arrangement 90. For reasons of clarity, the same or similar parts as in the design according to FIG. 1 are provided with the same reference numerals. The modified embodiment of the switching valve assembly 90 'has a regular cylindrical bore 92' which is formed in the housing 64 and a piston 100 "which has a protruding peripheral part 100'a which is sealingly and slidably movable in the cylindrical bore 92 ' was added. as shown, the pressure acting area formed on the lying to the left side of the protruding circumferential portion 100'a is the same as that. with formed on the rightmost side of a spring 114 ^1, between the right side of the protruding circumferential portion 100'a of Piston 100 and plug 96 is compressed, piston 100 "is held in its leftmost position, as shown, which it occupies during normal operation of both brake circuits and in the event of a failure of one brake circuit including inlet and outlet ports 10 and 108 . If, however, the other brake circuit is disturbed, the modified embodiment of the switching valve arrangement according to FIG. 4 operates in the same way as the switching valve arrangement 90 according to the embodiment described above.

Claims (4)

PATENTA-NWÄLTF-- Α .. GRUNECKER CWl- IC «H. KINKELDEY □ RING W. STOCKMAIR K. SCHUMANN DR KER ΝΛΤ ■ DIPL-PHVS P. H. JAKOB DIPL-lfgG. G. BEZOLD Dft RERNAT .-- DIPU-CHBVl NISSAN MOTOS CO., IiTD. No. 2, üakaxa-ciio Kanagawa-ku Yokohama City Japan 8 MUNICH MAXIMILIANSTRASSE P 15 677 November 7, 1980 Pressure medium pressure control valve for a dual-circuit brake system Patent claims 1. Medium pressure control valve for a dual-circuit brake V 'system of a wheeled vehicle, marked net through: two parallel metering valve assemblies (26, 28) each provided with pistons (30, 30 ') which
axially in a direction opposite to a common spring (60) depending on the respective
The pressure medium pressure applied to the inlet connections (18, 20) can be moved to regulate the strength of the pressure medium pressure at the respective outlet connections (20, 24), TBLBFON (OSS) 33 28 09 TELEQRAMMS MONAPTH TELECOPER a delay sensitive valve assembly (66) which, during normal operation of the first and second Brake circuit (116a, 116b) the strength of the common spring acting load depending on the degree of deceleration of the vehicle regulates, and a safety device (90) designed in such a way is that it creates a bypass passage between the inlet and outlet ports when the first brake circuit (116a) fails, so that the pressure in the second brake circuit inlet connection is transmitted directly to the second brake circuit outlet connection, and that the safety device (90) blocks the bypass passage when the second brake circuit (116b) fails, and allows the pressure in the first brake circuit to compress the common spring to the critical pressure in the first brake circuit in accordance with the change in the rate of increase of the outlet port pressure of the first brake circuit rises to the inlet connection pressure of the same. 2. Druckmitteldruckregelventxl according to claim 1, characterized ζ e I net that the delay-sensitive Valve arrangement has a piston (80) which at one end has the common spring carries, and that the piston is sealed in a bore (72) to form a closed expandable working chamber (72a) is arranged, which in connection with a spherical chamber (74) stands, in which a ball (84) is movably arranged. BAD ORiGiNAL 3. fluid pressure control valve according to claim 2 characterized ze ichnet _f that said safety device: a housing having a bore (92, 94, 92 ') and first, second, third and fourth passages (106, 108, 98, 102) that is related to this Standing bore, the first and second passage each with the second circle (116b) associated inlet and outlet ports (22, 24) and the third and fourth passages each with the inlet connection associated with the first brake circuit (116a) (118) and the ball chamber (74) of the delay-sensitive valve arrangement are, · a piston (100, 100 ¹ ) which is axially movably arranged in this bore to selectively achieve two states, wherein in the first state the first and second passages establish a connection, but the third and fourth passages are blocked, and in the second state the first and second passages are blocked, but the third and fourth passages connect, and a biasing device (114, 114 ') which biases the piston (100, 100') to its second position. 4. Pressure medium pressure control valve according to claim 3, characterized in that the Pressure-receiving surface of the piston, which is acted upon by the pressure of the second brake circuit inlet connection is smaller than the other pressure receiving area of the piston, which is from the pressure of the first brake circuit inlet port is applied.