KR970001106B1 - A motor vehicle braking system with an anti-skid device - Google Patents

Abstract

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Description

Vehicle Braking System with Anti-Skid Device

1 is a schematic diagram of a first embodiment of a vehicle braking system having an HT braking circuit according to the present invention;

2 is a schematic diagram of a second embodiment of a vehicle braking system having an LL braking circuit according to the present invention.

* Explanation of symbols for main parts of the drawings

2: vehicle braking system 3: pedal

4 braking pressure source 5 anti-skid device

6: 1st left split brake 7: 2nd left split brake

8: first right split brake 9: second right split brake

10: first vehicle shaft 11: left normal brake

12 right normal brake 13 second vehicle axle

24: control device I, II: braking circuit

The present invention relates to a vehicle braking system.

In a dual-circuit braking system, known from US Pat. No. 4,460,963, having a normal brake on one axis and a split brake on another axis, the second split brake on each side is a valve. Connected to the device, the valve device is electrically controlled in a complex manner by special control logic in accordance with the operation of the two valve devices of the first split brake. Bosch Technische Berichte (technical report) An anti-skid device with a valve device of the type described in pages 7 to 87 of Volume 7 number 2 has four normal brakes. It is mass-produced at low cost for vehicle braking systems. Such an an-skid device comprises three or four valve arrangements as an example depending on the design of the two braking circuits of the vehicle braking system. It would be possible to impart additional skid control to the vehicle braking system according to US Pat. No. 4,460,963 using wheels of the second vehicle shaft using a mass-produced anti-skid device with four valve arrangements. The braking pressures of the two brakes of the second vehicle axle can only be adjusted according to the select-low principle. This has the disadvantage of having a long braking distance, in particular when there is a severe and unavoidable stress on the wheel being braked which varies with the shape of the vehicle. This drawback is especially found when the vehicle has short wheel spacing, high center of gravity, and relatively large load capacity in the boot. However, since such electric control valve devices and their logic are relatively expensive, each additional electric valve device increases the cost of the vehicle braking system to obtain a short braking distance.

According to the present invention, the vehicle braking system has a double-circuit braking pressure source and also has a left first and second split on one axis on one axis, which receives a braking pressure from both braking circuits, on the other axis of the vehicle. An anti-skid device having a brake and a right first and second split brake, and also having at least three electric control valve devices for regulating braking pressure, the first valve device being associated with each first split brake, The second valve device controlled by the intermediate pressure is inserted between the braking pressure cloud and the second split brake, connected to the first split brake by two built-in non-return valves, and according to the select-low principle. It is designed to adjust the braking pressure of the second split brake to the respective low braking pressure of the first split brake.

This has the following advantages, i.e. having a divided brake on one axle and an anti-skid protection on all the wheels, controlled by pressure mediated pressure and disclosed in Federal Patent Application No. 3631128. It is possible to use an anti-skid device which is already mass produced and inexpensively mass produced in combination with an inexpensive type of valve device. As a result, the cost for the electrically controlled valve device is low and does not require new production equipment. Moreover, there is no need to test anti-skid devices equipped with additional electrical control valve arrangements.

Development with a third valve arrangement controlled only according to the mesh of rotation of the associated wheel is associated with each complete brake.

This has the following advantages: despite the fact that it uses the existing anti-skid device with four electric control valve devices, the braking pressure of the wheel braking of the second vehicle axle is mutually dependent on each principle to reduce the braking distance. It can be adjusted independently. As a result, the adhesion coefficient between the wheeled roads to be braked can be used in an appropriate manner regardless of whether there are different friction conditions on the left and right sides, and whether the vehicle rotates the corners or loads the cargo more or less.

In another development, the third valve device of one complete brake is connected to one braking circuit and the other third valve device of another complete brake is connected to another braking circuit.

This has the advantage that two return pumps can be developed to reduce the cost.

The present invention is described with reference to the accompanying drawings by way of example only.

In the first embodiment of FIG. 1, the vehicle braking system 2 comprises a double-circuit braking pressure source 4 for braking circuits I and II controlled by a pedal 3 and an anti-skid device 5. ), The first left split brake 6 and the second left split brake 7 on the first vehicle shaft 10, the first right split brake 8 and the second right split brake 9, It has a left normal brake 11 and a right normal brake 12 on two vehicle axles 13. The brakes 7, 8, 11 and 12 belong to the braking circuit II and the brakes 6 and 9 belong to the braking circuit I. This braking arrangement is commonly known as an H braking circuit.

The double-circuit braking pressure source 4 is, for example, a tandem master brake cylinder in which a pneumatic braking force booster 14 is involved.

The anti-skid device 5 is located between the braking pressure source 4 and the brakes 6, 7, 8, 9, 11, 12. The anti-skid device 5 comprises four electrical control valve devices 15, 16, 17, 18, two pressure medium accumulators 19, 20, and two returns driven by the motor 21. A pump 22, 23, a control device 24, wheel rotation sensors 25, 26, 27, 28 connected to the control device 24, and a valve device 29 controlled by a pressure mediated pressure. do.

The valve arrangements 15, 16, 17 and 18 are in the form of three-way, three-position valves as shown in the figure, but may be replaced by a combination of two two- and two-position valves. In the normal position, the valve device 15 connects the starting circuit I to the first left split brake 6. The valve device 16 connects the braking circuit II to the first right split brake 8. In the normal position, the valve device 17 connects the left normal brake 11 to the braking circuit II, and the valve device 18 connects the right normal brake 12 to the braking circuit II. The valve devices 15, 16, 17, 18 can be switched to an intermediate position in which the three valve connection points are closed to each other. In the third position the valve arrangement closes the brakes 6, 8, 11, 12 from the pressure medium pressure coming from the supply pressure source 4. However, when the valve devices 15, 16, 17, 18 are in the closed position, the brakes 6, 8, 11, 12 have the form of a one-way valve and open in the direction of the braking pressure source 4. The pressure can be released by the safety bypass valves 30, 31, 32, 33.

In the third position, the valve device 15 connects the first left split brake 6 to the pressure medium accumulator 19 and the return pump 22. On the output side, the return pump 22 is connected to the braking circuit I. The pressure medium accumulator 19 and the return pump 22 belong to the prior art and need not be described. Similarly, when anti-skid protection is required, the valve arrangement 16 connects the first right split brake 8 to a pressure medium accumulator 20 and a return pump 23 connected to the braking circuit II on the output side. .

The valve arrangements 17 and 18 are identical and, when in the third position, the left normal brake 11 and the right normal brake 12 are connected to the associated return pump of the pressure medium accumulator 20 and the braking circuit II. 23).

The wheel rotation sensor 25 is associated with the valve device 15 and emits a pulse in the rotation of the associated wheel, which pulse is taken in the control device 24 to detect the risk of wheel lock. If there is a risk of wheel lock, the braking pressure of the split brake 6 is adjusted in a known manner by the valve device 15. Similarly, valve arrangements 16, 17, 18 can be controlled using wheel rotation sensors 26, 27, 28 and control arrangement 24. The braking force of the brakes 11, 12 is thus directly controlled by the valve devices 17, 18. In contrast, on the other hand, the valve devices 15, 16 directly control the braking force of the split brakes 6, 8, and are also controlled by the valve device 29 controlled by the pressure mediated pressure. Control braking pressure of 9) at the same time.

The valve device 29 includes a first control having a first non-return valve 34, a second non-return valve 35, a first control piston 37, a cylinder 36, and a second control. Coaxially arranged second control cylinder 38 with piston 39, rod 40 guided to seal between control pistons 37 and 39, two return springs 41 and 42 and a spring support plate. Has (43,44). The spring support plates 43, 44 are positioned next to the control pistons 37, 39 in the bore 45 opposite the rod 40, the bore 45 having a larger diameter than the control cylinders 36, 38. Have The return springs 41 and 42 are installed under prestress and act on the spring support plates 43 and 44. The annular shoulder 47 forms a transition between the bore 45 and the control cylinder 36. Similarly, another annular shoulder 48 is located between the control cylinder 38 and the bore 46. Annular shoulders 47 and 48 form stops for spring support plates 43 and 44. The force of the return springs 41 and 42 exerts an effect on the control pistons 37 and 39 only when the spring support plates 43 and 44 do not contact the annular shoulders 47 and 48. The return springs 41 and 42, together with the spring support plates 43 and 44, form a return device for aligning the control pistons 37 and 39 to their respective normal positions as shown in the figure.

The bore 45 defines a pressure chamber 49 connected to the braking circuit I. Likewise, bore 46 defines another pressure chamber 50 connected to braking circuit II. The control cylinder 36, together with the control piston 37, defines a control chamber 51 which can be connected to the split brake 6 by a non-return valve 34.

Thus, another control chamber 52, which can be connected to the first split brake 8 by a non-return valve 35, is located in the control cylinder 38. Non-return valves 34 and 35 have valve balls 53 and 54 and springs 55 and 56. Moreover, opening rods 57 and 58 are provided between the control piston 37 and the valve ball 53 or between the control piston 39 and the valve ball 54. The length of the control pistons 37, 39 and the length of the rod 40 are designed to fit snugly between the spring support plates 43, 44 against the annular shoulders 47, 48. The lengths of the open rods 57 and 58 are selected even if the valve balls 53 and 54 are raised from the valve seats 59 and 60 when the pistons 37 and 39 are in the normal position. Therefore, when the control pistons 37 and 39 are in the normal position, the control chambers 51 and 52 are subjected to the pressure present in the split brakes 6 and 8.

Moreover, the control chamber 51 is permanently connected to the second split brake 9 on the right side of the vehicle. Thus, the other control chamber 52 is permanently connected to the second split brake 7 on the left side of the vehicle. When the control pistons 37 and 39 are in the normal position, the same pressure is present in the first left split brake 6 and the second right split brake 9. The same pressure is also present in the first right split brake 8 and the second left split brake 7. During normal braking operation, i.e. without the risk of wheel locks to be removed, if the vehicle braking system 2 is activated and thus the same pressure acts on the braking circuits I and II, the associated left and right wheels are of equal strength. Is braked.

As described above, if the braking pressure of the spring brake 6 is reduced by the valve device 15, the pressure medium exits the control chamber 51 and passes through the first non-return valve 34 to the pressure medium accumulator ( 19) Go inside As a result, the braking pressure in the second right split brake 9 and the control chamber 51 drops. As a result, an excessive pressure is generated in the pressure chamber 49 due to the pressure of the braking circuit I, and the excessive pressure controls the first control piston 37 for the second control against the force of the return spring 42. It moves along with the piston 39. As a result of the movement of the second control piston 39, the closing spring 56 moves the valve roll 54 and the opening roll 58 in the direction of the second pressure chamber 50. Eventually, the valve roll 54 is placed on the balance seat 60 and the non-return valve 35 is in the closed position. Therefore, the pressure medium from the braking circuit II does not flow into the control chamber 52. As a result, the control pistons 37, 39 are further moved to increase the volume of the control chamber 52, thus reducing the pressure in the connected second left split brake 7.

Thus, the above-described valve device 15 reduces the braking pressure in the two left split brakes 6, 7 and further causes a decrease in the braking pressure in the opposing split brake 8. In addition to eliminating the risk of wheel lock on the left wheel, this also has the advantage that the difference in braking force between the left wheel and the right wheel is limited so that the control of the vehicle is improved. As a result, when the anti-skid operation starts on the left side due to the yaw moment generated by the difference in the braking force of the left and right, the risk of the vehicle moving without being controlled to the right is much reduced.

Due to the symmetrical structure of the valve arrangement 29, even when the braking pressure is decreased, the braking pressure in the second left split brake 7 is opposed to the first split brake 8 on the right side of the vehicle and the braking circuit II By means of a valve device (16). It can be seen that the valve arrangement 29 sets the same braking pressure at the connection associated with the second split brakes 7, 9, which corresponds to the lower of the braking pressures in the first split brakes 6, 8. have.

If the braking circuit I breaks down as an example while the braking pressure is generated by the braking circuit II, the lack of pressure in the pressure chamber 49 and the pressure coming from the braking circuit II are on the control piston 39. Due to the acting on, the control piston 39 acts in the open direction of the non-return valve 35. As a result, the second left split brake 7 remains fully operational. The above principle applies even if the braking circuit II leaks and only the braking circuit I has a braking pressure.

The valve arrangement 29 may be replaced by another valve arrangement in which the non-return valve and the control piston are associated in different shapes. This example is disclosed in the Federal Republic of Germany Patent Specification No. 3631128.

As noted above, a standard valve arrangement 29 may be used, and also in combination with a standard pressure medium accumulator 29, 20 and a standard return pump 22, 23, a standard valve arrangement 15, 16, 17, 18 Can be used, an anti-skid device for a vehicle braking system with a divided brake on one axis can be produced at low cost.

If the independent braking pressure adjustments in the left brake 11 and the right brake 12 described as an example are omitted, the braking pressures of both brakes 11 and 12 can be simply collectively adjusted by using the valve arrangement 17 as an example. have. In this case, a standard anti-skid device with only three electronic control valve devices can be used. In this form, two standard parts can be used to supplement the anti-skid device.

As shown in FIG. 2, the second embodiment of the vehicle braking system also has a double-circuit braking pressure source 4 for the braking circuits I and II controlled by the pedal 3, and an anti-skid device. (5), the first left split brake (6) and the second left split brake (7) on the first vehicle shaft (10), the first right split brake (8) and the second right split brake (9) And a left normal brake 11 and a right normal brake 12 on the second vehicle shaft 13. The brakes 6, 9, 11 belong to the braking circuit I and the brakes 7, 8, 12 belong to the braking circuit II. This corresponds to the EL brake circuit.

Due to this EL brake circuit, if the same friction coefficient occurs in the left and right wheels, the return pumps 22 and 23 supply the same amount of pressure medium when the anti-skid device 5 performs the anti-skid operation. must do it. Thus, the return pumps 22, 23 may be of the same specification or may be smaller than the embodiment of FIG. In the embodiment of FIG. 1, due to the H braking circuit, several brakes are associated with the return pumps 22, 23.

Since the vehicle braking system 2a operates in the same way as the vehicle braking system 2 in anti-skid operation, detailed description is omitted.

Claims (3)

A first left split brake, a second left split brake, a first right split brake capable of receiving a dual-circuit braking pressure source, a left and right complete brake on one vehicle shaft, and a braking pressure on the other vehicle shaft from both braking circuits; In a vehicle braking system having an anti-skid device having a second right split brake and also having at least three electrical control valve devices for adjusting the braking pressure, the first valve device being associated with each of the first split brakes. A second valve device connected and controlled by the pressure mediated pressure is inserted between the braking pressure source and the second split brake, connected to the first split brake by two built-in non-return valves, and a second split. Select-low principle to adjust the braking pressure of the brake to the low braking pressure of the first split brake Designed according to the vehicle braking system according to claim. 2. A vehicle braking system according to claim 1, characterized in that it has a third valve device, which is controlled only in accordance with the rotational aspect of the associated wheel, and associated with each complete brake. 3. A vehicle braking system according to claim 2, wherein the third valve device of one complete brake is connected to the braking circuit (I) and the other third valve device of the other complete brake is connected to the braking circuit (II).

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