SE452294B - BLOCK PREVENTION VEHICLE BRAKE SYSTEM - Google Patents

Description

452 294 amplifier (compare, for example, the article "Système de freinage électronique pour véhicules industriels", the magazine "Ingenieurs de l'automobile", no. 12, 1971, p. 716, fig. 6). The electromagnet-controlled brake pressure relief valve is normally closed, while The electromagnet-controlled brake pressure holding valve is normally open, and the valves are connected to a brake valve and the actuating unit via a main pipeline and a common duct.

This braking system ensures - compared to the first, anti-lock braking system described above - more efficient braking and requires a lower working medium consumption by limiting the brake pressure relief phase by means of brake pressure maintenance, which is ensured by switching on the corresponding electromagnetic control valve at a time.

However, the order in which control signals are transmitted to the electromagnetically controlled valves affects the operability of said known braking system with a three-phase duty cycle. If the electromagnet-controlled pressure relief valve is switched on (activated) too early, the working medium is consumed excessively, and the braking effect is considerably reduced, which in other words means that the vehicle's driving speed decreases slowly, so the braking distance increases. If the electromagnetic pressure holding valve in this case is in the initial position, which can happen when the electronic control unit is incorrectly actuated, the brake system is transferred to critical condition because the pressure source to which the brake system is connected is directly connected to the atmosphere through the two electromagnetic valves. During the brake pressure relief phase, the brake system normally only works when the two valves are switched on at the same time, which leads to a considerable consumption of electricity.

An object of the present invention is to eliminate these disadvantages.

The main object of the invention is to provide an anti-lock braking system which has high operational safety and requires low electric power consumption by changing the constructive design and arrangement of the device for controlling the actuating unit of the braking system in such a way that the electromagnet-controlled veins The wheels can work individually during different phases of the braking system's workflow.

This is achieved according to the present invention by means of a blocking-preventing vehicle brake system comprising an electronic calculation unit and an actuating unit, which is connected to an electromagnet-controlled brake pressure relief valve and a normally open electromagnet-controlled brake pressure holding valve, which valves are connected to one of the vehicle driver added the first and second outputs of the electronic calculation unit, respectively, through a first and a second power amplifier, respectively, the electromagnet-controlled brake pressure relief valve, according to the invention, being normally open and arranged in the main pipeline between the electromagnet-controlled brake pressure stop valve and the brake valve. The electronic control unit comprises a two-channel shaper for shaping control signals occurring at different time intervals, the outputs of which are intended to function as the first travel unit of the electronic calculation unit. respective second output.

The anti-lock braking system described above can operate during the brake pressure relief phase and the brake pressure holding phase by separately connecting the corresponding electromagnet-controlled valves, so that the electric power consumption can be reduced.

If it is taken into account that a current of almost 100 A must be used for connection of the electromagnet-controlled valve in the specific known anti-lock braking systems and that a vehicle with a trailer requires at least twelve electromagnet-controlled valves when independently steering each wheel, It is clear that by using the braking system according to the invention a considerable saving of electric power can be achieved. In addition, when the solenoid-operated valves operate separately, disturbance pulses generated when switching high currents can be significantly reduced and which can cause malfunctions of the electronic unit to control the solenoid-operated valves of the system.

Nor can the system of the present invention - unlike the known 452 294 brake system used as a prototype - directly connect the pressure source to the atmosphere at any combination of signals for controlling the electromagnetic pressure relief and pressure hold valves, which increases the blocking prevention the system's functional safety and traffic safety. This is of particular importance during prolonged braking conditions, for example when driving on mountain roads (along slopes) and in quarries.

In order for the braking system according to the invention to be easily constructed of the known, most often useful components, it is suitable that the inputs of the two-channel shaper for forming control signals occurring at different time intervals are connected to a per se known shaper for synchronously emitted signals, which has a first output for outputting a signal with a longer duration and a second output for outputting a signal with a shorter duration. The two-channel shaper for forming control signals occurring at different time intervals may in this case comprise an inverter, the input of which is connected to the second output of the shaper for synchronously output signals, and an AND gate, one input of which is connected to the output of the inverter and whose second input is connected to the first output of the synchronous output shaper.

The first output and the second output of the electronic calculation unit must in this case be the second output of the synchronously emitted signal former and the output of the AND gate, respectively.

The invention is described in more detail below with reference to the accompanying drawing, in which Fig. 1 shows a block diagram of the anti-blocking system according to the invention, Fig. 2 shows an embodiment of the electronic calculation unit in the anti-blocking system according to the invention, Fig. 3 shows a second embodiment of the electronic calculation unit, Fig. 4 ae shows time diagrams explaining the operation of the units in the anti-blocking system with the electronic calculation unit designed according to Fig. 2, and Fig. 5 ae shows time diagrams clarifying the operation of the units in the blocking prevention system with the blocking system according to Figs. 3 designed the calculation unit. The anti-lock braking system comprises an electronic calculation unit 1 (Fig. 1), which is electrically connected to a speed sensor 2 for a vehicle wheel, and an actuating unit 3, which is connected to the unit 1 by means of electromagnetically controlled brake pressure relief valves 4 and brake pressure valves 4. 5, which are connected by a main pipeline 6 to a brake valve 7 which can be operated by a vehicle driver.

The valves 4 and 5 are connected to the first and second output 8 and 9, respectively, of the electronic calculation unit 1 by a first power amplifier 10 and a second power amplifier 11, respectively, and intended to form a device for controlling the influencing unit in combination with the unit 1 and the amplifier 10, 11. 3.

The calculation unit 1 can have a different constructive design and can, if required, be based entirely on the known electronic calculation unit in the known anti-lock braking system. An electronic calculation unit is described below as an example, which mainly consists of the calculation unit in the blocking prevention system known from U.S. Pat. No. 3,861,756.

The electronic calculation unit 1 comprises on the one hand a converter 12 (Fig. 2) for converting the speed signal for the vehicle wheel to a voltage, which is converted as the input of the unit 1 simultaneously functioning input is connected to the sensor 2, on the other hand a derivation circuit 13, and a former 14 synchronously output signals, which is electrically connected to the converter 12 and the derivation circuit 13, and on the one hand a two-channel former 15 for forming control signals occurring during different time intervals.

The per se known former 14 comprises a first, a second and a third comparison unit 16, 17 and 18, respectively. One input of the first comparison unit 16 is connected to the output of the converter 12 and its second input is connected to an output of a unit. 19 for approximating the speed of movement of the vehicle, which unit 19 is built up of a capacitor and a direct current output circuit. The input of the unit 19 is also connected to the output of the converter 12. One input of the second comparator unit 17 is connected to the output of the derivative circuit 13 and its second input is connected to an output of a so-called delay threshold shaper (a slowing threshold shaper) 20, which consists of a memory element. The third comparison unit 18 is similarly electrically connected to the derivation circuit 13 and an acceleration threshold shaper 21, which is also constituted by a memory element.

The output of the synchronously emitted signals 14 is connected to a first and a second AND gate 22 and 23, respectively. The inputs of the first AND gate 22 are connected to the outputs of the first and second comparator units 16 and 18, respectively, while the second AND gate 23 inputs are connected to the 16 and 17 outputs of the first and second comparison units, respectively. The output of the first AND gate 22 is intended to function as the first output 24 of the former 14, which is intended to emit a signal of longer duration, while the output of the second AND gate 23 acts as the second output 25 of the former 14, which is intended to start time emit a signal of shorter duration.

It is clear that the generator 14 for synchronously emitted signals can be constructed in another known manner, for example as the anti-blocking system used in the prototype, by the said article known in the French magazine.

The two-channel shaper 15 for generating control signals occurring at different time intervals comprises an inverter 26, the input of which is connected to the second output 25 of the shaper 14 for synchronously output signals, and an AND gate 27, one input of which is connected to the output of the inverter 26. and whose second input is connected to the first output 24 of the former 14. The first output of the calculation unit 1 functions as the second output 25 of the former 14 and the second output 9 of the unit 1 serves as the output of the AND gate 27.

The shaper 15 described above is suitably used when the calculation unit 1 comprises the shaper for synchronously output signals. It is clear that the former 15 can have a different design if the unit 1 is designed in a different way.

Fig. 3 shows an embodiment of the electronic calculation unit which comprises the converter 12 for converting the speed signal of the vehicle wheel to a voltage, the diverting circuit 13 and the two-channel shaper 15 for forming successive control signals. The former 15 comprises a threshold detector 282, the inputs of which are connected to the outputs of the transducer 12 and the derivation circuit 13, respectively, and an acceleration maximum throughput detector 29, the inputs of which are connected to the outputs of the derivation circuit 13 and the detector 28, respectively.

The threshold detector 28 consists of a Schmitt flip-flop, which is intended to emit an acceleration signal when the speed derivative (for the vehicle wheel) reaches its threshold value.

The acceleration maximum throughput detector 29 is a known device (compare, for example, the Soviet inventor's certificate 561 502).

The output of the threshold detector 28 functions as the first output 8 of the calculation unit 1, while the output of the detector 29 serves as the second output 9 of the unit 1.

The actuating unit 3 shown in Fig. 1 comprises a pressure source 30, which is constituted by a source of compressed air (for a pneumatic system) and which is connected to a brake cylinder 31 through an acceleration valve 32 and to the brake valve 7 through a pipeline 33.

The brake cylinder 31 is divided by means of a spring-loaded piston 34 into a piston rod space 35 and a space 36 without piston rod.

The acceleration valve 32 comprises a main space 37, which by means of a piston 38 is divided into a control space 39 and a controllable space 40, the piston 38 being spring-loaded from the side of the controllable space 40. The acceleration valve 32 further comprises (in addition to the main space 37) a further space 41. The controllable space 40 is connected to the space 36 of the brake cylinder 31 without piston rod by a pipeline 42, while the further space 41 is connected to the compressed air source 30 by a pipeline 43. end surface of a partition wall arranged between the main space 37 and the further space 41, which faces the further space 41, is intended to function as a seat 44 for a valve 45, which is constituted by a hole 46 provided, axially displaceable sleeve which is pressed against the valve seat 44 by means of a spring 47 arranged in the further space 41. the end surface of the valve 45 facing the valve seat 44 simultaneously functions as a seat for a valve 48 which has the shape of a rod arranged axially with the piston 38 and rigidly connected thereto in such a way that an annular gap 49 is left between the side surface of the valve 48 and the wall of the hole in the partition wall between. , ...., _._ .. ,, -. . .. .. _, .. ~ »v -» -....,. ~ .W ~ - 452 294 the main room 37 and the additional room 41.

The control space 39 of the acceleration valve 32 is connected to the brake valve 7 through the main pipeline 6 with the electromagnet-controlled valves 5 and 4 arranged therein. The two valves 4 and 5 are, according to the invention, normally open, wherein. the electromagnet-controlled brake pressure relief valve 4 is arranged in the main pipeline 6 between the electromagnet-controlled brake pressure holding valve 5 and the brake valve 7. The valve 4 has an outlet 50 to the atmosphere.

It should be mentioned here that the actuating unit 3 described above can, after introduction of slight obvious changes in its construction, also function as a hydraulic system.

The above-described blocking inhibitor b fl mßsysü fl mï works as follows.

In the initial position of the braking system, i.e. before the braking of the vehicle begins, the piston 38 of the acceleration valve 32 is in its upper position under the action of the spring, while the valve 48 is open, i.e. separated by a certain distance from its valve seat. The chamber 36 of the brake cylinder 31 without piston rod is therefore connected to the atmosphere through the pipeline 42, the controllable space 40 of the acceleration valve 32 and the hole 46 of the valve 45.

When the vehicle driver presses a pedal connected to the brake valve 7 (Fig. 1), compressed air is introduced from the source 30 through the pipeline 33 and the valve 7 into the main pipeline 6.

After its passage through the normally open electromagnet-controlled valves 4 and 5, the compressed air flows into the control space 39 of the acceleration valve 32, so that the piston 38 together with the valve 48 moves downwards. The valve 48 is pressed against its seat, thereby interrupting the connection between the chamber 36 of the brake cylinder 31 without piston rod and the atmosphere. During its continued downward movement, the valve 48 abuts the valve 45, which moves away from its valve seat 44, whereby the controllable space 40 is connected to the further space 41, which results in compressed air from the compressed air source 30 flowing into the space 36 of the brake cylinder 31. without piston rod through the pipeline 43, the interconnected valves 32 and 40 of the acceleration valve 32 and the pipeline 42. Under the influence of the increased pressure in the chamber 36 without piston rod, the piston 34 moves to the left (according to the drawing 452 294), at the same time as the piston rod activates the braking mechanism, whereby braking takes place.

In the calculation unit 1 (Fig. 2), by means of an output signal from the sensor 2, a signal V occurring above the output of the converter 12 is generated, which is proportional to the speed or rotational speed of the vehicle wheel (see curve a in Fig. 4). The diverting circuit 13, the input of which is supplied with the output signal from the converter 12, generates a signal Û which is proportional to the speed derivative of the vehicle wheel (see curve b in Fig. 4). When the speed (speed) of the vehicle wheel ~ at the same time as it decreases during braking of the vehicle - becomes lower than an approximate speed E (see a point A on curve a) of the vehicle (a signal for this speed is generated over the output of the unit 19 (Fig. 2)), one input of the AND gate 22 is fed with an output signal from the first comparison unit 16. When the output signal coming from the third comparison unit 18 occurs over the second input of the AND gate 22, is generated over the output of the AND gate 22 and consequently over the output 24 of the former 14 - if the output signal across the derivative circuit 13 is lower than the acceleration threshold value stored in the memory element of the former 21 - a signal which is fed to either input of the AND gate 27 in the former 15. If the amplitude of the output signal above the derivative circuit 13 is greater than that of the former 20 memory stored delay delay value, a signal is also generated over the output of the second comparison unit 17, which signal is transmitted to either input of the AND gate 23 and which in combination with the signal supplied to the second input of the AND gate 23 from the unit 16 acts as if the output signal appears over the AND gate 23 and the output signal appears over the output 25 of the former 14. The output signal from the output 25 is fed to the input of the inverter 26 and to the unit 1 first output 8 (see curve c in Fig. 4). Since the output signal does not appear across the inverter 26 (Fig. 2), the output signal is not generated across the AND gate 27, one input of which is de-energized. This results in the signal at this time not appearing over the second output 9 of the calculation unit 1 (see curve d in Fig. 4).

! . From the output of the amplifier 10, the input of which is supplied with the signal from the output 8 of the unit 1, the control signal is transmitted to the winding of the electromagnet-controlled valve 4, which thereby closes and closes the main pipeline 6, so compressed air from the accelerator valve chamber 32 flows out into atmosphere through outlet 50.

At the same time the piston 38 returns to the initial position, while the valve 45 is actuated on the valve seat 44 under the action of the spring 47 and closes the outlet 49 of the further chamber 41 to the main chamber 37. The compressed air in the chamber 36 so separate from the source 30 is diverted to the atmosphere. 42, the controllable space 40 and the opening 46 of the valve 45, which in this case is not closed by the valve 48, since the piston 38 connected thereto is in its upper position. The pressure in the cylinder 36 without piston rod decreases, whereby the respective vehicle wheels are braked. The system thus operates during the brake pressure relief phase (see a section BC of the pressure curve e in Fig. 4).

During braking, the vehicle wheel speed (speed) begins to increase. The output signal across the sensor 2 (Fig. 2) changes in proportion to the speed, so that the voltage V across the output of the converter 12 increases correspondingly (see curve a in Fig. 4). Vehicle wheel speed derivatives also increase. When the derivative representing the output signal V over the derivation circuit 13 at its decrease, to absolute value, from its maximum (curve b in Fig. 4) becomes lower than the delay threshold value stored in the former 20 (Fig. 2) (see a point F on curve b), the output signal disappears over the comparison unit 17, so the output signal does not appear over the output 25 of the former 14. The signal does not appear over the first output 8 of the calculation unit 1 either (see also the curve in Fig. 4). Since the output signal V over the converter 12 (Fig. 2) is at this time even lower than the output signal E over the unit 19 (see curve a in Fig. 4) and the output signal V over the derivation circuit 13 (Fig. 2) is lower than that stored in the memory 21 of the former 21 acceleration threshold value (see also the curve in Fig. 4), the inputs of the AND gate 22 are fed with the signals from the comparator units 16 and 18, respectively, so that the signal also appears over the output 24 of the former 24. From the output of the inverter 26, over which the signal is generated, the signal 452 294 11 of the gate 27, which signal in combination with the signal fed to the second input of AND gate 27 from the output 24, acts so that the signal is generated over the second output 9 of the unit 1 (see the curve in Fig. 4). From the output 9 (Fig. 1) of the unit 1, the signal amplified by the amplifier 11 is fed to the winding of the electromagnet-controlled pressure holding valve 5, which is closed at this time, so that compressed air can not flow out of the accelerator valve 32 control space 39 into the atmosphere. At the same time, the valve 4 is reopened, the winding of which has become de-energized. The pressure in the brake system, for example in the chamber 36 of the brake cylinder 31 without piston rod, becomes stable, because the valve 48 - when forces acting on the piston 38 from the control chamber 39 and from the controllable space 40 are equalized - is pressed against its valve seat, so compressed air can not diverted from the chamber 36 of the brake cylinder 31, the pipeline 42 and the controllable chamber 40 of the valve 32 to the atmosphere. When the valve 45, on the other hand, at the same time as it is pressed against the valve seat 44 by means of the spring 47, closes the annular gap 49, which connects the main chamber 37 with the further space 40, so that new portions of compressed air from the source 30 can be fed into the brake cylinder. 31 rooms 36 without piston rod. Compressed air, which is located in the control space 39 of the acceleration valve 32, is also closed, since the portion of the main pipeline 6, which connects the control space 39 to the valve 5, is adapted to a blind duct in the closed position of the valve 5. The system is thus operative during the brake pressure holding phase (see a section CG on curve e in Fig. 4).

When the output signal occurring across the derivation circuit 13 continues to increase, which corresponds to the speed derivative (speed derivative) of the vehicle wheel, the output signal becomes equal to the acceleration threshold level stored in the former 21 (see point H on the curve in Fig. 4). the movement unit 18 (Fig. 2) disappears. This results in the output signal no longer appearing over the AND gate 27 and consequently over the second output 9 of the unit 1 (see curve d in Fig. 4).

The two valves 4 and 5 (Fig. 1) assume the open initial position. When the speed during braking increases so that the output signal V over the converter 12 becomes larger than the output signal E appearing over the unit 19, which represents the vehicle w., W .. -. approximate travel speed (see a point K on curve a in Fig. 4), the output signal over the comparison unit 16 (Fig. 2) disappears, so that the output signals over AND gates 22 and 23 are blocked.

At the beginning of a new operating cycle for the brake system, the piston 38 - when the valves 4 and 5 are open - assumes its lower position under the influence of compressed air, which flows into the control chamber 39 of the acceleration valve 32, so the connection between the brake cylinder 31 chamber 36 and the atmosphere broken. In the future, the braking system works in the same way as above.

If the electronic calculation unit 1, the block diagram of which is shown in Fig. 3, is used in the anti-lock braking system, the system operates in the following manner.

When the velocity V at the deceleration of the vehicle becomes lower and the velocity derivative Û »changes correspondingly over the output of the derivation circuit 13, a time (a point D on the curve in Fig. 5) occurs when the velocity derivative becomes equal to the delay threshold value, thereby exceeding the threshold detector 28 the first output 8 of the calculation unit 1 generates a control signal (see curve c in Fig. 5), which is then transmitted over the amplifier 10 (Fig. 1) to the winding of the electromagnet-controlled valve 4, which results in the braking pressure in the pneumatic actuating brake unit 3 being relieved the method described above.

At the same time as the brake pressure is relieved, the vehicle wheel speed derivative (speed derivative) Ü increases, whereby it again reaches the second threshold value (a point F on the curve b in Fig. 5), after which the output signal over the threshold detector 28 (Fig. 3) disappears. At the same time as the threshold detector 28 is disconnected, it starts the acceleration maximum throughput detector 29, over the output of which a control signal is generated (see curve in Fig. 5), which is then fed from the second output 9 of the calculation unit 1 (Fig. 1) through the amplifier 11 to the electromagnetic valve 5. results in the brake pressure being maintained in the pneumatic actuating brake unit 3 in the manner described above.

The brake pressure holding phase continues until the signal V across the output of the derivation circuit 13 (Fig. 3) has passed through its maximum value during the acceleration phase (a point M on the curve b in Fig. 5). At this time, the control signal disappears over detek- - 1: -.- | down ulw fi flc fl ë- fl- Nvvvniw fl- OWOQQGCUWIII

Claims (2)

452 294 13 tower 29 output (see curve d in Fig. 5). Because the control signals from the two outputs 8 and 9 of the unit 1 are now not transmitted to the valves 4 and 5, respectively, these assume the normally open initial position, so that the pressure in the system begins to increase and the work process described above is repeated. It is clear that in the anti-lock braking system according to the invention other possible embodiments of the electronic calculation unit can be used, at the same time as the electromagnet-controlled valves are connected to the actuating unit in the manner described above. It should be noted that the series connection of the electromagnetically controlled valves to the main pipeline, which is intended to connect the brake valve to the control space in the acceleration valve, enables the system to be operated during many phases, at which the brake pressure can be maintained at any stage of the brake pressure increase or - the reduction in dependence on a control algorithm, which is realized by the electronic calculation unit. This nature constitutes one of the advantages of the system according to the invention compared to the known braking systems of this kind alongside the other advantages, i.e. the system's high functional safety, good economy, etc., which results from the electromagnetic valves being switched on separately during each phase of the braking system. workflow. P a t e n t k r a v Anti-lock braking system comprising an electronic calculation unit (1) and an actuating unit (3), which is connected to an electromagnetic brake pressure relief valve (4) and to a normally open electromagnetic brake pressure relief valve (5), the two valves (4 and 5) are connected to a brake valve (7) manoeuvrable by a vehicle driver through a main pipeline (6) and electrically connected to the first output (8) and the second output (9) of the electronic calculation unit (1), respectively, through a first and a other power amplifiers (10 and 11, respectively), ~ 1- wwß-: æ-nr www ..- 452 294 14 characterized in that the electromagnet-controlled brake pressure relief valve (4) is normally open and arranged in the main pipeline (6) between the electromagnet-controlled brake pressure holding valve (5) and the brake valve (7), while the calculation unit (1) comprises a two-channel former (15 and 15 ') for forming control signals occurring at different time intervals. which the outputs of the former are intended to function as the first and second outputs (8 and 9, respectively) of the calculation unit (1). System according to claim 1, characterized in that the inputs of the two-channel shaper (15) for forming control signals occurring at different time intervals are connected to a known shaper (14) for synchronously output signals, which has a first output (24) for outputting a signal of longer duration and a second output (25) for outputting a signal of shorter duration, the two-channel shaper (15) for signals occurring at different time intervals comprising an inverter (26), the input of which is connected to the second output ( 25) from the shaper (14) for synchronously output signals, and an AND gate (27), one input of which is connected to the output of the inverter (26) and the second input of which is connected to the first output (24) of the shaper (14) for synchronously output signals, while the first and second outputs (8 and 9, respectively) of the calculation unit (1) are constituted by the second output (25) of the synchronously output signals (14) and the AND gate (27) u, respectively. tgång.