FR2563791A1 - Commercial vehicle antilocking braking system - Google Patents

Abstract

The braking system uses a differential stage providing a wheel accelerationor retardation signal from the wheel velocity signal. A signal is provided whenthe acceleration or retardation signal attains its extreme value, fed to a selection and storage circuit forming part of a prognosis stage providing a signal representing the optimum wheel velocity during braking. This signal is compared with the actual wheel velocity for providing the braking pressure regulator. The prognosis stage incorporates a control circuit providing a signal representing the variation intensity of the wheel velocity signal.

Description

 The present invention relates to means of transport and in particular relates to an anti-lock braking system of means of transport.

 The invention is applicable in means of transport suitable for running on the ground and on other similar surfaces, but it is of most interest for vehicles operated on roads with an uneven surface or on land without roads, especially in quarries. The invention is especially applicable in vehicles provided with hydraulic braking controls and whose load capacity ranges from 15 to 180 t and more, which makes these vehicles very interesting for the mineral industry.

 One of the major problems in the construction and operation of the aforementioned vehicles is that of increasing safety during braking, which safety is largely a function of braking stability, stopping distance and maneuverability of these vehicles when braking.

 It is accepted as obvious that the braking stability and the service life of the tires increase considerably if the wheels of the vehicle can be prevented from braking when braking. Using anti-lock braking systems automatically adjusts the grip of the tires on the ground, on which the vehicle is in motion when braking, regardless of the road surface conditions, which contributes to increasing the efficiency of braking and vehicle stability when braking.

 There is an anti-lock braking system of a means of transport (see the author's certificates of the USSR Nua360753, 561502), which system comprises a trainer for the wheel speed signal, a differentiator, a trainer for the deceleration threshold of wheel, a comparator circuit and an executing member, which are all connected in series and whose operation is based on a principle consisting in analyzing the intensity of the variations in wheel speed during braking.

 It is well known that, when braking a vehicle, the speed of the wheel decreases in a manner proportional to the difference between the braking force applied and the actual momentary grip of this wheel.

 The actual momentary grip of a wheel depends on the grip coefficient of this wheel on the ground. The lower the grip coefficient of the wheel, the more important its braking, that is to say, the more important is the deceleration value of this wheel.

 This is precisely the reason why the deceleration value of the wheel is chosen, in the devices considered, as the parameter characterizing the locking of the wheel.

 When the wheel locks, the value of its deceleration exceeds a certain threshold value, this translates into the formation of a control signal actuating a brake pressure drop modulator so that it decreases the applied braking force. This reduction in braking torque is essential because, with the wheel locked, there is a decrease in the coefficient of adhesion, longitudinally as well as transversely, which ultimately affects the stability of the vehicle and the control of its direction. while increasing the braking distance.

 The operation of the devices described is however effective only on roads with a very regular surface, while in quarries or other similar terrains without roads well when the coating of existing roads is irregular, a considerable high frequency component comes overlap the wheel deceleration signal. This component is due to fluctuations in grip over time and the non-stable nature of the braking torque applied to the wheel as well as the elasticity of the tire material. This results in incorrect operation of the anti-lock system, which considerably affects the braking efficiency of the vehicle. In particular, there is a premature release of the brake before the braking torque exceeds a certain optimum value which is dependent grip conditions, which increases the stopping distance.

 At the same time, an exaggerated smoothing of the wheel speed derivative signal (i.e. a filtering of this signal or of the wheel speed signal), carried out in order to make the effect exerted by the high frequency components, however, is not capable of bringing a noticeable improvement in the efficiency of the controlled braking, since we then observe an increase in the response time of the electronic elements of the system.

 On the other hand, the difficulties relating to the adaptation of the wheel deceleration threshold to the actual braking conditions, which vary even during a single braking cycle, reduce the effectiveness of the controlled braking since the optimal adjustment errors increase at the end of the anti-lock system.

 Another anti-lock braking system of a means of transport is known (see, for example, United States patent No. 3832008), in which, to produce control signals for the brake pressure modulators, the speed of the wheel is predicted during braking, which speed is then accepted as a certain constant characteristic of the speed of the vehicle, and the actual speed of the wheel is compared to this predicted speed.

 The anti-lock device in question includes a wheel speed signal trainer, a differentiator in which the wheel speed signal, arriving at its input, is interpreted to produce a wheel speed derivative signal, a prognosticator block of the wheel speed comprising a memory element, comparator circuits carrying out logical operations on the basis of the signals formed in the device.

 Since the predicted wheel speed then appears as a certain constant characteristic of the vehicle speed, i.e. it corresponds to a predetermined value of the wheel slip coefficient, this speed is not close the optimum speed of the wheel only under well-defined braking conditions, and in particular, under conditions where the maximum values of the coefficient of adhesion correspond to the predetermined value of the coefficient of slip.

 In all other conditions. braking, when the predetermined value of the slip coefficient does not correspond to the maximum of the grip coefficient, the predicted speed does not correspond to the optimal value, resulting in reduced effectiveness of controlled braking.

 An anti-lock braking system is known for a means of transport having at least one wheel whose speed is controlled and modulators for dropping and maintaining the braking pressure (c t.Trudy Trudy nauchno-issledova-telkko i experimentalnogo instituta avtomobilnogo elekt 'I rooborudovania i avtopriborov. Collection no. 47, article: "Postroenie i issledovanie avtomobilnykh elektronnykh sistem avtomaticheskogo upravlenia", M., 1979, pp 61-68, figures 1-4).

 This system includes a wheel speed signal trainer which can be, for example, in the form of a wheel speed frequency transducer, of the known type, the output signal of which arrives at the input of a frequency-voltage converter. This converter must have a low-pass filter. The output of the converter serves as the output of the wheel speed signal trainer. Other embodiments of the wheel speed signal trainer are also known, in which the appropriate signal is formed using transducers mounted on several vehicle wheels. In addition to the trainer described, the system comprises a differentiator, a wheel speed predictor unit, a circuit for detecting the extreme value of the input signal, a wheel deceleration threshold trainer, a circuit for comparing the deceleration threshold with the output signal from the differentiator, a circuit for comparing the speed signal of the wheel with the predicted speed, as well as an "AND" circuit.

 The signal produced at the output of the wheel speed signal trainer arrives at the information input of the wheel speed prognostic block and, at the same time, at the input of the differentiator at the output of which a signal occurs corresponding to the acceleration or deceleration of the wheel. The output signal of the differentiating device is supplied to the input of the circuit detecting the extreme value of the signal and to one of the inputs of the circuit for comparing the wheel deceleration threshold with the output signal of the differentiating device.

 Produced at the output of the detector circuit of the extreme value of the input signal, the signal arrives at the control input of the wheel speed predictor unit. The block in question produces at its output a predicted speed signal corresponding approximately to the optimal wheel speed during braking and varying in accordance with the wheel speed signal presented at the information input of this block when its control input receives a signal from the output of the detector circuit of the extreme value of the input signal.The predicted speed signal and the wheel speed signal arrive at the inputs of the circuit for comparing these signals, which circuit produces a control signal actuating the brake pressure drop modulator when the predicted speed signal is greater than the wheel speed signal.

 When the inputs of the circuit for comparing the wheel deceleration threshold to the output signal of the differentiating device receive equal signals, one from the trainer of the wheel deceleration threshold and the other coming from the differentiating device, this comparison circuit produces a signal which arrives, with an output signal pro from the circuit for comparing the wheel speed signal with the predicted speed signal, in the "AND" circuit, the output signal of which is the control signal for the brake pressure maintenance modulator.

 The main elements of the anti-lock system are produced as described below. The differentiator is in the form of a differentiation circuit, widely applied in adjustment systems, providing at its output a derivative of the input signal, which derivative characterizes, in the given case, deceleration or acceleration of the wheel. The differentiator is normally provided with a low-pass filter intended for smoothing the output signal.

 The circuit for detecting the moment of presentation of the extreme value of the input signal comprises a peak detector whose use has been generalized in similar cases.

 The wheel speed prognostic block is a sampling and memory assembly with control and information inputs1 and an output, which set is also widely applied in control systems.

 The wheel deceleration threshold trainer is a reference signal source whose value is chosen by calculation and is established in advance.

 It is also easy to imagine that the signals controlling the modulator are first amplified using known devices and, then, arrive in the electromagnetic valves modifying the braking force applied to or to the wheels.

 However, this electronic device also does not make it possible to counter the effect of inertia of its elements that these exert on the formation of the control signals actuating the brake pressure modulators, which affects at the end of braking efficiency. During 9vU device operation, there is the appearance, at the output of the wheel speed prognosticator, of a signal whose value decreases in a staggered manner and, in the ideal case, must be equal to the optimal wheel speed when braking. When the actual wheel speed differs from the optimum speed, this is the time when control signals must be formed to activate the brake pressure drop modulator so as to match the actual wheel speeds with For an ideal electronic device, not subject to any retarding effect, the control signal for the brake pressure maintenance modulator must come into being just when the circular wheel deceleration becomes zero, i.e. tell when the braking moment applied to the wheel and the actual momentary grip of the latter are balanced. Both signals must end when the actual wheel speed becomes greater than the optimum speed, which is defined by when the actual wheel acceleration reaches its maximum value. It is also the moment when a correction of the value of the predicted speed must be made according to the actual wheel speed, the value of which is, at this moment, optimal for approximating the predicted speed to the optimal speed.

 However, the inertia of the elements constituting the anti-blocking system delays the formation of the control signals with respect to the above-mentioned moments of time. In fact, the signal obtained at the output of the wheel speed signal trainer is delayed with respect to the actual wheel speed, due to the presence of a low-pass filter. This is always the reason why there is a delay in the moments when the wheel speed and approximate predicted speed signals coincide with the optimum wheel speed.

 A similar delay characterized the appearance of the wheel speed derivative signal, obtained at the output of the differentiator and considered with respect to the actual wheel acceleration.

 There is a greater delay when it is a question of detecting the maximum wheel acceleration and of determining the final moment of the two control signals which is at the same time the moment of correction of the value of the speed. prognosticated.

 The delay at the end of the control signals is still not eliminated.

 In the electronic device in question, provision is made for the establishment of a constant value of the predicted speed and the formation of a signal for the brake pressure to drop as soon as the wheel speed, which is decreasing, coincides with the aforementioned constant value of the predicted speed, which is in reality only an advancement from the moment when the wheel speed decreases to the optimum value.

However, in this way, we sometimes see a deterioration in the controlled braking efficiency. This deterioration is due to a premature release of the brakes, i.e. to the reduction of the braking pressure
Ku braking torque), since the predicted speed approaches the optimum speed in a staggered manner.

The invariable value of the predicted speed, after it has undergone a correction according to the maximum value of the wheel speed derivative signal, when braking on a surface having a high coefficient of adhesion, inevitably leads to slackening premature braking, that is to say a release of the braking pressure during a so-called precritical braking regime, when the wheel is still unable to lock and when it can be continued to brake brutal speed by applying a higher braking torque. This premature release of the brakes leads to the reduction (or even loss) of the braking capacity effect.

 The tests carried out by the authors of the present invention show that advancing the moment when the derivative signal of the wheel speed becomes zero, by defining for this purpose a certain constant threshold of deceleration, does not produce any positive result since the variations in the derivative of the wheel speed are a function of several factors and their nature changes, during braking, even if this is operated on regular ground. This is precisely the reason why this certain constant threshold of wheel deceleration causes advancements of different values without taking into account the actual braking conditions, which can ultimately lead to a decrease in the efficiency of braking, otherwise to completely disordered operation of the anti-lock system.

 Thus, the inertia of the elements constituting this anti-lock braking system has the effect of reducing the effective braking efficiency of the vehicle.

 The invention therefore aims to develop an anti-lock braking system for means of transport which would make it possible to increase the braking efficiency on surfaces of different natures by reducing the delay of the control signals of the pressure modulators of braking and the elimination of premature release5 of the brakes.

 The problem is solved using an anti-lock braking system intended for a means of transport having at least one wheel whose speed is controlled and a modulator for dropping the brake pressure, of the type comprising a signal trainer. wheel speed, a differentiator producing at its output, as a function of the wheel speed signal, a wheel deceleration or acceleration signal, a circuit detecting the moment of presentation of the extreme value of the input signal, which is electrically connected to the output of the differentiator, a wheel speed prognostic block producing a predicted speed signal corresponding approximately to the optimal wheel speed during braking and varying as a function of the wheel speed signal arriving at the information input of the wheel speed prognostic block when the control input of this block receives a signal from the output of the moment detection circuit presentation of the extreme value of the input signal, a circuit for comparing the wheel speed signal with the predicted speed signal, producing a control signal for the brake pressure drop modulator when the predicted speed signal becomes higher to the wheel speed signal, which anti-lock system is characterized, according to the invention, in that it further comprises a circuit for controlling the wheel speed prognosticator, the control input of which receives the control signal intended for the brake pressure drop modulator, while the output of said control circuit is connected to an additional input of the wheel speed prognostic block in order to supply this block with a signal modifying the pace of the decrease the predicted speed signal produced by the output of the wheel speed predictor unit.

 This design of the anti-lock system allows, by modifying the predicted wheel speed using the control circuit, to compensate for the delay in the brake pressure drop modulator control signals and, at the same time, to prevent any slackening pre-matured brakes.

 The aforementioned problem is also solved by means of an anti-lock braking system provided for a means of transport having at least one wheel whose speed is controlled, a modulator for dropping the brake pressure and a holding modulator. of the brake pressure, a system of the type comprising a wheel speed signal trainer, a differentiator producing at its output, as a function of the wheel speed signal, a wheel deceleration or acceleration signal, - a circuit detector of the moment of presentation of the extreme value of the input signal, a wheel speed predictor block producing a predicted speed signal corresponding approximately to the optimal wheel speed during braking and varying as a function of the wheel speed signal arriving at the information input of the wheel speed prognostic block when the control input of this block receives a signal from the output of the mo presentation of the extreme value of the input signal, a circuit for comparing the wheel speed signal with the predicted speed signal, producing a control signal for the brake pressure drop modulator when the predicted speed signal becomes greater than the wheel speed signal, a wheel deceleration threshold trainer, a circuit for comparing said wheel deceleration threshold with the output signal of the differentiating member, producing an output signal when the signals arriving at its in inputs have similar values, an "AND" circuit, the output of which produces a control signal for the brake pressure maintenance modulator when the inputs of said "AND" circuit receive signals from the outputs of the above-mentioned comparison circuits , which anti-lock system is characterized, according to the invention, in that it further comprises a circuit for controlling the speed predictor unit wheel, whose control input receives the control signal intended for the brake pressure drop modulator, while the output of said control circuit is connected to an additional input of the wheel speed prognostic block for the purpose of d '' supplying this block with a signal modifying the rate of decrease of the predicted speed signal produced by the output of the wheel speed predictor block.

 It is rational that, in the two cases described above, the anti-lock braking system is produced so that the control circuit includes a reference voltage source, a switch whose information input is connected to the output. from the reference voltage source, the control input, this switch serving as the control circuit control input and the output of the switch serving as the control circuit output.

 It makes sense for the wheel speed prognostic block to include a sampling pulse trainer whose input serves as the control input for the wheel speed prognostic block, while the sampling and memory circuit comprises a switch and a memory element, the control input of the switch serving as a control input for the sampling and memory circuit and being electrically connected to the output of the sampling pulse formatter, the input d information of the switch serving as information input for the selection and memory circuit and being electrically connected to the information input of the wheel speed prognostic unit, the output of the switch being connected to one of the inputs of the memory element, the other input of which serves as additional input to the sampling and memory circuit and the output of the memory element serving as output from the sampling and memory circuit.

 It is advantageous that the wheel speed prognostic block includes, in the version described above, a comparison circuit and an adder, the inputs of the comparison circuit being connected to the information input and to the output of the circuit. sampling and memory, the output of the comparison circuit being connected to one of the inputs of the adder, while the electrical connection between the control circuit and the sampling and memory circuit consists of a branch of the output of the control circuit on the other input of the adder whose output is connected to the additional input of the sampling and memory circuit.

 In this case, the predicted speed follows the wheel speed during a slow pace of the decrease in the wheel speed, that is to say when the wheel is far from locking up.

 Another embodiment consists in that the wheel speed prognostic block further comprises a circuit for separating a portion of the wheel speed signal, the input of which serves as an information input for the wheel prognosticator block. the wheel speed and the output is connected to the information input of the sampling and memory circuit.

 This helps to increase the selection accuracy of the wheel speed value when the wheel speed has an optimal value during controlled braking.

 It is rational that in the third version of the wheel speed prognostic block it also includes an inhibition circuit to prohibit the sampling operation from the sampling and memory circuit when a signal appears. brake pressure drop modulator control, the inhibit circuit information input being connected to the output of the sampling pulse trainer and the inhibit input being connected to the control input of the switch.

 This method of producing the wheel speed prognostic block has the advantage of eliminating the harmful effect of the pulses of the wheel deceleration or acceleration signal.

 It is interesting that, in accordance with the fourth version of the wheel speed prognostic block, it also includes a rocker. RC whose inputs are connected to the control input and to the additional control input of the wheel speed predictor unit, an "OR" circuit, one input of which is connected to the output of the RC rocker, the electrical connection between the sampling pulse trainer and the control input of the sampling and memory circuit being made by connecting the other input of the "OR" circuit to the output of the above-mentioned trainer and by connecting the output of this "OR" circuit at the control input of the sampling and memory circuit.

 The advantage of this embodiment consists in a reduction in the sampling time due to the introduction of a prior tracking of the wheel speed signal.

 It is rational to make the anti-lock braking system so that it further comprises, for the control of the drop modulators and of maintaining the brake pressure, a reference signal source, a comparison circuit producing a signal of output when the wheel speed signal is not greater than the reference signal, which comparison circuit is connected by its inputs to the output of the wheel speed signal trainer and to the aforementioned reference signal source, as well as 'an inhibition circuit for inhibiting the brake pressure maintenance modulator control signal when there is an output signal from the comparison circuit, the information input of said circuit inhibition being connected to the output of the "AND" circuit and the inhibition input being connected to the output of said comparison circuit.

 This embodiment of the anti-lock system has the advantage of preventing any premature appearance of the brake pressure modulator control signal when the wheel locks.

 It is entirely convenient to produce the anti-lock system in accordance with another embodiment, characterized in that it further comprises a circuit separating the maximum value of wheel deceleration, for which the output signal from the differentiator is used as an information signal and the output signal from the detector circuit for the moment of presentation of the extreme value of the input signal is used as a control signal, which circuit is connected to the output of the differentiator, while the control circuit has an information input to which the output of said circuit separating the maximum wheel deceleration value is connected.

 This embodiment of the anti-lock system is of most interest for increasing the precision of selection of the control signals for the brake pressure drop modulator. It takes into account the actual braking conditions defined according to the maximum acceleration of the wheel.

 It is rational that in the version of the anti-blocking system which has just been described, the control circuit includes a reference voltage source, an adder and a switch, one of the inputs of the adder being connected to the output of said source. of reference voltage, the other input of the adder serving as an information input for the control circuit, the output of the adder being connected to the information input of the switch whose control input is used for the control circuit control input and the switch output serving as the control circuit output.

 Another embodiment of the claimed system consists in that it comprises in suture a circuit separating the maximum value of wheel deceleration, for which the output signal of the differentiating member serves as an information signal and the signal output of the circuit detecting the moment of presentation of the extreme value of the input signal serves as a control signal, while the trainer of the wheel deceleration threshold is of the controlled type, its control input being connected to the circuit output separator of the maximum wheel deceleration value.

 Because the wheel deceleration threshold is then adapted to the actual braking conditions, which threshold is used to form the control signal for the brake pressure maintenance modulator, this results in better precision of the ordered.

 In the case of variable braking conditions, it is rational to use an embodiment of the claimed system, characterized in that this system also comprises a circuit separating the maximum value of wheel deceleration, for which the signal of the differentiating device serves as an information signal and the output signal of the detector circuit for the moment of presentation of the extreme value of the input signal serves as a control signal, while the output of this separating circuit is connected at the input of the wheel deceleration threshold trainer, the control circuit of the wheel speed predictor unit having a. information input to which the output of said circuit separating the maximum wheel deceleration value is connected.

 This embodiment of the anti-lock system is characterized by better precision in compensating for the delays in the signals controlling the brake pressure drop modulator in the event of variations in the braking conditions.

 It is rational, to prevent the premature release of the brakes which may result from the erroneous functioning of the system when braking on a surface having a high coefficient of adhesion, to carry out the claimed system in such a way that it also comprises a reference signal source, a comparison circuit producing an output signal when the wheel deceleration signal is not greater, depending on the module, than the reference signal, and connected, by its inputs, to the output of the separator circuit of the maximum wheel deceleration value and to the reference signal source, as well as to the inhibition circuit of which one input is connected to the output of said comparison circuit, the other input is connected to the output of the comparison of the wheel speed signal with the predicted speed signal, the output of this inhibition circuit serving to produce a brake pressure drop modulator control signal.

 It is rational to make the circuit separating the maximum value of wheel deceleration so that it includes a peak detector whose input is used to receive the output signal from the differentiator, a switch connected to the output of said peak detector and connected, by its control input, to its input, which switch is intended to put this peak detector in initial state according to the wheel acceleration signal, a pulse trainer intended producing pulses at the moment of appearance of the maximum value of the wheel deceleration signal and the input of which is used to receive the output signal from the detector circuit from the moment of presentation of the extreme value of input signal, a sampling and memory circuit whose information input is connected to the output of the pulse trainer and the output serves as the output of the circuit separating the maximum value of wheel deceleration.

 In the event of a sudden change in braking conditions, in order to adapt the compensation for the delay of the system to this kind of change, it is rational to have recourse to an embodiment of the claimed system, characterized in that it further comprises a predicted speed correction block operating the correction of the predicted speed as a function of wheel acceleration or deceleration, one of the inputs of this correction block being connected to the output of the wheel speed predictor block, its another input being connected to the output of the differentiating member and its output being connected to the input of the circuit for comparing the wheel speed signal with the predicted speed signal.

 It is rational that the correction block is made so as to include an adder and a discriminator of the deceleration and wheel acceleration signals, the input of the discriminator serving as one of the inputs of the correction block, the outputs of said discriminator being connected. a first and a second input of the adder, a third input of which serves as the other input of the correction block, and the output of the adder serving as the output of this correction block.

 It is convenient to make the discriminator of the deceleration and acceleration signals of wheel so that it comprises at least one pair of diodes connected in series whose connection point is the input of the aforementioned discriminator and the free sockets are the outputs of this discriminator.

 It is rational to make the correction block in such a way that it includes an adder and a suppressor circuit intended to allow an output signal from the differentiator to pass, the value of which goes outside the limits of the non-sensitive area of the circuit. suppressor, the input of the suppressor circuit serving as one of the inputs of the correction block, the output of said circuit being connected to one of the inputs of the adder whose other input serves as the other input of the correction block, and the output of the adder serving as output from the aforementioned correction block.

 It is convenient to make the suppressor circuit in such a way that it is a combination of diodes connected in opposition and in parallel, which combination has at least one diode in each of the branches, the connection points of the branches serving as input and output of the suppressor circuit.

In order to increase the precision of compensation for delays of the elements constituting the anti-lock system by a more precise choice of the moment of correction of the predicted speed, this during variations in the braking torque during acceleration of the wheel, it is rational to have recourse to an embodiment of the claimed anti-lock system, characterized in that it comprises
in addition a block for determining the moment of the adhesion force which comprises an adder and a trainer of the braking torque signal, one of the inputs of the adder having to be electrically connected to the output of the braking torque signal trainer , the other input of said adder having to be connected to output of the differentiator and the output of the adder having to be connected to the input of the detector circuit of the moment of presentation of the extreme value of input signal, thanks to whereby an electrical connection is obtained between the output of the difierentiating member and the input of said detector circuit from the moment of presentation of the extreme value of input signal.

 The introduction of the abovementioned characteristics, provided that the rate of decrease of the predicted speed signal is necessarily controlled using the control circuit and the respective electrical connections, makes it possible to increase the accuracy of determining the optimal speed of wheel by the predicted speed as well by increasing the frequency of the amplitude correction of the predicted speed as by increasing the precision of choice of the appropriate moment for the implementation of this correction when modifying the braking torque applied. The presence of the control circuit is then essential to prevent any premature release of the brakes.

 We consider as optimal an embodiment of the block for determining the moment of the adhesion force, characterized in that it also includes a delay circuit whose input is connected to the output of the torque signal formator. brake and the output is connected to the respective input of the adder, whereby an electrical connection is obtained between the trainer of the braking torque signal and the adder.

The invention will be better understood and other objects, details and advantages thereof will appear better in the light of the explanatory description which will follow of various embodiments given by way of nonlimiting examples with reference to the appended drawings in which:
- Figure 1 shows a structural diagram of the anti-lock system according to the invention;
- Figure 2 shows a structural diagram of an embodiment of the claimed system applicable in a means of transport provided with a fall modulator and a brake pressure maintenance modulator;
- Figure 3 shows a structural diagram of a control circuit according to the invention;
- Figure 4 shows an embodiment of a predictor block of the wheel speed established in accordance with the invention;
- Figure 5 shows another embodiment of the wheel speed prognosticator block, established in accordance with the invention;
- Figure 6 shows a third embodiment of the wheel speed prognosticator block, established in accordance with the invention;
- Figure 7 shows a fourth embodiment of the wheel speed prognosticator block, established in accordance with the invention;
- Figure 8 shows a fifth embodiment of the wheel speed prognosticator block, established in accordance with the invention;
- Figure 9 shows a structural diagram of another embodiment of the claimed system;
- Figure 10 shows a structural diagram of another embodiment of the anti-lock system according to the invention; ;
- Figure 11 shows another embodiment of the anti-lock system according to the invention;
- Figure 12 shows a structural diagram of a following embodiment;
- Figure 13 shows a structural diagram of another embodiment of the claimed system;
- Figure 14 shows a structural diagram of another embodiment of the system according to the invention;
- Figure 15 shows an embodiment of the circuit separating the maximum value of wheel deceleration, established according to the invention;
- Figure 16 shows a structural diagram of an embodiment of the anti-lock system, allowing correction of the predicted speed;
- Figure 17 shows a correction block according to one invention ;;
- Figure 18 shows another embodiment of the correction block, established according to the invention;
- Figure 19 shows a structural diagram of another embodiment of the claimed system;
- Figure 20 shows a structural diagram of a block for determining the moment of the adhesion force according to the invention;
- Figure 21 shows diagrams of speeds, accelerations, moments of force and control signals, illustrating the operation of the claimed system;
- Figure 22 shows in principle the same diagrams as Figure 21.

 As shown in FIG. 1, the anti-lock system claimed for a means of transport having at least one wheel whose speed is controlled and a modulator for reducing the brake pressure, comprises a trainer 1 for the wheel speed signal, of which the output is connected to the input of a differentiator 2 and to the information input of a predictor unit 3 of the wheel speed.

The output of the differentiator 2 is connected to the input of a detector circuit 4 of the moment of presentation of the extreme value of the input signal, the output of which is connected to the control input of the prognosticator block 3 of the wheel speed is connected to one of the inputs of a circuit 5 for comparing the wheel speed signal with the predicted speed signal. The output of the trainer 1 of the wheel speed signal is connected to the other input of the above-mentioned circuit 5. The output of the comparison circuit 5 is used to produce a control signal for a brake pressure drop modulator.

 The wheel speed predictor unit comprises a control circuit 6, the input of which is connected to the output of the comparison circuit 5 and serves as an additional control input for the wheel speed predictor unit 3, as well as a circuit 7 for selection and memory.

This leads us to propose a new design for block 3, which will be described in detail in subsequent developments.

 It is possible to use, as trainer 1 of the wheel speed signal, a known device (not shown) comprising a wheel speed frequency detector whose output is connected to a frequency-voltage converter. The output of this converter serves as the output of the trainer 1. As mentioned above, the trainer in question necessarily includes a low-pass filter, the presence of which results in an increase in the inertia of the trainer. The differentiator 2 is in the form of a widely known differentiation circuit and is, like the circuit 5 for comparing the wheel speed signal with the predicted speed signal, a well-used comparator. moment of presentation of the extreme value of input signal is a device in which the level of the output signal varies when the input signal has maximum or minimum values, for example a zero member with capacitive input which is activated play during alternation of the input signal.

 Circuit 4 can be implemented so as to include a peak detector (not shown) operating, for example, when the polarity of the output signal of the differentiator 2 corresponds to the actual wheel acceleration, and a comparison circuit of the output signal of the differentiating member and of the output signal of the peak detector.

 The claimed anti-lock system can be used in a means of transport provided not only with a brake pressure drop modulator but also with a brake pressure maintenance modulator. A structural diagram of this embodiment of the invention is shown in Figure 2 of the drawings.

 This embodiment differs from that which has just been described in that the system further comprises a trainer 8 of the wheel deceleration threshold, a circuit 9 for comparing said wheel deceleration threshold with the output signal from the member. differentiator, which circuit is connected by its inputs to the output of the trainer 8 and to the output of the differentiator 2, as well as an "AND" circuit 10 connected by its inputs to the outputs of circuits 5 and 9 for comparison and whose output is used to produce a modulator control signal (not shown) for maintaining the brake pressure.

 In the embodiment considered, the trainer 8 of the wheel deceleration threshold is a known device (not shown) comprising a reference voltage source or a voltage divider with resistors and a voltage repeater mounted at the output of the latter and intended to counter the effect exerted by the following elements of the system on the transfer ratio of the voltage divider with resistors. The comparison circuit 9 is produced analogously to the comparison circuit 5, while the "AND" circuit 10 is also a widely used device carrying out the "AND" logic operation. The other elements constituting the system are produced in a manner analogous to that of which the elements described are designed.

 As described above, the embodiments of the invention present the wheel speed prognosticator block 3 comprising a control circuit 6 and a sampling and memory circuit 7. FIG. 3 represents a structural diagram of the control circuit 6.

According to the invention, the control circuit 6 comprises a reference voltage source 11 and a switch 12.

The information input of the switch 12 is connected to the output of the reference voltage source 11, the control input of the switch 12 serves as the control input for circuit 6 and the output of the switch 12 serves as the output of this circuit.

 According to another embodiment of the invention, the predictor block 3 of the wheel speed comprises a formatter 13 (FIG. 4) of sampling pulses, the input of which serves as the control input for this block. The sampling and memory circuit 7, used in this block 3, comprises a switch 14 and a memory element which is, in this case, in the form of an integrator 15.

The control input of this switch serves as the control input for the sampling and memory circuit and is connected to the output of the sampling pulse trainer 13. The information input of switch 14 serves input of the sampling and memory circuit and of block 3 in general The output of switch 14 is connected to an input of integrator 15, which input is used to introduce initial data into it, while than the other (main) entry of the integrataul
serves as additional input to the sampling and memory circuit and is connected to the output of the control circuit 6, the output of the integrator 15 serving as the output of the sampling and memory circuit and of the whole block 3.

 In accordance with another embodiment of the wheel speed prognosticator block 3 (FIG. 5), which mode has the advantage of increasing the sampling precision of the wheel speed value when the wheel speed has, during controlled braking, an optimal value, the block 3 in question further includes a circuit 16 separating a portion of the wheel speed signal, whose input is the information input of block 3 and the output is connected to the information input of switch 14. Circuit 16 can be in the form of a resistance voltage divider, of the known type, having a transfer ratio close to 0.8 - 0.9. the most rational to use, as this circuit, an element of inertia, which will allow to take into account the dynamic character of the variations of the wheel speed signal.

 In order for the predicted speed to be in pursuit of the wheel speed at a low speed reduction speed, that is to say when the wheel is far from locking up, it is proposed to use the embodiment of the wheel speed predictor block, the representation of which is shown in FIG. 6.

In accordance with this embodiment, the block 3 of the wheel speed predictor further comprises a comparison circuit 17 and an adder 18. The inputs of the comparison circuit 17 are connected one to the information input and the other at the output of comparator block 3, while the output of circuit 17 of comparai
sound is connected to one of the inputs of adder 18.

To electrically connect the control circuit 6 and the integrator 15, the output of the control circuit 6 is connected to the other input of the adder 18. The output of this adder is connected to the input of the integrator. 15.

 To counteract the undesirable effect of the deceleration or wheel acceleration signal pulsations, which pulsations cause the formation of a false sampling signal and the non-conformity of the predicted speed with the optimal value, it is rational make the tip block 3 as shown in FIG. 7.

 According to this embodiment, the block 3 predicting the wheel speed further comprises an inhibiting circuit 19 whose role is to inhibit the sampling operation when the output of the trainer 13 has a sampling signal. The information input of the inhibition circuit 19 is connected to the output of the sampling pulse trainer 13, the inhibition input is connected to the control input of the control circuit 6 and the output of the inhibition circuit 19 is connected to the control input of switch 14.

 An additional advantage characterizes the embodiment of the prognosticator block 3, represented in FIG. 8. As appears from this figure, the prognosticator block 3 furthermore comprises a flip-flop I'Z 20 whose inputs are connected to each other. control input and the other at the additional control input of the prognosticator block 3, an "OR" circuit 21 of which one of the inputs is connected to the output of the flip-flop RS 20.

To obtain an electrical connection between the selection pulse trainer 13 and the control input of switch 14 of the sampling and memory circuit, the other input of the "OR" circuit 21 is connected to the output of said trainer and its output is connected to the control input of switch 14.

 The aforementioned advantage lies in the reduction of the sampling time, which reduction becomes possible by virtue of a prior tracking of the wheel speed signal.

 The anti-lock braking system can also be established in accordance with another embodiment, the structural diagram of which is shown in FIG. 9.

 Represented in this figure, the system further comprises a source 22 of the reference signal, a circuit 23 for comparison, producing a signal. output when the wheel speed signal does not exceed, depending on the module, the reference signal and connected by its inputs to the output of the trainer 1 of the wheel speed signal and to said source 22 of the reference signal, as well as an inhibition circuit 24 having the role of inhibiting the brake pressure maintenance modulator control signal when the comparison circuit 23 produces an appropriate signal. The information input of the inhibition circuit 24 is connected to the output of the "AND" circuit 10 and its inhibition input is connected to the output of the above-mentioned comparison circuit 23.

 This design of the anti-lock system makes it possible to prevent the premature presentation of the brake pressure maintenance modulator control signal when the wheel locks.

 FIG. 10 of the appended drawings represents another embodiment of the anti-lock system given in FIG. 1. In accordance with this embodiment, the system also comprises a circuit 25 separating the maximum value of wheel deceleration, the signal of which of information is that which comes from the output of the differentiating member 2. The signal supplied by the circuit 4 which detects the moment of presentation of the extreme value of the input signal serves, for the circuit 25, as a control signal, circuit 4 being connected to the differentiator. In accordance with the embodiment considered, the control circuit 6 has an information input to which the output of the circuit 25 separating the maximum wheel deceleration value is connected.

 This embodiment of the anti-lock system is of most interest for raising the precision of compensation for the delays of the brake pressure drop modulator control signals. It takes into account the actual braking conditions defined according to the maximum wheel deceleration.

 Figure 11 shows the control circuit 6 in more detail.

 The control circuit 6 includes a reference voltage source 11, an adder 26 and a switch 12, one of the inputs of the adder 26 being connected to the output of the reference voltage source 11, the other between of adder 26 serving as an information input for control circuit 6, the output of adder 26 being connected to the information input of switch 12, the control input of which serves as control input for circuit 6 control, the output of the switch 12 serving as an output of this control circuit 6.

 The anti-blocking system shown in FIG. 2 can be produced in accordance with another embodiment shown in FIG. 12. Just as in the embodiment given in FIG. 10, the anti-blocking system comprises (FIG. 12) a separator circuit. of the maximum wheel deceleration value whose information signal is in the form of the output signal from Q differentiator 2, while the output signal provided by the circuit 4 detector of the moment of presentation of the extreme value of input signal serves as a control signal. The trainer 8 of the wheel deceleration threshold is however of the controlled type, its control input being connected to the output of the circuit 25 separating the maximum value of wheel deceleration.

This embodiment is of most interest when
that the compensation accuracy of the pressure maintenance modulator control signals needs to be increased
braking. This high precision is obtained by adapting the wheel deceleration threshold, which is used to form the control signal for the brake pressure maintenance modulator, to the actual braking conditions.

 The anti-lock system can also be produced in accordance with another embodiment given in FIG. 13. It differs from the embodiment in FIG. 12 in that the control circuit 6 has a control input and can be established as in figure 11.

The output of the circuit 25 separating the maximum wheel deceleration value is then connected to I1 information input of the control circuit 6.

 This embodiment makes it possible to increase the precision of compensation for delays when controlling the drop modulators and of maintaining the brake pressure under variable braking conditions.

 A further development of the embodiment described above characterizes the anti-lock braking system of the means of transport shown diagrammatically in FIG. 14. According to this embodiment, the anti-lock system further comprises a source 27 of the reference signal, a circuit 28 of comparison producing an output signal when the wheel deceleration signal does not exceed, depending on the module, the reference signal. One of the inputs of the comparison circuit 28 is connected to the output of the source 27 of the reference signal and its other input is connected to the output of the circuit 25 separating the maximum wheel deceleration value. The system further comprises an inhibiting circuit 29 of which one of the inputs is connected to the output of the comparison circuit 28 and the other input is connected to the output of the circuit 5 for comparing the wheel speed signal with the predicted speed signal, the circuit output 29 inhibition used to produce a control signal for the brake pressure drop modulator.

This embodiment is very interesting, when it is necessary to prevent the premature release of the brakes, which can result from the erroneous functioning of the system when
brakes on a surface with a high coefficient of adhesion.

Preferred is the embodiment of the circuit 25 separating the maximum value of wheel deceleration, referenced
schematically felt in FIG. 15. According to this embodiment, the circuit in question comprises a peak detector 30 whose input is connected to the output of the differentiator 2, a switch 31 connected to the output of the peak detector 30 and connected, by its control input, to the input of said peak detector 30.

The switch 31 is intended to put the detector of
peak 30 in initial state in response to the wheel acceleration signal.

wheel.

 On the other hand, the circuit 25 includes a pulse trainer 32 intended to produce pulses at the time of presentation of the maximum value of wheel deceleration. The input of the formatter 32 is connected to the output of the circuit 4 which detects the moment of presentation of the extreme value of the input signal. And finally, the circuit 25 includes a sampling and memory circuit 33 whose information input is connected to the output of the peak detector 30, the control input is connected to the output of the pulse trainer 32 and the output serves as the output of circuit 25.

 To properly adapt the anti-lock system to sudden variations in braking conditions, it is rational to use another embodiment shown diagrammatically in FIG. 16.

 This embodiment constitutes a development of the system illustrated in FIG. 2.

 As can be seen from FIG. 16, the anti-lock system also comprises a block 34 for correcting predicted speed. One of the inputs of the corrector block 34 is connected to the output of the wheel speed prognostic block 3, the other input of the block 34 is connected to the output of the differentiator 2 and the output of this block is connected to the input of circuit 5 for comparing the wheel speed signal with the predicted speed signal.

 The device shown in FIG. 17 is one of the embodiments of the correction block 34. As shown, the correction block in question comprises an adder 35 and a discriminator 36 of the acceleration and deceleration signals for the wheel. The input of said discriminator serves as one of the inputs of the corrector block 34 and is connected to the output of the differentiator 2. The outputs of the discriminator 36 are connected one to a first and the other to a second input of the adder 35, a third input of the adder 35 serving as the other input of the corrector block 34 and being connected to the output of the block 3 predicting the wheel speed. The output of the adder serves as the output of the correction block 34. FIG. 17 in question also gives an embodiment of the discriminator 36 which comprises, as shown, a pair of diodes 37 and 38 connected in series whose connection point serves input of said discriminator 36, while the other sockets of these diodes serve as output of said discriminator.

 The device represented in FIG. 18 constitutes another embodiment of the corrector block 34. In accordance with this embodiment, the corrector block 34 comprises an adder 39 and a suppressor circuit 40 serving to let pass an output signal from the differentiator 2, the value of which goes beyond the limits of the non-sensitive area of this suppressor circuit.

The input of the suppressor circuit 40 serves as one of the inputs of the correction block 34 and is connected to one of the inputs of the adder 39 whose other input serves as the other input of the correction block 34, the output of the adder 39 being the output of this correction block.

 As can be seen from the same figure 18, the suppressor circuit can be in the form of a combination of diodes 41 and 42 connected in opposition and in parallel, which combination has at least one diode in each of the branches, the connection points of the branches serving as input and output of the suppressor circuit 40.

 So that the accuracy of compensation for delays of the elements constituting the anti-lock system can be increased by a more precise choice of the moment of correction of the predicted speed, this during variations in the braking torque during acceleration of the wheel, it is rational. to use an embodiment shown in FIG. 19. According to this embodiment, the anti-lock system comprises, in addition to the elements given in FIG. 1, a block 43 for determining the moment of the adhesion force, which block consists of an adder 44 and a trainer 45 of the braking torque signal. One of the inputs of the adder 44 is electrically connected to the output of the trainer 45, the other input of the adder 44 is connected to the output of the differentiator 2 while the output of this adder is connected to the input of the circuit 4 detector of the moment of presentation of the extreme value of the input signal.

 The trainer 45 of the braking torque signal can be in the form of a braking torque sensor and an amplifier connected in series. The braking torque sensor can be a tensometric sensor bonded, for example, to the brake shoes.

 It is very interesting, from a practical point of view, to use as a trainer 45 of the braking torque signal, a combination (FIG. 20) comprising a braking torque sensor 46 and an amplifier 47 connected in series, both being of a known type. It is desirable that the amplifier has a static characteristic corresponding to the dependence of the braking torque on the braking pressure.

 By using a delay circuit 48, it is possible to obtain a better correspondence of the output signal of the block 43 for determining the moment of the adhesion force with the real value of the moment of the adhesion force.

 The trainer 45 of the braking torque signal can also be produced in the form of a circuit simulating, using known means, the variations of the braking torque over time and operating in synchronism with the control signals of modulators of brake pressure.

 The anti-lock system, object of the present invention, operates as follows.

An analog signal is obtained at the output of the trainer 1 of the wheel speed signal, the voltage of which has an amplitude equivalent to the angular speed of the wheel of the means of transport, which analog signal is the product of an appropriate conversion of the signals from of the angular speed sensor forming part of said trainer and of a filtering of these signals in the frequency-voltage converter, operated in order to smooth the speed signal. Because the speed signal formator 1 includes a low-pass filter, there is a delay of the speed signal relative to the actual wheel speed (see FIG. 21a), where Vk is the actual angular wheel speed and Vk is the wheel speed signal which appears at the output of the trainer 1. For the purposes of this description, the variables Vk and as well as the variable Va of the speed of means of transport (see
always figure 21), are reduced to the same scale.

The output signal from the trainer 1 of the wheel speed signal arrives in the differentiator 2 where it undergoes differentiation and smoothing. Produced at the output of the differentiator 2, the derivative signal Vk is already longer behind the actual derivative of speed Vk. The wheel speed signal Vk is also sent to one of the inputs of the comparison circuit 5, the other input of which receives a predicted speed signal from the output of the wheel speed predictor block 3 corresponding approximately to a speed. so-called "optimal" wheel, that is to say ensuring the wheel the best coefficient of grip on the ground during braking and, thereby, the minimum stopping distance by means of transport. 21, the optimal wheel speed is referenced in VO. When the value of the wheel speed signal is greater than the value of the predicted speed signal Vn, the output signal of the comparison circuit 5 is equal to zero, but when the wheel speed signal is less than the predicted speed signal , the comparison circuit 5 produces a signal whose value is other than zero.

 At the start of the braking of a means of transport fitted with the anti-lock system, there is a completely ordinary process: the braking torque M, applied to the wheel, increases, the wheel speed Vk, as does the signal. V k corresponding to it, decreases, the wheel deceleration Vk, just as the wheel deceleration signal Vk, increases. When the wheel speed and predicted speed signals coincide, a signal U5 occurs at a time t1 at the output of the comparison circuit 5, which signal is that of the pressure drop modulator control command.

 The control signal dX braking pressure drop modulator being produced (see FIG. 21 b), there is a reduction in the braking pressure (FIG. 21d), which reduction takes place with a delay t1 due to the inertia of the modulator and of the braking control execution members. After that, there is a decrease in the wheel deceleration signal Vk, since the decrease in the braking torque applied to the wheel causes a decrease in the speed of variation of the wheel speed and, subsequently, even an acceleration of wheel.

When the wheel acceleration signal Xk reaches
k
its maximum value, the circuit 4 detector of the moment of presentation of the extreme value of input signal produces a pulse of a certain duration. This pulse arrives at the control input of block 3 predicting the wheel speed and causes a forced input (selection) of the value of the signal Vk into the circuit 7 of selection and memory.

 This operation is an amplitude correction of the predicted speed and takes place at a time tk corresponding roughly to the maximum actual wheel acceleration value and, therefore, to the maximum grip coefficient. We know that the coefficient of adhesion is determined by the slip of the wheel. Then, the determination, at the given time, of the wheel speed is, in reality, the determination of the so-called critical wheel slip, that is to say of the slip corresponding to the best coefficient of adhesion. Thanks to this feature, the anti-lock system becomes adaptable to real braking conditions and predicts a wheel speed close to optimal speed (VO) in all braking conditions.

 To increase the effectiveness of the braking controlled by compensating for the delays due to the inertia of the elements constituting the system, the control circuit 6 is required to control the rate of variation of the predicted speed in such a way that the coincidence of the wheel speed and predicted speed signals take place with an advancement of the moment of time at which the actual wheel speed Vk becomes equal to the optimal speed VO. To this end, the rate of modification of the predicted speed becomes lower, in the braking phases where the wheel speed becomes weaker, than the rate of modification of the optimal speed.

In order to achieve this, the input of the control circuit 6 (FIG. 1) is connected to the output of the comparison circuit 5.

 The specific cases of the speed variation control of the predicted speed V n are as follows.

 In one of said cases, during the braking pressure growth phase, that is to say when the output of the comparison circuit 5 does not produce a control signal, no signal occurs at the output of the control circuit 6 as a result of which the output signal of the selection and memory circuit 7 is invariable and, therefore, invariable remains the value of the predicted speed. When the wheel speed and predicted speed signals coincide, the output of the circuit 5 of comparison produces a control signal (FIG. 21, time of time t1), which signal then arrives in the brake pressure drop modulator (not shown) and, at the same time, at the input of circuit 6 of control by pushing the latter to produce a signal other than zero. This signal, which differs from zero, causes the reduction of the predicted speed at a speed defined by the value of said circuit output signal 6. The choice of allule suitable for modification of the predicted speed ensures, in the case of braking on a surface having a low coefficient of adhesion, the abovementioned advancement of the time moment when the actual wheel speed becomes, increasing, equal to the optimal speed VO (FIG. 21a, points A and A ').

 In another of the aforementioned cases, the formation of the predicted speed signal occurs in a manner similar to that described above, however, the invariable value of the predicted speed is formed at the output of the block 3 predicting the speed of wheel (Figure 1) not before but after time t1. In this case, it is useful to advance the time when the wheel speed will become equal to the optimal speed while decreasing (Figure 21a, point B). By choosing the appropriate speed for decreasing the predicted speed, we can prevent the premature release of the brakes at the same time as obtaining the aforementioned advancement (Figure 21a, point B ').

 In the optimal case, the decrease in the predicted speed occurs before as well as after the time moment t1, but at different gaits. This makes it possible to advance the moments of time when the wheel speed becomes equal to the optimal speed VO during cyclic variations in the wheel speed, the latter being decreasing as well as increasing. This mode of formation of the predicted speed signal is illustrated in Figure 21a. In this case, it is possible to prevent the premature release of the brakes, the wheel speed being reduced.

 In the case where the braking torque M decreases, using the anti-lock system, and becomes equal to a moment My of the adhesion force, its subsequent reduction is irrational. To limit the braking torque in this case, a brake pressure maintenance modulator is normally used. The values M and being in coincidence, the wheel acceleration Vk becomes equal to zero, which is used for the formation of the control signal of the brake pressure maintenance modulator.

 In the embodiment of the anti-lock system given in FIG. 2, the wheel acceleration signal Vk arrives at one of the inputs of the comparison circuit 9 where it is compared with the reference signal supplied to the other input of this circuit at from trainer 8 of the deceleration threshold. The aforementioned reference signal normally has zero level or some other constant level.

 When the signal in question exceeds the derivative Vk of the reference signal, the output of the comparison circuit 9 produces a signal which arrives at one of the inputs of the "AND" circuit IO whose other input receives a pressure drop signal. braking.

 When the two inputs of the "AND" circuit IO each benefit from a signal, its output produces a command signal for the brake pressure maintenance modulator (FIG. 21c). Maintaining the braking torque M occurs with a delay t2 with respect to the time time t2 marking the appearance of the control signal at the output of the "AND" circuit IO (FIG. 2).

 The end of the maintenance of the braking pressure takes place when the wheel speed becomes, increasing, greater than the predicted speed (FIG. 21a, point A ').

At this time time t3, there is the disappearance of the signal at the output of the comparison circuit 5 (FIG. 2) and, at the same time, the disappearance of the signal at the output of the "AND" circuit IO.

 In this state of affairs, the operating cycle of the anti-lock system can be divided into three phases: phase of increasing the braking pressure which extends from the start of braking to t1 + At1, phase of dropping the braking pressure of t1 +; t1 to t2 + ss t2, and brake pressure maintenance phase which continues from t2 + t2 to t3 = # t3.

# t3 is the delay of the start of a new increase in the braking pressure (of the braking torque M) compared to the time moment t3, due to the
tie of the modulators, the brake control and the brakes themselves.

 As already mentioned above, the control circuit 6 can be designed differently; FIG. 3 of the drawings represents, in particular, an embodiment of this circuit which ensures the implementation of all the above-mentioned cases of predicted speed control.

This embodiment of the circuit 6 operates as follows.

 In the initial state, no signal is observed at the output of the comparison circuit 5 and the switch 12 transmits in the sampling and memory circuit 7 a portion of the voltage produced by the reference voltage source 11. This results in a decrease in the speed predicted at a given pace (Figure 21a, curve Vn, sections from O to t1 and from t3). At a time time t1, the control input of switch 12 (FIG. 3) receives a signal from the comparison circuit 5, which signal disconnects switch 12. From this moment we observe, at the output of the control circuit 6, all the voltage produced by the source 11, which contributes to the reduction in the predicted speed going at a greater pace (FIG. 21a, curve Vn, section from t1 to t3).

 By modifying the construction of the switch 12 in a known manner, it is easy to obtain each of the particular control cases mentioned above. For the first of these cases, when the switch 12 is, in the initial state, normally closed, the output of the control circuit 6 must produce a zero voltage, while in the second case the switch 12 is, the initial state tial, normally open.

 When it is necessary to normalize the duration of the signal coming from circuit 4 (FIGS. 1, 2) at the control input of block 3 predicting the wheel speed, it is rational to have recourse to the embodiment of this block, shown in Figure 4.

 A signal from the output of circuit 4 arrives at the input of the sampling pulse trainer 13.

The trainer 13 allows, whatever the duration of the input signal, a constant duration of the output signal which then goes to the control input of the switch 14.

The switch 14 is switched on and introduced into the memory element (integrator 15), at a time time tk, the value of the wheel speed signal Vk.

This value constitutes the initial value of the output signal of the integrator 15 and subsequently decreases to a speed defined by the output signal from the control circuit 6, which output signal is integrated by this integrator 15 (figure 21a, section t3 - tk)
We manage to prevent premature brake releases more effectively, by using a block 3 predicting the wheel speed, established in accordance with the embodiment given in FIG. 5.

 Since the speed of modification of the wheel speed is small, the signal from the output of the comparison circuit 17 arrives in the adder 18, to be added to the output signal of the control circuit 6, and controls the integrator 15 so that the output voltage of this integrator is in pursuit of the output voltage produced by the circuit 16 separating a portion of the wheel speed signal. In this case of low speed reduction of the wheel speed, the brakes being applied or not, the wheel speed signal and the predicted speed signal cannot meet, which excludes any premature release of the brakes.

 If there is a sudden decrease in wheel speed, that is to say when the wheel speed decreases at a high speed, the output signal of the integrator 15 always decreases at a constant-determined speed and fails to track the output signal produced by circuit 16, which is a specified portion of the wheel speed signal.

 In this case, the wheel speed and predicted speed signals meet, resulting in a command to drop the brake pressure. Thereafter, the anti-lock system works as onli already described. It is important to underline here that the linear decrease in the predicted speed only occurs when the speed of decrease of the wheel speed exceeds a predetermined limit, which effectively prevents any premature release of the brakes.

The embodiment of the tip block 3, given in FIG. 6, makes it possible to increase the sampling precision of the wheel speed value. Established in accordance with this embodiment, the block 3 operates in a manner analogous to that described for the purposes of FIG. 4, a design made so that the switch 14 introduces into the integrator 15 not the full value of the signal Vk but only a portion of this value, which portion is defined by the circuit 16 separating a portion of the wheel speed signal. This is essential because during time At1 (FIG. 21a), which constitutes the delay in detecting the value maximum acceleration, the signal
Vk of wheel speed happens, increasing, to exceed the optimal value (figure 21a, point A). So that the dynamics of modification of the wheel speed signal can be taken into account, it is rational to use, as circuit 16, a delay circuit, in particular, an inertia element allowing a delay corresponding to t1.

 When resorting; in the embodiment of the tip block 3, shown in Figure 7, there is a better insensitivity to parasites of the anti-blocking system. When we are in the presence of the control signal for the brake pressure drop, the inhibition circuit 19 prohibits the passage of the output signal from the trainer 13 of sampling pulses to the control input-switch 14. It is in this way that the inhibition circuit 19 makes it possible to avoid any erroneous correction of the predicted speed, which correction could occur during a locking of the wheel, its speed being reduced, in the phase of brake pressure drop.

 The correction of the predicted speed, that of which it was above, is not a momentary operation and requires a certain time resulting from the inertia of the circuit 7 of sampling and memory (figu rets1,2), which is, in particular, the final time essential for the introduction of the initial conditions into the integrator 15.

The embodiment of the prognosticator block 3, the representation of which is made in FIG. 8 of the drawings, makes it possible to reduce the time necessary for sampling. Established in accordance with this embodiment, the prognosticator block 3 operates so that the signal from circuit 5, which signal is produced during
that the wheel speed signal exceeds, increasing, the predicted speed signal, switches on the scale
RC 20. The output signal of the flip-flop passes, from this moment, through the "OR" circuit 21 and connects, through the control input, the switch 14, from which results a signal which is introduced into the integrator 15 and which is present on the other input of switch 14 (output signal of circuit 16 separating a portion of the wheel speed signal). When the output of circuit 4 produces a signal corresponding to the value maximum of its input signal, this signal arrives at the other input of the flip-flop RC 20 and disconnects it. By means of the sampling pulse trainer 13, the switch 14 remains connected, for more reliability, a certain time which may already be significantly less than those which appear in the preceding embodiments. After the switch 14 has been disconnected, the integrator 15 has a voltage corresponding to the optimum wheel speed. It should be emphasized here once again that the sampling time, which is defined by the duration of the pulse In this embodiment, the output produced by the trainer 13 can be as low as desired, which contributes to reducing the inertia of the anti-lock system and improving the precision of the adjustments.

 To prevent the premature presentation of the brake pressure maintenance modulator control signal, this when the wheel is locked, it is rational to use an anti-lock system established in accordance with the embodiment shown in Figure 9 of the drawings.

 The wheel speed signal Vk arrives in the comparison circuit 23 where it is compared with a reference signal produced by the respective source 22. When the signal Vk becomes lower than the reference signal, there is the appearance, at the output of the comparison circuit 23, of a signal-al which brings into play the inhibition circuit 24.

The output signal of the "AND" circuit IO cannot then pass through the inhibition circuit 24, which prevents any maintenance of the braking pressure.

During cyclic variations in wheel speed, without
the wheel locks up, equality of the wheel acceleration V k to zero normally means that the braking torque M is equal to the moment Mf of the adhesion force, which is used for training purposes the brake pressure maintenance signal. On the other hand, when the wheel is locked, the equality of its acceleration to zero does not prove the equality between M and M, but results from the zero speed of the locked wheel. In this case, the brakes must be released by an additional drop in the braking pressure (reduction of the braking torque M). In these conditions, we manage to avoid maintaining the braking pressure, the signal 9 of acceleration of wheel being zero, as described above.

 To increase the efficiency of compensation for delays in the control signals of the brake pressure drop modulator, this depending on the actual braking conditions, it is rational to use an anti-lock system in accordance with the embodiment, object of the figure IO.

 When a signal is presented at the control input of the circuit 25 separating the maximum wheel deceleration value, said circuit retains, in its memory, the value of the signal gk corresponding to the maximum deceleration of the wheel. wheel. The output signal of circuit 25 arrives at the input of training of control circuit 6.

 When the braking conditions vary, in particular, when the vehicle passes over ground with a lower coefficient of adhesion, there is an increase in the maximum value of wheel deceleration and the Max ss level (figure 21a) of the wheel acceleration signal tk, which level corresponds to this maximum deceleration value. The coefficient of adhesion being more reliable, the deceleration of the vehicle, possible as much as possible, is also lower, resulting in a less significant pace of the decrease in the optimal wheel speed.

Then, to approximate the value of the predicted speed to that of the optimal wheel speed, the control circuit 6 uses the value Max | -Vk | the wheel deceleration signal. In this case, it is rational to use the embodiment of the control circuit 6, represented in FIG. 11.

 The signal for the maximum wheel deceleration value arrives from the inputs of the adder 26, the other input of which receives a signal of opposite polarity from the reference voltage source 11. Then, produced by the output of the adder 26, the total signal has a polarity which ensures the reduction of the predicted wheel speed. For the rest, the circuit operates in a manner analogous to that relating to FIG. 3.

 Thanks to the proposed design of the control circuit 6, the rate of modification of the predicted wheel speed decreases when the signal Max | Vk | is increasing and vice versa. This contributes to bringing the value of the predicted wheel speed Vn dz closer to the optimum value VO under variable braking conditions and makes delay compensation more effective.

If the trainer 8 of the wheel deceleration threshold is a controlled version (see FIG. 12), the accuracy of compensation for the delays in maintaining the braking pressure is raised. The trainer control input 8 receives the signal Max corresponding to the maximum value of the wheel deceleration. The output of this trainer 8 produces a predetermined portion of this signal. Thus obtained, the output signal E (see FIG. 21a) is then used in order to form a control signal for the brake pressure maintenance modulator (FIG. 21c), as described above for FIG. 2. From this done, we benefit from an advancement At5 compared to the moment (figure 21a, point C ') when the wheel acceleration signal Vk takes the value zero. We then see that the maintenance of the braking pressure begins with less delay compared to when the actual wheel acceleration becomes zero (figure 21a, point C and figure 21d, t2 + At2)
The embodiment of the system of the invention, given in FIG. 13, is the result of an improvement which the embodiments, objects of FIGS. 10 and 12 have undergone. The operation of this embodiment is analogous to that described above and relating to FIGS. 10 and 12.

 When braking on a surface with a high coefficient of adhesion, even when the predicted speed is decreasing, there may be a malfunction of the anti-lock system, due to an incorrect correction of the predicted speed, possible due to pulsations maximum of the wheel acceleration signal. This erroneous correction may possibly result from a short-term variation in the wheel speed. In order to avoid any premature release of the brakes in this case, it is rational to have recourse to the embodiment shown in FIG. 14.

Comparison circuit 28 opposes the signal Max
iVkt, corresponding to the maximum value of the wheel deceleration, to the reference signal from the source 27 and controls the inhibition circuit 29 in such a way that, when the Max signal is less than the reference signal, the circuit inhibition 29 prohibits the passage of the control signal to the brake pressure drop modulator.

 This is how you can prevent premature release of the brakes when braking on a surface characterized by a high coefficient of adhesion.

 For all the embodiments shown in Figures IO, I2, 13, 14, the circuit 25 (see Figure 15) separating the maximum value of the wheel deceleration signal operates as follows. The signal Vk, changing cyclically, leaves the output of the differentiator 2 (FIG. 1) to arrive at the input of the peak detector 30 at the same time, at the control input of the switch 31.

The diode, which is part of the peak detector 30, separates a portion of the signal Vkf that which corresponds to the wheel deceleration (the polarity of connection of the diode being as in FIG. 15, these are the negative values of the signal Vk which correspond to the wheel deceleration). When the wheel deceleration is increasing, there is the charge of the capacitor which is also part of the peak detector 25. When the wheel deceleration begins to decrease, the capacitor always has the voltage corresponding to the maximum value of wheel deceleration.

By obeying a control signal produced by the pulse trainer 32, the sampling and memory circuit 33 retains in its memory the value of the voltage presented by said capacitor, that which corresponds to the maximum wheel deceleration. To prepare the peak detector 30 for the detection of the maximum deceleration in the next cycle, the switch 31 comes into play so as to discharge the peak detector 30 when the signal Vk present at the control input of this switch acquires the polarity corresponding to the wheel acceleration (positive polarity for figure 15).

To make the adaptation of compensation faster
Because of the delays of the anti-lock system to sudden variations in the braking conditions, in particular to variations in the grip coefficient of the wheel on the ground, it is rational to use the embodiment shown in FIG. 16.

 As shown in the figure in question, the corrector block 34 operates the correction of the predicted speed signal Vn, arriving at one of its inputs, in accordance with the signal Vk of derivative of the wheel speed, arriving at its other input, and in such a way that the output signal resulting from the correction reports the instantaneous actual braking conditions, and in particular, the speed of modification of the wheel speed.

In version, object of Figure 17, block 34 operates as follows. The input of the discriminator 36 receives a signal from the differentiator 2. Depending on the polarity of the said signal, a diode 37, 38 opens which supplies this signal to the respective input of the adder 35. The adder 35 is also provided with a signal Vn of predicted speed of a polarity such that the adder 35 can exercise the operation
V = Vn - aVk (1) where: V is the output signal from adder 35;
a is the scaling factor of the adder; at
Note that

 The factor a takes different values in accordance with the polarity of the signal kw i.e. it is different for the acceleration and deceleration of the wheel. This design of the discriminator 36 widens the possibilities of introducing the correction optimal value of the predicted speed. On the other hand, this makes it possible to vary the correction as a function of the operating phase of the anti-lock system, hence a more precise compensation of the delays, which contributes significantly to the adaptation of the system to sudden variations (depending on the adhesion ) braking conditions.

 Compared to the embodiment of the anti-lock system, represented in FIG. 2, the comparison circuit 5 (FIG. 16) operates the comparison of the wheel speed signal Vk not with the predicted speed signal Vn but with a value V resulting from the correction. Then, in accordance with (1) and (2), when the wheel is decelerating, a negative value -a1tk is subtracted by subtracting the signal Vn of predicted speed. In reality, there is an increase in the predicted speed signal by a value which is a function of the wheel deceleration, that is to say instantaneous braking conditions.

 The coincidence of the wheel speed signal Vk with the output signal V of the correction unit 34 is signaled at a certain time t1, when the wheel deceleration signal has a value -Vk1 (see FIG. 22a, d).

 When the wheel speed increases, we observe that, in accordance with (1) and (2), the signal Vn of predicted speed loses, as a result of the subtraction, a positive value + Vk of the acceleration signal , that is to say: the signal V, result of the correction, becomes lower than the predicted speed signal. The coincidence of the wheel speed signals Vk and V (output signal from the correction unit (34) occurs at a time time t3, when the signal V resulting from the correction is less than the signal V n of predicted speed by value a2tk3 (figure 22a, d).

 The values of the factor a are determined by calculation using a multifactor optimization by calculating machine and is of a magnitude of the order of 0.01s.

 Let us now turn to the examination of another embodiment of the correction block 34, that which is the subject of FIG. 18.

 One of the inputs of the adder 39 receives a signal V n of predicted speed, while its other input receives a signal Vk of opposite polarity.

The adder 39 operates in a manner analogous to that described above (see (1) and (2)) by subtracting from the signal V n of predicted speed a portion of the signal Vk of derivative of the wheel speed, this signal
Vk arriving at the respective input of the adder 39 via the suppressor circuit 40. The suppressor circuit 40 insures the introduction of the correction from a selected minimum value of the rate of modification of the wheel speed.

Indeed, if, for example, during the acceleration of the wheel, the value of the signal V of acceleration of
k wheel is less than the opening voltage of the diode, for example, of diode 41 (which is very characteristic for the case of acceleration of the wheel on a surface having a low coefficient of adhesion, in particular, on an icy surface), this diode does not open and there is no correction of the predicted speed.

This contributes to the reliability of the system since it is possible to avoid any premature production of a signal for an increase in the braking pressure when the coefficient of grip of the ground is very low. It also happens, analogously, to ward off the risk of premature presentation of a signal for a fall in the brake pressure when operating on a ground having a high coefficient of adhesion. In the latter case, the wheel to be braked has a slight circumferential deceleration and the signal corresponding to this deceleration is less than the opening voltage of the diode 42. Once again, there is no correction.

 Thus, the diodes 41 and 42 determine the range in which the correction of the predicted speed signal is especially effective and prohibits any correction under extreme braking conditions, where the correction of the predicted speed signal can only affect the effectiveness of anti-lock system operation.

 Figures 19 and 20 show an embodiment in which the circuit 4 determines the maximum value of the output signal from the block 43 for determining the moment of the adhesion force, while the tip block 3 operates the speed correction predicted when the maximum value of this signal appears.

In this case, the accuracy and the frequency of correction are higher than in the embodiments described above. Indeed, from the main equation of the balance of the moments of forces which are felt during braking:
M - My = -CoIVk (3) where: I is the moment of inertia of the wheel,
C is the coefficient of relation between the acceleration
circumferential and conventional acceleration
of the wheel, it follows that, whatever the variations in the braking torque M, the maximum value of the sum (M + cIid) corresponds to the maximum value of the moment of the adhesion force. addition of the braking torque signals, coming from the output of the trainer 45, and of the wheel speed derivative, coming from the output of the differentiator 2, addition operated by the adder 44 using the scaling factors respective, provides a grip force moment signal, the maximum value of which corresponds to the maximum value of the actual moment of the grip force, i.e. corresponds to the optimal braking conditions.

Because the maximum values of the moment M t of the adhesion force appear twice as often as the maximum values of the acceleration
Vk wheel (figure 21a, d and 22a, d), the correction of the predicted speed also occurs twice as often. For what is shown in Figures 21 and 22, the correction of the predicted speed will have takes place both at time tk and at time corresponding to the maximum value My of the adhesion force in the range from O to t2
Because the braking torque signal normally occurs at the output of the trainer 45 with a delay, with respect to the torque M, which is lower than the delay with which the signal Vk of derivative of the wheel speed occurs with respect to the real derivative Vk, their temporal correspondence is obtained by delaying the signal supplied by the output of the formatter 45 with the aid of the retarder circuit 48 (FIG. 20).

It is rational that the value of this delay is not less than the delay of the derivative signal Vk with respect to the actual wheel speed derivative Vk. The block 43 for determining the moment of the adhesion force being designed as described, the signal from the brake pressure sensor 46 is amplified using the amplifier 47 and arrives at the input of the retarder circuit 48 where it is delayed by a chosen deadline. The output signal supplied by the delay circuit 48 where it is delayed by a chosen delay. The output signal supplied by the delay circuit 48 arrives at the input of the adder 44 where it is added with the signal Vk of the wheel speed derivative.

The signal presented at the output of the adder 44 corresponds to the real moment of the adhesion force.

 On the other hand, the implementation of a delaying operation makes it possible to compensate, to a certain extent, for the delay of the braking torque on the braking pressure.

Claims (22)

R E V E N D I C A T I O N S  1.- Anti-lock braking system of a means of transport provided with at least one wheel whose speed is controlled and with a brake pressure drop modulator, of the type comprising a trainer 1 of the wheel speed signal , a differentiator 2 producing at its output, as a function of the wheel speed signal, a wheel acceleration or deceleration signal, a circuit 4 detector of the moment of presentation of the extreme value of the input signal, which circuit detector is electrically connected to the output of the differentiator 2, a block 3 predicting the wheel speed having a circuit 7 for sampling and memory and producing a signal of predicted speed corresponding approximately to the optimal wheel speed during the braking and varying as a function of the wheel speed signal supplied to the information input of block 3 wheel speed predictor when the control input of this nloc 3 wheel speed predictor r receives a signal from the output of circuit 4 detector of the moment of presentation of the extreme value of the input signal, a circuit 5 of comparison of the wheel speed signal with the predicted speed signal, producing a control signal of the modulator for dropping the braking pressure when the predicted speed signal becomes greater than the wheel speed signal, characterized in that the block 3 predicting the wheel speed further comprises a control circuit 6, the control input of which, serving as an additional control input for the wheel speed predictor block 3, receives the control signal from the brake pressure drop modulator, while the output of said control circuit 6 is electrically connected to an additional circuit input 7 sampling and memory in order to provide it with a signal controlling the rate of modification of the predicted speed signal produced by the output of the block 3 prognostics wheel speed iquor.  2.- Anti-lock braking system. Of a means of transport equipped with at least one wheel whose speed is controlled, a brake pressure drop modulator and a brake pressure maintenance modulator , type system comprising a trainer 1 of the wheel speed signal, a differentiator 2 producing at its output, as a function of the wheel speed signal, a wheel acceleration or deceleration signal, a circuit 4 moment detector for presenting the extreme value of the input signal, which circuit is electrically connected to the output of the differentiator, a block 3 predicting the wheel speed having a circuit 7 for sampling and memory and producing a signal predicted speed approximately corresponding to the optimum wheel speed during braking and varying as a function of the wheel speed signal supplied to the information input of block 3 predicting the wheel speed when the control input said wheel speed predictor block 3 receives a signal from the output of the circuit 4 detector of the moment of presentation of the extreme value of the input signal, a circuit 5 for comparing the wheel speed signal with the speed signal predicted, producing a control signal of the brake pressure drop modulator when the predicted speed signal becomes greater than the wheel speed signal, a trainer 8 for the wheel deceleration threshold, a circuit 9 for comparing the deceleration threshold wheel to the output signal of the differentiating member 2, producing an output signal when the signals arriving at its inputs have analogous values, an "AND" circuit 10 the output of which produces a control signal dw modulator for maintaining the brake pressure when the inputs of said "AND" circuit receive signals from the aforementioned comparison circuits 5 and 9, characterized in that the block 3 pronos wheel speed tiqueur further comprises a control circuit 6 whose control input, serving as additional control input for block 3 wheel speed prognosticator, receives the control signal from the pressure drop modulator braking, while the output of said control circuit 6 is electrically connected to an additional input of the sampling and memory circuit 7 in order to provide it with a signal modifying the pace of the decrease in the predicted speed signal produced by the output of block 3 wheel speed predictor.  3. Anti-lock braking system according to one of claims 1 and 2, characterized in that the control circuit 6 comprises a source 11 of reference voltage and a switch 12 whose information input is connected to the output of said reference voltage source 11 and in that the control input of switch 12 serves as the control circuit control input 6 while the output of said switch 12 serves as output of this control circuit 6.  4. Anti-lock braking system according to one of claims 1 and 2, characterized in that the block 3 predictor of the wheel speed comprises a trainer 13 of sampling pulses whose input serves as a control input. of the wheel speed predictor block 3, while the sampling and memory circuit 7 comprises a switch 14 and a memory element 15, the control input of the switch 14 serving as the control input of the circuit 7 d sampling and memory and being electrically connected to the output of the sampling pulse trainer 13, the information input of said switch 14 serving as information input of the sampling and memory circuit 7 and being connected electrically at the information input of block 3 predicting the wheel speed, the output of this switch 14 being connected to one of the inputs of the memory element 15, the other input of which serves as additional input to the circuit 7 d and memory and the output of this memory element 15 serving as an output of the circuit 7 for sampling and memory.  5. Anti-lock braking system according to claim 4, characterized in that the block 3 predictor of the wheel speed further comprises a circuit 16 for separation of a portion of the wheel speed signal, the input of which serves information input of the wheel speed predictor block 3 and the output is connected to the information input of the sampling and memory circuit 7.  6. Anti-lock braking system according to claim 5, characterized in that the block 3 predictor of the wheel speed further comprises a circuit 17 for comparison and an adder 18, the inputs of the comparison circuit being connected to one the information input and the other at the output of the sampling and memory circuit 7, the output of said comparison circuit 17 being connected to the inputs of the adder 18, while the electrical connection between the control 6 and the sampling and memory circuit 7 consists of connecting the output of the control circuit 6 to the other input of the adder 18 whose output is connected to the additional input of the sampling circuit 7 and of memory.  7. Anti-lock braking system according to claim 4, characterized in that the block 3 predictor of the wheel speed further comprises an inhibition circuit 19 to prohibit the sampling operation from the sampling circuit 7 and memory when a braking pressure drop modulator control signal appears, the information input of this inhibition circuit being connected to the output of the sampling pulse trainer 13, its input inhibition being connected to the control input of the control circuit 6 and the output of the inhibition circuit 19 being connected to the control input of the switch 14.  8. Anti-lock braking system according to claim 4, characterized in that the block 3 of the wheel speed prognosticator further comprises an RC C 20 lever whose inputs are connected one to the control input and the other at the additional control input of said wheel speed predictor block 3, an "OR" circuit 21 of which one of the inputs is connected to the output of the RC rocker 20, while the electrical connection between the trainer 13 of sampling pulses and the control input of the sampling and memory circuit 7 is produced by connecting the other input of said XOU circuit "21 to the output of the above-mentioned formatter 13, the output of the" OR "circuit being connected to the control input of circuit 7 for sampling and memory.  9. Anti-lock braking system according to claim 2, characterized in that it further comprises a source 22 of reference signal, a comparison circuit 23 producing an output signal when the wheel speed signal is not higher than the reference signal, which comparison circuit is connected, by its inputs, to the output of the trainer 1 of the wheel speed signal and to said source 22 of the reference signal, it also includes an inhibition circuit 24 intended to inhibit the production of the braking pressure-maintaining modulator control signal when the output signal from the comparison circuit 23 is present, the information input of the inhibition circuit 24 being connected to the output of the "AND" circuit 10 and the input  inhibition of this circuit being connected to the output  of the aforementioned comparison circuit 23.  10.- Anti-lock braking system according to one  of claims 1 and 2, characterized in that it  further includes a circuit 25 separating the value  maximum wheel deceleration, the output signal  of the differentiator 2 serving, for this circuit  separator 25, information signal, and signal  output from circuit 4 time of presentation detector  the extreme value of the input signal used to  control signal, and in that the control circuit  6 presents an information entry to which is  connected the output of the circuit 25 separating the maximum value of the wheel decelerator.  11.- Anti-lock braking system according to  claim 10, characterized in that the circuit for  command 6 includes a reference voltage source 11,  an adder 26 and a switch 12, one of the inputs  of the adder 26 being connected to the output of the  reference voltage source, the other input to the addi  actuator 26 serving as an information input for the control circuit 6, the output of the adder 26 being connected to the information input of the switch 12, the control input of which serves as the control input of said control circuit 6 and the output of the switch 12 serving as the output of the control circuit 6.  12.- Anti-lock braking system according to  claim 2, characterized in that it further comprises  a circuit 25 separating the maximum value of detected  wheel ration, the output signal of the different body  divider 2 serving, for this separating circuit 25, as a signal  information, and the output signal of circuit 4 detector  the moment of presentation of the extreme value of the signal  input serving as a control signal, and in that  the trainer 8 of the wheel deceleration threshold is  controlled type, its control input being connected to the output of the circuit 25 separating the maximum value of wheel deceleration.  13. - anti-lock braking system according to claim 2, characterized in that it further comprises a circuit 25 separating the maximum value of wheel deceleration, the output signal of the differentiating member 2 serving, for this separating circuit 25, of information signal, and the output signal of circuit 4 detector of the moment of presentation of the extreme value me of the input signal serving as its control signal, and in that the control circuit 6 of block 3 Wheel speed predictor has an information input to which the output of the circuit 25 separating the maximum wheel deceleration value is connected, which output is also connected to the input of the trainer 8 of the wheel deceleration threshold.  14. - anti-lock braking system according to claim 13, characterized in that it further comprises a source 27 of reference signal, a comparison circuit 28 producing an output signal when the wheel deceleration signal is not higher, depending on the module, than the reference signal, which comparison circuit is connected by its inputs to the output of the circuit 25 separating the maximum wheel deceleration value and to said source 27 of the reference signal, as well as a circuit inhibition 29, one of the inputs of which is connected to the output of the aforementioned comparison circuit, the other input of which is connected to the output of the circuit 5 of comparison of the wheel speed signal with the predicted speed signal, while the output of said inhibition circuit 29 serves to provide a control signal for a brake pressure drop modulator.  15. - anti-lock braking system according to one of claims 10, 12 and 13, characterized in that the circuit 25 separating the maximum wheel deceleration value comprises a peak detector 30 whose input receives a signal from the output of the differentiator 2, a switch 31 connected to the output of said peak detector 30 and connected, by its control input, to the input of this peak detector, which switch 31 is intended to set the peak 30 in the initial state in response to the wheel acceleration signal, a pulse trainer 32 used to produce pulses at the moment of appearance of the maximum value of the wheel deceleration signal and the input of which receives the signal output from circuit 4 detector of the moment of presentation of the extreme value of the input signal, a circuit 33 of sampling and memory whose information input is connected to the output of said peak detector 30, l 'coma entry nde is connected to the output of the pulse trainer 32 and the output of which serves as the output of the circuit 25 separating the maximum value of wheel deceleration.  16. - anti-lock braking system according to one of claims 1 and 2, characterized in that it further comprises a block 34 corrected for predicted speed operating the correction of the predicted speed as a function of acceleration or deceleration wheel, one of the inputs of said corrector block 34 being connected to the output of the wheel speed predictor block 3, its other input being connected to the output of the differentiator 2 and its output being connected to the input of the circuit 5 for comparing the wheel speed signal with the predicted speed signal.  17. - anti-lock braking system according to claim 16, characterized in that the corrector block 34 comprises an adder 35 is a discriminator 36 of the acceleration and deceleration signals of the wheel, the input of said discriminator 36 serving as one of inputs of the correction block 34, the outputs of this discriminator 36 being connected one a first and the other has a second input of the adder 35 of which a third input serves as the other input of the correction block 34, the output of the adder 35 serving as the output of this correction block.  18. - anti-lock braking system according to claim 17, characterized in that the discriminator 36 of the wheel acceleration and deceleration signals comprises at least one pair of diodes 37, 38 connected in series whose connection point serves as input of the aforementioned discriminator 36 and the free sockets are the outputs of this discriminator.  19. - anti-lock braking system according to claim 16, characterized in that the corrector block 34 comprises an adder 39 and a suppressor circuit 40 used to let pass an output signal from the differentiator 2, the value of which comes out of the limits of the non-sensitive area of the suppressor circuit 40, the input of this suppressor circuit 40 serving as one of the inputs of the corrector block 34, its output being connected to one of the inputs of the adder 33 whose other input serves as the another input of said correction block 34.  20. - anti-lock braking system according to claim 19, characterized in that the suppressor circuit 40 is a combination of diodes connected in opposition and in parallel, which combination comprises at least one diode in each of the branches, the connection points of the branches serving as input and output of said suppressor circuit 40.  21. - anti-lock braking system according to one of claims 1 and 2, characterized in that it further comprises a block 43 for determining the moment of the adhesion force which comprises an adder 44 and a signal trainer 45 of braking torque, one of the inputs of the adder 44 being electrically connected to the output of the trainer 45 of the braking torque signal, its other input being connected to the output of the differentiator 2 and the output of this adder 44 being connected to the input of circuit 4 detector of the moment of presentation of the extreme value of the input signal, whereby an electrical connection is obtained between the output of the differentiator 2 and the input of said circuit 4 detector of the moment of presentation of the extreme value of the output signal.  22. - anti-lock braking system according to claim 21, characterized in that the block 43 for determining the moment of the adhesion force further comprises a delay circuit 48 whose input is connected to the output of the signal trainer 45 of braking torque and the output is connected to the respective input of adder 44, whereby an electrical connection is obtained between said trainer 45 of the braking torque signal and adder 44.