FR2565185A1 - Antiskid brake servo valve - Google Patents

Abstract

The two brake circuits are separated by a wall through which a thrust rod presses. The first circuit operates directly between the pressure supply and the brakes. The open circuit is switched to a closed circuit when the anti-skid control operates. The switching valve switches the servo pressure for the closed circuit via the servo valve. The pedal operated control piston is fitted with a servo stop incorporating a sprung support with a failsafe setting on servo failure.

Description

 The invention relates to a brake booster or brake force booster, in particular with multiple circuits, to which an anti-lock device (ABS) and a race simulator device are associated and comprising a control valve for applying the pressure. from a pressure supply device.

Servo brakes are universally known, including multi-circuit servos (Republic patent applications
Federal Republic of Germany published under Nos. 25 31 264 and 31 51 292).

These known booster brakes can have a constitution in which one braking circuit is closed, while the other braking circuit is usually an open braking circuit. The open braking circuit is directly attacked by accumulator pressure transmitted from a pressure supply by a distributor or a control valve. In the event of a pressure supply failure, the open braking circuit is transformed into a closed braking circuit. Usually, the open brake system includes an annular piston which is mounted on a pedal plunger actuated by a brake pedal.

There is a demand for brake servos which, being combined with an anti-lock device (ABS), are integrated into the anti-lock assembly so that they can also be used, at least indirectly, as an integral part, for the performance of ABS functions. , so that, while having an acceptable capacity of action for the anti-lock device, it is possible to produce a combined group "brake booster device / anti-lock device" having a cost price and also a considerably reduced complexity and in which " group
Integrated ABS "the brake booster device performs a double function.

 We already know, from the aforementioned patent application 31 51 292, an anti-lock brake protection device using an application of the pressure to the closed braking circuit in certain operating circumstances, thereby determining the opening of the closed braking circuit. This measure requires a relatively large expenditure of technical resources for monitoring the application of pressure, as well as the pressure supply, which must be switched off in the event of failure.

The brake booster device according to the invention is characterized in that, in the case of at least two braking circuits (a closed braking circuit and an open braking circuit), a partition is interposed between the pressure chambers of these circuits, in that the partition is crossed by an extension of the pusher of the pedal which passes through it with a seal and in that this extension is placed at a predetermined distance from the primary side of the closed brake circuit piston of the master cylinder, relative to the excursion stroke of the control valve in the stroke simulator device, the application of the pressure on the primary side of the closed brake circuit piston of the master cylinder being controlled by an electromagnetic distributor which operates, in
In the case of an ABS intervention, in such a way that the modulation of your ABS pressure for the closed brake circuit occurs via the brake booster device.

 This brake booster device according to the invention has the advantage of making it possible to achieve a combination of ABS servo-control functions thanks to appropriate possibilities for modulating the pressure in a brake booster device which works with an open braking circuit and a brake circuit. braking closed.

Pressure control for the execution of ABS functions in the closed brake circuit is effected by changes in the pressure on the primary side of the piston of this brake circuit of the master cylinder, the pressurized fluid being sent outside with hermetic separation of the two pressure chambers assigned respectively to the closed braking circuit and to the braking circuit opened by an electrovalve which operates in response to the appearance of ABS signals and which simultaneously performs, by its operation, ranges partial of the pressure modulation, more precisely of a pressure reduction in the particular embodiment considered. Here, another advantage consists in that the push-button of the pedal, which crosses the partition provided with a tight seal which separates the two pressure chambers, is at a distance from the piston of the master cylinder, which is assigned to the braking circuit which is closed in this case, sufficient so that in pre sence of a reduction in the pressure in this circuit it is possible to obtain a reduction in the braking pressure in the closed circuit at a very low pressure level, almost zero, and even when the user of the vehicle equipped with such an installation requires full braking power by correspondingly depressing the brake pedal.

 The invention has the advantage of a very simple construction, with a short overall length and safety resulting from this simplicity, and it does not require any expenditure of technical means for the circuit for monitoring the ABS valves, nor pressure supply to the brake booster device.

 Furthermore, it is also possible to keep the ABS functions in the open braking circuit in the event of a closed braking circuit failure, which is particularly advantageous for vehicles comprising the conventional mode of dividing the braking circuits (front / rear). . Furthermore, the possibility of emergency braking is entirely preserved in the presence of a failure in the assistance pressure, in any case for the closed braking circuit.

 The invention makes it possible to obtain, with extremely simple means, a completely reliable combination of a brake booster device with integrated ABS, while maintaining fully acceptable power behavior and with considerable reduction in the number of A8S elements and components required, including the speed sensors.

It is particularly advantageous to provide an open brake circuit piston stop, which comes into play in the event of failure of the assistance pressure with simultaneous prohibition of the total depressing of the brake pedal, which is obtained thanks to The use of an intermediate spring plunger
Other characteristics and advantages of the invention will be better understood on reading the following description of several embodiments and with reference to the accompanying drawings in which
- Figure 1 shows a first embodiment of a brake booster device with distributor placed
The exterior, in a sectional view, the figure also showing the associated ABS valve block;
- Figure 2 is a detail view on an enlarged scale of the open brake circuit piston of the master cylinder, which is crossed by the pusher of the pedal.

 The brake booster device shown in Figure 1 comprises a master cylinder with two circuits 10, in which two pistons 11 and 12 are arranged one after the other. It goes without saying that the brake booster device shown by way of example in FIG. 1 does not limit the applications of the present invention; on the contrary, the invention is applicable to all possible forms of production of brake booster devices equipped with a racing simulator device, in which, when the pedal is actuated, at least one brake cylinder piston can be pushed under The effect of applying your pressure from a pressure supply outside the circuit.

The front piston 11 of the master cylinder is held in the position shown in the drawing by a return spring 13, of
The usual way and, in this way, it maintains at the same time open a communication (inlet port 13a) between a reserve or additional tank 14 and the working chamber 15 of the master cylinder. A first braking circuit I, called a closed circuit, is connected to this chamber, as shown, the pressure line being designated by a.

The complete installation shown in FIG. 1 comprises a pressure supply 20, the hydraulic booster device or hydraulic brake force amplifier 3C and a valve block 40, placed in front thereof, intended to produce
ABS functions, Sending pressurized fluid to the corresponding wheel brake cylinders, the left front cylinder (AVG), the right rear cylinder LATE) * the left rear cylinder (ARG) and the right front cylinder (AVD) in passing through the corresponding ABS electrovalves, as will be described below. The electrovalves or multi-way electromagnetic valves of the ABS device, which are connected to the different wheel brake cylinders, are constructed so that we will not describe more precisely in the following, so as to adapt the braking pressure prevailing in the two braking circuits I and 11, possibly separately for the different wheels, according to the characteristics of the roadway or the behavior of the wheels, by bringing in a electronic logic control circuit which receives input signals from a corresponding set of wheel sensors.

 The second piston 12 housed in the master cylinder 10 is an annular piston and it is crossed by the pedal plunger 19 actuated by the brake pedal 16. The annular piston slides in the corresponding part of the master cylinder and, by its surface internal, it limits a pressure chamber 17 which is connected via a channel 18 to a control valve or distributor 21 of the brake booster device. In the embodiment shown, the distributor 21 is located outside the axis of the tandem master cylinder 10, but parallel to it. The actuation of the distributor as well as of the pedal push-button is effected from of the brake pedal, by means of a plate 22 to which a finger 23 can be fixed which can cooperate with a switch S2 for detecting the position of the travel of the pedal (position monitoring). The plate further carries, in the region of a race simulator device 24, a slide 26 which bears elastically by means of a race simulator spring 25, and serves to actuate the dispenser. At this time, the pressure is transmitted from the pressure supply 20 to the working chamber 17 of the open braking circuit.

The pressure supply 20 comprises a pump 27 associated with an accumulator 28. The pressure of the accumulator is transmitted by a hydraulic connection line 29 to a non-return valve 31 provided on the control valve 21.

 Between the two pressure chambers, the pressure chamber 17 of the open brake circuit and the pressure chamber 32, which is a chamber located on the primary side of the piston II of the closed brake circuit of the master cylinder, is located a partition interior 33 which is pressure-tight and which, which is necessary in the event of a failure of the pressure supply, is crossed with a seal by an extension of the pusher 19 of the pedal, or by an intermediate pusher 34 of the pusher 19. From this way, in the event of failure of the pressure supply, by continuing to depress the pedal, one can act mechanically on the front piston 19 or open brake circuit piston of the master cylinder I. The displacement of the front piston 11 of the master cylinder can be sensed by a sensing finger 35, which moves on a corresponding ramp 36 of the piston and actuates a corresponding switch S1 which can also be produced in the form of an analog position encoder emitting an electrical output signal.

 As can be seen in FIG. 1, the intermediate pusher 34 carried by the pusher 19 of the pedal is at a predetermined distance A from the surface Primary side limit of the piston 11 of the master cylinder, this distance corresponding roughly to the control stroke of the stroke simulator device associated with the control valve 21. We will return to this subject in more detail below.

The ABS valves of the valve block 40 are arranged as follows: this block first comprises a separate electromagnetic switching distributor 35 constructed so that, in the case of braking in which an ABS function occurs,
The dual function of the brake booster device is realized by the fact that in the event of braking The pressurized fluid injected by
The distributor 21 in the brake circuit II (pressure line b) arrives from a bypass line b 'at the primary side of the piston II of the closed brake circuit I of the master cylinder, passing through the switching distributor 35 and returning in this sense by the pressure line c. In the following, we will return to the construction of the control valves included in the ABS valve block 40, giving the explanation of the principle operating mode.

 The operating mode is such that, in the case of intervention of ABS functions, these functions are carried out for the open braking circuit II using a three-position distributor 36 for the following known functions: raising the pressure, maintaining pressure, reducing pressure; the ABS distributor is a 3/3 electromagnetic distributor. The modulation of the pressure for the closed circuit performs in another way; more precisely, this modulation is carried out by the cooperation of the closed braking circuit with the aforementioned switching distributor 35, constituted by an electromagnetic distributor 3/2. switching distributor performs the function of reducing the braking pressure, i.e. if a reduction of the braking pressure is to be achieved in the two wheel brake cylinders, in response to the servo signal The corresponding ABS, that is to say in the embodiment shown, at the front left and at the front right (AVG * AVD), this 3/2 distributor operates. A certain quantity of pressurized fluid then flows from the pressure chamber on the primary side of the piston 11 of the master cylinder, which determines a corresponding reduction in pressure in the closed braking circuit. It is essential that this recoil of the piston of the master cylinder is not stopped by the extension 34 of the pedal plunger when the driver continues to hold the brake servo control at the maximum (about 30% of the total stroke of the pedal) This stop is avoided by the aforementioned distance h, which allows the master cylinder piston to return to the region of the inlet port 13s, and thereby guarantees a drop in pressure to a very low level.

If only a unilateral reduction in pressure occurs on one of the two front recipes, AVG or AVD, the supply channel which does not participate in the reduction of pressure is switched to closure c ' that is to say on the maintenance of the pressure, by means of a simple electromagnetic distributor 2/2, 37 or 37 ', corresponding to the branching branch of the pressure a' and a "
So far, in one of the possible embodiments and combinations of the control valves 35, 36 and 37, 37 ', this is a conventional subdivision of the front / rear braking circuits) ; of course, it is also possible to use a diagonal division of the braking circuit, in which the open braking circuit II acts only on the wheel brake cylinder AVD and the closed circuit as well on the wheel brake cylinder AVG then also on the set of
The region of the rear axle, through the distributor 2/2 37 '.

 The two position encoders S1 and 52 can be used to detect a circuit failure.

 Given that the distance A separating the pedal plunger from the piston 11 of the closed brake circuit I of the master cylinder can be disadvantageous in the event of a failure of the brake circuit II, since the brake pedal is depressed by a distance equal to the aforementioned distance, an advantageous embodiment of the present invention, according to FIG. 2, provides for the arrangement of a piston stop, further enlarged by an intermediate spring plunger.

2 shows the piston 12 of the open brake circuit II of the master cylinder, in an enlarged sectional view; in its starting position shown in FIG. 2 (stop on the right),
The annular piston is in communication with the pressure of the supply or the pressure of the accumulator by means of a connecting channel that any 41 forms inside the body, for example, by means of '' an appropriate supply of pressure from the accumulator coming from the distributor 21. The pusher 19 of the pedal is mounted in the central position in the annular piston 12 and it can have on the input side a larger piston diameter which corresponds to the selected amplification of the brake force amplifier or brake booster device. The pressure of the accumulator P is transmitted by bilateral seals
Sp (O-rings 42io 4Zb) up to a pressure inlet 43 formed in the annular piston and, from there, in a working chamber 44 of an operating piston 45 mounted in the annular piston 12 in a position shifted relative to its axis, but arranged parallel to this piston, and which is subjected to a pressure preload by a spring, this operating piston 45 serving to move a control pusher 46. In the normal case, in the presence of your pressure the accumulator, The control pusher 46 is therefore in the collected position shown in FIG. 2 of the drawing.

 There is a locking device intended to couple the plunger 19 of the pedal to the annular piston 12 and which is composed of a slide 47 or of another suitable locking member which is mounted to move in radial iranslation in a bore. transverse of the annular piston. The slide 47 has a central passage 49 in which the conical shaped end region, shown at 50, of the pusher 19 of the pedal can penetrate a partial distance; this end region is then extended by an intermediate spring-mounted plunger 51, which is mounted to slide in a central housing bore 52 formed in the plunger 19 of the pedal, against the pressure of a spring 52 The slide 47 has, in the radial direction, at least one wall region 53 which is also of conical shape. Furthermore, the slide 47 also comprises a bore 54 offset from its central axis and which, in the case of normal braking, in which the slide 47 is in the position shown in FIG. 2, is aligned with the control pusher 46 so that, in response to a failure in the pressure of the accumulator, this pusher can advance and penetrate in the hole 54 to lock the slide 47 and prevent it from moving radially.

 An enlarged end hole 55 formed in the annular piston 12 is still traversed by an axial projection 56 of the slide 47, so that there still remains a predetermined distance between the end of this axial projection 56 and an annular base 57 formed on the intermediate pusher 51. This distance is designated by A '.

 The mode of action is as follows. In the case of normal braking and when the pressure of the accumulator is available, the pusher 19 of the pedal which moves to the left in the plane of the drawing in FIG. 2 slightly pushes the slider 47, from its position shown, upwards and, consequently, radially in the plane of the drawing, under the effect of the meeting of the ramps 50/53, so that the pusher can describe its movement without obstacle, while the piston 12 of the master -cylinder remains resting against its rear stop. This piston is also held against this stop by the pressure of the pressurized fluid which acts on its front face and which is transmitted via the distributor 21.

If the accumulator pressure is faulty, which is comparable to a failure of the braking circuit II, the control pusher 46 locks the slide 47 in its position shown in FIG. 2. This has the consequence that the pusher 19 of the pedal meets the slide 47 by its ramp 50, is locked and drives the piston 12. After another short movement, which serves to cover the distance A ′, The base 47 formed on the intermediate spring plunger 51 is applied against the projection 56 of the slide 47 and, in this way, transmits the force of the push-button of the pedal to the other piston i1 of the masteryLindre by a connection by safety form. We recognize in this description of the operation that, if the supply in pressure is intact and in the absence of locking of the slide 47, this is always pushed radially (upwards), by the combination of "ramps" or "inclined planes", so that, if necessary,
The base 57 of the intermediate pusher 51 no longer meets your projection 56 of the slider frontally since the latter has moved away, jointly with the slider, from the stop region with
The base 57. The intermediate pusher 51 therefore has the corresponding axial freedom of movement and it lets the piston 11 of the master cylinder return to its starting position to ensure the pressure reduction necessary in the closed braking circuit I.

 The spring mounting of the intermediate pusher 51 in the intermediate position in the pusher 19 of the pedal allows, in the case where the accumulator pressure supply is intact, to depress the pusher of the pedal without problem, up to the stop against the rear wall on the primary side of the piston 11 of circuit I of the master cylinder, in any case as far as desired, in order to be able to apply the pressure to the fullest extent desired by means of the distributor 21. Thanks to the possibility of translation of the intermediate pusher 51 which is free in the case where the pressure supply is intact, the axial return movement of this piston is made possible without difficulty under the effect of the pressure of the piston 11 of the master cylinder when the latter, due to the realization of the ABS functions, determines a corresponding pressure reduction in its closed braking circuit I. In these circumstances, the spacing which has been indicated above, in connection with the examples of embodiment of FIG. 1, of the extension of the pedal pusher relative to the piston 11 of the master cylinder, is not necessary and the intermediate pusher 51 can bear directly against this piston in the starting position. ABS pressure can therefore also be perceived by the driver, via the brake pedal, in the form of vibrations. There is free mobility of all components in the case of normal braking and in the case of performing ABS functions, while in the case of a failure of the accumulator pressure supply, with simultaneous locking of the piston annular 12 on the pusher 19 of the pedal, the blocking of the intermediate pusher 51 is also determined by your axial projection 56 carried by the slide 47, so that all the elements now form a unit secured by an obstacle connection and that the two pistons 11, 12 are moved mechanically by the pusher 19 of the pedal. In this case, the base 57 is in abutment on the axial projection 56.

 Of course, various modifications can be made by those skilled in the art to the devices which have just been described only by way of nonlimiting examples without departing from the scope of the invention.

Claims (10)

1. Brake booster device or braking force amplifier, in particular with multiple circuits, with which an anti-lock device (ABS) and a race simulator device are associated, and comprising a control valve for applying the pressure from a pressure supply device, characterized in that, in the case of at least two braking circuits (closed braking circuit I open braking circuit II), a partition (21) is interposed between the pressure chambers ( 17, 32) of these circuits, in that the partition (21) is traversed by an extension (34) of the pedal pusher which passes through it with a seal and in that this extension is placed at a determined distance (A) on the primary side of the piston cry1) of the closed braking circuit (I) of the master cylinder, related to the excursion stroke of the control valve (21) in the stroke simulator device, The application of pressure at the primary side of the brake circuit piston (Il) closed age (I) of the master cylinder being controlled by an electromagnetic distributor (35) which operates, in the case of an ABS intervention, in such a way that the ABS pressure modulation for the closed braking circuit (I) occurs via the brake booster device (30). 2. Brake booster device according to claim 1, characterized in. that the switching distributor (35) which determines The transmission of pressure to the primary pressure chamber (32) of the closed braking circuit (I) is an electromagnetic distributor (3/2) which, in the case of an ABS signal for reduction of pressure, links this chamber primary pressure t32) on the way back so that the piston (11) of the closed brake circuit (I) of the master cylinder can return, thanks to the distance (A) which separates it from the extension (34) of the pusher of the pedal, even in the case of the transmission of the full pressure via the control valve (21), at a pressure drop position at an almost zero value for the closed braking circuit (I). 3. Brake booster device according to one of claims 1 and 2, characterized in that, on the outlet side of the closed braking circuit (I), are arranged two 2/2 electromagnetic distributors (37, 37 '), preferably for the wheel brake cylinders of the left front wheel and the right front wheel, with a 3/3 electromagnetic distributor (36) in the open brake circuit (II). 4. Brake booster device according to any one of claims 1 to 3, characterized in that, for monitoring the operation of the switching distributor (3/2 electromagnetic distributor (35) interposed in the pressure line leading to the pressure chamber primary pressure (32) of the closed brake circuit (I), the pressure encoder pressure signal (S1) associated with this piston (11) of the master cylinder is interpreted. 5. Brake booster device according to any one of claims 1 to 4, characterized in that there is provided locking means (slide 47) which come into action immediately in the event of failure of the accumulator pressure supply and which connect by an obstacle connection the pedal lifter (19) to the open brake circuit piston (II) of the master cylinder (annular piston 12) which receives it. 6. A brake booster device according to claim 5, characterized in that there is provided in the annular piston (12) a constantly open communication channel (41) which leads from the source (20) of pressure supply to accumulator to a pressure chamber (44) which is formed by a bore in the annular piston (12) parallel to the axis and which receives an operating piston (45) provided with an operating pusher (46). 7. brake booster device according to claim 6, characterized in that the locking member (slide 47) is mounted movable in radial translation in the annular piston (12) and is traversed, at least indirectly, by the pusher (19) of the pedal, and in that there are opposite pressure surfaces (50, 53) which, when the blocking member (slide 47) is blocked in radial translation, determine the drive of the annular piston (12) by obstacle in response to movement of the pusher (19). 8. Brake booster device according to one of claims 6 and 7, characterized in that, to determine the radial blocking of the movement of the slide, the operating plunger (46) carried by the control piston (45) which is no longer subject to the action of the pressure of the accumulator penetrates into an axial bore (54) of the slide (47) so that annular surfaces (50) carried by the push of the pedal meet oblique surfaces (53) carried by the slide (47) to ensure the drive of the annular piston by the pusher. 9. Brake booster device according to any one of claims 5 to 8, characterized in that an intermediate pusher (51) which forms an extension (34) of the pusher (19) of the pedal is mounted in this pusher (19) so as to be able to slide axially with sliding under an elastic preload. 10. Brake booster device according to claim 9, characterized in that there is provided a base (57) on the intermediate plunger (51) and an axial projection (56) on the slide (47), this base and this projection being placed at a mutual spacing (A '), however, when the pressure supply is intact, the push-button (19) of the pedal simultaneously slides the axial projection (56) provided on the slide (47), during the radial translation of this slide, from a stop position with the base (57) of the intermediate plunger (51), so that this intermediate plunger can describe an axial return movement under the action of the piston (11) of the master -cylinder which is part of the closed braking circuit (I) in the presence of a reduction in the pressure of this circuit which results from ABS signals.