ACTION CONTROL DEVICE FOR AN ELECTRIC STEERING RACK OF A LAND VEHICLE

Abstract

An action control device (DCA), on the one hand, equips a steering rack (CD) comprising an axis (AC) capable of translating to steer wheels of a land vehicle (V) according to a command from an electric steering control device (DCD) of this vehicle (V), and, on the other hand, is arranged, in the event of a malfunction of the steering control device (DCD), to block the axis (AC) in a chosen blocking position. Figure 1

Description

Title of the invention: ACTION CONTROL DEVICE FOR AN ELECTRIC STEERING RACK OF A LAND VEHICLE Technical field of the invention

[0001] The invention relates to land vehicles comprising wheels steerable by a steering rack as a function of a command from an electric steering control device, and more precisely the control of the action of such a steering rack. State of the art

[0002] Certain land vehicles, generally of the automobile type, comprise a steering rack responsible for orienting at least some of their steered wheels according to a command which comes from an electric steering control device (called in English "steer by wire"), possibly assisted. For this purpose, the steering rack comprises an axis which is capable of translating according to the command to orient the steered wheels concerned.

[0003] In order to secure electric steering control devices, all their safety components are currently being doubled to have a master architecture with a parallel redundant architecture. This significantly increases their cost, and above all, since the redundant architecture is very close to the master architecture, in the event of a malfunction of the master architecture, the redundant architecture can also be subject to this malfunction when the cause is common (for example a faulty computer or a power supply problem).

[0004] Malfunction of an electric steering control device may cause a lack of control for the steering rack or the provision of erroneous controls to the steering rack, which may be (very) dangerous for the vehicle and its passengers and for objects and living beings located in the environment of this vehicle.

[0005] It is sometimes possible to steer a vehicle by means of systems other than its electric steering control device associated with its steering rack. This is the case, for example, when a vehicle has front and rear steered wheels and / or a complex braking system and / or a controlled differential ("torque vectoring" in English). However, as is known to those skilled in the art, in the presence of a malfunction of the electric steering control device, the guidance of the vehicle by another system is slow and / or ineffective, or even unstable.

[0006] The invention therefore aims in particular to improve the situation. Presentation of the invention

[0007] For this purpose, it proposes in particular an action control device intended to equip a steering rack comprising an axis capable of translating to orient the wheels of a land vehicle as a function of a command from an electric steering control device of this vehicle.

[0008] This action control device is characterized by the fact that it is arranged, in the event of a malfunction of the steering control device, to lock the axis of the steering rack in a chosen locking position.

[0009] Thanks to this locking of the steering rack in the event of a malfunction of the steering control device, it is now possible to use other system(s) or device(s) of the vehicle to steer the latter efficiently, quickly and stably.

[0010] The action control device according to the invention may include other characteristics which may be taken separately or in combination, and in particular:

[0011] - in a first embodiment, it can be arranged to block the axis of the steering rack in a selected locking position which is a current position;

[0012] - in a second embodiment, it can be arranged to block the axis of the steering rack in a so-called centered position suitable for causing the vehicle to move in a straight line, and for locking this axis in a chosen locking position which is this centered position;

[0013] - it can comprise, on the one hand, a body comprising a chamber having first and second sub-parts communicating respectively with first and second circuits in which a fluid circulates and coupled to a compensation reservoir, on the second hand, first and second rods secured via an interface part, mounted in translation in the chamber, and opening respectively out of the first and second sub-parts in order to be connected to two opposite parts of the axis of the steering rack, and, on the third hand, first and second movable pistons mounted in translation respectively on the first and second rods in the first and second sub-parts in order either to be translated independently by the interface part during translations of the first and second rods when the steering control device is operating correctly,either to be placed by the fluid in respective positions defining the chosen locking position in the event of malfunction of the steering control device;

[0014] - in the presence of the last option, each of the first and second circuits can have a first state in which it allows free and bidirectional fluid transfer between the compensation tank and the corresponding first or second sub-part when the steering control device is operating properly, and a second state in which it only allows one-way fluid transfer from the compensation tank to the corresponding first or second sub-part in the event of a malfunction of the steering control device;

[0015] - in the presence of the last sub-option, on the one hand, the first circuit can comprise a first sub-part coupled to the compensation tank and to the first sub-part of the chamber and comprising a first solenoid valve having a passing state defining the first state and a non-passing state participating in the second state, and a second sub-part coupled to the compensation tank and to the first sub-part of the chamber and comprising a first non-return device authorizing only the unidirectional transfer of fluid from the compensation tank to the first sub-part of the chamber, and, on the other hand, the second circuit may comprise a first sub-part coupled to the compensation tank and to the second sub-part of the chamber and comprising a second solenoid valve having a passing state defining the first state and a non-passing state participating in the second state,and a second sub-part coupled to the compensation tank and to the second sub-part of the chamber and comprising a second non-return device allowing only the one-way transfer of fluid from the compensation tank to the second sub-part of the chamber;

[0016] - also in the presence of the last sub-option, the room may comprise a third sub-part interposed between its first and second sub-parts and communicating with the latter, and first and second blocking elements fixedly installed respectively at the interfaces with the first and second sub-parts and capable of respectively blocking the translations of the first and second movable pistons;

[0017] - also in the presence of the second embodiment and the last sub-sub- option, in the selected blocking position the interface part can be housed in the third sub-part of the chamber, and the first and second movable pistons can be pressed respectively against the first and second blocking elements by the fluid coming from the compensation tank when the first and second solenoid valves are in their non-passing state.

[0018] The invention also proposes a steering rack, suitable for equipping a land vehicle and comprising wheels which can be steered as a function of a command from an electric steering control device of the vehicle, and comprising, on the one hand, an axis suitable for translating to steer the wheels as a function of this command, and, on the other hand, at least one action control device of the type presented above and connected to this axis.

[0019] The invention also proposes a land vehicle comprising, on the one hand, wheels which can be steered according to a command from an electric steering control device, and, on the other hand, a steering rack of the type presented above and coupled to these wheels.

[0020] For example, this vehicle may be of the automobile type. Brief description of the figures

[0021] Other characteristics and advantages of the invention will appear on examining the detailed description below, and the appended drawings, in which:

[0022] [Fig. 1] schematically and functionally illustrates an exemplary embodiment of a land vehicle comprising front wheels steerable by a steering rack equipped with an action control device according to the invention and associated with a steering control device, and a GMP transmission chain with an electric motor,

[0023] [Fig.2] schematically and functionally illustrates, in a sectional view, a exemplary embodiment of an action control device according to the invention, placed in a first non-blocked intermediate state allowing the steering wheels to be oriented to the right when the steering control device is operating correctly

[0024] [Fig.3] schematically and functionally illustrates, in a sectional view, the action control device of [Fig.2], placed in a second intermediate non-blocked state allowing a very slight orientation of the steered wheels towards the left at the moment when the direction control device is subject to a malfunction, and

[0025] [Fig.4] schematically and functionally illustrates, in a sectional view, the action control device of [Fig.2], placed in a selected blocked state due to the fact that the direction control device is malfunctioning. Detailed description of the invention

[0026] The invention aims in particular to propose an action control device DCA intended to equip a steering rack CD responsible for orienting steered wheels RV of a land vehicle V according to a command from an electric steering control device DCD, in order to control the actions of this steering rack CD.

[0027] In the following, it is considered, by way of non-limiting example, that the land vehicle V is of the automobile type. It is for example a car, as illustrated in [Fig.l]. But the invention is not limited to this type of land vehicle. It in fact relates to any type of land vehicle comprising steered wheels whose orientation is controlled by a steering rack associated with an electric steering control device (possibly assisted).

[0028] Furthermore, it is considered in the following, by way of non-limiting example, that the (land) vehicle V comprises a transmission chain with a powertrain (or GMP) of the all-electric type (and therefore whose drive is provided exclusively by at least one electric motor MME). But the GMP could be of the hybrid (thermal and electric) or purely thermal type.

[0029] [Fig.l] schematically illustrates an exemplary embodiment of a (land) vehicle V comprising steered wheels RV, steerable by a steering rack CD equipped with an action control device CDA according to the invention and associated with an electric (and preferably assisted) steering control device DCD, and an electric GMP transmission chain (and therefore with an electric motor MME).

[0030] The transmission chain has a GMP which is, here, purely electric and therefore which comprises, in particular, an electric motor MME, a motor shaft, and a transmission shaft. Here, the term "electric motor machine" means an electric machine arranged so as to provide engine torque to move the vehicle V when it is supplied with electrical energy, as well as possibly to recover torque in the transmission chain.

[0031] The electric motor MME (here an electric motor) is supplied with electrical energy by a main battery (not shown), rechargeable and possibly cellular. Furthermore, this electric motor MME is coupled to the motor shaft, to provide it with motor torque by rotational drive, and this motor shaft is here coupled to a reducer RD which is also coupled to the transmission shaft, itself coupled to a first train T1, preferably via a differential DF.

[0032] This first train T1 is here located in the front part PVV of the vehicle V. Consequently, in this example the wheels RV of the first train T1 are both driving and steering. But in a variant this first train T1 could be the one which is here referenced T2 and which is located in the rear part PRV of the vehicle V, and in this case the (front) wheels RV are only steering (the rear wheels of the second rear train T2 then being at least driving and also possibly steering).

[0033] The steering rack CD is coupled to the steered wheels RV and is responsible for orienting the latter (RV) according to a command from the steering control device DCD. It (CD) comprises an axis AC (possibly in two parts) and control members OC. These control members OC comprise in particular at least one toothed wheel (or pinion) and an electric motor driving this toothed wheel in rotation, possibly via a reducer, according to each aforementioned command received. The axis AC is coupled to the steered wheels RV and comprises at least one toothed sector which is meshed with the toothed wheel. This meshing allows to translate the AC axis, and therefore to orient the RV steered wheels. In other words, the AC axis is capable of translating to orient the RV steered wheels according to each command received.

[0034] The direction control device DCD is associated with the steering wheel VV which allows the driver of the vehicle V to control the direction of the steered wheels RV of the first axle T1 (front). It (DCD) comprises for this purpose a mechanical part PM connected to the steering wheel VV but not connected to the steering rack CD because it (DCD) is electric. This direction control device DCD also comprises a steering computer CL coupled to the steering rack CD and responsible for determining each command intended for the steering rack CD as a function in particular of the action of the driver on the steering wheel VV.

[0035] The action control device DCA equips the steering rack CD and is arranged, in the event of a malfunction of the steering control device DCD, to block the axis AC of the steering rack CD in a chosen blocking position (here illustrated non-limitingly in [Fig.4]).

[0036] By locking the steering rack CD in the event of a malfunction of the steering control device DCD, it is now possible to use other system(s) or devices of the vehicle V to steer the latter (V) efficiently, quickly and stably, such as for example the braking system and / or the rear steering wheels and / or a controlled differential DF (torque vectoring). In addition, this can make it possible to reduce the number of safety components, or even to only have a master architecture (without parallel redundant architecture), and therefore to reduce the costs, size and weight of the vehicle V.

[0037] At least two embodiments of the DCA action control device can be envisaged.

[0038] In a first embodiment, the action control device DCA can be arranged so as to block the axis AC of the steering rack CD in a chosen blocking position which is its current position. In other words, in this first embodiment the steering rack CD is blocked in its current position, preventing any modification of the latter.

[0039] In a second embodiment, the action control device DCA can be arranged so as to start by translating the axis AC of the steering rack CD into a so-called centered position which is suitable for causing the vehicle V to move in a straight line. This centered position is illustrated in [Fig.4]. Then, the action control device DCA can be arranged so as to block this axis AC in a chosen blocking position which is this centered position. In other words, in this second embodiment, the steering rack CD is first repositioned in a centered position allowing the vehicle V to move in a straight line, then the steering rack CD is locked in this centered position, because this facilitates the guidance of the vehicle V by at least one of the aforementioned systems or devices allowing its steering to be acted upon. The locking is therefore progressive and converges towards the centered position.

[0040] A non-limiting example of an action control device DCA is illustrated in FIGS. 2 to 4. In this example, the action control device DCA comprises at least one body CP, first T1 and second T2 rods, an interface part PI, first PMI and second PM2 movable pistons, first C1 and second C2 (hydraulic) circuits and a compensation reservoir RC.

[0041] A fluid, such as oil, circulates under pressure in the first C1 and second C2 circuits.

[0042] The compensation tank RC is coupled to the first C1 and second C2 circuits in order to collect fluid from the latter (C1 and C2) or to supply stored fluid to the first C1 and second C2 circuits because it is under overpressure.

[0043] The body CP comprises a chamber CC having at least first SP1 and second SP2 sub-parts which communicate respectively with the first C1 and second C2 (hydraulic) circuits. The first sub-part SP1 and the first circuit C1 can thus exchange fluid when needed. Similarly, the second sub-part SP2 and the second circuit C2 can exchange fluid when needed.

[0044] The first T1 and second T2 rods are secured via the interface part PI and mounted in translation (along a common direction) in the chamber CC. In addition, they respectively open out of the first SP1 and second SP2 sub-parts in order to be connected respectively to two opposite parts of the axis AC of the steering rack CD in order to be able to act in translation on this axis AC.

[0045] The first PMI and second PM2 movable pistons are mounted in translation respectively on the first T1 and second T2 rods in the first SP1 and second SP2 sub-parts. This translational mounting allows the first PMI and second PM2 movable pistons either to be translated independently by the interface part PI during translations of the first T1 and second T2 rods when the direction control device DCD is operating correctly, or to be placed by the fluid in respective positions defining the selected locking position in the event of a malfunction of the direction control device DCD.

[0046] In other words, when the direction control device DCD is functioning correctly, the assembly consisting of the first T1 and second T2 rods and the interface part PI can translate freely (without hindrance) in the chamber CC in order to allow the axis AC to translate normally and in the same way to orient the steered wheels RV. On the other hand, in the event of a malfunction of the direction control device DCD, pressurized fluid can be injected by one of the first Cl and second C2 circuits in the first SP1 or second SP2 corresponding sub-part of the chamber CC, either to freeze the current position of the aforementioned assembly and therefore block the steering rack CD in its current blocking position, or to translate the first PMI or second PM2 mobile piston concerned and cause the same translation of the aforementioned assembly by pushing on the interface part PI until an immobilization blocking the steering rack CD in the centered blocking position (see [Fig.4]).

[0047] Each of the first C1 and second C2 circuits may have first and second states. In its first state, the first C1 or second C2 circuit allows free and bidirectional fluid transfer between the compensation reservoir RC and the corresponding first SP1 or second SP2 sub-part of the chamber CC when the direction control device DCD is operating correctly. This first state is illustrated in [Fig. 2]. In its second state, the first C1 or second C2 circuit only allows one-way fluid transfer from the compensation reservoir RC to the corresponding first SP1 or second SP2 sub-part of the chamber CC in the event of a malfunction of the direction control device DCD. This second state is illustrated in Figures 3 and 4.

[0048] Also for example, and as illustrated non-limitingly in Figures 2 to 4, the first circuit C1 may comprise first SPC11 and second SPC12 sub-parts, and the second circuit C2 may comprise first SPC21 and second SPC22 sub-parts.

[0049] The first sub-part SPC11 of the first circuit Cl is coupled to the compensation tank RC and to the first sub-part SP1 of the chamber CC, and comprises a first solenoid valve El having a passing state defining the first state (and illustrated in [Fig.2]), and a non-passing state participating in the second state (and illustrated in Figures 3 and 4). The second sub-part SPC 12 of the first circuit Cl is coupled to the compensation tank RC and to the first sub-part SP1 of the chamber CC, and comprises a first non-return device DAR1 authorizing only the one-way transfer of fluid from the compensation tank RC to the first sub-part SP1 of the chamber CC (see [Fig.3]). This first non-return device DAR1 may, for example, be a non-return valve.

[0050] The first sub-part SPC21 of the second circuit C2 is coupled to the compensation tank RC and to the second sub-part SP2 of the chamber CC, and comprises a second solenoid valve E2 having a passing state defining the first state (and illustrated in [Fig.2]), and a non-passing state participating in the second state (and illustrated in Figures 3 and 4). The second sub-part SPC22 of the second circuit C2 is coupled to the compensation tank RC and to the second sub-part SP2 of the chamber CC, and comprises a second non-return device DAR2 authorizing only the transfer of fluid one-way from the RC compensation tank to the second sub-part SP2 of the CC chamber. This second non-return device DAR2 can, for example, be a non-return valve.

[0051] Preferably, when the first E1 and second E2 solenoid valves are electrically powered, they are automatically placed in their on state, and when the first E1 and second E2 solenoid valves are not electrically powered, they are automatically placed in their off state. Thus, in the absence of electrical power supply to the solenoid valves E1 and E2 caused by a malfunction in the vehicle V, the latter (E1 and E2) are automatically and advantageously off, thus allowing the steering rack CD to be blocked without having to resort to an electrical power supply.

[0052] It will be noted that the arrangement of the action control device DCA illustrated in FIGS. 2 to 4 is suitable for locking the steering rack CD in the centered position.

[0053] Indeed, the chamber CC comprises, here, a third sub-part SP3 and first EB1 and second EB2 blocking elements. This third sub-part SP3 is interposed between its first SP1 and second SP2 sub-parts and communicates with the latter (SP1 and SP2). The first blocking element EB1 is fixedly installed at the interface with the first sub-part SP1 of the chamber CC and is capable of blocking the translations of the first mobile piston PMI at this interface. In other words, when (here) the first mobile piston PMI translates to the right, its translation is interrupted by the first blocking element EB1 just before the third sub-part SP3 of the chamber CC. The second blocking element EB2 is fixedly installed at the interface with the second sub-part SP2 of the chamber CC and is capable of blocking the translations of the second mobile piston PM2 at this interface.In other words, when (here) the second movable piston PM2 translates to the left, its translation is interrupted by the second blocking element EB2 just before the third sub-part SP3 of the chamber CC.

[0054] It will be noted that the first EB1 and second EB2 blocking elements do not hinder the translations of the interface part PI, so that it (PI) can translate the first movable piston PMI (here) to the left or the second movable piston PM2 (here) to the right when the direction control device DCD is operating correctly.

[0055] For example, the first EB1 and second EB2 locking elements may be “Circlips” (registered trademark).

[0056] It will also be noted, as illustrated non-limitingly in [Fig. 4], that in the chosen locking position (and here centered) the interface part PI is housed in the third sub-part SP3 of the chamber CC, and the first PMI and second PM2 movable pistons are pressed respectively against the first EB1 and second EB2 blocking elements by the fluid which comes from the compensation tank RC (via the second sub-parts SPC 12 and SPC22 respectively of the first Cl and second C2 circuits) when the first El and second E2 solenoid valves are in their non-passing state. It will be understood that, due to the overpressure prevailing in the compensation tank RC, at least part of the fluid stored in the latter (RC) is forced to circulate in the second sub-parts SPC12 and SPC22 in order to reach the first SP1 and second SP2 sub-parts of the chamber CC and thus push and maintain the first PMI and second PM2 movable pistons respectively against the first EB 1 and second EB2 blocking elements by causing the placement and immobilization of the interface part PI in the third sub-part SP3 of the chamber CC (centered blocking position).

[0057] Examples of operation (and therefore action) of the DCA action control device, illustrated in Figures 2 to 4 and described above, are provided below.

[0058] A first example is illustrated in [Fig.2] and corresponds to a situation in which the direction control device DCD operates correctly and requires that the axis AC of the steering rack CD moves to the left to steer the steered wheels RV to the right. The first solenoid valve E1 is electrically powered and therefore placed in its on state, which allows the transfer of fluid from the first sub-part SP1 of the chamber CC to the compensation reservoir RC, via the first sub-part SPC12 of the first circuit C1. This transfer is caused by the free translation to the left of the assembly (T1, PI, T2) which translates the first movable piston PMI to the left by the same amount, this free translation being caused by the translation to the left of the axis AC, as requested by the direction control device DCD.

[0059] A second example is illustrated in Figures 3 and 4 and corresponds to a situation in which the direction control device DCD is malfunctioning, and therefore the steering rack CD must be locked in its centered locking position. Here, at the moment when the direction control device DCD begins to malfunction, the interface part PI of the assembly (T1, PI, T2) has placed the second movable piston PM2 in the second sub-part SP2 of the chamber CC, and the first El and second E2 solenoid valves change from their on state to their off state, as illustrated in [Fig. 3].This passage causes, due to the overpressure prevailing in the compensation tank RC, the circulation of at least part of the fluid stored in the latter (RC) in the second sub-part SPC22 of the second circuit C2 via the second non-return device DAR2 into the second sub-part SP2 of the chamber CC, which pushes the second movable piston PM2 towards the second blocking element EB2. The second movable piston. PM2 being in contact with the interface part PI, it translates the latter (PI) to the left until its movement is interrupted by the second blocking element EB2. The interface part PI is then housed in the third sub-part SP3 of the chamber CC, where it is immobilized (or blocked) because at the same time the pressure exerted by the fluid in the first sub-part SP1 of the chamber CC presses the first movable piston PMI against the first blocking element EB1. In other words, the steering rack CD is blocked in its centered blocking position. This blocking is therefore progressive, convergent, and carried out without electrical power.

Claims

Claims

1. Action control device (DCA) for a steering rack (CD) comprising an axis (AC) capable of translating to orient wheels of a land vehicle (V) according to a command from an electric steering control device (DCD) of said vehicle (V), characterized in that it is arranged, in the event of malfunction of said steering control device (DCD), to lock said axis (AC) in a chosen locking position.

2. Action control device according to claim 1, characterized in that it is arranged to lock said axis (AC) in a chosen locking position which is a current position.

3. Action control device according to claim 1, characterized in that it is arranged to translate said axis (AC) into a so-called centered position suitable for causing movement of said vehicle (V) in a straight line, and to block said axis (AC) in a chosen blocking position which is said centered position.

4. Action control device according to one of claims 1 to 3, characterized in that it comprises i) a body (CP) comprising a chamber (CC) having first (SP1) and second (SP2) sub-parts communicating respectively with first (Cl) and second (C2) circuits in which a fluid circulates and coupled to a compensation reservoir (RC), ii) first (Tl) and second (T2) rods secured via an interface part (PI), mounted in translation in said chamber (CC), and opening respectively outside said first (SP1) and second (SP2) sub-parts in order to be connected to two opposite parts of said axis (AC),and iii) first (PMI) and second (PM2) movable pistons mounted in translation respectively on said first (Tl) and second (T2) rods in said first (SP1) and second (SP2) sub-parts in order either to be translated independently by said interface part (PI) during translations of said first (Tl) and second (T2) rods when said direction control device (DCD) is operating correctly, or to be placed by said fluid in respective positions defining said selected locking position in the event of a malfunction of said direction control device (DCD).,

5. Action control device according to claim 4, characterized in that each of said first (C1) and second (C2) circuits has a first state in which it allows a free and bidirectional fluid transfer between said compensation tank (RC) and said first (SP1) or second (SP2) corresponding sub-part when said direction control device (DCD) is functioning correctly, and a second state in which it only allows a one-way fluid transfer from said compensation tank (RC) to said first (SP1) or second (SP2) corresponding sub-part in the event of a malfunction of said direction control device (DCD).

6. Action control device according to claim 5, characterized in that said first circuit (Cl) comprises a first sub-part (SPC11) coupled to said compensation tank (RC) and to said first sub-part (SP1) of the chamber (CC) and comprising a first solenoid valve (El) having a passing state defining said first state and a non-passing state participating in said second state, and a second sub-part (SPC 12) coupled to said compensation tank (RC) and to said first sub-part (SP1) of the chamber (CC) and comprising a first non-return device (DAR1) authorizing only said one-way transfer of fluid from said compensation tank (RC) to said first sub-part (SP1) of the chamber (CC),and in that said second circuit (C2) comprises a first sub-part (SPC21) coupled to said compensation tank (RC) and to said second sub-part (SP2) of the chamber (CC) and comprising a second solenoid valve (E2) having a passing state defining said first state and a non-passing state participating in said second state, and a second sub-part (SPC22) coupled to said compensation tank (RC) and to said second sub-part (SP2) of the chamber (CC) and comprising a second non-return device (DAR2) only authorizing said one-way transfer of fluid from said compensation tank (RC) to said second sub-part (SP2) of the chamber (CC).,

7. Action control device according to one of claims 4 to 6, characterized in that said chamber (CC) comprises a third sub-part (SP3) interposed between said first (SP1) and second (SP2) sub-parts and communicating with the latter (SP1, SP2), and first (EB1) and second (EB2) elements of locks fixedly installed respectively at the interfaces with said first (SP1) and second (SP2) sub-parts and suitable for blocking respectively the translations of said first (PMI) and second (PM2) mobile pistons.

8. Action control device according to the combination of claims 3 and 7, characterized in that in said selected blocking position said interface part (PI) is housed in said third sub-part (SP3) of the chamber (CC), and said first (PMI) and second (PM2) movable pistons are pressed respectively against said first (EB1) and second (EB2) blocking elements by said fluid coming from said compensation reservoir (RC) when said first (El) and second (E2) solenoid valves are in their non-passing state.

9. Steering rack (CD) suitable for equipping a land vehicle (V) and comprising wheels which can be steered according to a command from an electric steering control device (DCD) of said vehicle (V), said steering rack (CD) comprising an axis (AC) suitable for translating to steer said wheels according to said command, characterized in that it further comprises an action control device (DCA) according to one of claims 1 to 8, connected to said axis (AC).

10. Land vehicle (V) comprising wheels which can be steered according to a command from an electric steering control device (DCD), characterized in that it further comprises a steering rack (CD) according to claim 9, coupled to said wheels.

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