Suspension damper assembly

The invention relates to a suspension damper assembly comprising a suspension damper, in particular intended for producing the suspension device of a vehicle, this suspension damper comprising two ends, a cylinder, a piston movable inside this cylinder, and two capacities defined inside the cylinder and separated by said movable piston, this piston being provided with main passages for the fluid from one capacity to the other, said suspension damper further comprising a device for adjusting its damping force which comprises: at least one additional fluid passage, connecting the two capacities of the damper; a valve arranged on said additional passage and comprising a movable element for closing off this additional passage; and, a member for adjusting the position of said closure element.

Such a damper assembly can be used, in particular, in vehicles, such as passenger cars, utility vehicles, motorcycles and rail vehicles.

The existing variable damping dampers operate in an open loop, that is to say by adjusting the theoretical value of the damping from an adjustment command which does not take into account the instantaneous real value of the damping. .

In principle, a theoretical configuration of the damper makes it possible to obtain a desired damping value. In reality, the value obtained for the damping is different from the desired value, the difference between the two values ​​resulting from the manufacturing tolerances of the damper, from its wear, and mainly from the operating temperature.

Current and future damping requirements, especially with regard to the response time of a variable damper, which is desired to be in the order of 20 milliseconds, but which is in fact often greater than 300 milliseconds , condemn the known variable dampers in the short term, with mechanical damping adjustment, using an electric motor for adjusting the position of an adjustment valve, and often transmission gears.

The invention intends to solve the problem associated with the search for a variable shock absorber with rapid response. To do this, according to the invention, the damper assembly further comprises at least one sensor for measuring an operating parameter of said damper, such as a sensor of the relative speed of the ends of this damper or a sensor of the relative position of said ends of the damper, the output of said measuring sensor being connected to said member for adjusting the position of said movable valve closing element.

The following advantageous arrangements are furthermore preferably adopted:

the sensor for measuring an operating parameter of the shock absorber is a HALL effect sensor;

- the damper being interposed between a suspended body and a frame, said damper assembly further comprises; a plurality of other state sensors measuring state parameters of said suspended body, such as the speed of this suspended body, the longitudinal and transverse linear accelerations of said suspended body, the angular roll and yaw speeds of the suspended body; a set of reference registers indicating the correspondence between the set of values ​​of the state parameters of the suspended body and a theoretical value of said operating parameter of the damper; a comparator of the value measured by said sensor for measuring the operating parameter of the shock absorber and said theoretical value which determines the difference of these two values ​​and whose output is connected to the member for adjusting the position of said movable element d closure of the valve;

- The shock absorber comprises a piston rod which is integral, vis-à-vis the sliding of the piston inside the cylinder of the shock absorber, of said piston, while said movable valve closing element is constituted by a drawer which is movably mounted within said piston rod;

- Said slide is coupled to the core of a solenoid which comprises a winding mounted in a housing that comprises said piston rod.

The main advantage of the invention lies in obtaining a closed loop adjustment taking into account the effectively measured value of an operating parameter of the damper, as well as in obtaining short response times, significantly lower than those of known shock absorbers.

The invention will be better understood, and secondary characteristics and their advantages will appear during the description of embodiments given below by way of example.

It is understood that the description and the drawings are given only as an indication and are not limiting.

Reference will be made to the accompanying drawings, in which:

- Figure IA is an axial section of a damper assembly according to a first variant embodiment according to the invention;

- Figure IB is a perspective view of a constituent element of the assembly of Figure IA;

- Figure 2 shows the diagram of a damper assembly according to a second variant embodiment according to the invention;

- Figure 3A is an axial section of a damper assembly according to a third variant embodiment according to the invention, in a first operating configuration;

- Figure 3B is a partial axial section of the damper assembly of Figure 3A shown in a second operating configuration;

- Figure 4A is an axial section of a damper assembly according to a fourth variant embodiment according to the invention, in a first operating configuration;

- Figure 4B is a partial axial section of the damper assembly of Figure 4A shown in a second operating configuration;

- Figure 5 is an axial section of a damper assembly according to a fifth variant embodiment according to the invention:

- Figure 6A is an axial section of a damper assembly according to a sixth variant embodiment according to the invention, in a first operating configuration; and

- Figure 6B is a partial axial section of the damper assembly of Figure 6A, shown in a second operating configuration.

FIG. 1A represents a shock absorber 1 comprising:

- a cylinder 2;

a piston 3 slidably mounted inside the cylinder 2 and delimiting inside this cylinder two chambers 4 and 5;

- A piston rod 6, which is integral with the piston 3 and crosses with sealing one (7) of the two bottoms 7 and 8 of the cylinder, this bottom 7 cooperating to delimit the chamber 4 of small cross section;

- an envelope 9, generally cylindrical, fixed on the base 7, containing the whole of the cylinder 2 and delimiting between itself and this cylinder 2 a closed enclosure 10;

- Another envelope tube li, having an opening 13, partially containing the envelope 9 and constituting a mechanical protection against impact, bearing on a shoulder 12 of the part of the piston rod 6 external to the cylinder 2 to be fixed on this piston rod 6;

a force sensor 14, surmounting the face of the bottom 15 of the casing tube 11 opposite to the shoulder 12;

a pad 16, generally made of elastomer, arranged on either side of an opening 17 made in the frame 18 of a motor vehicle, itself surmounting the force sensor 14;

a nut 19, which cooperates with the threaded end 20 of the piston rod 6 to secure together the base 15, the force sensor 14 and the stud 16;

- a HALL effect sensor 21, fixed on the bottom 7 of cylinder 2, sensitive to the magnetic field, and capable of moving opposite a thin plate 22, supporting magnetized lines 23, 24 alternately constituting North poles 23 and South poles 24, said plate 22 being fixed to the internal face of the envelope tube 11.

The piston 3 is crossed by main fluid passages 25, which connect the two chambers 4 and 5, and on which are arranged restrictions braking the fluid conveyed by said main passages, in one direction and in the opposite direction (of a room to the other, and vice versa). Likewise, the bottom 8 of the cylinder 2 is provided with passages 26 forming restrictions, connecting the chamber 5 to the enclosure 10. Said chambers 4, 5 and enclosure 10 contain a damping liquid capable of passing from one adjacent to the other depending on the movements of the piston 3 inside the cylinder 2. The opposite end of the casing 9 at the bottom 7 is also shaped as an eye 27 for fixing an unsprung mass 28 of the vehicle, comprising in particular a wheel of this vehicle.

FIGS. 3A and 3B represent an alternative embodiment of the shock absorber of FIG. IA, in which the piston rod comprises three parts 6A, 6B, 6C assembled to each other, and, part 6C to the piston 3, by threads 28 and threads 29. The intermediate part 6B comprises an axial housing 30, which opens into a duct 31 passing through the part 60 fixed to the piston 3 and said piston 3 itself. The housing 30 is shaped as a cylindrical bore inside which is slidably mounted a hollow piston traversed by holes 33 capable 3B) with a first series 34 or with

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piston rod and opening in the opposite direction, the piston 32 closing off the holes 34, 35 (FIG. 3A).

The piston 32 separates the housing 30 into two chambers 36, 37 which communicate freely, the chamber 37 further opening into the duct 31. The piston 32 is made integral, by welding 38, with the magnetic core 39 of a solenoid, of which the The winding 40 is in the chamber 36 and fixed to the wall of the intermediate part 6B. A spring 41, interposed between the winding 40 and the piston 32, has an effect antagonistic to that of the solenoid, an effect tending to move the magnetic core 39 away from the winding 40.

As shown in the figures, in the configuration of Figure 3A, the only communications between the chambers 5 and 4 are those of the main passages 25, which provide a powerful damping, while, in the configuration of Figure 3B, a complementary passage consists of the conduit 31, the chamber 37, the holes 33 and the series of holes 34 (arrow F), the end of the magnetic core 39 having been attracted by the winding 40, and a damping lower than the previous one being obtained.

The variant of Figures 4A, 4B is very close to that of Figures 3A, 3B. It comprises similar elements, identified by the same reference numbers, except the following elements:

- There is only one series of orifices 42 passing through the wall of the intermediate part 6B of the piston rod, either closed (FIG. 4A) by the piston 32, or uncovered (partially or totally) by the piston 32 (Figure 4B);

- The additional damping, produced by the part of the holes 42, not covered by the piston 32, is also obtained by means of a conventional device mounted on the part 6C of the piston rod, comprising elastic washers 43 arranged transversely on the conduit 31, held by a screw 44 screwed onto said part 6C. The washers 43 either close the duct 31 (FIG. 4A), or provide a passage 45 at their outer periphery between themselves and the part 6C of the piston rod, the fluid flowing from the chamber 5 to the following chamber 4 the arrow HA (FIG. 4B), or finally leave a passage 46 between themselves and the central screw 44, the fluid flowing from the chamber 4 to the chamber 5 following the arrow HB (FIG. 4B). The elements 43 are formed either by a single washer or by several washers.

The variant of FIG. 5 is also close to that of FIGS. 3A, 3B and comprises similar elements, identified by the same reference numbers, except for the following elements:

- There is only a series of orifices 47 passing through the wall of the intermediate part 6B;

- The magnetic core 39 has a shoulder 53 and is provided with a transverse stop washer 49;

- A spring 48 is interposed between one end of the winding 40 and the stop washer 49 and has an effect tending to push the magnetic core 39 out of the winding 40, antagonistic to that of the solenoid;

- Fluid passages 54 extend the conduit 31 and pass through the part 6C of the piston rod;

- One or more resilient washers 52 are arranged opposite said fluid passages 54 and are capable of being held in abutment on the transverse portion of said part 6C into which the fluid passages 54 open, via the shoulder 53 and spring 48;

- finally, the washers 52, either close the fluid passages 54, the damping, powerful, being obtained by the rolling of the fluid only during the passage in the main conduits 25 and the crossing of the conventional fluid rolling devices arranged on these main conduits or partially uncover the fluid passages 54; passages 50 adjacent to the outer periphery of the washers 52, in the direction of the arrows KA, the fluid passing from the chamber 5 to the chamber 4, or, passages 51 adjacent to the center of the washers 52, in the direction of the arrows KB, the fluid passing from chamber 4 to chamber 5. In these fluid transit configurations also along the paths of the arrows KA or KB, the damping obtained is less than that corresponding to the sealing of the fluid passages 54.

The embodiment of FIGS. 6A, 6B uses many elements already described above and identified by the same reference numbers. On the other hand, the following provisions are specific to this realization:

- a housing 55, open towards the winding 40, is arranged in the housing 30 of the intermediate part 6B of the piston rod, and is fixed there, held between one end of the winding 40 and one end of the part 6A piston rod;

- The end of the magnetic core 39 opposite the conduit 31 is provided with an internal thread 58 for fixing the thread 57, with which a rod 56 is provided;

- A HALL effect sensor 60 is fixed to the bottom of the housing 55 and is placed opposite a permanent magnet 59 fixed to the end of the rod 56.

The spring 41, as has already been described, tends to push the piston 32 integral with the magnetic core 39 in the configuration of closing the holes 42 (FIG. 6A), and has an effect antagonistic to that of the solenoid, which tends on the contrary in moving the piston 32 until the holes 42 are uncovered (FIG. 6B) and in making a complementary passage of fluid through the holes 42, according to the arrow G of FIG. 6B. The supply current for the winding 40 comes from an amplifier analogous to the amplifier 86 of FIG. 2, the control system, analogous to that of FIG. 2, further taking into account the information coming from the sensor to HALL effect 59-60, then integrated into an assembly such as that 61 in figure 2.

Returning to the diagram of Figure 2, there is the force sensor 14 of Figures IA, IB, and we further note the presence of the following elements:

a set 61 of vehicle operating state sensors, including a sensor 61A, the output 62A of which is proportional to the load (to the mass) of the vehicle; a sensor 61B, the output 62B of which is proportional to the relative speed of the piston 3 with respect to the cylinder 2 of the shock absorber; a sensor 61C, the output of which 62C is proportional to the longitudinal acceleration of the vehicle; a sensor 61D, the output of which 62D is proportional to the angular speed of gallop of the vehicle; a sensor 61E, the output of which 62E is proportional to the transverse acceleration of the vehicle; and, a sensor 61F, the output of which 62F is proportional to the angular roll speed of the vehicle;

a central 63 for synthesizing the information transmitted by said sensors and comprising in particular: three comparators 64, 65, 66; two AND elements 67 and 68; three generators 69, 70, 71 of distinct voltages; and the electrical connections 62A entering the comparator 64, which compares the load P of the vehicle with a determined value PC; two connections leaving the comparator 64, the connection 72, energized when the load P is at most equal to

PC, connected to the input of comparator 65, and, connection 73 energized when the load P is greater than PC, connected to the input of voltage generator 71; two connections 74, 75 leaving the comparator 65 which compares the load P with another determined value PV, lower than PC, significant of the empty mass, the connection 74, excited when P is lower than PV, entering the generator 69 of which the output connection 76 delivers a voltage U equal to a first value UMIN (minimum voltage), and, the connection 75, energized when P is at least equal to PV and enters the voltage generator 70; connection 62B entering comparator 66; the connections 77, 78, which come out of the comparator 66, the connection 77 entering the voltage generator 70, when the signal VA detected by the sensor 61B is at most equal to a determined value VR (good road), and, the connection 78 entering the voltage generator 71, when VA is greater than VR (bad road); the connections 62C and 62D which enter the AND element 67, from which exits a connection 79 which enters the voltage generator 71; the connections 62E and 62F which enter the AND element 68, from which exits a connection 80 entering the voltage generator 71;

a connection 81, leaving the voltage generator 70, which delivers a voltage U equal to a second value UNOM (nominal voltage); a connection 82, leaving the voltage generator 71, which delivers a voltage U equal to a third value UMAX (maximum voltage); the connections 76, 81, 82 meet at the input of a comparator 83, as does the connection 84 connecting the output of the force sensor 14 to this comparator 83; a connection 85 connects the output of the comparator 83 to the input of a control amplifier 86, the output of which is connected by a connection 87 to the winding 40 of the solenoid for adjusting the value of the damping of the damper 1 .

The shock absorber 1 of FIG. 1A is of one of the types described in detail with reference to FIGS. 3A, 3B; 4A, 4B; 5; 6A, 6B and in particular comprises a solenoid 39-40 for adjusting the value of the damping. This damper, associated with a control circuit such as that of FIG. 2, therefore has its damping permanently adjusted to the optimum value by means of the solenoid 39-40, supplied by the current leaving the amplifier 86. The adjustment obtained is optimal, because it takes into account the various operating parameters measured by the sensors 61A, 61B,

61C, 61D, 61E and 61F whose signals are compared to PC reference values; PV; VR, or accumulated (elements AND 67, 68) to deliver one of the three output voltages UMIN; UNOM; or UMAX. In addition, when the force sensor 14 is provided, as is the case with the embodiment of FIG. 1A, the measured damping force is used for the actual adjustment of the damping value.

Of course, the embodiments shown were only examples; the invention covering the variants not shown, but which result from the above. Thus, it is clearly understood that, according to a simplified variant, the number of sensors of the assembly 61 can be reduced. Likewise, the force sensor 14 may not be adopted. The principle remains to adjust the value of the damping, not by means of a command from the driver carried out once and for all during a journey or a portion of a journey, but permanently as a function of the measured values ​​of the behavior of the vehicle and / or of the shock absorber itself, and, of course, of reference values ​​introduced in particular into the synthesis unit 63. These reference values ​​can also be collated in reference registers such as recorded curves, or even recorded reference surfaces.

When the HALL effect sensor is provided (figures IA, IB), it measures the speed VA of the piston 3 of the shock absorber with respect to the cylinder 2, which makes it possible to take into account an additional operating parameter of the vehicle and its components. shock absorbers.

The core 39 can be either magnetic steel or soft iron, depending on the desired use of the solenoid.

The relative position and the relative speed of the piston 3 of the shock absorber with respect to the cylinder 2 can moreover be measured by means of the HALL effect sensor 59-60 of the embodiment of FIG. 6A.

The main advantage of the invention is, first of all, to continuously adapt the damping characteristics to the optimum values, taking into account the operation itself of the vehicle, or more generally of the body suspended from a frame. An interesting additional characteristic is the possibility of installing the shock absorber assemblies in accordance with the invention without having to modify the vehicle, possibly even if this is desired, by replacing existing shock absorbers.

The invention is not limited to the embodiments described, but on the contrary covers all the variants which could be made to them without departing from their scope or from their spirit.