WO2019092480A1

WO2019092480A1 - Shock absorbing system of a vehicle

Info

Publication number: WO2019092480A1
Application number: PCT/IB2017/057037
Authority: WO
Inventors: Simone MARANINI
Original assignee: Maranini Simone
Priority date: 2017-11-10
Filing date: 2017-11-10
Publication date: 2019-05-16

Abstract

A shock absorbing system interposable between a frame and a wheel of a road vehicle comprising dissipating means (3) for dissipating kinetic energy, the dissipating means in turn comprising: - a plunger (30) in turn comprising: a rod (34) and a first piston (31) applied to the rod (34); - a lining (33) in which the plunger (30) slides and in which an operating fluid is located; said first piston (31 ) brushes the lining (33) and identifies by separation thereof a first and a second chamber (331, 332) inside the lining (33); said first piston (31) being at least partly crossed by a passage (310) which enables communication between the first chamber and the second chamber (331, 332); - a sleeve (4) which partly houses said lining (33) and identifies a housing (40) of the fluid which at least in a first configuration is in fluid communication with the first chamber (331). The plunger (30) comprises a second piston (32) applied to said rod (34); said second piston (32) identifies by separation thereof, the second chamber and a third chamber (332, 333) and is at least partly crossed by a passage (320) which enables communication between the second chamber and the third chamber (332, 333).

Description

DESCRIPTION

SHOCK ABSORBING SYSTEM OF A VEHICLE

Technical Field

The present invention relates to a shock absorbing system of a road vehicle.

Prior Art

There are known shock absorbing systems comprising:

- a spring;

- a dissipating system for dissipating the kinetic energy of the spring which determines the heating of an operating liquid, typically oil.

The dissipating system comprises a plunger provided with a rod and a piston sliding in a lining. A sleeve envelops the lining and defines an interposed annular chamber.

When the vehicle transits on a bumpy road surface, there is an alternating of a compression stroke and an expansion stroke of the plunger inside the lining. In fact, one of the two is solidly constrained to a frame of the vehicle and the other one is solidly constrained to an axis of a wheel of the vehicle. During a compression stroke of the plunger, the oil present in the lining partly crosses the piston, transiting through a passage fashioned therein and is partly pushed into the annular chamber. The load loss encountered by the oil crossing the piston can be regulated by the addition or removal of calibrating plates or by adjusting a calibrating spring. Instead, during the expansion stroke of the plunger, the oil is returned into the lining from the annular chamber and crosses the piston in an opposite direction to what occurs during the compression stroke.

There is further present a flange arranged along the rod, which defines a narrow annular opening in combination with the wall of the lining.

The passage of the oil through the piston and at the flange determines a sharp heating of the oil, which can also reach 100°C.

The kinetic energy of the spring is thus dissipated in the form of heat.

A drawback of the above-described solution is linked to the fact that to increase the calibration of the piston it is necessary to increase the calibrating plates or to raise the spring calibration. This however introduces the drawback of exaggeratedly braking the stroke of the shock absorber. As a consequence, there would be a very stiff suspension and a loss of comfort for the vehicle users.

Aim of the invention

In this context, the technical task underlying the present invention is to provide a shock absorbing system of a vehicle which obviates the drawbacks in the prior art as described above.

In particular, an object of the present invention is to provide a shock absorbing system able to increase the dissipation of kinetic energy without having a negative effect on comfort.

The set technical task and the specified objects are substantially attained by a shock absorbing system, comprising the technical characteristics as set out in one or more of the accompanying claims.

Brief description of the drawings

Further characteristics and advantages of the present invention will become more apparent from the indicative and thus non-limiting description of a preferred, but not exclusive, embodiment of a shock absorbing system, as illustrated in the accompanying drawings, in which:

- figures 1 -3 illustrate a shock absorbing system according to the present invention in three different configurations;

- figure 4 is an enlargement of figure 3;

- figure 5 is an enlargement of figure 1 .

Detailed description of preferred embodiments of the invention

In the appended figures, reference numeral 1 denotes a shock absorbing system of a road vehicle. This system 1 is operatively and/or physically interposable between a frame and a wheel of the vehicle. In particular, the system 1 connects a portion of a support of a wheel of the vehicle to a part solidly constrained to the frame of the vehicle.

This shock absorbing system 1 advantageously comprises elastic means 2 for suspension of the vehicle (partially illustrated in a schematic form in figure 3). Typically this is a spring, preferably a helix spring. The elastic means 2 are thus interposed between the frame and the wheel of a vehicle.

The shock absorbing system 1 comprises dissipating means 3 for dissipating kinetic energy. In particular, the dissipating means dissipate the kinetic energy which the elastic suspension means 2 have. The dissipating means 3 comprise a plunger 30. The plunger 30 is preferably at least partly located inside the volume identified by turns of the spring. The plunger 30 advantageously has a longitudinal axis that is parallel, preferably coaxial, to the longitudinal axis of the helix spring.

In turn, the plunger 30 comprises a rod 34 and a first piston 31 . The first piston 31 is applied to the rod 34. It is typically splined on the rod 34 and kept in position by spacers and blocking elements as will be more fully explained in the following.

The dissipating means 3 comprise a lining 33 in which the plunger 30 slides and in which a fluid is located. The fluid is typically a non- compressible fluid, typically a liquid, advantageously oil.

The first piston 31 brushes the lining 33. In particular, the first piston 31 brushes an internal lateral surface of said lining 33. Annular fluid-dynamic sealing means are advantageously present between the first piston 31 and the internal lateral surface of the lining 33. The first piston 31 is annular. The lining 33 is advantageously cylindrical. The first piston 31 identifies, by separating them, a first and a second chamber 331 , 332 inside the lining 33. The first piston 31 is at least partly crossed by a passage 310 which enables communication between the first chamber and the second chamber 331 , 332. The passage 310 is advantageously entirely contained in the first piston 31 . A plurality of passages 310 are advantageously present and cross the first piston 31 . The passage 310 can advantageously extend parallel to a preponderant extension direction of the rod 34. The dissipating means 3 advantageously comprise a sleeve 4 that at least partly (preferably entirely) houses the lining 33. The sleeve 4 identifies a housing 40 of the fluid which at least in a first configuration is in fluid communication with the first chamber 331 . The sleeve 4 is advantageously coaxial to the lining 33.

The plunger 30 comprises a second piston 32 applied to the rod 34. The second piston 32 identifies, by separating them, the second and a third chamber 332, 333 and is at least partly crossed by a passage 320 which enables communication between the second chamber and the third chamber 332, 333. The passage 320 is advantageously entirely contained in the second piston 32. A plurality of passages are advantageously present and cross the second piston 32. Annular fluid-dynamic sealing means are advantageously present between the second piston 32 and the internal lateral surface of the lining 33. The second piston 32 is annular. The first piston 31 is preferably located in proximity of an end of the rod 34.

The minimum distance between the first and the second piston 31 , 32 is greater than 0.5 centimetres. A spacer 35 is advantageously interposed. In the preferred solution the lining 33 and/or the sleeve 4 are constrained to the frame of the vehicle while the plunger 30 is constrained to an axis of one of the wheels of the vehicle (or vice versa). The connection of the sleeve 4 with the frame advantageously takes place by means of an annular member 71 (see figure 3). The connection of the plunger 30 with the mechanical assembly connected to the axis of the wheels takes place by means of an annular member 72.

The first and the second piston are advantageously located between an abutment 74 fashioned on the rod 34 and a retaining element located at an end of the rod 34. This retaining element is advantageously a lock-nut 73.

The system 1 comprises a two-way bottom valve 5 which opens when a predetermined pressure difference between upstream and downstream is exceeded. The bottom valve 5 is interposed between the first chamber 331 and the housing 40. This valve 5 thus regulates the outflow of the fluid from the lining 33 and the re-entry thereof.

The first piston 31 can be calibrated for regulating a load loss through the passage 310 of the first piston 31 . The second piston 32 can advantageously be calibrated for regulating the load loss through the passage 320 of the second piston 32. The load loss through the passage 310 of the first piston 31 is preferably identical to the load loss through the passage 320 of the second piston 32 (with a tolerance on the identical amount that is lower than 10%). Therefore, the passage 310 of the first piston 31 has the same calibration as the passage 320 of the second piston 32.

To regulate the calibration of the first and second piston 31 , 32 known systems can be used, by adjusting a calibrating spring or by increasing the number of plates 36 associated to the corresponding piston (and which determine a variation in the load loss, i.e. the resistance encountered by the fluid in crossing the piston).

The system 1 further comprises a first rod guide 61 and a second rod guide 62. The first and the second rod guide 61 , 62 are at least partly arranged outside the lining 33. In particular, the first and the second rod guide 61 , 62 are interposed between the sleeve 4 and the rod 34. The first and the second rod guide 61 , 62 enable a stiffening of the system 1 in a maximum extension configuration of the plunger 30 (i.e. when the rod 34 is in the maximum extraction position from the lining 33).

The first and the second rod guide 61 , 62 are annular and adjacent. The first and the second rod guide 61 , 62 are advantageously solidly constrained to the sleeve 4. The rod 34 crosses them. A housing cup 63 of the first and second rod guide 61 , 62 is advantageously present. The cup 63 is located inside the sleeve 4 and is in contact with an internal surface of the sleeve 4.

The fluid is advantageously oil having a viscosity lower than 10 cSt at 100°C (preferably lower than 6.5 cSt at 100°C), and advantageously lower than 70 cSt at 40°C (preferably lower than 50 cSt at 40°C).

In a particular solution, not illustrated, the system 1 comprises regulating means for regulating the distance between the first and the second piston 31 , 32. In particular, the regulating means enable modifying the relative distance between the first and the second piston 31 , 32 measured along the longitudinal direction of the rod 34. For example, the regulating means can comprise a spindle which can move inside the rod 34 and is constrained to the second piston 32. The spindle can advantageously be activated by a user in proximity of the annular member 72. The rod 34 advantageously comprises a slot that enables the connection of the spindle to the second piston 32 splined on the rod 34. A longitudinal displacement of the spindle determines a distancing/nearing of the first and the second piston 31 , 32. In an alternative and non-limiting solution the spindle, instead of translating inside the rod 34, can rotate determining an axial displacement of the second piston 32. In this case, the spindle can comprise a wheel having helical cogs which enmeshes with a rack solidly constrained to the second piston 32.

By modifying the distance, it is possible to adjust the response of the shock absorbing system. In particular, by nearing the first and the second piston 31 , 32, the shock absorbing system will be more rigid.

During operation, when the wheel of a vehicle encounters a bump the plunger 30 moves towards a configuration in which it is more greatly compressed inside the lining 33. In this way, the fluid present in the second chamber 332 will move towards the third chamber 333 by crossing the second piston 32 while the fluid present in the first chamber 331 will move partly into the second chamber 332 through the first piston 31 and partly into the housing 40. This is accompanied by a dissipation of kinetic energy and an increase in the temperature of the fluid. Thereafter, by the action of the spring, the plunger 30 will move towards a greater extension configuration (or also extraction from the lining 33). This is accompanied by the return of the fluid:

- from the housing 40 in the first chamber 331 ;

- from the third to the second chamber 333, 332 through the second piston 32;

- from the second to the first chamber 332, 331 through the first piston 31 . The above-described oscillation is repeated up to the complete dissipation of this kinetic energy.

The present invention provides important advantages.

Primarily it enables increasing the dissipation velocity of the ground bumps without this causing an excessively rigid suspension to the detriment of comfort. The Applicant has in fact carried out a plurality of tests which confirm the result obtained.

Secondly, the present invention enables a shock absorbing system to be made available that is sturdy and reliable, particularly suitable for use in bumpy terrains.

The invention as it is conceived is susceptible to numerous modifications and variants, all falling within the scope of the inventive concept characterising it. Further, all the details can be replaced with other technically-equivalent elements. In practice, all the materials used, as well as the dimensions, can be any according to requirements.

Claims

1 . A shock absorbing system interposable between a frame and a wheel of a road vehicle comprising dissipating means (3) for dissipating kinetic energy, the dissipating means in turn comprising:

- a plunger (30) in turn comprising: a rod (34) and a first piston (31 ) applied to the rod (34);

- a lining (33) in which the plunger (30) slides and in which an operating fluid is located;

said first piston (31 ) brushes the lining (33) and identifies by separation thereof a first and a second chamber (331 , 332) inside the lining (33); said first piston (31 ) being at least partly crossed by a passage (310) which enables communication between the first chamber and the second chamber (331 , 332);

- a sleeve (4) which partly houses said lining (33) and identifies a housing (40) of the fluid which at least in a first configuration is in fluid communication with the first chamber (331 );

characterised in that the plunger (30) comprises a second piston (32) applied to said rod (34); said second piston (32) identifies by separation thereof, the second chamber and a third chamber (332, 333) and is at least partly crossed by a passage (320) which enables communication between the second chamber and the third chamber (332, 333).

2. The system according to claim 1 , characterised in that the first piston (31 ) is located in proximity of an end of the rod (34).

3. The system according to claim 1 or 2, characterised in that the minimum distance between the first and the second piston (31 , 32) is greater than

0.5 centimetres.

4. The system according to any one of the preceding claims, characterised in that it comprises a two-way bottom valve (5) which opens when a predetermined pressure difference between upstream and downstream is exceeded; said bottom valve (5) being interposed between the first chamber (331 ) and said housing (40).

5. The system according to any one of the preceding claims, characterised in that the first piston (31 ) can be calibrated for regulating the load loss through the passage (310) of the first piston (31 ) and/or the second piston (32) can be calibrated for regulating the load loss through the passage (320) of the second piston (32).

6. The system according to any one of the preceding claims, characterised in that it comprises a first rod guide (61 ) and a second rod guide (62) arranged outside of the lining (33) and interposed between said sleeve (4) and said rod (34).

7. The system according to claim 6, characterised in that the first and the second rod guide (61 , 62) are annular and adjacent.

8. The system according to any one of the preceding claims, characterised in that the passage (310) of the first piston (31 ) has the same calibration as the passage (320) of the second piston (32).

9. The system according to any one of the preceding claims, characterised in that said fluid is oil with a viscosity of lower than 10 cSt at 100°C.

10. The system according to any one of the preceding claims, characterised in that it comprises regulating means for regulating the distance between the first and the second piston (31 , 32).