DE2163980A1 - - Google Patents

Description

PATENT OFFICE THOMSEN - TlEDTKE - B'JHLINGn λ η oqorj

TEL. (0811) 53 0211 TELRX: ί-24 * 13 topet * F Q V 5 W U

530212

PATENTANWÄLTE Munich: Frankfurt / M .:

Dipl.-Chem. Dr. D. Thomsen Dipl.-Ing. W. Weinkauff Dipl.-Ing. H. Tiedtke (Fuchshohl 71)

Dipl.-Chem. G. Buehling Dipl.-Ing. R. Kinne Dipl.-Chem. Dr. U. Eggers

8000 Munich 2

Kaiser-Ludwig-Platz 6 December 22nd, 1971

Nissan Motor Company, Limited Yokohama City, Japan

and

Atsugi Motor Parts Company, Limited Atsugi City, Japan

Shock absorbers

The invention relates to a shock absorbing device and more particularly to a hydro-

k> pneumatic shock absorber designed so that

* ° er when loaded under a mechanical pressure or

"Impact as a result of a collision is contractible and with Beo Freedom from this load in the original position «" is expandable. The shock absorber is in particular as

Verbal agreements, intbetonder “by telephone, require written bedfill Postichtck (Munich) account 116974 Drwdner Bank (Munich) account 55 * 709

Bumpers or shock absorbers suitable for automobiles, causing mechanical shock as a result of a vehicle collision is weakened to protect vehicle occupants from injury. The shock absorbing device With the features described below, other practical application possibilities can of course also be used. ^ find independent of motor vehicles.

A variety of shock absorbers or shock absorbing devices for automobiles have heretofore been proposed and developed. These include devices that use hydraulic springs, or destructible structural parts Use compression springs. However, difficulties arise with all of these known shock-absorbing devices, so that they are not suitable for practical use as bumpers for automobiles. The butt ■ absorbing device or the shock absorber using e.g. the hydraulic spring is constructed in such a way that the impact energy by displacement of a liquid through narrowed openings or channels in a suitable Construction part is consumed, which is immersed in the liquid. Those in a closed liquid chamber The liquid contained in the device expands when the temperature rises, so that the pressure in the liquid chamber from time to time depends on the ambient

BATH ORIGINAL

2 0 9 8 31/0556

temperature fluctuates. As a result, the hydraulic spring cannot be used in a stable and reliable manner, not to mention changes in the ambient temperature. The problem of this kind can be avoided in that a specially designed temperature control device is used, or a device that can compensate for the temperature fluctuation in the liquid chamber. The order such a device, however, leads to disproportionately complex and large-volume constructions of hydraulic Spring units, which are therefore expensive and cumbersome to manufacture. The destructible shock absorbing device usually uses a honeycomb structure or an element that can be sheared or destroyed when it is subjected to considerable stress, whereby the impact energy acting on the device through Destruction or compression of the honeycomb structure or plastic deformation or destruction of the part is consumed that is ready to shear. The device of this special design can therefore no longer be used, after it has been in use or has been in a crash condition and must be replaced with a new one, which is usual is considerably expensive. In the shock absorbing device using a compression spring, usually a Is coil spring, it is generally difficult to convert the impact energy with satisfactory efficiency. In order to Such a spring stabilizes the impact energy in a

BATH ORIGINAL 209B31 / Ü556

Can absorb state, the coil spring must have a correspondingly large coil diameter, which inevitably leads to an increased volume of the device as a whole. In addition, the collision condition ceases and can accordingly take the shock-absorbing device back to its original position, the in The energy stored in the coil spring is suddenly released, so that the device is violently pushed back. this leads to a so-called second collision in a motor vehicle, provided such a device is in a bumper is used.

The object of the invention is to create a hydropneumatic shock-absorbing device which has in combination an outer cylinder with a closed end wall, an inner cylinder firmly seated in the outer cylinder and ending at a distance from the closed end wall, which has an inner chamber in its interior and an outer chamber bounded between the outer cylinder and the inner cylinder, the inner chamber and the outer chamber are partly filled with a liquid and partly with a gas under pressure, furthermore a piston, which in the inner cylinder in the longitudinal direction _r γ * -μδι

209831 / 0BB6

is slidable, which has a plurality of narrowed openings in its peripheral wall in the portion which is substantially has the same extent as a full piston stroke in the inner cylinder and which is immersed in the liquid so that the openings establish fluid communication between the inner chamber and the outer chamber, and with a piston rod that extends from the piston to the outside of the outer cylinder in the opposite direction to the closed one Extends the end of the outer cylinder.

The invention is explained in more detail below with reference to schematic drawings of several exemplary embodiments explained.

Figure 1 is a longitudinal sectional view showing a first preferred embodiment of a hydropneumatic shock absorber according to the Invention clarifies;

FIG. 2 is a representation corresponding to FIG. 1, which is a second preferred Embodiment of a shock absorber according to the invention illustrates;

FIG. 3 is a representation corresponding to FIG. 1, showing a third embodiment a shock absorber according to the invention illustrates.

209 8 31/0556

Reference is first made to FIG. 1. The hydropneumatic shock absorber shown has a stationary outer cylinder Io which is fastened directly or through a suitable intermediate part to a stationary structure (not shown). This fixed structure can be the body of a motor vehicle. The outer cylinder Io has a closed end wall 12 and is closed at its open end with the aid of a cap 1 <4, which in the present case is screwed onto the outer cylinder Io, for example. The outer cylinder Io has in its interior an inner cylinder 16 which is attached at one end to the outer cylinder in the immediate vicinity of the cap lh at 18, while its end wall 2o is at a suitable distance from the closed end wall 12 of the outer cylinder. The outer cylinder and the inner cylinder Io or 16 thus form an outer chamber between them, while the inner cylinder 16 encloses an inner chamber which is designated by 22. The outer chamber is divided into two separate sub-chambers 24 and 26, specifically with the aid of a separating device 3o, which can be displaced in the outer cylinder Io between the end walls 12 and 2o of the outer cylinder or inner cylinder Io and 16. This displaceable device 3o can be a floating piston, as shown, or a bellows or a membrane, which are fastened at their edges to the outer cylinder. If a floating piston is used, between the

$ 209831/055

Inner surface of the outer cylinder and an annular groove (not designated) in the floating .Kolben a piston ring 32 can be housed. One of the sub-chambers formed in this way, namely the sub-chamber 2k and the inner chamber 22, which is located within this sub-chamber, are filled with an incompressible liquid, for example with oil, while the other sub-chamber 26 is filled with a compressible gas under pressure, for example with Pressurized nitrogen gas. The sub-chambers 24 and 26 thus form a liquid chamber and a gas chamber, respectively. The inner cylinder 16 is closed at its open end with the aid of a stopper 3'4 which is located on the cap 14.

A piston 36 is displaceable in the inner cylinder 16 between the end wall 2o and the opposite plug 34. The inner cylinder 16 has several calibrated nozzles or narrowed openings 38 in its peripheral wall and a central opening 4o in its end wall 2o, which results in a fluid connection between the inner ^{chamber 22 and the fluid chamber 2 1} J of the outer chamber. The narrowed openings 38 are located in that section of the peripheral wall of the inner cylinder 16 which has essentially the same extent as a full stroke of the piston 36 in the chamber. The central opening 4o in the end wall or end wall 2o is provided with a one-way check valve 42 which, as shown, consists of a flexible valve plate which is attached to the outer surface of the end wall 2o by means of a

2 09831/0556. _BAD original

Bolt 44 is attached. The one-way check valve 42 can, however, be designed in any way, as far as it allows the flow of liquid from the inner chamber 22 to Plüssigkeitskammer 24 allowed through the central opening 4o and prevents the backflow of the liquid.

On the piston 36 there is a piston rod 46, which extends out of the outer cylinder Io through holes in the end plug 34 and cap 14. Between the Piston rod 46 and the end plug 34 is an annular sealing body 48, which is in the end plug according to Representation is embedded. The hydropneumatic damper this structure is combined with a fender or a bumper 5o that is fixed to the front end of the piston rod 46 is connected so that an impact exerted on the push rod 50 by the piston rod 46 on the piston 36 is transmitted.

Despite the specific designation of the outer cylinder and inner cylinder, they do not necessarily have to have a circular cross-section but can have other cross-sections, e.g. rectangular cross-sections, if so desired.

If the bumper 5o meets a resistance and if the collision results in a shock which is transmitted to piston 36 via piston rod 46, it becomes the piston moved in the inner cylinder 16 in the direction of its end wall 2o,

209831/0556 bad g

the liquid located in the chamber 22 between the piston 36 and the end wall 2o corresponding to the withdrawn liquid Divide through the narrowed openings into the liquid chamber 24 and into the chamber 22 between the piston and the end plug is pressed through the narrowed one there Orifice, indicated by the reference numeral 38, the flow being indicated by an arrow in broken line is indicated. The liquid thus pressed into the liquid chamber 24 acts on the floating piston 3o and 3o moves this by a distance which is substantially proportional to the displacement of the piston 36 in the inner chamber 22, whereby the gas in the gas chamber 26 is further compressed.

The liquid passing through the openings 38 in the inner cylinder 16 is subjected to certain restrictions, so that the liquid pressure in the inner chamber 22 between the piston 36 and the end wall 20 increases progressively with the movement of the piston 36. A reaction force thus acts on the piston rod 46. The total area of the narrowed openings 38 through which the liquid passes from the inner chamber 22 to the liquid chamber 24 decreases with the movement of the piston 36 in the direction of the end wall 20 of the inner cylinder 16. therefore, if the nozzles or narrowed openings 38 are properly calibrated and located in the peripheral wall of the inner cylinder 16, can

209831/0556

- Io -

the efficiency of the device for absorbing the impact energy can be increased in a satisfactory manner.

The increase in fluid pressure in the inner chamber 32 due to the flow restrictions through the narrowed holes 38 is generally proportional to the square of the speed of the piston movement 36 in the inner cylinder 16. The greater the speed of the inward movement. movement of the piston rod 46 relative to the obstacle, the greater the increase in the fluid pressure and, accordingly, the reaction force on the piston 36. Thus, when the shock absorber is used as a bumper in a motor vehicle, the motor vehicle body must be constructed as rigidly as possible. However, certain limitations are imposed on the rigidity of the automobile body for certain practical reasons. This problem is completely solved by the shock absorber according to FIG. Thus, when the fluid pressure in the inner chamber 22 between the piston 36 and the inner end wall 2o reaches a predetermined fourth, the one-way check valve 42 is operated to open the central opening 4o in the end wall 2o so that the pressure in the chamber 22 is relieved through the opening 4o into the liquid chamber 24. The pressure in the liquid chamber 22 between the piston 36 and the end wall 2o is kept below the predetermined value in this way, even when the piston rod 46 and

209331/05 5 6

the piston 36 gives a shock with an unusually high To be exposed to violence.

The increase in the liquid pressure in the liquid ^{chamber 2 1} J as a result of the displacement of the piston 36 is largely compensated for by the compression of the pressurized gas in the gas chamber 26, although a limited amount of liquid pressure enters the inner chamber 22 behind the piston 36 through the narrowed opening 38 ' is relieved. If the collision state ends and the piston 36 is released from the pressure in the direction of the end wall 2o, the pressure stored in the gas chamber 26 now acts on the floating piston 30 in order to move it against the liquid pressure in the liquid chamber 2 ^l \. The liquid in the liquid chamber 24 is thus forced to flow into the inner chamber 22 between the piston 36 and the end wall 2o in the opposite direction to the solid arrows. Since the flow of liquid through the nozzles or narrowed openings 38 is restricted in this state, the piston 36 returns to its original position at a limited speed so that the device is not violently thrown back. If the piston has been returned to the gas chamber under the action of the pressurized gas, the device can be used again as soon as the piston and the piston rod assume their starting position.

209831/0558

Where the shock absorber shown structure changes in temperature is subject to, the liquid in the inner cylinder and liquid compartment can expand, causing an increase in pressure results. Such increased liquid pressure is caused by contraction of the gas chamber 26 and the Movement of the floating piston away from the end wall of the inner cylinder is relieved. The pressure in the gas chamber increases and the floating piston comes into equilibrium when the two sides of the piston press against each other are the same. The increase in the volume of the liquid in the inner chamber and the liquid chamber will compensated in this way by the movement of the floating piston, so that an unusual increase in the pressure of the Liquid can be prevented automatically. In this way it results that the pressure in the liquid is proportional to increase the pressure in the gas in the gas chamber increases, however, such an increase in liquid pressure is practical is negligible in comparison with the increase in liquid pressure, which is more fixed in an envelope Capacity would occur, as is the case, for example, with the known shock absorbers.

The pressure of the liquid in the inner chamber between the piston and the end wall of the inner cylinder increases during the use of the device to a considerable extent. In the event that the inner cylinder is under the Influence of such an increased fluid pressure breaks,

209831/0556

become the pressures in the inner chamber and in the liquid chamber instantly equal to each other. The increased pressure in the inner chamber becomes accordingly deleted so that no destructive force is effective on the outside of the outer cylinder.

In the figure 2 a further preferred embodiment of a shock absorbing device according to the invention is shown. The device shown here is essentially the same as that of FIG. 1 in structure and mode of operation, with the exception that the movable separating device, for example the floating piston according to the previous embodiment, is omitted. Larger parts of the inner chamber and the outer chamber are occupied by an incompressible liquid and the remainder by the negative gas pressure. The liquid and gas are in direct contact with one another, their contact surfaces being essentially parallel to the axis of the inner and outer cylinders. The nozzles or narrowed openings 38 and 38 'are housed in that part of the inner cylinder 16 which is immersed in the liquid, as shown in e3. Calibrated nozzles or narrowed openings 52 and 52 'are provided in that part of the inner cylinder 16 which is enclosed by the pressurized gas so that the gas travels under pressure between the inner chamber and the outer chamber

209831/0556

can if it is compressed or re-expanded during use or by expansion of the liquid. The shock absorber constructed and arranged in this way should be arranged so that its axis is substantially is held in its horizontal plane so that the liquid is below the pressurized gas as it is is shown. The device shown here is advantageous in that the outer cylinder can be shortened and accordingly, the entire device can be made smaller in size due to the lack of a separate gas chamber.

FIG. 3 shows a third preferred embodiment of the hydropneumatic shock-absorbing device according to the invention. The device shown here is similar to that according to FIG.! As far as it has an outer cylinder Io and an inner cylinder 16, a piston 36 which is displaceable in the inner cylinder, a piston rod 46 which extends from the piston 36 and a floating piston 3o in the outer cylinder Io having. In contrast to the device according to FIG. 1, the device according to FIG. 3 also has a rigid sleeve 54 which telescopically accommodates the outer cylinder Io, as well as a resiliently flexible sleeve 56 which encloses part of the circumferential wall of the inner cylinder 16. The piston rod 46 and the rigid sleeve 5 ¹ * are fixedly attached to a fixed structure 58 which may be part of a vehicle body where the airbag absorbing device acts as a bumper. to use for a motor vehicle

209331/0866

is. In this case, the outer cylinder 10 is at that of the fixed construction facing away from closed end wall 12 directly connected to the bumper or the fender 50, as it is shown. The steel sleeve 5 * J is used for reinforcement of the outer cylinder 10 against the bending stress that can be generated when the outer cylinder one in the direction impact force directed on the fixed structure 58 is exposed. The resilient sleeve 56 is located in such a position that it normally covers some of the narrowed openings 38 of the inner cylinder 16. These resilient sleeve 56 is expanded or diametrically deformed when exposed to an increased fluid pressure that is built up in the inner cylinder 16 in order to this Way to restrict the flow of liquid through the narrowed openings 38 enclosed by the resilient sleeve are. This not only leads to an improved spring effect also in the event that the device is relatively shock-resistant small size, but also prevents the bumper from bouncing back when the impact ceases or has been downgraded.

The one-way check valve, now designated by the reference numeral 42 ', which is located on the front end wall 20 of the inner cylinder 16 is to be arranged, here uses a Belleville spring, which at one end on a spring seat (not designated) sits, which is supported by a rod firmly connected to the inner cylinder (not designated), and at the other end on a resilient valve plate (not designated) based on an outer surface of the end wall 20 of the inner cylinder

209831/0 B 56

Linders 16 rests in such a way that the opening provided there ^ O is ordinarily closed, which is opened when it is exposed to increased pressure in the inner cylinder.

The operation of the shock-absorbing device according to FIG. 3 does not require any explanation with regard to the preceding Explanations based on FIG. 1, so that these explanations are not repeated.

The device according to Fi p ,. 3 is essentially the same in its construction as the device according to FIG. 1, insofar as than they are in separate liquid chambers and gas chambers the outer chamber has; it can be seen, however, that the essential features of the embodiment of FIG this structural arrangement according to the device in FIG. 3 can be used.

It is clear from the present description that the hydropneumatic shock absorbing device according to the invention is capable of generating impact energy in a stable and reliable manner regardless of fluctuations in ambient temperature absorbent and free from rebound effects when the shock ceases or has been dampened. Such a device can be made sufficiently small and compact and not only simple and cheap but can also in a limited work space, such as. B. a vehicle can be accommodated.

BATH ORIGINAL

209831/0556

The device according to the invention can moreover be used repeatedly without replacing its components and offers a robust construction that ensures durability over long periods of time. The device this structure is advantageously used as a shock absorber in a motor vehicle, although it has other uses can.

BATH ORIGINAL

209831/0566

Claims (1)

Claims Λ. Hydro-pneumatic shock-absorbing device, characterized by an outer cylinder (10) with a closed end wall (12), an inner cylinder (16) which sits firmly in the outer cylinder and ends at a distance from the closed end wall and encloses and between an inner chamber (22) and the outer cylinder bounds an outer chamber (24), wherein the inner chamber and the outer chamber are partially filled with liquid and partially with pressurized gas, by a piston (56) which is longitudinally displaceable in the Irinenzyliruler, which constricts a plurality of Has openings (8) in the part of its peripheral wall which extends over the length of the full piston stroke inside the inner cylinder and which is immersed in the liquid, these openings establishing a liquid connection between the inner chamber and the outer chamber, and through a piston rod (46) starting from the piston and extending to the outside of the outer cylinder, in the opposite direction to the closed end wall of the outer cylinder. 2. Apparatus according to claim 2, characterized in that the inner cylinder (16) in its the closed End wall (12) of the outer cylinder (10) facing the end wall (20) has an opening (40) in order to provide a further fluid connection establish between the inner chamber and the outer chamber. 3, device according to claim 2, characterized by iO9831 / 0S56 BAD ORIGINAL 21S398G a one-way check valve (42, 44) seated on the end wall (20) of the inner cylinder (16), the one-way check valve (42, 44) Liquid passage from the inner chamber (22) to the outer chamber through the opening (40) in the end wall of the Inner cylinder permitted and prevents the flow of liquid in the opposite direction. 4. Device according to one of the preceding claims, characterized by a movable separating device (30) which the outer chamber (24) divided into a liquid chamber and a gas chamber (26), which at one end by the closed End wall (12) of the outer cylinder is limited, the inner chamber (22) and the liquid chamber (24) from the liquid and the gas chamber is filled with a pressurized gas. 5. Device according to one of the preceding claims 1 to 3 »characterized in that larger parts of the inner chamber and the outer chamber are filled by a pressurized gas and the liquid is in direct contact with the gas Contact is located, the contact surfaces essentially parallel to the axis of the outer cylinder and the inner cylinder and wherein the narrowed openings (38) in the Part of the peripheral wall of the inner cylinder are provided, which is immersed in the liquid and in which one of which is under pressure standing gas enclosed part of the peripheral wall of the inner cylinder through openings (52, 52 ') are provided. .. 6. Apparatus according to claim 1 to 5, characterized 209831 / 0BB6 draws that the outer cylinder with its closed end wall on a fixed structure and the piston rod connected to a bumper. 7. Apparatus according to claim 1 to 5, characterized in that the piston rod is fixed to its Pührungsende with a fixed construction and the closed end wall of the outer cylinder facing away from it with a bumper is firmly connected. 8. The device according to claim 7, characterized by a rigid sleeve (5 * 0, die.teleskopartig the outer cylinder (10) receives and is attached to the fixed structure. 9. Apparatus according to claim 7 or 8, characterized by a portion of the peripheral wall of the inner cylinder (16) enclosing resilient sleeve (56) which normally blocks some of the narrowed openings (38). 209831/0556