DE2751046A1 - PISTON ARRANGEMENT FOR SHOCK ABSORBER - Google Patents

Description

Monroe Belgium N.V.

Schuurhovenveld November 16, 1977

Sint-Truiden, Belgium Lawyer File M-4425

Piston arrangement for shock absorbers

The invention relates to a piston arrangement for shock absorbers according to the preamble of claim 1 .

In the construction of piston assemblies for motor vehicle shock absorbers, it has been customary to use valve assemblies with a single valve disk or those with a plurality of valve disks. A typical piston arrangement having a single valve disk is described in FR-PS 2,146,611 . A typical valve assembly includes a plurality of valve plates is disclosed in US-PS 3 134 46o. However, each of these valve assemblies is subject to some criticism from shock absorber manufacturers. The present invention is therefore intended to create a new, improved piston arrangement by means of which the disadvantageous properties of both the valve arrangements of the shock absorber piston, which have a single valve disk, and the valve arrangements for shock absorber pistons , which have a plurality of valve disks , are eliminated. Using

809850/0554

of valve assemblies with a single valve disk it is in particular It is necessary that the load on the valves when the shock absorber is subjected to tension or compression is brought into line will. These loads occur during rebound (extension of the shock absorber) or during compression (shortening of the shock absorber) on. It was therefore practically impossible to precisely adjust the extension characteristics of such a shock absorber without simultaneous Change of the running-in characteristics. A related problem is valve component fatigue; this leads to certain limitations in the power that can be obtained from a shock absorber, so that there are no premature malfunctions in the valve arrangement appear.

As far as the valve arrangements already mentioned above with a plurality of valve disks are concerned, the pistons assigned to them are expensive to manufacture. Although one can use such a piston valve assembly with multiple valve disks as they for example, U.S. Patent 3,134,460 is an independent amendment the retraction characteristics and extension characteristics can bring about, it has been found to be disadvantageous there that the Leakage current control for tensile load and pressure load cannot be changed independently of one another. As the fluid control is of considerably greater importance for currents moving at low speeds in modern motor vehicles the possibility of independent influencing of the extension and retraction characteristics at both low and high speeds practically indispensable for the piston movement.

Generally speaking, the present invention relates to a novel

809850/0654

term, improved piston assembly through which the above-described Disadvantages of conventional piston assemblies and conventional piston valve assemblies are eliminated. This is done according to the invention in that a piston assembly is provided which has two piston bodies. These have an identical structure and can consequently be exchanged for one another. Between the piston bodies there are two inlet valve bodies, which are connected by one between them lying woodruff springs are resiliently biased away from each other and in contact with the piston body. One of the extension characteristics of the shock absorber predetermined valve arrangement in the case of tension is arranged in the vicinity of the side of one of the piston bodies and has one or more valve disks and an associated throttle disk. Similarly, one is the break-in characteristic of the shock absorber in the event of a pressure load, the valve arrangement on the opposite side of the other of the piston bodies arranged. It also has one or more valve disks and an associated throttle disk. With this arrangement it is possible to use throttles to modify the extension characteristics and to use retraction characteristics of the shock absorber that are completely different and therefore also independent can be adjusted from one another to provide flow control at low working fluid flow rates to modify during extension and retraction of the shock absorber. According to the present invention is also the The object is to create a new, improved piston assembly for shock absorbers of motor vehicles, in which the extension leakage and the entry leakage current are independent and independent of each other are adjustable from each other.

809850/0554

Another essential feature of the piston assembly given above can be seen in the fact that the valve disks of the valve assembly responding when the shock absorber is retracted and that of the valve assembly when it is extended the shock absorber-responsive valve assembly can have different size and thickness. It can also use valve disks same area and different thickness or those with the same thickness and different area can be used. In this way the pressure relief of the piston by fluid discharge when extending the piston can be independent of that when retracting of the piston.

According to an advantageous development of the invention, there is a spacer body arranged in the immediate vicinity of the extending valve assembly and retracting valve assembly, and the thickness of this spacer can be adjusted so that an additional possibility of outflow control is obtained in this way. Through the The present invention is therefore also intended to obtain a discharge control by changing the number and dimensioning (both thickness and diameter) of the valve disks and the associated spacer can be changed.

The present invention is also intended to provide a new, improved Piston assembly for motor vehicle shock absorbers are created that has the structure described above and in which the flow rate control for high speed working fluid flowing can be predetermined by the dimensions of selected ones of the fluid passages provided in one of the piston bodies and in the same way also changes dimensions of selected fluid passages of the other piston body.

809850/0554

A similar arrangement is described in US Pat. No. 3,134,460; in 4 there, multiple piston bodies are shown. A very significant difference between this conventional arrangement and However, the present invention resides in that, in the conventional piston, each of the piston bodies has a part of the retraction characteristic and determines part of the extension characteristic; thus, independent leakage current control is not possible like this in the present invention is the case in which one piston body specifies the extension characteristic and the other piston body the run-in characteristics. The present invention is therefore also intended to provide a new, compared to that in US Pat. No. 3,134,460 improved piston assembly can be created.

The invention is also intended to provide a new, improved piston assembly for motor vehicle shock absorbers are created in which a majority of the components contained in it are interchangeable is so that the amount of tooling required and the associated manufacturing costs are so small be held as possible.

The invention is explained in more detail below using an exemplary embodiment with reference to the accompanying drawings. In this show:

Fig. 1 is a longitudinal section through a shock absorber for

Motor vehicles with a piston arrangement according to the invention;

FIG. 2 shows an enlarged section through the piston arrangement of the shock absorber shown in FIG. 1; and

Fig. 3 is an exploded perspective representation

809850/0554

treatment of the piston assembly shown in FIG.

In Fig. 1, a shock absorber is designated as a whole by 10. It has a pressure cylinder 12 in which a reciprocating piston assembly 14 is provided. The piston assembly 14 is of the one End of a reciprocating piston rod 16 carried on whose opposite end protruding in the axial direction from the pressure cylinder 12 has a connecting part 18 attached. That The opposite end of the printing cylinder 12 is also provided with a connecting part 20. In this way, the Attach shock absorbers 10 in a known manner between a sprung and a non-sprung part of a motor vehicle to to achieve a damping of the relative movement between these two parts. The shock absorber 1O has a dirt shield 22 that a coaxially to the piston rod 16 and extending in the radial direction outward at a distance from the outer surface of the pressure cylinder 12 arranged cylindrical portion 24 has. The cylindrical section 24 is connected to the piston rod 16 via an im essential cup-shaped end part 26 connected.

A working chamber 28 is provided in the interior of the pressure cylinder 12, in which a volume of hydraulic fluid used for damping is arranged. It is also one with pressurized Gas-filled gas chamber 30 is provided, and the working chamber 28 and the gas chamber 30 are arranged by a floating piston separated from each other in a known manner.

Referring now to FIG. 2, the structure and the

809850/0554

The operation of the piston assembly 14 is described in more detail. The piston rod 16 has a reduced diameter end portion 34 through which a substantially radial direction extending shoulder 36 is limited. On an externally threaded outermost end portion 38 of the end portion 34 is a Screwed on nut 40, by means of which the piston arrangement is held in its working position on the piston rod 16. The piston assembly 14 has two identical piston bodies, one of which is denoted by 42 in the drawing. The other piston body is designated by 42 '. Its components are provided with the same reference numerals as those of the piston body 42 and the following Description of the piston body 42 applies in the same way to the piston body 42 '.

As can best be seen from Fig. 2, the piston body 42 has a first set of spaced apart in the circumferential direction, axially extending passages 44 for the working fluid and a second set in the circumferential direction spaced apart, axially extending passages 46 for the working fluid. The passages 46, viewed in the radial direction, are offset inwardly relative to the passages 44. The upper end face of the piston body 42 forms an upper surface 48 provided with an annular valve seat 50. This is located in the radial direction between passages 44 and 46 and extends concentrically around the top of piston body 42. The lower face of the Piston body 42 is formed by a lower surface 52, which in turn has two valve seats arranged coaxially with one another 54 and 56 is formed, the former in the radial direction

809850/0554

is inside and the latter is outside in the radial direction. As As can be seen from the drawing, the valve seat 54 is arranged in the axial direction essentially below the valve seat 50, while the valve seat 56 is disposed radially outward of the outer set of passages 44. It should be pointed out that in the piston assembly 14 of the piston body 42 is arranged exactly the other way around as the piston body 42. Thus, the Valve seats 54 'and 56' from the piston body 42 'upwards, while the corresponding valve seats of the piston body 42 point downwards. The piston body 4 2 has a central, annular opening 57, in which the reduced diameter end section 3 4 of the piston rod 16 is received. The piston body 42 'is provided with an identical central opening 57', in which the end section 34 of the piston rod is received in the same way. The piston bodies 4 2 and 42 ′ are thus coaxial with one another aligned, as best seen in FIG.

Between the piston bodies 42 and 42 'are two inlet valve disks 58 and 60 arranged. These are made of suitable spring steel or the like and have a central opening 62 and 64, respectively through which the end portion 3 4 of the piston rod extends. The inlet valve disks 58 and 60 are attached to the Valve seats 54, 56 or 54 ', 56' can be placed. Between the valve discs 58 and 60 a valve disc spring 66 is arranged, which also is formed with a central opening 68 and a plurality of circumferentially spaced apart, in having corrugations 70 extending in the radial direction (see FIG. 3). The valve disks 58 and 60 are forced by the woodruff spring 66 to the associated valve seats on the piston bodies 42 ′ and

809850/0554

42 created.

Centrally within the valve disks 58 and 60 and the woodruff spring 56 a spider-shaped positioning and spacer body 72 is arranged. The spacer body 72 has a central opening 74, through which the end portion 34 of the piston rod is passed. The spacer body 72 also has a plurality, preferably three, in the circumferential direction at a distance one after the other, in arms 76 extending radially outward. The outermost sections of these arms in the radial direction terminate in the vicinity of the inner peripheral edge of the valve disks 58 and 60 and the disk spring 66. In this way the movement of these parts is limited in a radial plane. If desired, it can be in the radial direction outside the valve disks 58,60 and the disc spring 60 a piston ring 78 can be provided, which in a known manner on the inner wall of the pressure cylinder 12 is fluid-tight.

In the vicinity of the top of the piston body 42 is a valve arrangement which responds to pressure when the shock absorber is loaded 80 provided. This has two or the like made of spring steel. manufactured Valve disks 82 and 84, which are provided with a central opening 86 and 88, respectively, through which the end portion 34 of the piston rod 16 extends therethrough. Between the underside of the valve disk 84 and the valve seat 50 is a throttle disk 90 arranged. The latter is with a central opening 92 and with a plurality of radially inwardly extending Notches 94 provided, the latter along the circumference of the Throttle disc are distributed. As can be seen from the drawing,

809850/0554

the outer diameters of the valve disks 82 and 84 and the throttle disk 90 are essentially the same size and all somewhat larger than the diameter of the valve seat 50, so that they protrude over this in the radial direction. The notches are aligned 94 in the axial direction substantially with the valve seat 50. In this way there is a limited flow of working fluid possible between the throttle disc 90 and the valve seat 50. This current is the leakage current mentioned above.

In the axial direction directly above the valve disk 82 is a spacer ring 96 arranged. This also has a central opening 98 through which the end section 3 4 of the piston rod extends. Directly above the spacer ring 96, a support disk 100 is arranged, which has a central opening 102 and directly on the The underside of the shoulder 36 rests, as can be seen from the drawing. As will be described in greater detail below, works valve assembly 80 responsive to pressure loading of the shock absorber such that it increases the amount of working fluid controls that flows upwardly through the set of passages 46 of the piston body 42 when the piston assembly 14 is even under load of the shock absorber is moved downward under pressure in the working chamber 28.

A valve assembly responsive to tensile loading of the shock absorber 104, which has a structure similar to that of the valve arrangement already described above, which responds to the pressure load on the shock absorber 80, is in the vicinity of the bottom of the piston body 42 'arranged. The valve assembly 104 has two or the like made of spring steel. manufactured valve disks 106 and 108, the

809850/0554

have a central opening 110 or 112 through which the end section 34 the piston rod protrudes downwards. Between the top of the valve disk 108 and the valve seat 50 'is a Throttle plate 114 arranged, also with a central opening 116 and a plurality of radially inwardly extending, at a distance in the circumferential direction successive Notches 118 is provided. A spacer ring 120 with a central Opening 122 is in the axial direction directly below the valve disc 106 arranged. A support disc 124 with a central opening 126 is located between the spacer ring 120 and the on the end portion 38 of the piston rod 16 screwed nut 40. In this way, the support disks 124 and 100, the spacer rings 120 and 96, the valve disks 106,108,82 and 84, the Throttle plates 114 and 90, the piston bodies 42 and 42 'and the spider-shaped spacers 72 held together between the nut 40 and the shoulder 36.

The shock absorber 10 described so far operates as follows: When a pressure load is applied, the piston arrangement 14 is within the pressure cylinder 12 moved down. Hydraulic oil flows up through the set of passages 44 'of piston body 42' and opens the valve disc 60, i.e. pushes the valve disc 60 upwards from the valve seats 54 'and 56', overcoming the restoring force of the Woodruff key 66 away. The hydraulic oil then flows inward in the radial direction between the outwardly directed arms 76 of the spider-shaped spacer 72 and then flows axially upward through the set of passages 46, the are formed in the piston body 42. Then the hydraulic oil flows in the radial direction outwards between the top of the valve

809850/0554

Seat 50 and the notches 94 of the throttle plate 90 through and into the upper end of the working chamber 28. At the point in time at which the pressure acting on the valve disks 82 and 84 has a predetermined value Value reached, the valve disks 82 and 84 are lifted from the valve seat 50 under the action of force, so that a larger Hydraulic oil throughput is possible. This operating state corresponds to the movement of the piston assembly 14 at high speed.

When the shock absorber retracts, i.e. when the piston assembly moves upwards 14 within the pressure cylinder 12, the hydraulic oil flows axially downward through the set of passages 44 of the piston body 42. The hydraulic oil pushes the valve disc 58 from the valve seats 54 and 56 overcoming the restoring force the woodruff key 66 away. The hydraulic oil then flows in the axial direction and radial direction between the outwardly protruding ones Arms 76 of the spider-shaped spacer 72 through and flows then axially downward through the set of passages 46 'formed in piston body 42'. Then it flows Ilydrauliköl between the valve seat 50 'of the piston body 42' and of the plurality of notches 118 formed in orifice plate 114 are formed, and then reaches the lower end of the working chamber 28. Then, when the acting on the valve disks 106 and 108 If the pressure reaches a predetermined value, the valve disks 106 and 108 are moved away from the valve seat 50 '; This is then the case when the piston assembly is moved at high speed. In this way, there is a predetermined, higher hydraulic oil throughput possible.

A particularly important feature of the present invention lies

8098 5 0/0554

in that the orifice plates 90 and 114 can be changed or modified independently of one another. In this way, the Working characteristics of the shock absorber 10 for low speeds be changed. This can be done in particular in such a way that the extension characteristics and the retraction characteristics of the Shock absorbers can be changed independently. Another important feature of the present invention is that the valve disks 82,84 and 106,108 can be modified so that the working behavior and the performance of the Piston arrangement 14 is predeterminable. For example, the valve disks 82, 84 and 106, 108 can be modified by changing the material the thickness, the diameter and / or the number of valve disks changes so that a desired working behavior of the shock absorber is achieved receives. In addition, the diameter and / or thickness of the spacer rings 96 and 120 can be changed to the extent of the To specify the outflow of working fluid from the valve disks 82, 84 and 106, 108. Another key feature of the present invention is that the cross-sectional size and / or the number of fluid passages 44, 46 and 44 ', 46' can easily be modified as desired to suit the working characteristics of the piston assembly 14 to be modified. For example, the passageways 46 'can be modified to accommodate high speed deployment behavior adjust the piston assembly; the passages 46, on the other hand, can be modified separately to accommodate the high speed retraction characteristics the piston assembly 14 to be able to adjust to pressure when the shock absorber is stressed. Another one An important feature of the present invention is to be seen in the fact that a large number of the components of the piston assembly are interchangeable. In this way, the col-

809850/055 *

_ ₁₈ _ 275 I 046

produce ben arrangement with significantly lower tool costs. For example, the piston bodies 42 and 42 'can be interchangeable with one another the valve disks of the valve assemblies responding when retracting or extending and / or the inlet valve disks 58 and 60. Another important feature of the present invention is that the piston assembly provided valve disks have a significantly lower material fatigue than with conventional piston arrangements. Consequently For example, the life of the piston assembly 14 described above is greater than that of conventional piston assemblies. In the drawing and in the description of the figures above, the piston assembly 14 has been described in connection with a shock absorber, the has a canister filled with pressurized gas. It should be understood that the present invention works equally well at Shock absorbers can be used that have two tubes or a plurality of tubes.

Summary:

A piston assembly for a hydraulic shock absorber is provided, the latter being a single tube or a plurality of pipes may have. The piston assembly is attachable to one end of a reciprocating piston rod which in turn, for example, can be connected to the sprung part of an associated motor vehicle. The piston assembly has a first Piston body and a second piston body, which are arranged coaxially to one another. Each of the piston bodies has one radially inner set of axially extending passages for working fluid and one radially outer Set of passages running in the axial direction for working flow

8098.S 0/0554

Claims (11)

2751Q46 -y- Monroe Belgium N.V. Schuurhovenveld November 16, 1977 Sint-Truiden, Belgium Lawyer File M-4425 Claims _v Piston arrangement for shock absorbers, characterized by a first piston body (42) and a second piston body (42 ¹ ), which are arranged coaxially to one another and each have a radially inner and a radially outer set of axially extending passages (44, 46) for the working flow have means; by a first valve arrangement (8O) which responds to pressure when the shock absorber is loaded and which is arranged on one side of the piston bodies (42, 42 *); by a second valve arrangement (104) which responds to tension when the shock absorber is loaded and which is arranged on the other side of the piston bodies (42, 42 '); and by an inlet valve arrangement (5O-72) which is arranged between the piston bodies (42,42 ') and the fluid communication between certain of the passages (44,46) of the one piston body (42) and certain of the passages (44', 46 ') of the second piston body (42') selectively controls. 2. Piston arrangement according to claim 1, characterized in that the Inlet valve assembly a first valve body (58) and a 809850/0554 -2- 275104b second valve body (60), the first valve body (58) having a valve seat provided on one of the piston bodies (42) (54,56) cooperates and the other of the valve body (60) with one on the second piston body (42 ') arranged Valve seat (54 ', 56') cooperates. 3. Piston arrangement according to claim 2, characterized by an between the first valve body (58) and the second valve body (60) arranged spring (66), through which the valve body in System on the valve seat assigned to them (54,56 or 54 ', 56') are resiliently biased. 4. Piston arrangement according to one of claims 1 to 3, characterized in that that one of the valve arrangements (8O; 1O4) has at least one valve disk (82, 84) and one throttle disk (90), wherein the throttle disc is arranged between the one valve disc (82, 84) and an associated valve seat (5O), which the latter is formed on the adjacent piston body (42). 5. Piston arrangement according to claim 4, characterized in that each of the valve arrangements (80; 104) has at least one valve disc (82.84; 1O6.1O8) and a throttle disc (9O; 114), wherein the throttle disk is between the associated one of the valve disks and an adjacent valve seat of the associated one Piston body is arranged, whereby the flow of working fluid between the associated valve seats and valve bodies, which takes place at low speed, can be controlled. 809850/0554 6. Piston arrangement according to one of claims 1 to 5, characterized in that that the first piston body (42) and the second piston body (42 ') are substantially the same size and substantially have the same structure. 7. Piston arrangement according to one of claims 1 to 6, characterized in that that for each of the piston bodies (42, 42 ') on one end face a first valve seat (50) and on the opposite one End face a pair of valve seats (54,56) is formed, the last-mentioned valve seats with inlet valve bodies (58.60) work together. 8. Piston arrangement according to claim 7, characterized in that the first and second valve assemblies (80; 104) at least one valve disc (82.84; 1O6.1O8) and a throttle disc (9O; 114), wherein the throttle disk is arranged in each case between the associated one of the valve disks and adjacent valve seats whereby the low velocity flow of fluid between the associated valve seats and valve disks is controllable. 9. Piston arrangement according to claim 8, characterized by an between the first valve body (58) and the second valve body (60) arranged spring (66), through which the valve body in Direction to rest against the associated valve seats are resiliently biased. 10. Piston arrangement according to claim 9, characterized by a positioning device (72), which are related to the inlet valve 809850/055 * ben (58,60) and the associated valve spring (66) arranged centrally and serves to align the inlet valve disks coaxially so that they are axially aligned with pairs of valve seats (54,56; 54 ', 56') which are aligned on the first piston body (42) or on the second piston body (42 ') are. 11. Piston arrangement according to claim 10, characterized by a piston ring (78) which is arranged coaxially to the piston arrangement (42, 42 ') and is located in the radial direction outside the first and second inlet valve discs (58,56). 809850/0554