CN114941677A

CN114941677A - Damping valve device for shock absorber

Info

Publication number: CN114941677A
Application number: CN202210134100.8A
Authority: CN
Inventors: J·罗塞勒; A·科内泽维奇
Original assignee: ZF Friedrichshafen AG
Current assignee: ZF Friedrichshafen AG
Priority date: 2021-02-16
Filing date: 2022-02-14
Publication date: 2022-08-26
Also published as: DE102021201420B4; DE102021201420A1

Abstract

The invention relates to a damping valve device for a shock absorber having an axially movable piston rod in a cylinder filled with a damping medium, wherein the damping medium is displaced through the damping valve device as a function of the piston rod movement, wherein a valve element of variable radial diameter is deflected in a valve seat towards a flow guide surface, wherein the flow guide surface is formed by an outer lateral surface of the piston rod.

Description

Damping valve device for shock absorber

Technical Field

The present invention relates to a damping valve device for a shock absorber according to the preamble of claim 1.

Background

DE102016210790a1 discloses a damping valve device which is essentially formed by a variable-diameter valve body, a valve seat and a flow guide surface. It describes various variants of valve seats and guide surfaces which together form a damping valve device with progressive damping force characteristics.

All variants have in common that: the valve body widens radially outwards, for example towards the inner wall of the cylinder barrel, the piston skirt or the side of the base valve body.

According to the exemplary embodiment shown in fig. 4, the damping valve device can also be designed with a valve seat which is arranged in a stationary manner in the cylinder of the shock absorber.

Disclosure of Invention

The object of the invention is to show further embodiment variants for such a damping valve device.

This object is achieved in that the guide surface is formed by an outer lateral surface of the piston rod.

The outer side of the piston rod is the most valuable component inside a conventional shock absorber in terms of dimensional accuracy and surface quality. The function of the damper valve arrangement is benefited by this.

In one embodiment, the valve seat is arranged in a stationary manner in the cylinder barrel. The entire radial installation space between the side of the piston rod and the inner wall of the cylinder is available for the damping valve device.

In order to optimize the assembly effort of the damping valve device, the valve seat is formed by a piston rod guide of the cylinder. After the piston rod guide is installed, the valve seat is also fastened in the shock absorber.

In a further embodiment, the piston rod guide has a piston rod seal which seals an annular gap between the piston rod guide and a side face of the piston rod, wherein a working chamber of the vibration damper on the side close to the piston rod has a flow channel which opens into a further working chamber and which extends hydraulically parallel to the annular gap. The damping medium displaced by the damping valve device therefore does not have to flow into the compensation chamber via the annular gap toward the piston rod seal as a function of the leakage oil volume. The flow channel may be used for this purpose.

Alternatively, the piston rod can have a functional section with a guide surface which, depending on the stroke position of the piston rod inside the cylinder barrel, projects into a through-opening radially defined by the valve element and thus functionally uses the damping valve device. The functional section may be formed, for example, by an end-side piston rod pin, which projects into the valve seat. With this design, a speed-dependent function of the damping valve device as a function of the stroke position can be achieved. Alternatively, the piston rod can also have a radial constriction which does not generate a damping force when it is in register with the valve seat. However, a guide surface is also provided on the piston rod outside this constriction of the piston rod.

Alternatively, the valve seat is arranged on the piston rod. If necessary, the annular gap between the valve seat and the inner wall of the cylinder can be closed by means of a seal or at least reduced in cross section.

In a further development, the damping valve device has a first valve element of variable diameter on the inner diameter of the valve seat and a second valve element of variable diameter at a region radially further outward relative thereto toward the second flow guide surface. A better satisfactory damping valve device can be achieved with two separate valve elements.

In the simplest embodiment, the operating principle of the damping valve device is based on a speed-dependent pressure reduction inside the throttle point formed by the flow guide surface and the valve element. In an expanded embodiment, the valve seat has at least one pressure chamber which is connected to the groove for the valve element, wherein the pressure chamber is hydraulically connected to at least one working chamber of the cylinder via at least one inflow opening. The adjusting movement of the valve element can be additionally influenced by the pressure from the pressure chamber.

In a first variant, the first valve element and the second valve element are connected to a common pressure chamber. This embodiment is advantageous in particular in the case of small radial installation spaces.

Alternatively, the first valve element and the second valve element are connected to hydraulically separate pressure chambers in order to be able to apply different pressures to the two valve elements.

Drawings

The invention is explained in detail in the following description of the figures.

Wherein:

fig. 1 shows a damping valve device in the region of a piston rod guide;

fig. 2 shows the damping valve arrangement according to fig. 1 with a stroke-dependent function;

fig. 3 and 4 show the damping valve arrangement according to fig. 1 on the piston rod;

fig. 5 to 8 show a damping valve device with two valve elements.

Detailed Description

Fig. 1 shows a section through a vibration damper 1 with a cylinder 3 in which a piston rod 5 with a piston 7 performs an axial stroke movement. The piston 7 divides the cylinder 3 filled with damping medium into a piston rod-side working chamber 9 and a working chamber 11 remote from the piston rod. The two

working chambers

9, 11 are hydraulically connected via

damping valves

13, 15, which perform a stroke movement as a function of the pressure level at their

valve disks

17, 19. The precise design of the

damping valves

13, 15 is subject to the present invention.

The cylinder 3 is closed at the end by a rod guide 21 connected to a rod seal 23. An outer reservoir 25 surrounds the cylinder 3 and defines, together with the cylinder 3, a compensation chamber 27 which is only partially filled with damping medium for the damping medium volume displaced by the retracted and extended piston rod 5.

Between the outer lateral surface 29 of the piston rod 5 and the guide surface 31 of the through-opening 33 of the piston rod guide 21 there is a defined, very small annular gap which fills the oil sump 35 of the piston rod guide 21 with leakage oil from the piston rod-side working chamber 9. The through opening 33 may also be formed by a separate bearing bushing located inside the piston rod guide 21. The leakage oil volume ensures lubrication of the piston rod 5 and thus a reduction of friction. An overflow channel 37 is present between the oil sump 35 and the compensation chamber 27.

In addition to the

damping valves

15, 17 in the piston 7, the vibration damper 1 has a damping valve device 39 with a valve seat 41 and a valve element 43 with a radially variable diameter. Valve element 43 forms together with guide surface 29 a throttle point 45. The higher the flow velocity inside the throttle point 45, the lower the pressure level inside the throttle point 45. Thereby deforming the valve element 43 toward the flow surface. In the case of the damping valve device 39 according to fig. 1, the flow guide surface of the damping valve device 39 is formed by the outer circumferential side 29 of the piston rod 5. The piston rod 5 thus forms part of the damping valve device 39, in particular of the throttle point 45. For a resilient valve element, for example made of plastic or a slotted metal ring, the valve element 43 narrows uniformly in diameter towards the flow guide surface 29. However, it is also possible for the valve element 43 to be composed of a plurality of individual elements forming a ring, so that the individual elements produce a radial movement or a pivoting movement about a pivot bearing point. The pivot bearing point can, for example, connect two individual elements to one another. Such an embodiment is known, for example, from the earlier document DE102019215558a 1.

Furthermore, the valve seat 41 is arranged in a stationary manner in the cylinder 3. Fig. 1 shows two embodiments of a damping valve device 39. In the left half a valve seat 41 is shown, which is independent with respect to the piston rod guide 21. The valve seat 41 does not have to bear directly against the piston rod guide 21. The fixation of the valve seat 41 inside the cylinder is simplified by direct contact. At least one crimping element 47 in the cylinder 3 ensures that the valve seat 41 is secured on both sides.

In the right half of fig. 1, the valve seat is formed by a piston rod guide 21 of the cylinder 3.

Common to both embodiments of the damping valve device 39 is that the piston-rod-side working chamber 9 of the shock absorber 1 has a flow channel 49 which opens into the other working chamber and which extends hydraulically parallel to the annular gap on the piston-rod guide 21. The further working chamber is formed in this embodiment by a compensation chamber 27 of the shock absorber 1. For this purpose, a transition opening 51 is formed in the cylinder 3, which coincides with the flow channel 49. In principle, the other working chamber can also be connected, for example, to the working chamber 11 remote from the piston rod.

The valve seat 41 has an annular groove with a diameter at the bottom 53 of the annular groove that is larger than the outer diameter of the valve element 43. The valve element is, if necessary, biased radially outward by a restoring spring 54 toward the annular groove bottom 53, but does not rest against the annular groove bottom 53. Between the annular groove bottom 53 and the valve element 43, a pressure chamber 55 is thus present, which has an inflow opening 57 from the piston-rod-side working chamber 9. The inflow opening 57 can be formed by an additional opening in the groove side wall 59 of the valve seat 41 or via a radial gap between the valve element 43 and the groove side wall 59 of the valve seat 41.

The pressure chamber 55 is connected to the compensation chamber 27 via an outflow opening 61. The outflow opening 61 can open directly into the compensation chamber 27 or be connected to the flow channel 49.

Fig. 1 shows the vibration damper 1 in a stationary state. The return spring 54 keeps the valve element 43 at a distance from the guide surface 29 of the piston rod 5. At the throttle point 45, a cross section of maximum size is present. During compression of the piston-rod-side working chamber 9, the damping medium displaces the piston 7 via the damping valve 15. In the event of a defined piston rod extension speed being exceeded, the pressure inside the throttle point 45 decreases, but the pressure in the pressure chamber 55 is increased via the inflow opening, so that an additional radial force acts on the valve element 43, which reduces the cross section of the throttle point 45 against the force of the restoring spring 54. Thereby significantly increasing the damping force level of the damping valve device 39.

Fig. 1 also shows a third variant in which the damping valve device 39 is fastened in the cylinder 3 at a distance from the piston rod guide 21. The design of the damping valve device 39 corresponds, for example, to the functional design of the damping valve device 39 at the piston rod guide 21. In order to control the damping force characteristic of the damping valve device 39, the piston rod 5 has a cross-sectional contour 63, for example a longitudinal groove or a constriction, in order to enlarge the outlet cross section of the throttle point 45 over a certain travel range of the piston rod 5. By such expansion of the throttle point 45, the initial operating point (Einsatzpunkte) of the damping valve device 39 can be determined according to the stroke position of the piston rod 5. In principle, the damping valve device 39 operates as a function of the flow velocity inside the throttle point and thus as a function of the movement of the piston rod 5. However, an and logic (Und-Verknun. upfang) with the stroke position of the piston rod 5 still exists.

The embodiment of the invention according to fig. 2 is based on a damping valve device 39 according to fig. 1. The construction and function of the valve element 43 are identical. The difference is that the piston rod 5 has a functional section 65 with a guide surface 29 which, depending on the stroke position of the piston rod 5 inside the cylinder 3, projects into a through-opening 67 radially delimited by the valve element 43, so that the damping valve device 39 is functionally used. The functional section is formed by a piston rod pin 65. In contrast to fig. 1, the damping valve device 39 is fixed in position relative to the cylinder 3 in the working chamber 11 remote from the piston rod, in this case also on the cylinder 3.

During the stroke movement, in which the piston rod pin 65 is located outside the damping valve device 39, only the damping valve 15 in the piston 7 and the foot valve 69 at the transition between the working chamber 11 and the compensation chamber 27 remote from the piston rod are active. As soon as the piston rod pin 65 with its outer guide surface 29 passes through the through-opening 67 of the valve seat 41, the damping valve device 39 can be activated. The application then additionally depends on the retraction speed of the piston rod 5.

Fig. 3 to 8 show an embodiment in which the valve seat 41 of the damping valve device 39 is arranged on the piston rod 5. The valve seat 41, the valve element 43 and the return spring 54 correspond to the construction and function according to fig. 1. The difference is that the valve seat 41 according to fig. 3 and 4 has a cylinder seal 71 which seals the annular gap between the valve seat 41 and the inner wall of the cylinder 3. The valve seat is held, for example, by two star-shaped discs 73 connected to two bearing discs 75 and two retaining rings 77 on the piston rod 5. The spider has radial recesses, as is known from spider springs. In principle, an alternative fastening technique is of course also conceivable. The flow path along deflector surface 29 on the inner diameter of valve seat 41 should be more readily understood in conjunction with this illustration.

When the piston rod moves, the damping medium can escape from the compressed piston-rod-side working chamber 9 through the throttle point 45 and then through the valve 15 in the piston 7 into the working chamber 11 remote from the piston rod. However, if the speed of the piston rod 5 also increases here beyond a defined limit, the inner diameter of the valve element 43 and thus also the cross section of the throttle point 45 is reduced. This radial constriction of the throttle point 45 is supported by the effect of the pressure chamber 55 according to the embodiment shown in fig. 1.

Fig. 5 to 8 relate to an embodiment variant of the damping valve device 39, which has a first valve element 43A of variable diameter on the inner diameter of the valve seat 41 and a second valve element 43B of variable diameter at a radially outer region thereof in the direction of the second flow guide surface 79. The seal used in fig. 3 and 4 is therefore replaced by an additional valve element 43B. The inner wall of the cylinder thus forms a second deflector surface 79. The second valve element 43B also has a restoring spring 81, which however generates a radially inwardly directed restoring force.

Just like the valve element 43A for the throttle point 45A interacting with the piston rod 5, the throttle point 45B also has a pressure chamber with the inner wall of the cylinder 3 as a flow surface 79. The first and

second valve elements

43A, 43B are connected to a common pressure chamber 55.

The two

throttle points

45A, 45B which are already present can be used in succession by designing the throttle cross section in its initial position in combination with the return springs 54, 81, so that a damping force characteristic of the shock absorber 1 which is stepped in the direction of the steps is produced. Here, the ratio of the surfaces to which pressure is applied to the

valve elements

43A, 43B also plays an important role. The pressure-loaded surface, i.e. the radially inner and outer side surfaces at the second valve element 43B, is significantly larger than the comparable surface at the inner first valve element 43A.

Fig. 7 and 8 show an alternative damper valve device 39 with two

damper valve elements

43A, 43B, the first and

second valve elements

43A, 43B being connected to hydraulically

separate pressure chambers

55A, 55B. Thus,

separate inflow openings

57A, 57B and

outflow openings

61A, 61B are also present, by means of whose cross-section the respective pressure level in the

pressure chambers

55A, 55B can be adjusted as a function of the piston rod speed. The initial point of action and the closing characteristic of the two

valve elements

43A, 43B can be controlled independently of one another with different cross-sectional dimensions. The general function of this embodiment corresponds to that described with respect to fig. 5 and 6.

List of reference numerals:

1 vibration damper

3 cylinder barrel

5 piston rod

7 piston

9 working chamber at one side of piston rod

11 working chamber far away from piston rod

13 damping valve

15 damping valve

17 valve disk

19 valve disk

21 piston rod guide

23 piston rod seal

25 container

27 compensating chamber

29 side/flow guide surface

31 guide surface

33 through opening

35 oil pool

37 overflow channel

39 damper valve device

41 valve seat

43 valve element

45 throttle point

47 crimping element

49 flow channel

51 transition opening

53 annular groove bottom

54 return spring

55 pressure chamber

57 inflow opening

59 groove side wall

61 outflow opening

63 contour

65 functional section

67 through opening

69 bottom valve

71 cylinder barrel seal

73 star-shaped disc

75 supporting disc

77 retainer ring

79 second flow guide surface

81 return spring

Claims

1. A damping valve device (39) for a shock absorber (1) having an axially movable piston rod (5) in a cylinder (3) filled with a damping medium, wherein the damping medium is displaced through the damping valve device (39) as a function of the piston rod movement, wherein a valve element (43) of variable radial diameter is deflected in a valve seat (41) towards a flow guide surface (29), characterized in that the flow guide surface (29) is formed by an outer side of the piston rod (5).

2. The damping valve device according to claim 1, characterized in that the valve seats (41, 21) are arranged in a stationary manner in the cylinder barrel (3).

3. A damper valve device according to claim 2, characterized in that the valve seat (41) is formed by a piston rod guide (21) of the cylinder (3).

4. A damping valve device according to claim 3, characterized in that the piston rod guide (21) has a piston rod seal (23) which seals an annular gap between the piston rod guide (21) and a side face (29) of the piston rod, wherein the working chamber (9) of the shock absorber on the side close to the piston rod has a flow channel (49) which opens into the other working chamber (27), said flow channel running hydraulically parallel to the annular gap.

5. The damper valve device according to claim 2, characterized in that the piston rod (5) has a functional section (65) with a guide surface (29) which, depending on the stroke position of the piston rod (5) inside the cylinder (3), projects into a through-opening (67) radially defined by the valve element (43) and thus functionally uses the damper valve device (39).

6. The damper valve device according to claim 1, characterized in that the valve seat (41) is arranged on the piston rod (5).

7. A damper valve device according to claim 6, characterized in that the damper valve device (39) has a first valve element (43A) of variable diameter on the inner diameter of the valve seat (41) and a second valve element (43B) of variable diameter at a radially further outer region relative thereto towards the second guide surface (79).

8. Damping valve device according to at least one of claims 1 to 7, characterized in that the valve seat (41) has at least one pressure chamber (55) which is connected to a groove for the valve element (43, 43A, 43B), wherein the pressure chamber (55) is hydraulically connected to at least one working chamber (9, 11) of the cylinder (3) via at least one inflow opening (57, 57A, 57B).

9. The damping valve device according to claim 8, characterized in that the first and second valve elements (43A, 43B) are connected at a common pressure chamber (55).

10. The damper valve arrangement according to claim 8, characterized in that the first and second valve elements (43A, 43B) are connected at hydraulically separated pressure chambers (55A, 55B).