CN113958644A

CN113958644A - Damping valve device with increasing damping force characteristic curve

Info

Publication number: CN113958644A
Application number: CN202110819473.4A
Authority: CN
Inventors: J·罗塞勒; A·克内泽维奇
Original assignee: ZF Friedrichshafen AG
Current assignee: ZF Friedrichshafen AG
Priority date: 2020-07-21
Filing date: 2021-07-20
Publication date: 2022-01-21
Also published as: DE102020209102A1

Abstract

A vibration damper with a damping valve device, the vibration damper comprises a throttling point connected with a valve body, the valve body changes from a flow-through position to a throttling position depending on the flow speed in the throttling point, wherein the valve body follows the flow velocity. As the flow velocity of the damping medium increases, it moves in the closing direction in that the valve body is designed as a ring element with a variable diameter, which performs a radial closing movement in the direction of the flow guide surface, with a defined minimum throughflow being maintained. The cross section, in which at least one component influencing the damping force of the throttling point varies depending on the stroke position of the vibration damper.

Description

Damping valve device with increasing damping force characteristic curve

Technical Field

The invention relates to a damping valve device with an increasing damping force characteristic curve.

Background

A vibration damper with a damping valve device having an increasing damping force characteristic curve is known from DE 102016210790 a 1. The radial expansion movement of the annular element is used here to form a variable throttle point together with the flow guide surface. With the following effect, the cross section of the throttle point is reduced, the flow velocity of the damping medium in the throttle point is increased, and thus the damping force is increased disproportionately.

In terms of stroke position, the axial velocity of the piston rod is greatest in the intermediate stroke range. In the end position, the force of the vehicle suspension spring has a greater effect in the compression movement and therefore compensates for the excitation force. During the rebound movement, the suspension spring is longer and longer, whereby the spring force is reduced.

On the other hand, when the corresponding excitation is greater in the compression direction or rebound direction, possible damage occurs when the piston rod has an excessively high energy input in its end position.

Push-pull stops are known from the prior art, which exert a reaction force on the piston rod movement mechanically and/or hydraulically. These push-pull stops are designed specifically for damping the piston rod in the end position.

In principle, it is conceivable to combine a travel stop and a damping valve arrangement with an increasing damping force characteristic curve in a vibration damper. However, the problem is that the installation space for the travel limiter is already required for the damping valve device. Furthermore, vibration dampers having travel stops and damper valve arrangements are relatively expensive.

Disclosure of Invention

The object of the present invention is to solve the problems known in the prior art.

This object is achieved in that at least one component which influences the damping force of the throttle point is varied depending on the stroke position of the vibration damper.

With this construction principle, the piston is effectively prevented from hitting the piston rod guide or the bottom valve. Since the throttle point is a component of the damping function which is dependent on the stroke position, the conventional stroke limiter, which may also cause a stroke length loss due to its structural manner, can be dispensed with.

In one embodiment, the effective diameter of the flow guide surface varies depending on the stroke position of the vibration damper. Thereby, the application point of the throttle point is shifted in the direction of the lower activation speed. Furthermore, the achievable damping force level also increases.

A simple way of implementing this design is that the flow guide surface is formed by the inner wall of the cylinder of the vibration damper, wherein the cylinder has a diameter reduction in the region of the end position of the stroke path.

Alternatively, the annular element can be held on a carrier body which has an annular groove for receiving the annular element, wherein the annular groove and the annular element form a pressure chamber which has at least one flow channel which opens into a working chamber of the vibration damper, wherein the flow channel is controlled in terms of its cross section as a function of the stroke position of the vibration damper. In this case, for example, flow channels for supplying damping medium to the annular space depending on the stroke can be added or flow channels for letting damping medium out of the annular space can be reduced in order to increase the pressure level in the annular space, so that the radial expansion movement of the annular element can be increased in terms of speed and expansion degree.

In another embodiment, the spring element controls the flow passage.

That is, the spring element can have a larger closing surface for the flow channel as the pretension increases, for example, in that: the spring element is constituted by an elastomeric spring element or the end coils of a helical spring are radially expanded.

In an embodiment for controlling the switching movement of the flow cross section, it is proposed that the carrier of the annular element is mounted so as to be axially movable within a certain range. Due to this basic function, the spring element can be more or less pretensioned by the carrier and thus actuates the closing surface.

Alternatively, the flow channel may be assigned a bypass, which may depend on the trip switch.

A particularly simple solution is distinguished in that the carrier interacts with an axially movable throttle disk, which forms a throttle cross section with the flow guide surface, depending on the stroke position of the vibration damper. In this solution, particularly simple and low-load components are used, which can optionally be used. A standard component can thus be provided for the throttle point, which standard component can be combined with an axially movable throttle disk.

The throttle point is simple and stable in its structure as a component. These advantages are used in a further embodiment to simply combine the two throttle points in that: the vibration damper with the cylinder and the axially movable piston rod therein has two parts which are movable relative to one another, wherein a first throttle point is arranged in a positionally fixed manner relative to one of the two parts and a second throttle point, which has a reduced throttle cross section as the flow velocity increases, is used depending on the stroke position.

For a significant damping force increase, the second throttle point has a smaller throttle cross section than the first throttle point at the same flow speed.

The application point of the second throttle point is simply determined in the following way: the second throttle point is mounted so as to be axially movable against a stop spring.

The invention shall be explained in detail with the aid of the following description of the figures.

Drawings

In the drawings:

fig. 1 shows a sectional illustration through a vibration damper with a cylinder body of reduced section.

Fig. 2 shows the damping valve device according to fig. 1 with an axially movable throttle disk.

Fig. 3 shows a damping valve device with two speed-dependent throttle points.

Fig. 4 shows a damper valve device with a radially expandable control element.

Fig. 5 shows a damping valve device with a controlled outflow from the pressure chamber of the throttle point.

Fig. 6 shows a damping valve device with a controlled inflow from the pressure chamber of the throttle point.

Detailed Description

Fig. 1 shows a damping valve arrangement 1 for a vibration damper 3 of any design (shown only partially). The damping valve device 1 comprises a first damping valve 5 having a damping valve body embodied as a piston 7, which is fastened on a piston rod 9.

The damping valve body 7 divides the cylinder 11 of the vibration damper into a working chamber on the side of the piston rod and a working chamber 13 far away from the piston rod; 15, both working chambers are filled with a damping medium. In the damping valve body 7, through-channels 17 for the respective throughflow direction; 19 are implemented on different pitch circles. The design of the through-channel is to be regarded as exemplary only. A through channel 17; the outlet side of 19 is at least partially covered by at least one valve disc 21; 23 are covered.

Additionally, the vibration damper has a second damping valve 25 which is fixed directly to the piston rod 9 in space between the piston 7 and the piston rod by means of a positive connection.

The carrier 29 of the second damping valve 25 with the disk-shaped base body 31 has a circumferential annular groove 33 in which an annular element 35 of variable diameter is guided. This annular element 35 is elastic in the radial direction and constitutes a valve body for a throttle point 37 which is part of the damping valve device 1. The annular element 35 forms a throttle point 37 with an inner wall 39 of the cylinder 11, wherein the inner wall 39 forms a flow guide surface.

The ring element carries a stop collar 41 on the outside (for example in the form of a retaining ring). The stop collar 41 may define the maximum expansion movement of the ring element, however also providing a restoring force for the ring element 35. The circumferential annular groove 33 is connected to the piston-rod-side working chamber 13 via a flow channel 43 for the supply of damping medium and a discharge channel 45, so that a hydraulic expansion force acts on the annular element 35. The region of the circumferential annular groove 33 forms a pressure chamber 47 for hydraulic expansion forces radially inside the annular element.

When the piston rod speed is in a first operating range (e.g. less than 2m/s) the throttle point 37 is fully open. The damping force then only acts from the valve disc 21; 23 connected through-channel 17; 19 is produced. In inflow valve disc 21; 23, valve disc 21; 23 from its seating surface 47; 49 are raised. The lifting movement is correspondingly carried out by the support disc 51; 53 limit.

In a second operating range at a piston rod speed greater than the limit speed of the first operating range, i.e. greater than the exemplarily given 2m/s, the ring element 35 is transferred into the throttle position and here performs a closing movement in the direction of the flow guide surface 39. Due to the high flow velocity of the damping medium, a negative pressure is formed in the throttle point 37, which is shaped as an annular gap, which negative pressure causes the annular element 35 to expand radially. The complete blocking of the throttle point is prevented by constructional measures in the following way: for example, the ring element has an outer contour or a stop ring 41 to serve as a stop.

In addition to the dependence of the throttle point 37 on the flow velocity, it is proposed that at least one component influencing the damping force of the throttle point 37 is varied depending on the stroke position of the vibration damper 3. In this embodiment, the effective diameter of the guide surfaces 39 depends on the stroke position of the vibration damper 3 in such a way that: the guide surface 39 is formed by the inner wall of the cylinder of the vibration damper, wherein the cylinder has a diameter reduction 59 in the region 57 of the end position of the stroke path. In principle, the diameter reduction 59 could also be achieved by a reducing sleeve fitted into the cylinder, the wall thickness of which is however relatively small for safe operation. Thus, the risk of damaging the reducing sleeve is relatively high.

In the region of the normal position of the vibration damper 3 (i.e. in the middle stroke position outside the region 57), the throttle point 37 has a wider throttle cross section. The throttle point thus only acts at higher flow speeds and has a more gradual damping force characteristic curve.

When the annular element 35 enters a region with a reduced diameter 59, the throttle cross-section decreases. A greater damping force can be achieved at lower flow velocities.

In the embodiment according to fig. 2, the same hydraulic effect as in fig. 1 is utilized. The difference is that the carrier 29 of the annular element 35 interacts with an axially movable throttle disk 61, which forms with the guide surface 39 an inflow cross section 63 which is reduced compared to the carrier 29 toward the throttle point 37, depending on the stroke position of the vibration damper 3. The throttle disk 61 achieves a higher flow velocity in the region of the radially expandable annular element 35. The throttle disk 61 is pressed against a cover surface 67 of the carrier 29 by a stop spring (which is axially supported, for example, on the piston rod guide 27). For this purpose, only a small pretensioning force is required. In the further extension movement, the throttle disk 61 and the carrier 29 move synchronously. During the retraction movement of the piston rod, i.e. when the stop spring 65 is released again, the throttle disk lifts its effective region at the end from the cover surface 67 and the second damping valve 25 again follows a speed-dependent damping force characteristic curve with a more gentle slope. The realization of the defined stroke position 57 thus corresponds to a switching function which causes the second damping valve to adjust between the two damping force characteristic curves.

In the embodiment according to fig. 3, the vibration damper 3 with the cylinder 11 and the piston rod 9 axially movable therein has two parts movable relative to one another, wherein the first throttle point 37 is arranged in a positionally fixed manner relative to one of the two parts (i.e. the piston rod 9) and, depending on the stroke position, uses a second throttle point 69, the throttle cross section of which is reduced as the flow speed increases. The vibration damper 3 has two carriers 29; 71 and two radially expandable annular elements 35; 73. the second throttle point is identical in construction to the first throttle point 37. The second carrier 71 with the second throttle point 39 is mounted axially movably on a stop spring 65, which is in turn supported on the piston rod guide 27. Once the first carrier 29 abuts the second carrier 71, the two throttle points 37; 69 are added. Preferably, the second throttle point 69 has a smaller throttle cross section than the first throttle point 37 at the same flow velocity, so that the damping force is significantly increased. As also shown in fig. 3, the action of the second throttle point 69 is stopped when the carrier 29 is no longer in contact with the second carrier 71 during the retraction movement of the piston rod 9.

In the variant according to fig. 4, the annular element 35 of the second damping valve 25 is held on a carrier 29, the surrounding annular groove 33 of which forms with the annular element 35 a pressure chamber 47 having at least one flow channel 43 facing the working chamber 15 of the vibration damper 3. The velocity dependent expanding motion of the annular element may be assisted by pressure against the inner surface 75 of the annular element 35. For this purpose, the pressure chamber 47 has a flow channel 45 for the damping medium flowing in from the damping medium volume between the piston rod guide 27 and the carrier 29. The outflow channel 45 allows the control volume to flow out of the pressure chamber 47. The volume flow through the pressure chamber 47 is controlled in a targeted manner by: the flow channel or outflow channel, in this case the outflow channel 45, has its cross section controlled depending on the stroke position of the vibration damper 3.

The spring element 79 supported on the support ring 77 serves as a control element for the outflow channel 45, and the outer sealing diameter of the spring element 79 serves as a control parameter. It is used here that the spring element 79 has a larger closing surface for the outflow channel 45 as the pretensioning force increases. The spring element 79 is made of an elastomer.

The pretensioning movement of the spring element 79 is based on the fact that: the carrier 29 of the annular element 35 is supported within a certain range so as to be axially movable relative to the spring element 79. The securing ring 81 defines an initial position of the carrier 29 and thus an initial diameter of the spring element 79, which may radially overlap the outflow channel 45. Starting from the defined travel position 57, the stop spring 65 takes care of the axial compression movement of the elastomer body between the piston rod guide 27 and the carrier 29, which elastomer body then partially closes the outflow channel 45. The ratio of inflow and outflow from the pressure chamber 47 thus changes as follows: the pressure level in the pressure chamber 47 increases all the time and thus an increasingly greater radial expansion force is exerted on the annular element.

In fig. 5, the second damping valve 25 has the operating principle of fig. 4. The difference is that the lift spring 83 and the throttle disk assume the function of an elastomer in fig. 4, and the support ring 77 assumes the function of an elastomer as a stationary throttle disk. In this case, too, the outflow channel 45 is controlled by the relative movement of the carrier 29 with respect to a support ring 77 fastened to the piston rod 9.

Fig. 6 shows that, in the second damping valve 25, it is also possible to vary the effective cross section of the flow duct 43 in the direction of the inflow into the pressure chamber 47. To this end, the flow channel 43 is assigned a bypass 85, which may be dependent on the stroke switch. The bypass 85 leads from the working chamber 13 likewise into the pressure chamber 47. An isolated first disc spring 87 is arranged between the cover surface 67 of the carrier 29 and the clamping disc 89. This first disk spring 87 has a sealing edge on the inner and outer diameter, respectively, facing the cover surface 65 and facing the clamping disk 89. The cup spring bears on a segment-shaped, annular, inclined edge 91.

The second disk spring 93 is supported radially on the inside of the pitch circle on which the inflow opening of the bypass channel 85 is arranged and likewise seals with its outer diameter and its inner diameter against the clamping disk 89 and the cover surface 67 of the carrier 29. Thus, the two disc springs 87; 93 and the clamping disk 89 delimit an annular space 95. When starting from the defined travel position 57, the clamping disk 89 comes into contact with the stop spring 65, and then, in the further movement of the piston rod, the two disk springs 87; 93 and at least the first disc spring 87 performs a tilting movement by means of the tilting edge 91, thereby releasing the inflow opening into the annular space and thus into the bypass 85. Thereby, the ratio of the volume flow into the pressure chamber 47 to the outflow cross section of the outflow channel 45 is greatly increased, which achieves a maximum expansion force acting on the ring element 35.

List of reference numerals

1 damping valve device

3 vibration damper

5 damping valve

7 damping valve body

9 piston rod

11 cylinder body

13 working chamber on the piston rod side

15 working chamber far away from piston rod

17 through passage

19 through passage

21 valve disk

23 valve disk

25 second damping valve

27 piston rod guide

29 vector

31 disc-shaped base body

33 annular groove

35 annular element

37 throttle point

39 flow guide surface

41 stop collar

43 flow channel

45 outflow channel

47 pressure chamber

49 seat surface

51 seat surface

53 support disc

55 support disc

57 area of terminal position

59 reduced diameter section

61 throttle disc

63 inflow cross section

65 stop spring

67 cover

69 second throttle point

71 second carrier

73 second annular element

75 surface of

77 support ring

79 spring element

81 fixed ring

83 lifting spring

85 bypass

87 first disc spring

89 clamping disc

91 inclined edge

93 second Belleville spring

95 annular space

97

99

101

103

105

107

109

111

113

115

117

119

Claims

1. A vibration damper (3) having a damping valve device (1), comprising a throttle point (37) connected to a valve body (35) which, depending on the flow velocity in the throttle point (37), is moved from a flow-through position into a throttle position, wherein the valve body (35) is moved in a closing direction as the flow velocity of the damping medium increases, in such a way that: the valve body (35) is designed as an annular element with a variable diameter, which performs a radial closing movement in the direction of the flow guide surface (39), wherein a defined minimum flow cross section is maintained, characterized in that at least one component influencing the damping force of the throttle point (37) is varied depending on the stroke position of the vibration damper (3).

2. The vibration damper according to claim 1, characterized in that the effective diameter (59) of the flow guide surface (39) varies depending on the stroke position of the vibration damper (3).

3. The vibration damper according to claim 2, characterized in that the flow guide surface (39) is constituted by an inner wall of a cylinder (11) of the vibration damper (3), wherein the cylinder (11) has a diameter reduction (59) in the area of the end position (57) of the stroke path.

4. The vibration damper according to claim 1, characterized in that the ring element is held on a carrier (29) having a ring groove (33) for accommodating the ring element (35), wherein the ring groove (33) and the ring element (35) form a pressure chamber (47) having at least one flow channel (43; 45) leading to a working chamber (13) of the vibration damper, wherein the flow channel (43; 45) is controlled in terms of its cross section depending on the stroke position of the vibration damper (3).

5. The vibration damper according to claim 4, characterized in that a spring element (79; 87; 93) operates the flow channel (43; 45).

6. The vibration damper according to claim 5, characterized in that the spring element (79) has an enlarged closing surface for the flow channel (45) with increasing pretension.

7. The vibration damper according to claim 5, characterized in that the carrier (29) of the ring element (35) is supported axially movable within a certain range.

8. The vibration damper according to claim 5, characterized in that the flow channel (43) is assigned a bypass (85), which can be switched depending on the stroke.

9. The vibration damper according to claim 1, characterized in that the carrier (29) of the annular element (35) cooperates with an axially movable throttle disk (61) which, depending on the stroke position of the vibration damper (3), forms an inflow cross section (63) with the guide surface (39).

10. The vibration damper according to claim 1, characterized in that the vibration damper (3) is provided with a cylinder (11) and a piston rod (9) axially movable therein, the vibration damper (3) having two parts movable relative to each other, wherein a first throttle point (37) is arranged fixed in position relative to one of the two parts (9) and a second throttle point (69) with a reduced throttle cross section is used as the flow velocity increases depending on the stroke position.

11. The vibration damper according to claim 10, characterized in that the second throttle point (69) has a smaller throttle cross section than the first throttle point (37) at the same flow velocity.

12. The vibration damper according to claim 10, characterized in that the second throttle point (69) is axially movably supported against a stop spring (65).