WO2015135706A1

WO2015135706A1 - Vibration damper comprising a bypass opening that is variable according to the temperature

Info

Publication number: WO2015135706A1
Application number: PCT/EP2015/052582
Authority: WO
Inventors: Thomas Nowotka; Georg Memmel
Original assignee: Zf Friedrichshafen Ag
Priority date: 2014-03-14
Filing date: 2015-02-09
Publication date: 2015-09-17
Also published as: DE102014204739A1

Abstract

Disclosed is a vibration damper (1) comprising a cylinder (3) inside which a piston rod (5) is guided along with a piston (7) in a piston rod guide (9). A working chamber (15) of the cylinder (3) and a compensation chamber (19) are connected via a bypass duct (23, 25, 57, 59, 61, 63) which is controlled by a temperature-responsive valve (21, 21') located inside the piston rod guide (9). The temperature-responsive valve (21, 21') is designed as a spool valve, the valve body (35, 37) of which is affected by at least one valve spring (39, 41), the actuation force of which follows a temperature function.

Description

Vibration damper with a temperature-dependent bypass opening

The invention relates to a vibration damper according to the preamble of patent claim 1.

From DE 31 31 262 A1 discloses a vibration damper in a two-pipe design with a temperature compensation is known, which is achieved in that a bypass opening between a piston rod side working space and a compensation chamber is controlled by a slotted valve ring. When heating the valve preferably made of plastic valve ring expands, thereby reducing the slot width, which defines a throttle cross-section.

DE 36 05 207 A1 describes a structurally similar vibration damper. Notwithstanding, a bimetallic disc is used instead of a plastic ring, which functionally represents a valve disc. The bimetallic disc and the bypass opening form a seat valve which is more or less open depending on the temperature within the vibration damper. A serious disadvantage of this design is that the pressure in the working space exerts a closing force on the seat valve, ie the bimetallic disc must generate a Abhubkraft against the working pressure.

The object of the present invention is to achieve a vibration damper with a temperature compensation, in which the problems known from the prior art are eliminated.

The object is achieved in that the temperarturabhängige valve is designed as a slide valve whose valve body is acted upon by at least one valve spring, the actuation force of a temperature function follows.

The slide valve has the great advantage that a working pressure within the working space has no influence on the operating behavior of the valve. Consequently, valve springs with a comparatively low operating force can also be used. If, according to an advantageous subclaim, a plurality of temperature-dependent valves having different temperature setting ranges are used, then the damping behavior of the vibration damper can be adapted particularly well to a predetermined operating behavior.

In one embodiment, the bypass channel is designed as an axial channel and the valve body is guided in a transverse channel to the bypass channel. The transverse channel can be designed radially to the piston rod but also in the circumferential direction to the piston rod.

In order to meet the performance of the spring with temperature-dependent spring force more accurately, this is associated with a return spring. Both springs form a spring balance, which acts on the valve body.

In order to make better use of the space in the piston rod guide, the at least one spring, which acts on the valve body, an arc shape.

In one embodiment, the bypass channel is designed as an axial channel and the valve body is guided parallel to the longitudinal axis of the piston rod. This design principle can be realized even with small installation spaces in the piston rod guide.

In a further design it is provided that the bypass channel is designed as an axial channel and the valve body is guided obliquely to the piston rod. Also piston rod guides with larger difference between outer tube diameter and cylinder diameter then still provide enough space for the bypass channel.

In a further advantageous embodiment, a cover closes the transverse channel in the direction of the working space at least partially. The comparatively small valve components are reliably protected, so that the use of an additional spring, which is supported axially on the piston rod guide, is simplified in the piston rod-side working space.

In particular, when several valves are used, it is advantageous if the valve body has a marking for determining the installation position. A preferred embodiment is characterized in that the marking is designed as a positive locking element. The form-fitting element can, for. B. are used in a mounting device very easy for a location-appropriate mounting by the correct mounting position is automatically secured when accessing the interlocking element.

In a further advantageous embodiment, the positive-locking element can form a sliding guide with a piston-rod guide-side region. If this sliding is not possible, then there is obviously a wrong assembly.

With regard to a standardized piston rod guide, the bypass channel has at least one throttle insert.

The invention will be explained in more detail with reference to the following description of the figures.

It shows:

Fig. 1 vibration damper in longitudinal section

2 partial section of Fig. 2nd

Fig. 3 - 6 piston rod guide in different views

Fig. 7 - 9 piston rod guide with different valve positions

Fig. 10 - 13 alternative variant to Fig. 3-9

1 shows a vibration damper 1 in two-pipe design. In a cylinder 3, a piston rod 5 is mounted axially movable together with a piston 7. A piston rod guide 9 guides the piston rod 5 and thereby closes the cylinder 3 and an outer tube 11 surrounding the cylinder. The cylinder is axially supported on a bottom 13 of the outer tube 1 1, wherein between the cylinder 3 and the bottom 13, a bottom valve, not shown, is arranged.

The piston 7 divides the cylinder 3 in a piston rod side and a piston rod remote working space 15; 17, both of which are completely filled with a damping medium. are filled. In the piston 7 known per se directionally effective throttle valves are executed, via which the two working spaces 15; 17 are connectable. The outer tube 1 1 and the cylinder 3 define an annular space which is partially filled with damping medium and forms a compensation chamber 19 for the displaced by the piston rod 5 damping medium.

2, a valve 21 in the piston rod guide 9 can be seen, which controls a bypass channel between the piston rod-side working chamber 15 to the compensation chamber 19 as a function of temperature to the damping valves in the piston.

FIG. 3 shows an exploded view of the piston rod guide 9 according to FIGS. 1 and 2. The piston rod guide 9 has two axial channels 23 in this variant; 25, which connect the two sides of the piston rod guide 9. Two based on the axial channels 23; 25 as transverse channels 27; 29 executed recordings contain a throttle insert 31 with a throttle opening 33. The transverse channel connects to the end of the axial channel in the direction of the piston rod side working space 15 at. This throttle opening 33 determines the damping force that can be generated via the damping medium flowing through the bypass channel. The throttle insert 31 is a separate to the piston rod guide 9 component, which is interchangeable.

A valve body 35; 37 is designed as a slide which in the transverse channel 27; 29 a sliding movement against the force of at least one spring 39; 41 can perform whose actuation force follows a temperature function, preferably a spring made of shape memory material. A return spring 43; 45 acts on the spring 39; 41 with temperature-dependent spring force. The valve body 35; 37 has guide pins for the springs. Furthermore, a mark in the design of a form-locking element 47; 49 recognizable. An annular lid 51 closes the at least one transverse channel 27; 29, so that the components of the valves 21 can not fall out of the piston rod guide 9. The lid 51 has edge-side cutouts 53 which are connected to the positive-locking element 47; 49 of the valve body 35; 37 form a sliding guide, about which also the correct fit of the valve body 35; 37 is controllable. In the present embodiment, the at least one transverse channel 27; 29 a straight design for straight springs on. In the case of particularly small installation spaces or high actuating forces, the transverse channel can also have a curved shape in the circumferential direction relative to the piston rod, and the springs 39-45 can then also be bent.

FIGS. 7 to 9 show a plan view of the piston rod guide 9 without cover 51. The two valves 21; 21 ^' are constructed point-symmetrical to the central axis of the piston rod guide 9. In a defined temperature range, both valves 21; 21 ^' open (Fig. 7), z. At low temperatures to compensate for the higher viscosity of the damping medium. A closing movement takes place in a clockwise direction.

In a middle temperature range, Fig. 8, for example, the valve 21 ^'is open and the second valve 21 is closed. By a suitable selection of the springs 39; 41 and the return spring 43; 45, the resulting operating force and thus the operating position of the valve body 35; 37 are determined.

In Fig. 9 take both valves 21; 21 ^' a closed position to z. B. at particularly high temperatures to compensate for the low viscosity of the damping medium.

The group of figures of FIGS. 10 to 13 describes a variant embodiment with the same functional principle as the concept according to FIGS. 1-9. Deviating from this is the bypass channel as an axial channel 23; 25 executed and the valve body 35; 37 is guided in an axial channel parallel to the piston rod 5. The axial channel 23; 25 connects the piston rod side working chamber 15 with a radial channel. In the second radially offset axial passage 57; 59 is the valve 21; 2Γ arranged, which performs an operating movement on an axis parallel to the longitudinal axis of the piston rod guide. This staggered arrangement of the valve 21; 21 ^' to the axial channel 23; 25 simplifies the use of longer valve springs.

The second axial channel 57; 59 is like the first axial channel 23; 25 also executed as a blind hole. The valve body 33; 35 includes a circumferential collar 65. The peripheral collar 65 forms with the radial channel 61; 63 the valve 21; 21 ^' . Held the valve components of a clamping ring 67 which is pressed end in the second axial channels.

Also in this variant, two valves 21; 21 ^' are used, which are set to different temperature ranges. As can be seen from FIG. 10, the valve 21 assumes a blocking position and the valve 21 ^' is opened so that damping medium can flow out of the piston rod-side working space 15 into the compensation chamber 19.

The piston rods 9 in the embodiment according to FIG. 14 essentially correspond to the variant according to FIGS. 10 to 13. Deviating from these are the bypass channels 57; 59 running obliquely to the piston rod 5. For the collar 65 having the largest diameter on the valve body 35; 37 represents more space. Also, an upper edge region of the piston rod guide compared to the embodiment of FIG. 10 have a greater wall thickness. Another difference to the construction of FIG. 10 is that the axial channels 57; 59 is formed by a multi-stepped passage opening and not by a blind hole opening. A passage opening can be produced more easily, in particular by cleaning chips. It is not shown, but you could also the axial channels 23; Run 25 obliquely to the piston rod 5, but so that the center lines of the axial channels 23 and 57 or 25 and 59 intersect. Then one could at the transverse channels 61; 63 to dispense with the sections between the respective Axialkanalpaaren so that, if necessary, a simplification of the construction would be achieved.

In a vibration damper in Zweirohrausführung the piston rod-side working space 15 must be filled at a retraction movement of the piston rod into the cylinder with damping medium. For this purpose, the piston is equipped with a non-return valve which opens in the retraction direction. The damping force is generated by the bottom valve, which throttles the displaced by the piston rod 5 Dämpfmediumvolumen. The valve 21; 21 ^' within the piston rod guide 9 is therefore connected hydraulically in parallel to the bottom valve. Depending on the configuration z. B. at low temperatures both valves 21; 21 ^' in the piston rod guide to compensate for the high viscosity of the damping medium. In a normal temperature range is perhaps only one valve 21 is opened and the second valve 21 ^'is closed and in a high temperature region both valves 21; 21 ^' closed in the piston rod guide.

In a piston rod extension movement, the damping medium is displaced directly through the valve 21, 21 ^' in the piston rod guide. The damping valve in the piston 7 is then also connected in parallel hydraulically to this valve. A portion of the damping medium flows through the valve 21, 21 ^' within the piston rod guide and a volume fraction may flow through the damping valve in the piston.

The valve 21; 21 ^' within the piston rod guide is thus used for both piston rod movement directions.

REFERENCE CHARACTERS

Vibration damper 63 Radial channel

Cylinder 65 fret

Piston rod 67 Clamping ring Piston

Piston rod guide

outer tube

ground

piston rod side working space

Kolbenstangenferner workspace

compensation space

temperature-dependent valve

axial

Axi alkanal

Querkanal

throttle insert

throttle opening

valve body

feather

Return spring

Form-fitting element

cover

Clear cut

Center axis of the piston rod guide

axial

radial channel

Claims

claims

1 . Vibration damper (1) comprising a cylinder (3) in which a piston rod (5) together with a piston (7) in a piston rod guide (9) is guided, wherein a working space (15) of the cylinder (3) and a compensation space (19 ) are connected via a bypass channel (23; 25; 57; 59; 61; 63) controlled by a temperature-dependent valve (21; 21 ^' ) arranged inside the piston rod guide (9), characterized in that the temperature-dependent Valve (21, 21 ^' ) is designed as a slide valve whose valve body (35, 37) is acted on by at least one spring (39, 41) whose actuating force is followed by a temperature function.

2. Vibration damper according to claim 1, characterized in that a plurality of temperature-dependent valves (21, 21 ^' ) are used with different temperature control ranges.

3. Vibration damper according to claims 1 or 2, characterized in that the bypass channel as an axial channel (23; 25) is executed and the valve body (35; 37) in a transverse channel (27; 29) is guided to the bypass channel.

4. Vibration damper according to at least one of claims 1 to 3, characterized in that the spring (39; 41) with a temperature-dependent spring force is associated with a return spring (43; 45).

5. Vibration damper according to at least one of claims 1 to 4, characterized in that the at least one spring (39-45), which acts on the valve body (35, 37), has an arcuate shape.

6. Vibration damper according to at least one of claims 1 to 4, characterized in that the bypass channel as an axial channel (23; 25) is executed and the valve body (35; 37) is guided parallel to the piston rod (5).

7. Vibration damper according to at least one of claims 1 to 4, characterized in that the bypass channel is designed as an axial channel (57; 59) and the valve body (35; 37) is guided obliquely to the piston rod (5).

8. Vibration damper according to one of claims 1-6, characterized in that a cover (51) at least partially closes the transverse channel (27, 29) in the direction of the working space (15).

9. Vibration damper according to one of claims 1-7, characterized in that the valve body (35, 37) for determining the installation position has a mark (47, 49).

10. Vibration damper according to claim 9, characterized in that the marking is designed as a form-fitting element (47, 49).

1 1. Vibration damper according to claim 9, characterized in that the positive-locking element (47; 49) forms a sliding guide with a piston rod guide-side region (51).

12. Vibration damper according to one of claims 1 - 1 1, characterized in that the bypass channel has at least one throttle insert (31).