Vibration damper for vehicle spring systems

• US 4,084,667 A
• Filed: 11/23/1976
• Issued: 04/18/1978
• Est. Priority Date: 05/26/1973
• Status: Expired due to Term

• Current Assignee: Daimler-Benz AG (Mercedes-Benz Group AG)
• Original Assignee: Daimler-Benz AG (Mercedes-Benz Group AG)
• Inventors: Kurrat, Klaus
• Primary Examiner(s): Blix, Trygve M.
• Assistant Examiner(s): Kazenske, Edward R.
• Application Number:
  US05/744,453
• Time in Patent Office: 511 Days
• Field of Search: 188/275, 188/279, 188/280, 188/282, 188/285, 188/299, 188/316, 188/317, 188/319, 188/320, 188/322, 267/64 R, 267/65 R, 267/65 D, 267/DIG. 1, 280/714
• US Class Current: 188/275
• CPC Class Codes: B60G 17/08 Characteristics of fluid dampers adjusting fluid dampers in general F16F9/44 - F16F9/53
• CPC Class Codes: F16F 9/512 Means responsive to load action, i.e. static load on the damper or dynamic fluid pressure changes in the damper, e.g. due to changes in velocity F16F9/504, F16F9/516 take precedence; non-automatic damper adjustment from a distance using servo control, the servo pressure being created by the flow of damping fluid F16F9/465; self-pumping fluid springs in vehicle suspensions B60G17/044

Abstract

A vibration damper with a hydraulic damping mechanism for vehicle spring systems, in which damping valves operating by throttling the pressure medium displaced out of one working space into the other working space are interconnected between two working spaces of the hydraulic pressure medium; the two working spaces are short circuited by a by-pass connection by-passing the damping valves whereby a by-pass valve is also interconnected into the by-pass connection which operates as a function of oscillation velocity and whose valve adjusting member adjusts the by-pass connection to a narrower cross section with rising oscillation velocities.

Claims

1. A vibration damper comprising:

cylinder means,

piston means movably disposed in said cylinder means with a first fluid working space at one side of said piston means and a second fluid working space at the other side of said piston means,

first damping valve means for permitting passage of fluid medium from said first space to said second space in response to a predetermined increase of pressure in said first space upon movement of said piston means in a direction toward said first space,

second damping valve means for permitting passage of fluid medium from said second space to said first space in response to a predetermined increase of pressure in said first space upon movement of said piston means in a direction toward said second space,

bypass connection means for accommodating passage of fluid medium between said first and second spaces in bypassing relationship to said first and second damping valve means,

and bypass valve means for continuously and automatically controlling the flow cross-section of said bypass connection means in dependence on at least one influencing magnitude during both directions of flow of said fluid medium between said first and second space, such that during an increase in said influencing magnitude the flow cross-section of said bypass connection means is reduced and the temporal quantity of said fluid medium directly passing through said first and second damping valve means without throttling is simultaneously increased, each of said first and second damping valve means and said bypass valve means operating independently relative to one another,

wherein one of said cylinder means and piston means includes means for attaching itself to a vehicle superstructure and the other of said cylinder means and piston means includes means for attaching itself to a vehicle wheel, and

wherein said bypass valve means includes a movable adjusting stepped piston having three stepped piston sections of different diameters, said stepped piston being slidably mounted in an axial bore of said piston means, and wherein a closure member closes one end of said axial bore.

2. A vibration damper according to claim 1, wherein a spring means is interposed between the closure member and the stepped piston to spring load the stepped piston with respect to the closure member, said closure member being fixedly held in the piston means.

3. A vibration damper according to claim 2, wherein the piston means includes a piston member slidable along said cylinder means and a piston rod supporting the piston member, and wherein aperture means are provided in the piston rod, said piston member being provided with overflow channel means valved by the damping valve means.

4. A vibration damper according to claim 3, wherein the overflow channel means extend essentially in the axial direction and wherein bore means are provided which intersect the overflow channel means and are in communication with the aperture means.

5. A vibration damper according to claim 4, wherein the bore means extend substantially at right angle to the overflow channel means and generally in a radial direction of the piston member.

6. A vibration damper according to claim 5, wherein said stepped piston includes control surfaces to directly control the opening of said aperture means in dependence on the axial position of said stepped piston in said piston rod.

7. A vibration damper comprising:

cylinder means,

piston means movably disposed in said cylinder means with a first fluid working space at one side of said piston means and a second fluid working space at the other side of said piston means,

first damping valve means for permitting passage of fluid medium from said first space to said second space in response to a predetermined increase of pressure in said first space upon movement of said piston means in a direction toward said first space,

second damping valve means for permitting passage of fluid medium from said second space to said first space in response to a predetermined increase of pressure in said first space upon movement of said piston means in a direction toward said second space,

bypass connection means for accommodating passage of fluid medium between said first and second spaces in bypassing relationship to said first and second damping valve means,

and bypass valve means for continuously and automatically controlling the flow cross-section of said bypass connection means in dependence on at least one influencing magnitude during both directions of flow of said fluid medium between said first and second space, such that during an increase in said influencing magnitude the flow cross-section of said bypass connection means is reduced and the temporal quantity of said fluid medium directly passing through said first and second damping valve means without throttling is simultaneously increased, each of said first and second damping valve means and said bypass valve means operating independently relative to one another,

wherein one of said cylinder means and piston means includes means for attaching itself to a vehicle superstructure and the other of said cylinder means and piston means includes means for attaching itself to a vehicle wheel,

wherein said bypass valve means includes a movable adjusting piston means which controls the cross-section of said bypass connection means, said adjusting piston means including first pressure surface means continuously acted upon by the pressure of the fluid medium in one of said spaces such that said adjusting piston means is continuously forced in a first direction by said pressure in said one of said spaces,

wherein said adjusting piston means includes second pressure surface means continuously acted upon by the pressure of the fluid medium in the other of said spaces such that said adjusting piston means is continuously forced in said first direction by said pressure in said other of said spaces,

wherein a static vehicle load acts on said vibration damper, and wherein said adjusting piston means is provided with a piston pressure surface adapted to be acted upon by a pressure dependent on the static vehicle load and with a further piston pressure surface adapted to be acted upon by a lower pressure and operable in the opposite direction, and

wherein said adjusting piston means is a stepped piston having three stepped piston sections of different diameters adapted to valve aperture means forming part of said bypass connection means, and characterized in that a closure member closes one end of a space in a piston rod of said piston means which accommodates said stepped piston.

8. A vibration damper according to claim 7, wherein a spring means is interposed between the closure member and the stepped piston to spring load the latter with respect to the former which is fixedly held in the piston assembly.

9. A vibration damper according to claim 8, wherein said aperture means are provided in said piston rod supporting thereon a piston member of said piston means, said piston member being provided with overflow channel means valved by said damping valve means.

10. A vibration damper according to claim 9, wherein the overflow channel means extend essentially in an axial direction of the piston member and wherein bore means are provided which intersect the overflow channel means and are in communication with the aperture means.

11. A vibration damper according to claim 10, wherein the bore means extend substantially at right angle to the overflow channel means and generally in a radial direction of the piston member.

12. A vibration damper comprising:

cylinder means,

piston means movably disposed in said cylinder means with a first fluid working space at one side of said piston means and a second fluid working space at the other side of said piston means,

first damping valve means for permitting passage of fluid medium from said first space to said second space in response to a predetermined increase of pressure in said first space upon movement of said piston means in a direction toward said first space,

second damping valve means for permitting passage of fluid medium from said second space to said first space in response to a predetermined increase of pressure in said first space upon movement of said piston means in a direction toward said second space,

bypass connection means for accommodating passage of fluid medium between said first and second spaces in bypassing relationship to said first and second damping valve means,

and bypass valve means for continuously and automatically controlling the flow cross-section of said bypass connection means in dependence on at least one influencing magnitude during operational use of said damper with said piston and cylinder moving relative to one another,

wherein said bypass valve means includes a movable adjusting piston means which directly controls the cross-section of said bypass connection means, said adjusting piston means being a stepped piston having three stepped piston sections of different diameters and having respective first through fourth separate pressure surfaces, said first pressure surface being acted on by a pressure indicative of vehicle static load, said second and third pressure surfaces being acted on by pressures in said respective working spaces, said fourth pressure surface being acted on by atmospheric pressure, and

wherein a bore extends axially in said adjusting piston means for communicating said atmospheric pressure with said fourth pressure surface.