Pneumatic motor vehicle seat with stabilized static height

Details Pneumatic motor vehicle seat with stabilized static height Pneumatic motor vehicle seat with stabilized static height

2001-09-21

2003-09-09

Ramirez, Ramon O. (Department: 3632)

Supports

Resilient support

Including additional energy absorbing means, e.g., fluid or...

C248S421000, C248S562000, C248S588000, C248S631000

Reexamination Certificate

active

06616116

ABSTRACT:

BACKGROUND OF THE INVENTION
The invention relates to a motor vehicle seat supported so as to be able to vibrate by means of a mechanical vibration system and a pneumatic spring having the characteristic features of the preamble of claim 1 for holding the static height of the motor vehicle seat constant independently of the weight of the respective seat occupant.
Motor vehicle seats of this type are known from DE 27 53 105 C2 filed by the applicant. They operate with a control cam whose end-side trigger cams mount the valve plunger of an aerating valve dependent on the vibration travel when the vibration travel of the vibration system exceeds a level deemed acceptable above or below the motor vehicle seat's static height to be held constant. The air pressure in the pneumatic spring decreases or increases accordingly. When the respective vibration travel reverses its motion and shortly before reaching the static height to be held constant the respective open valve is closed again in that the trigger cam of the control cam is pulled down again from the valve plunger by the trigger cam.
In order to achieve such varying distances between the vibration travel switch positions and the constant static height when opening and closing the valves,the motor vehicle seat known in the art operates with a so-called trailing control cam, where a driving pin mounted on a rod of the scissors-type rod vibration system first has to pass a certain trailing distance in a trailing distance recess of the control cam after the respective vibration has reversed its motion until it stops at the end of the trailing distance recess and is able to pull down the trigger cam of the control cam from the valve plunger of the valve.
The invention is based on the above state of the art. One objective of this invention is to reduce the problems of noise and wear related to this kind of trailing control system.
Also, previously the seats always had the disadvantage that the seats were able to freely vibrate upward from the respectively set static height up to the limit stop. This means that the upper part of the seat, including the driver, is able to vibrate up to said upper limit stop, for example when the driver gets up. With a height adjustment range of 100 mm, for example, and a vibration travel of +/−40 mm, for example, this could mean an upward vibration of up to 140 mm in the lowest height adjustment position. One potential consequence is that the driver is hampered when he exits the vehicle.
Therefore, another objective of the invention is to provide a motor vehicle seat in which the maximum vibration is adjustable so as to prevent the above disadvantages.
Noise problems in the known trailing control systems are primarily caused by the driving pin mounted on the vibration system striking the ends of the trailing distance recess of the control cam and also by the trigger cams of the control cam striking the plunger of the valves before they are able to mount said valve plungers. Said striking noises intensify as the trailing control cam gets dirtier and thus moves more sluggishly.
The problems of wear in the known trailing control cams are primarily related to the trigger cams of the control cam and the valve plungers of the valves and have increased in recent years because the on-board compressed air systems of the motor vehicles which also supply compressed air to the pneumatic spring of the motor vehicle seat increasingly operate at a higher pressure level.
SUMMARY OF THE INVENTION
To solve the problem of reducing noise and wear in trailing control systems it is proposed in accordance with the invention to omit in a motor vehicle seat operating according to the method of DE 27 53 105 C2 for holding the static height constant the above mechanical trailing control cam with said valves and instead using valves and a control system which are characterized in that the valves each have a stopping device (for example in the form of a cylinder piston, a ball, or the like), which lifts off of its valve seat for opening the valve against the force of a closing spring, where the stopping device consists of a ferromagnetic material and is disposed in a plastic valve housing and where the control system for opening the valves consists of a control lever or a control carriage with a permanent magnet that approaches the stopping device of the aerating valve non-contacting dependent on the vibration travel in such a way that the respective stopping device in the open valve position has a distance from the permanent magnet which is shorter, yet non-contacting, by the lifting motion of the stopping device from its valve seat.
The inventive solution offers considerable advantages.
For one, by using a permanent magnet positioned in a pivoting control lever or a shifting control carriage the stopping device of an aerating valve or a deaerating valve can be actuated without requiring any mechanical contact between said components for this purpose.
Thus, the problem of wear between said components is prevented. The proposal of installing a permanent magnet in the control lever or control carriage suggests itself because no power supply lines have to be installed in the moving parts as would be the case if a similarly acting magnetic field were to be provided by means of current-carrying electrical conductors, which is also feasible, in principle.
The strength of the magnetic field is not affected by a valve housing, which, according to the theory of the invention, consists of plastic, but it is affected by the ferromagnetic material of which the stopping devices of the valves have to be made. Said materials provide a considerable field-strengthening effect for the magnetic field. The magnetic field acts as a pulling force both on the opposite pole surfaces of the permanent magnet and on the respective stopping device, which force also depends, among others, on the distance between the permanent magnet and the stopping device.
The above physical facts are employed by the theory of the invention in that in the open valve position the respective stopping device has a distance from the permanent magnet which is shorter by the lifting motion of the stopping device from its valve seat. Then the magnetic attractive powers are higher with the result that the valve will be held longer in its open position when the control lever or control carriage with the permanent magnet is moved away from the stopping device of the valve dependent on the vibration travel. In other words, the point in time of closing the valve “trails” relative to the motion of the permanent magnet which is controlled by the vibration travel similar to the state of the art with the mechanical trailing control cam, but having the very substantial advantage that said trailing process in accordance with the theory of the invention is now non-contacting and thus results in less wear and less noise.
An especially suitable practical embodiment of the invention is proposed which is characterized in that both valves (aerating valve and deaerating valve) are housed in a common plastic valve housing (as is basically known in the art) and that they are oriented relative to each other such that their respective stopping devices perform lifting motions off of their respective valve seats which are parallel and oriented in the same direction. The common plastic valve housing is intended to largely hermetically seal the valve parts against external effects, pollution and the like, and the permanent magnet should be mounted on a pivoted lever which is disposed so as to pivot on an external wall surface of the valve housing and, in dependence of the vibration travel, causes the permanent magnet on the external wall surface of the valve housing and transversely to the lifting motions of the stopping devices to approach the respective stopping devices such that in the final stage of approaching the pole surface of the permanent magnet is plane-parallel opposite and at a distance of the preferably plane bottom area of the stopping device.
With the inventive solution of

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