Ventilation of an Operating Element

- ZF FRIEDRICHSHAFEN AG

A method of actuating a piston having a first side and a second side includes the steps of generating a counter-ventilation pulse having a duration and amplitude defined to achieve a predetermined operating speed of the piston and a predetermined damping of a final position of a piston, applying an actuating pressure to the first side of the piston, and venting a second side of the piston in a defined manner using the counter-ventilation pulse so as to prevent a buildup of a maximum possible ventilation pressure.

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Description

The present invention relates to a method to reduce the mechanical load and to increase the operating speed during the actuation of an operating piston, especially the operating piston of an operating element, according to the generic part of claim 1.

According to the state of the art, the operating elements are first pressurized on the opposite side until their actuation. As soon as the pressure for the desired movement has been applied, the opposite side is vented, a process in which the final stop is damped by the air cushion and by the dynamic pressure created by the movement, thus reducing the mechanical load. Various devices for implementing this concept are known in the state of the art.

German patent specification DE 197 02 948 C2 describes a valve arrangement comprising a main valve with a feed channel that can be connected to a pressure source and with a work channel that can be connected to a consumer, and comprising a movable valve member that regulates the fluid connection between the feed channel and the work channel, whereby a charging surface that can be charged with a fluid pilot medium that is at an actuating pressure for moving the valve member is associated with the valve member, whereby said medium can be fed via a pilot channel that is supplied by a pressure source and that is regulated by a pilot valve.

Here, the pilot channel has a pressure regulator that serves to specify the actuating pressure, and a counter-charging surface oriented axially opposite from the charging surface is associated with the valve member, said counter-charging surface being charged via a counter-pressure channel with the operating pressure that prevails in the work channel.

German patent application DE 101 56 099 B4 describes a control device for the pressure-actuated pneumatic drives of fittings, comprising a housing, a pressure feed line, a pressure discharge line, a vent and an operating piston that runs in a cylinder bore as well as piston disks that divide the cylinder bore into control chambers, whereby, in order to move the operating piston from a first operating position to a second operating position and vice versa, a control means can be employed to apply pressure to one of the control chambers or to vent the chamber, whereby, depending on the operating position of the operating piston, the pressure discharge line is connected either to the pressure feed line or to the vent through one of the other control chambers. Here, one of the control chambers can be connected to the vent in order to be vented and the control means is arranged in the housing.

The solutions known from the state of the art entail the drawback that a shortening of the operating time is hampered by the outflow of air on the opposite side.

The present invention is based on the objective of proposing a method to reduce the mechanical load and to increase the operating speed during the actuation of an operating piston, particularly the operating piston of an operating element, so that the execution of the method can bring about a fast piston movement with sufficient damping of the final position.

This objective is achieved by the features of claim 1. Other inventive embodiments and advantages can be gleaned from the subordinate claims.

Accordingly, a method to reduce the mechanical load and to increase the operating speed during the actuation of an operating piston, particularly the operating piston of an operating element, is being proposed, within the scope of which the side facing away from the actuating pressure (opposite side) is vented in a defined manner by means of a counter-ventilation pulse in such a way that the maximum possible ventilation pressure cannot build up in the operating cylinder.

According to the invention, the duration and the amplitude of the counter-ventilation pulse are defined in such a way as to achieve a faster movement of the piston, while concurrently achieving a sufficient damping of the final position.

In this context, the counter-ventilation pulse can be generated shortly before the actuation of the operating piston, that is to say, shortly before the triggering of the valve to the target position, and then switched off once the triggering of the valve to the target position begins, or else the pulse can be maintained for a certain period of time so as to overlap. The time interval between the beginning of the counter-ventilation and the beginning of the triggering of the valve to the target position can be set according to the invention as a function of the desired damping and operating speed.

Within the scope of a variant of the method according to the invention, it is proposed that, in order to set a defined damping, the opposite side should only be vented by a counter-ventilation pulse after the beginning of the pressure charging of the operating piston or after the beginning of the triggering of the valve to the target position.

According to the invention, the point in time, the duration and/or the amplitude of the counter-ventilation pulse all depend on the type of cylinder (differential cylinder, through-rod cylinder, 2-position cylinder, 3-position cylinder); in the case of a differential cylinder, the point in time, the duration and/or the amplitude are also dependent on the direction of movement and, in the case of a 3-position cylinder, on the initial position and on the target position.

The type and duration of the counter-ventilation pulse can also advantageously depend on the required operating speed (e.g. power operation, gentle operation, etc.).

The operations to switch the counter-ventilation pulse ON and/or OFF can also be configured to be event-controlled and/or time-controlled.

Owing to the concept according to the invention, the operating times are shortened, a process in which a sufficient and variable damping of the final position is achieved. Another advantage consists of the fact that the valves needed for the counter-ventilation can be dimensioned to be smaller, as a result of which less electricity is consumed.

The invention will be described below with reference to the accompanying drawings. These show the following:

FIG. 1—a schematic depiction of an operating piston as well as of the pressure lines and venting connections;

FIG. 2—by way of an example, the course of the signal of the valve for the counter-ventilation as well as of the signal of the valve for the target position of the piston; and

FIG. 3—by way of another example, the course of the signal of the valve for the counter-ventilation as well as of the signal of the valve for the target position of the piston according to the invention.

FIG. 1 shows an operating piston 1 that is arranged so as to be axially movable in an operating cylinder 2; the possible actuation movement is illustrated by the arrow. The reference numerals 3, 3′ indicate pressure lines and 4, 4′ indicate venting connections. In order to achieve an actuation movement of the operating piston 1 towards the right, the side of the operating piston 1 facing away from the direction of the actuation movement (actuation side) is charged with actuation pressure; due to the defined ventilation of the side of the operating piston 1 facing away from the actuation pressure (opposite side) by means of a counter-ventilation pulse, a sufficient damping of the final position at a high operating speed is achieved according to the invention.

Here, the duration and the amplitude of the counter-ventilation pulse are defined in such a manner that the maximum possible ventilation pressure that limits the piston speed cannot build up. In particular, the duration and the amplitude of the counter-ventilation pulse can serve to set the operating speed (for instance, power operation, gentle operation) and the damping of the final position. Moreover, the point in time, the duration and/or the amplitude of the counter-ventilation pulse are dependent on the type of cylinder.

Two possible examples of the course of the counter-ventilation pulse are shown in FIGS. 2 and 3.

In the case of the course shown in FIG. 2, in order to set a defined damping, the opposite side is only vented after the beginning of the time when the operating piston is charged with pressure or after the beginning of triggering of the valve to the target position. In this context, the time interval between the beginning of the triggering of the valve to the target position and the beginning of the counter-ventilation can be set as a function of the desired damping and operating speed.

FIG. 3 shows the case in which the counter-ventilation pulse is generated shortly before the actuation of the operating piston, that is to say, shortly before the triggering of the valve to the target position, and is maintained for a certain time so as to overlap. The time interval between the beginning of the counter-ventilation and the beginning of the triggering of the valve to the target position can be set according to the invention as a function of the desired damping and operating speed.

LIST OF REFERENCE NUMERALS

  • 1 operating piston
  • 2 operating cylinder
  • 3 pressure line
  • 3′ pressure line
  • 4 venting connection
  • 4′ venting connection

Claims

1-7. (canceled)

8. A method of actuating a piston having a first side and a second side, the method comprising:

generating a counter-ventilation pulse having a duration and amplitude defined to achieve a predetermined operating speed of the piston and a predetermined damping of a final position of a piston;
applying an actuating pressure to the first side of the piston; and
venting a second side of the piston in a defined manner using the counter-ventilation pulse so as to prevent a buildup of a maximum possible ventilation pressure.

9. The method as recited in claim 8, wherein the piston is an operating piston of an operating element.

10. The method as recited in claim 8, wherein the venting increases an operating speed of the piston and reduces a mechanical load on the piston.

11. The method as recited in claim 8, wherein the generating of the counter-ventilation pulse is performed shortly before the applying of the actuation pressure.

12. The method as recited in claim 11, wherein the duration of the counter-ventilation pulse is such that the counter-ventilation pulse is switched off before the applying of the actuation pressure.

13. The method as recited in claim 11, wherein the duration of the counter ventilation pulse is such that the counter-ventilation pulse overlaps the applying of the actuation pressure.

14. The method as recited in claim 11, wherein the applying of the actuating pressure includes applying an fluid flow to the first side of the piston, and further comprising adjusting a time interval between a beginning of the counter-ventilation pulse and a beginning of the applying of the fluid flow as a function of the predetermined damping and operating speed.

15. The method as recited in claim 8, wherein the generating of the counter-ventilation pulse is performed shortly after a beginning of the applying of the actuation pressure.

16. The method as recited in claim 15, wherein a time interval between the beginning of the applying of the actuation pressure and the generating of the counter-ventilation pulse is set as a function of the desired damping and operating speed.

17. The method as recited in claim 8, wherein the piston moves within a cylinder and further comprising determining at least one of the duration and the amplitude based on a parameter of the cylinder.

18. The method as recited in claim 8, wherein cylinder is a differential cylinder, and wherein at least one of the duration and the amplitude are determined based on a direction of movement of the piston.

19. The method as recited in claim 18, wherein the differential cylinder is a 3-position cylinder, wherein at least one of the duration and the amplitude are determined based on an initial position of the piston and a target position of the piston.

Patent History

Publication number: 20090004027
Type: Application
Filed: Dec 9, 2006
Publication Date: Jan 1, 2009
Applicant: ZF FRIEDRICHSHAFEN AG (FRIEDRICHSHAFEN)
Inventors: Robert Ingenbleek (Kressbronn), Markus Ulbricht (Tettnang), Mario Steinborn (Friedrichshafen), Armin Brentel (Eriskirch)
Application Number: 12/097,858

Classifications

Current U.S. Class: Processes (417/53)
International Classification: F04B 49/00 (20060101);