DE102010005235A1 - Method and device for controlling a throttle of a pneumatic damper - Google Patents

Abstract

The present invention relates to a method for controlling a throttle of a pneumatic damper with a step of receiving status information about a vibration profile (331) of the pneumatic damper, a step of detecting an upcoming extreme value of the vibration profile (331) based on the status information and a step of Providing an opening signal (333) for opening the throttle when the upcoming extreme value is detected.

Description

The present invention relates to a method and apparatus for driving a throttle of a pneumatic damper and to a pneumatic damper, which can be used for example in the vehicle sector.

Pneumatic dampers are not standard, but still known and are also used in individual cases. They consist essentially of two pneumatic damping volumes and a damping throttle, which either has a constant cross-sectional area, or is dependent on pressure difference. The disadvantage of pneumatic dampers is often that they are either too expensive or that the steam energy is insufficient. This has hitherto prevented the use of the damper type in mass production. To increase the damping energy, the pressure in the damper can be increased, but only for damper types that are independent of an air spring.

It is the object of the present invention to provide an improved method and apparatus for driving a throttle of a pneumatic damper and an improved pneumatic damper.

This object is achieved by a method according to claim 1, an apparatus according to claim 12 and by a pneumatic damper according to claim 13.

The invention is based on the finding that the damping force of this throttle can be increased by an "ideal" throttle, which can change its cross-sectional area. The core of the invention is a secure component solution or an algorithm for a targeted control of a throttle valve. Here, the invention is based on the idea that the ideal throttle can be approximated via an electronic sensor system and actuator system with a defined algorithm.

The present invention provides a method of driving a throttle of a pneumatic damper, comprising the steps of: receiving state information about a waveform of the pneumatic damper via an interface; Detecting an upcoming, current or swept extreme value of the waveform based on the state information; and providing an opening signal to open the throttle when the upcoming extreme value is detected.

The pneumatic damper can be used to dampen a vehicle body. For this purpose, the damper between a vehicle axle and a vehicle body can be arranged and designed to dampen an axle vibration and / or a swinging motion of the vehicle body. The throttle may have a throttle valve, via which a fluid flow can be controlled. By the fluid flow, the damping effect of the damper can be achieved. According to the invention, the damping effect of the damper can be increased by a specific opening and closing of the throttle valve. By opening the throttle valve, a cross-sectional area can be increased through which the fluid can flow. The vibration of the damper can be detected by a change in length of the damper, which can be caused by stochastic executed compression movements and rebound movements. Also, the vibration can be detected by a repetitive pressure change in one or both damper volumes. The state information may characterize a current state of the damper. In particular, the state information can define in which phase of the oscillation the damper is currently located. The state information can be detected and provided by suitable sensors. Over time, the state information may have a continuous value history or consecutive discrete values. The extreme value may define a phase of the oscillation in which the oscillation direction changes or reverses. For example, the extreme value can characterize a maximum or a minimum in the course of the oscillation, that is to say, for example, a maximum or minimum linear expansion occurring during the oscillation or a maximum or minimum pressure occurring within the damper during the oscillation. The opening signal may be configured to cause the opening of the throttle before the extreme value of the waveform is reached. The opening of the throttle can take place from a fully closed state of the throttle or from a partially open state of the throttle out. The opening signal may be an electrical signal, for example an electrical voltage or an electric current. By means of the opening signal, a current flow through an electrical coil can be controlled, by means of which the throttle can be opened or closed.

In this case, the opening signal may also correspond to the current flow through the coil.

According to one embodiment, the waveform may relate to a pressure waveform within a damper volume of the pneumatic damper, and the state information may include information about a pressure within the damper volume. In this case, the status information can be detected via a pressure sensor. Alternatively or additionally, the Vibration course relate to a spring movement of the pneumatic damper and the state information may include information about a spring travel of the pneumatic damper. The spring travel may define a distance by which the damper is extended or rebounded from a neutral position. In this case, the state information can be detected by means of a suitable sensor, for example via corresponding waypoints.

The upcoming extreme value can be recognized based on a temporal course of the state information. For this purpose, temporally successive status information can be received and compared with each other. If a predetermined change occurs in the respective difference of successive state information, this can be interpreted as an indication of an imminent extreme value. This may in particular be the case if successive status information only slightly differ from each other. For example, a derivative, in particular a first derivative, can be formed and evaluated over successive values of the state information. In this case, the upcoming extreme value may be detected based on the derivation of a time history of successive state information.

For example, the state information or a value determined from the state information can be compared with a threshold value in order to detect the upcoming extreme value. For example, the first derivative of the time profile of the state information can be compared with one or more threshold values. In this case, a first threshold value can be assigned to an extreme value in the form of a minimum and a second threshold value to an extreme value in the form of a maximum.

In one embodiment, the opening signal may be configured to maintain the throttle opening until a predetermined close event. The closing event may define a point in time when the pressure exchange through the throttle is fully or mostly completed, for example at 50% or 75%. The closing event can be detected via a sensor, which in turn is designed to provide corresponding sensor information for controlling the opening signal. Alternatively, the closing event may be characterized by a lapse of a predetermined period of time commencing with the opening of the throttle.

Furthermore, the method according to the invention may comprise a step of providing a closing signal for closing the throttle. The closing signal may be provided when the throttle is in an open state. From the open state, the throttle may be placed in a fully or partially closed state in response to the closing signal. The closing signal may be provided in response to the closing event. In particular, the closing signal can be provided temporally after the occurrence of the extreme value and before the occurrence of a further extreme value.

The closing signal may be configured to hold the throttle in a closed state for a predetermined period of time. In this way, unintentional opening can be prevented.

According to one embodiment, the throttle may include a throttle valve for controlling a flow of fluid through the throttle and an electrical winding for actuating the throttle valve. The opening signal may be configured to cause a current flow through the winding required to open the throttle valve. Accordingly, the closing signal may be formed to effect a current flow through the winding required to close the throttle valve. A winding is easy to control and provides a reliable and cost effective way to control the opening behavior and closing behavior of the throttle. For closing and keeping closed the throttle valve, a flow of current in a first current direction can be provided. To open the throttle valve, an opposite current flow can be provided for a short time. Alternatively, the throttle can be closed automatically by the decreasing pressure difference in the two damper chambers.

According to an embodiment, providing the opening signal may be prevented when an amplitude of the waveform is smaller than a predetermined minimum amplitude. In this way, small oscillations can be suppressed.

For example, providing the opening signal may be prevented when the state information indicates a pressure change that is below a predetermined minimum pressure difference. The pressure change may define a pressure difference between a pressure at rest and a current pressure. In this case, it is necessary to have a certain minimum pressure difference for the algorithm to work. Below this minimum pressure difference, the throttle will not open. This unnecessarily frequent switching, for example, on good roads prevented.

The present invention further provides an apparatus for driving a throttle of pneumatic damper, comprising: receiving means for receiving state information about a waveform of the pneumatic damper via an interface; recognition means for detecting an upcoming extreme value of the waveform based on the state information; and providing means for providing an opening signal for opening the throttle when the upcoming swing reversal is detected. The device may be designed to implement or carry out the steps of the method according to the invention. The device may be implemented as a logic unit in hardware or software. For example, it may be a control unit that can be connected via corresponding electrical interfaces with the throttle and the throttle coupled sensors.

Further, the present invention provides a pneumatic damper having: first and second damper volumes; a throttle disposed between the first and second damper volumes to control fluid flow between the first and second damper volumes; a detection means for detecting a state information of a vibration of the pneumatic damper; and a device according to the invention for controlling the throttle. The pneumatic damper can be used in a vehicle. For this purpose, the damper may be connected on the one hand to a vehicle axle and on the other hand to a vehicle body. The damper volume can be formed by a damper piston or damper bellows.

Preferred embodiments of the present invention will be explained in more detail below with reference to the accompanying drawings. Show it:

1 an illustration of a pneumatic damper according to the invention;

2 a flow diagram of a method according to the invention for driving a throttle of a pneumatic damper;

3 a pressure change curve without damping;

4 another pressure curve without damping; and

5 a true pressure curve.

In the following description of the preferred embodiments of the present invention, the same or similar reference numerals are used for the elements shown in the various drawings and similar, and a repeated description of these elements will be omitted.

1 shows a pneumatic damper, according to an embodiment of the present invention. The damper has a first damper volume 101 and a second damper volume 102 on. The first damper volume 101 and the second damper volume 102 can form enclosed spaces in which a damper fluid is arranged. The first damper volume 101 can through a damper bellows and the second damper volume 102 can be formed by a damper piston. The fluid may be air. The first damper volume 101 can with the second damper volume 102 exclusively via a throttle 105 be connected. When the throttle 105 When in an open state, the fluid may be from the first damper volume 101 in the second damper volume 102 , and vice versa, flow. When the throttle 105 is in a closed state, there is no pressure equalization between the first damper volume 101 and the second damper volume 102 possible. The throttle 105 may have a throttle valve. The throttle valve may be an electromechanical component. For example, the throttle valve may have a throttle valve that can release or close a valve opening. An opening state of the throttle valve may be controlled by an electric coil. If the coil is traversed by an electric current, the coil can form a magnetic field. The magnetic field may be suitable for attracting the throttle valve and thereby closing the valve opening. The throttle valve can be opened when there is a corresponding pressure difference between the damper volume 101 . 102 exists and the coil is traversed by any current or by a momentarily opposite current.

The throttle 105 can through a device 110 for controlling the throttle 105 be controlled. In particular, the device can 110 be configured to control an opening and closing of the throttle valve. This can be done by the device 110 for example, via an electrical power to the throttle 105 be connected. About the electrical line, the device 110 For example, provide a current through a coil of the inductor 105 is directed. In addition, the device can 110 be connected to a sensor, for example via a further electrical line. The sensor may be coupled to the damper to detect state information of the damper. The state information can make a statement as to what kind of vibration state the damper is currently in. For example, the sensor may be a pressure sensor configured to generate a pressure in the first damper volume 101 or in the second damper volume 102 capture. Likewise, the sensor may be designed to detect a spring travel of the damper. Thus, the state information may be a measured value. The device 110 may be configured to receive and evaluate, in chronological succession, a plurality of values of the state information. For example, the device 110 be formed to form a derivative of a time course of the values of the state information and evaluate. For this purpose, the derivative can be compared, for example, with one or more threshold values. Depending on a comparison result, the device 110 be formed to a corresponding control signal, for example, to open the throttle valve, to the throttle 105 provide. After providing a control signal for opening the throttle valve, the device 110 be trained to the throttle 105 to control so that the throttle valve remains open for a certain period of time. The period of time may be selected such that a certain pressure equalization between the first damper volume 101 and the second damper volume 102 can take place. After opening the throttle valve, the device can 110 be formed to another control signal to the throttle 105 provide that causes a closing of the throttle valve. Alternatively, closing the throttle 105 also done automatically.

2 shows a flowchart of a method for driving a throttle of a pneumatic damper, according to an embodiment of the present invention. The method may, for example, in the in 1 be implemented device shown. In one step 221 a status information can be received. The state information may, for example, be provided by a sensor and include information about a vibration course or a vibration state of the damper. In one step 223 For example, the vibration pattern of the damper may be analyzed based on the state information or based on a plurality of consecutive state information to detect in advance an upcoming extreme value in the waveform. If such an impending extreme value is detected, then in one step 225 an opening signal is provided. The opening signal may be a control signal for controlling an opening behavior of the throttle. The opening signal can thus be provided to the throttle and cause an opening of the throttle valve.

According to one embodiment, the method according to the invention can be described by an algorithm. The algorithm may be characterized by the points listed below, which may be implemented by alternative or further method steps.

First, a determination of a vibration-relevant variable, such as a pressure or a spring travel, take place. Following this, a first derivative of the vibration-technical quantity for determining a limit value before a vibration peak can be determined. Thereafter, an initiation of a throttle opening operation may be performed based on a limit underflow signal. The limit underflow signal may be provided based on a comparison of the first derivative with the threshold. Subsequent retention of the throttle opening may be performed until pressure replacement is complete or substantially complete. Subsequently, an automatic or forced resealing of the throttle can take place. Thereupon, to prevent accidental opening during a next pressurization phase, a defined closed-loop hold may occur.

3 showed a pressure curve without damping, according to an embodiment of the present invention. Shown is a course of a vibration signal 331 , The vibration signal 331 may have a sinusoidal shape and correspond to a vibration to be damped. According to this embodiment, the vibration signal indicates 331 a pressure curve within the pneumatic damper. Accordingly, the time t is given in seconds on the abscissa and the pressure in bar on the ordinate. Furthermore, in 3 a current course 333 , a time 351 , Time periods 353 . 355 . 357 . 359 and a pressure increase 360 of 0.2 bar shown.

4 shows a dp / dt curve 441 without damping including switching points, according to an embodiment of the present invention. The course curve 441 represents a derivative of the in 3 shown vibration signal 331 Accordingly, the abscissa represents the time t in seconds and the ordinate the derivative of the pressure over time. Furthermore, in 4 an upper limit 443 and a lower limit 445 shown. The limits 443 . 445 respectively define predetermined values of the derivative of the pressure over time, in reaching, exceeding or falling below a switching signal can be provided. According to this embodiment, a first switching signal 447 provided when the trajectory 441 the upper limit 443 below. A second switching signal 447 is provided when the trajectory 441 the lower limit 445 exceeds. According to these embodiments, no switching signals 447 provided when the trajectory 441 the upper limit 443 exceeds or the lower limit 445 different. The upper limit 443 indicates a positive value and the lower limit 445 a negative value. In terms of amount, the upper and lower limits can be determined 443 . 445 correspond. The limits 443 . 445 can be approximately midway between an extreme value of the trajectory 441 and a subsequent zero crossing of the trajectory 441 be arranged. For example, the extreme values in a window may be between one quarter and three quarters of a respective amplitude of the trace 441 be arranged. Responding to the switching signals 447 a throttle opening can be effected. These can be the sound signals 447 For example, be configured to provide a suitable drive current to the throttle.

3 shows a time course of a signal for driving a throttle in the form of the current waveform 333 , A the course of the current 333 corresponding current can be provided to an electrical coil of the throttle, with the opening and closing of the throttle can be controlled. First, the current course 333 a value suitable for keeping the throttle in a closed state. At a time 351 has the vibration signal 331 a slope that causes the derivative of the vibration signal 331 falls below the upper limit, as in 4 is shown. In response, the current course drops 333 then back to the original value. The waste and subsequent increase in the course of the current 333 for example, a period of time 353 of 5 ms. In response, the current history 333 for a period of time 355 of, for example, 35 ms again have the original value. Furthermore, in 3 a period of time 357 shown between the top of the current 333 , which leads to the opening of the throttle, and the maximum of the vibration signal 331 lies. The duration 357 may for example be 10 ms. A period of time 359 between two consecutive zero crossings of the oscillation signal 331 may for example be 42 ms. Thus, the opening of the throttle, for example, take place in a time window which is one quarter of the oscillation period of the oscillation signal 331 begins before a respective extreme value and ends with the respective extreme value. For example, the opening of the throttle can be one eighth of the oscillation period of the oscillation signal 331 be performed before the respective extreme value.

According to the in the 3 and 4 shown embodiments may by the first derivative 441 the illustrated vibration signal 331 , here the pressure signal, a limit 443 . 445 which then passes to the electrical "fan-out" 353 a winding, which then opens the valve between two pneumatic damper chambers. The current course 333 is in 3 shown. Due to the exceeding of the limit value, the switching point may be before TDC, which is due to the finite duration of the real deaeration, as in 5 also makes sense. The "Entstromen" takes place faster through a "counter-current" so that the magnetic flux is prevented as soon as possible. This is followed by a targeted phase 355 the secured Wiederbestromung, z. B. 35 ms, so that when putting the pressure ventilation curve on the lower pressure curve is not a random renewed exceeding the dp / dt limit 443 . 445 to reopen the valve. Thereafter, the process begins in the opposite direction.

5 shows a true pressure gradient 570 with air exchange, according to an embodiment of the present invention. Shown is the in 3 shown pressure signal 331 , a first waveform 571 and a second waveform 573 , The waveforms 571 . 573 are parallel to the pressure signal 331 , Here is the first waveform 571 with respect to the pressure signal 331 up and the second waveform 573 moved down. Furthermore, again, the pressure increase 360 of 0.2 bar and a spring travel 560 shown for example 65 mm. Initially, the throttle is for a period of time 581 in a state where the throttle is closed. Subsequently, the throttle is for a period of time 582 in a state in which the throttle is open. Subsequently, the throttle is for a period of time 583 in a state where the throttle is closed. The duration 582 , in which the throttle is open, can be 14 ms.

During the period 581 , in which the throttle is closed, the pressure increases 570 according to the first waveform 571 at. As soon as the throttle is opened, the pressure drops 570 from. The throttle can be opened before the maximum of the first waveform is reached. After opening the throttle, the pressure drops 570 during the period 582 from, until the pressure curve 570 on the second waveform 573 touches down. Once the pressure 570 so far dropped that the second waveform 573 is reached, the throttle is closed. During the period 583 , in which the throttle is closed, the pressure drops 570 according to the second waveform 573 from. Before the minium of the second waveform 573 is reached, the throttle can be opened again to cause an increase in pressure.

The described embodiments are chosen only by way of example and can be combined with each other.

LIST OF REFERENCE NUMBERS

101

first damper volume

102

second damper volume

105

throttle

110

contraption

221

first step

223

second step

224

Third step

331

vibration signal

333

current profile

351

time

353

first period of time

355

second period of time

357

third period of time

359

fourth period of time

360

pressure rise

441

trajectory

443

upper limit

445

lower limit

447

switching signal

571

first waveform

573

second waveform

560

travel

581

closed state

582

opened state

583

closed state

Claims (13)

Method for controlling a throttle ( 105 ) of a pneumatic damper comprising the following steps: receiving ( 221 ) a state information about a waveform ( 331 ) of the pneumatic damper via an interface; Detect ( 223 ) an upcoming, current or swept extreme value of the waveform based on the state information; and deploy ( 225 ) of an opening signal ( 333 . 447 ) to open the throttle when the extreme value is detected. Method according to Claim 1, in which the oscillation profile ( 331 ) a pressure curve within a damper volume ( 101 . 102 ) of the pneumatic damper and the state information comprises information about a pressure within the damper volume or wherein the waveform relates to a spring movement of the pneumatic damper and the state information comprises information about a spring travel of the pneumatic damper. Method according to one of the preceding claims, in which the imminent extreme value is based on a time course ( 441 ) of the state information is detected. Method according to one of the preceding claims, in which the upcoming extreme value is based on a first derivative of a time profile ( 441 ) of the state information is detected. Method according to one of the preceding claims, in which the status information or a value determined from the status information ( 441 ) with a threshold ( 443 . 445 ) is compared to detect the upcoming extreme value. Method according to one of the preceding claims, in which the opening signal ( 333 . 447 ) is formed around the opening of the throttle ( 105 ) up to a predetermined closing event. Method according to one of the preceding claims, comprising a step of providing a closing signal for closing the throttle ( 105 ). Method according to Claim 7, in which the closing signal is designed to close the throttle ( 105 ) in a closed state for a predetermined period of time. Method according to one of the preceding claims, in which the throttle ( 105 ) comprises a throttle valve for controlling a fluid flow through the throttle and an electrical winding for actuating the throttle valve, and in which the opening signal ( 333 . 447 ) is formed to a current flow required for opening the throttle valve ( 333 ) through the winding and / or the closing signal is formed to effect a current flow required to close the throttle valve through the winding. Method according to one of the preceding claims, wherein the providing ( 225 ) of the opening signal ( 333 . 447 ) is prevented when an amplitude of the waveform ( 331 ) is less than a predetermined minimum amplitude. Method according to one of claims 2 to 10, wherein the providing ( 225 ) of the opening signal ( 333 . 447 ) is prevented when the state information indicates a pressure change that is below a predetermined minimum pressure difference. Contraption ( 110 ) for driving a throttle ( 105 ) of a pneumatic damper, comprising: receiving means for receiving state information about a waveform the pneumatic damper via an interface; recognition means for detecting an upcoming extreme value of the waveform based on the state information; and providing means for providing an opening signal for opening the throttle when the upcoming swing reversal is detected. Pneumatic damper, comprising: a first and a second damper volume ( 101 . 102 ); a throttle ( 105 ) disposed between the first and second damper volumes to control fluid flow between the first and second damper volumes; a detection means for detecting a state information of a vibration of the pneumatic damper; and a device ( 110 ) for driving the throttle, according to claim 12.

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