DE102020200892A1 - Pneumatic release system for a clutch arrangement and a device, a computer program and a method for determining a leakage rate of a fluid, in particular in the case of a pneumatic release system - Google Patents

Abstract

The present invention relates to a device (110) for determining a leak rate of a fluid, in particular in a pneumatic release system (120). The device (110) comprises a signal generator (112), which is designed to generate a periodic signal (113), and a controller (114), which is designed to generate a manipulated variable signal (115) which is based on a change a pressure of the fluid is dependent. The device (110) further comprises a signal processing unit (116) which is designed to determine the leakage rate based on a comparison between the manipulated variable signal (115) and the periodic signal (113).

Description

The present invention relates to a pneumatic release system for a clutch arrangement and a device, a computer program and a method for determining a leakage rate of a fluid, in particular in the case of a pneumatic release system.

Different applications lead to different wear (e.g. due to different contamination levels) in pneumatic release systems, in particular of seals, in the field / driving operation, so that an individual wear behavior cannot be adequately represented by an (exemplary) model.

The wear and tear that occurs in pneumatic release systems can promote leakage of the seals or a change in the leakage rate. This can lead to field failures and / or breakdowns.

The disclosure document DE 10 2011 003 365 A1 describes a release system with a leak warning device. The leak warning means is designed to detect a duration of a predetermined actuating state of a pneumatic valve.

This means, for example, additional technical outlay for detecting the predetermined actuating state, for example by implementing sensors which are designed to detect the predetermined actuating state.

It can therefore be regarded as an object of the present invention to provide an improved concept for determining a leakage rate.

This object can be achieved by the subjects of the independent and dependent claims.

According to a first aspect, the present invention relates to a device for determining a leakage rate of a fluid, in particular in the case of a pneumatic release system. The device comprises a signal generator which is designed to generate a periodic signal, and a controller which is designed to generate a manipulated variable signal which is dependent on a change in a pressure of the fluid. Furthermore, the device comprises a signal processing unit which is designed to determine the leakage rate based on a comparison between the manipulated variable signal and the periodic signal.

The fluid can be a gas such as air or nitrogen.

The gas is present, for example, in a pressure volume which is enclosed by a housing and a piston of the pneumatic release system that can be moved relative to the housing.

The pneumatic release system can be actuated by adapting the pressure of the fluid present in the pressure volume. An increase in pressure, for example, causes the piston to extend.

The leakage rate can be understood to mean a leakage flow of the fluid which escapes from the pressure volume, for example through leaks. Such leaks can occur due to wear at an interface between the piston and the housing. The leakage rate can optionally be determined as a relative ratio to an earlier leakage rate.

The signal generator describes, for example, a signal-generating generator, an electronic device, an assembly or a circuit for generating the periodic signal.

The periodic signal can in particular be a voltage or a current signal which has an oscillating oscillation.

The controller includes, for example, a proportional-integral (PI) controller or a proportional-integral-derivative (PID) controller.

In connection with such regulators, the manipulated variable signal can be designed to control the pressure, for example to maintain or specifically change the pressure. For example, to control the pressure, an inlet valve coupled to a pressure reservoir and / or an outlet valve can be controlled indirectly or directly by the manipulated variable signal.

When controlling the pressure, compensation for a pressure loss that is dependent on the leakage rate can be taken into account by the manipulated variable signal.

In the case of a control for maintaining a defined pressure, an influence of the manipulated variable signal on the inlet valve can ideally cause the pressure loss to be compensated.

The manipulated variable signal can therefore be indicative of the leak rate. The manipulated variable signal can be proportional or indirectly proportional to the leakage rate.

To determine the leakage rate, the comparison between the manipulated variable signal and the periodic signal can provide, for example, a comparison of amplitudes of the manipulated variable signal and the periodic signal.

The leakage rate can be determined, for example, on the basis of overlapping of the amplitudes and / or on the basis of the resulting intervals between such overlaps.

The signal processing unit, which is designed to determine the leakage rate, comprises, for example, a processor, a processor circuit, a microprocessor or programmable hardware similar to the aforementioned.

By means of the device described herein, it is possible, for example, in automotive applications, such as a pneumatic release system for actuating a vehicle clutch, to determine the leakage rate while driving.

In this way, for maintenance purposes, for example, a state of wear of the pneumatic release system can be deduced. In this way, field failures such as a vehicle breakdown and the associated circumstances can be avoided.

The determination of the leakage rate on the basis of control parameters, such as the manipulated variable signal and the periodic signal, can mean less technical effort and / or lower cost compared to determining the leakage rate in known release systems.

In some exemplary embodiments of the device, the manipulated variable signal is dependent on a controlled variable characterizing a change in the pressure.

The controlled variable characterizes, for example, a time differential of the pressure.

In some exemplary embodiments of the device, the controlled variable indicates a change in a position of a piston that at least partially encloses the fluid.

When the pneumatic release system is actuated, the piston can, for example, “release” in response to an increase in pressure and thus change its position. A known relationship can therefore be used to deduce the pressure of the fluid from the position of the piston. The change in position can be implicitly indicative of the change in pressure.

Conventional pneumatic release systems can already have displacement measuring systems for determining (changing) the position of the piston, for example to monitor the actuation of a clutch in the vehicle. Using the change in the position of the piston for the controlled variable therefore does not involve any additional technical effort in some cases compared to some conventional pneumatic release systems.

In some exemplary embodiments, the controlled variable indicates a change in the pressure of the fluid.

The change in pressure can be determined, for example, by means of a pressure sensor designed for this purpose, which can be implemented in some conventional pneumatic release systems. Therefore, using the change in pressure for the controlled variable does not mean any additional technical effort compared to conventional pneumatic release systems in some cases.

In some exemplary embodiments of the device, the periodic signal has a sawtooth oscillation.

The sawtooth oscillation has, for example, a linearly rising and a vertically falling signal edge. Compared to alternative periodic signals, using the sawtooth oscillation for the comparison with the manipulated variable signal is associated with less technical effort.

Alternative periodic signals include, for example, a triangular wave or a sinusoidal signal.

In some exemplary embodiments of the device, the signal processing unit is also designed to generate a control signal for controlling the pressure that is dependent on the comparison between the manipulated variable signal and the periodic signal. Furthermore, the signal processing unit can be designed to determine the leakage rate on the basis of the control signal.

To control the pressure, the control signal can regulate a valve position of the inlet valve or of the outlet valve. These can, for example, assume two different valve positions (for example “open” and “closed”).

The control signal can therefore be a discrete signal.

In some exemplary embodiments of the device, the control signal has a pulse-width-modulated signal.

The signal processing unit generates, for example, a control signal that is dependent on the overlapping of the manipulated variable signal with the periodic signal, such as a square-wave signal.

The square-wave signal is therefore, for example, indicative of the comparison between the manipulated variable signal and the periodic signal and thus of the leakage rate.

In some exemplary embodiments of the device, the signal processing unit is designed to determine the leakage rate on the basis of a duty cycle of the pulse-width-modulated signal.

The duty cycle is, for example, directly or indirectly proportional to the leakage rate.

In some exemplary embodiments of the device, the signal processing unit is also designed to determine a disengagement time of the piston based on a comparison between the manipulated variable signal and the periodic signal, and the leakage rate based on the disengagement time.

For example, when regulating to a specific pressure of the fluid or a specific position of the piston, the comparison between the manipulated variable signal and the periodic signal can be used to determine the disengagement time of the piston, which in the case of regulation is until the specific pressure or the specific position is reached elapses.

In some exemplary embodiments of the device, it also includes a warning device which is designed to output a warning signal as a function of a comparison of the manipulated variable signal with a reference value.

The warning device includes, for example, a comparator circuit for comparing the manipulated variable signal with the reference value.

The reference value indicates, for example, a value of the manipulated variable signal that is characteristic of a wear limit or a maximum permissible leakage rate. If the manipulated variable signal falls below or exceeds the reference value, the warning signal can be output, for example, in the form of an electrical, audible or visual signal.

In a second aspect, the present invention relates to a pneumatic release system for a clutch assembly. The pneumatic release system comprises a device as described above for determining a leak rate of a fluid in the pneumatic release system.

The pneumatic release system is designed, for example, as a so-called concentric, pneumatic release cylinder or pneumatic central release.

The pneumatic release system can be used to actuate a clutch, particularly in the case of clutches in commercial vehicles.

In the case of a commercial vehicle in particular, a defect in the pneumatic release system while driving can mean economic damage.

When the device designed to determine the leakage rate is used for maintenance purposes, a defect in the pneumatic release system can be prevented in order to avoid economic damage associated therewith.

According to a third aspect, the present invention relates to a method for determining a leak rate of a fluid, in particular in a pneumatic release system. The method comprises generating a periodic signal and generating a manipulated variable signal which is dependent on a change in a pressure of the fluid. The method further includes comparing the manipulated variable signal with the periodic signal to determine the leakage rate.

The method can in particular be carried out by means of the device described above and / or the pneumatic release system.

In some exemplary embodiments of the method, the manipulated variable signal is dependent on a controlled variable characterizing a change in the pressure.

In some exemplary embodiments, comparing the manipulated variable signal with the periodic signal further includes generating a control signal adapted to control the pressure based on a comparison between the manipulated variable signal and the periodic signal for determining the leakage rate on the basis of the control signal.

As described in connection with the device, the control signal can be generated based on a comparison of amplitudes of the manipulated variable signal and the periodic signal.

The leakage rate can be determined on the basis of the duty cycle and / or the pulse width of the control signal.

According to a fourth aspect, the present invention relates to a computer program which is adapted to carry out an embodiment of the method described above when it is carried out on a processor.

The processor can be understood to mean any programmable hardware, such as an (electronic) data processing system / circuit or an integrated circuit.

• 1 pneumatisches Ausrücksystem mit einer Vorrichtung zum Bestimmen einer Leckagerate;
• 2 schematische Darstellung einer Erzeugung eines Steuersignals;
• 3 Darstellung einer Proportionalität zwischen dem Steuersignal und der Leckagerate; und
• 4 schematische Darstellung eines Verfahrens zum Bestimmen der Leckagerate als Flussdiagramm.

Some examples of exemplary embodiments of the invention are explained in more detail below with reference to the accompanying figures, merely by way of example. Show it:

• 1 Pneumatic release system with a device for determining a leak rate;
• 2 schematic representation of a generation of a control signal;
• 3 Representation of a proportionality between the control signal and the leakage rate; and
• 4th schematic representation of a method for determining the leakage rate as a flow chart.

Various embodiments will now be described in more detail with reference to the accompanying drawings, in which some embodiments are shown.

Although exemplary embodiments can be modified and changed in various ways, exemplary embodiments are shown in the figures as examples and are described in detail herein. It should be made clear, however, that the intention is not to restrict exemplary embodiments to the respectively disclosed forms, but rather that exemplary embodiments are intended to cover all functional and / or structural modifications, equivalents and alternatives that are within the scope of the invention.

In the case of pneumatic release systems, there may be leaks, in particular due to wear, so that a fluid provided for controlling the pneumatic release system can escape.

Depending on the leakage rate of the fluid, the pneumatic release system can malfunction. For maintenance purposes it may therefore be desirable to determine the leakage rate of the pneumatic release system.

1 shows a pneumatic release system 120 and a device 110 for determining a leak rate of a fluid (not shown) in the pneumatic release system 120 . The device 110 includes a signal generator 112 , which is designed to generate a periodic signal 113 to generate and a controller 114 , which is designed to generate a manipulated variable signal 115 to generate which is dependent on a change in a pressure of the fluid. The device also includes 110 a signal processing unit 116 , which is designed to be based on a comparison between the manipulated variable signal 115 and the periodic signal 113 determine the leak rate.

The device 110 serves here, as described below, for example a leakage detection in the pneumatic release system 120 by means of control parameters, in particular by means of the periodic signal 113 and the manipulated variable signal 115 .

The pneumatic release system 120 includes, for example, a pressure volume enclosed by a piston (not shown) and a housing (not shown) in which the fluid is located. Depending on the pressure of the fluid, the pressure volume can vary by moving the piston.

The manipulated variable signal 115 is dependent on a controlled variable characterizing a change in pressure 126 . In this example there is the controlled variable 126 for example a change in a position of the piston of the pneumatic release system 120 on. The change in the position of the piston is detected by a displacement sensor 124 recorded.

In further exemplary embodiments, the controlled variable 126 alternatively indicate a change in the pressure of the fluid.

For comparing the periodic signal 113 and the manipulated variable signal 115 these are sent to the signal processing unit 116 transmitted.

The signal processing unit 116 is designed to use a comparison between the manipulated variable signal 115 and the periodic signal 113 dependent control signal 117 to generate the control of the pressure and based on the control signal 117 determine the leak rate.

The signal processing unit 116 controls via the control signal 117 a state of a valve unit 122 which includes, for example, an inlet valve (not shown). The inlet valve 122 can for example depend on an amplitude of the control signal 117 opened or closed.

The inlet valve 122 couples that in the pneumatic release system, for example 120 located fluid with a pressure reservoir (not shown) or a pump in order to be able to increase the pressure of the fluid in the open state.

From a change in the control signal over time 117 can the signal processing unit 116 determine a change in the leak rate over time.

The valve unit 122 can be designed to flow through a flow stream 123 to determine. In connection with the flow rate 123 an absolute leak rate can be deduced.

2 shows an example of a possible time course of the periodic signal 113 , the manipulated variable signal 115 and the control signal 117 .

In a second diagram 220 is the control signal 117 plotted against time t.

The periodic signal 113 corresponds to a sawtooth oscillation in the example shown.

The manipulated variable signal 115 is, for example, (approximately) indirectly proportional to the (temporal) change in pressure.

The signal processing unit 116 is designed, for example, to depend on a comparison of the manipulated variable signal 115 and the sawtooth wave 113 the control signal 117 to create.

The manipulated variable signal 115 is for example through the controller 114 adjusted so that the control signal 117 , which results from the comparison of the manipulated variable signal 115 and the sawtooth wave 113 results, is suitable to regulate to a certain pressure.

The signal processing unit 116 generates the control signal 117 for example in such a way that when the manipulated variable signal 115 greater than the sawtooth oscillation 113 is the control signal 117 a first state 117a and in the opposite case, a second state 117b occupies.

A duty cycle of the control signal 117 , which results from a temporal relationship between the first and second state 117a and 117b is therefore related to the leak rate.

3 shows a bar graph 300 , in which the leakage rate qualitatively versus the duty cycle 117-1 is applied. The bar graph shows that the duty cycle 117-1 behaves (approximately) proportionally to the leakage rate.

Alternatively, a comparison of the manipulated variable signal can be used 115 and the sawtooth wave 113 or based on the duty cycle 117-1 of the control signal 117 a release time 117-2 can be determined, which elapses in a regulation to a certain pressure or a certain position of the piston.

The disengagement time indicates, for example, a time which elapses in the control until the duty cycle 117-2 or the control signal 117 reached a constant / steady state.

As in 3 If shown qualitatively, the release time can have a proportional relationship to the leakage rate. Due to the proportional relationship, the release time 117-2 the leak rate can be inferred.

Optionally, the device also includes a warning device 111 . The warning device 111 is designed, for example, to depend on a comparison of the manipulated variable signal 115 with a reference value 118 a warning sign 119 to spend.

This enables the pneumatic release system to reach a critical state of wear 120 be signaled at which the pneumatic release system 120 should be maintained in order to avoid a defect while driving.

Components (the warning device 111 , Signal generator 112 , Regulator 114 and the signal processing unit 116 ) of the device 110 each separate from one another or as a combination within a common circuit.

For a person skilled in the art, it is obvious that the signals (periodic signal 113 , Manipulated variable signal 115 , Control signal 117 and warning signal 118 ) can be present both as a voltage signal and optionally as a current signal.

4th shows a flow diagram of a method 400 to determine the leakage rate of the fluid, especially in the pneumatic release system 120 . The method includes generating 410 of the periodic signal 113 and generating 420 the manipulated variable signal dependent on a change in a pressure of the fluid 115 . The method also includes 400 a comparison 430 of the manipulated variable signal with the periodic signal 113 to determine the leak rate.

The procedure 400 can in particular with the aid of a computer program for controlling the device 110 be performed.

In some exemplary embodiments, the computer program can at least partially be carried out by the signal generator 112 , the controller 114 and / or the signal processing unit 116 are executed.

Alternatively, the computer program can be executed on an external processor (not shown).

The aspects and features that are described together with one or more of the previously detailed examples and figures can also be combined with one or more of the other examples in order to replace an identical feature of the other example or to add the feature in the other example to introduce.

Furthermore, the following claims are hereby incorporated into the detailed description, where each claim can stand on its own as a separate example. While each claim may stand on its own as a separate example, it should be noted that although a dependent claim in the claims may refer to a particular combination with one or more other claims, other examples also combine the dependent claim with the subject matter of each other dependent or independent claims. Such combinations are explicitly suggested here unless it is indicated that a particular combination is not intended. It is also intended to include features of a claim for any other independent claim, even if that claim is not made directly dependent on the independent claim.

List of reference symbols

110

Device for determining a leak rate of a fluid

111

Warning device

112

Signal generator

113

periodic signal

114

Regulator

115

Manipulated variable signal

116

Signal processing unit

117

Control signal

117a

first state

117b

second state

117-1

Pulse width

117-2

Duty cycle

118

Reference value

119

Warning sign

120

pneumatic release system

122

Valve unit / inlet valve

123

Flow rate

124

Displacement sensor

126

Controlled variable

210

first diagram

220

second diagram

300

bar graph

400

Method for determining a leak rate of a fluid

410

Generating a periodic signal

420

Generating a manipulated variable signal

430

Compare the manipulated variable signal with the periodic signal to determine the leak rate

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 102011003365 A1 [0004]

Claims (15)

Device (110) for determining a leak rate of a fluid, in particular in a pneumatic release system (120), comprising: a signal generator (112) which is designed to generate a periodic signal (113); a controller (114) which is designed to generate a manipulated variable signal (115) which is dependent on a change in a pressure of the fluid; and a signal processing unit (116) which is designed to determine the leakage rate based on a comparison between the manipulated variable signal (115) and the periodic signal (113). Device (110) according to Claim 1 , wherein the manipulated variable signal (115) is dependent on a controlled variable (126) characterizing a change in the pressure. Device (110) according to Claim 2 , wherein the controlled variable (126) indicates a change in a position of a piston at least partially enclosing the fluid. Device (110) according to Claim 2 , wherein the controlled variable (126) indicates a change in the pressure of the fluid. Device (110) according to one of the preceding claims, wherein the periodic signal (113) has a sawtooth oscillation. Device (110) according to one of the preceding claims, wherein the signal processing unit (116) is further designed to to generate a control signal (117) dependent on the comparison between the manipulated variable signal (115) and the periodic signal (113) for controlling the pressure; and to determine the leakage rate based on the control signal (117). Device (110) according to Claim 6 wherein the control signal (117) comprises a pulse width modulated signal. Device (110) according to Claim 7 , wherein the signal processing unit (116) is further designed to determine the leakage rate on the basis of a duty cycle (117-2) of the pulse-width-modulated signal (117). Device (110) according to Claim 3 , wherein the signal processing unit (116) is further designed to determine a disengagement time of the piston based on a comparison between the manipulated variable signal (115) and the periodic signal (113) and the leakage rate based on the disengagement time. Device (110) according to one of the preceding claims, further comprising a warning device (111), wherein the warning device (111) is designed to output a warning signal (119) depending on a comparison of the manipulated variable signal (115) with a reference value (118). Pneumatic release system (120) for a clutch arrangement, comprising a device (110) according to one of the preceding claims for determining a leakage rate of a fluid of the pneumatic release system (120). A method (400) for determining a leak rate of a fluid, in particular in the case of a pneumatic release system (120), comprising: Generating (410) a periodic signal (113); Generating (420) a manipulated variable signal (115) which is dependent on a change in a pressure of the fluid; Comparing (430) the manipulated variable signal (115) with the periodic signal (113) to determine the leakage rate. Method (400) according to Claim 12 , wherein the manipulated variable signal (115) is dependent on a controlled variable (126) characterizing a change in the pressure. Method (400) according to Claim 12 or 13th , the comparison (430) of the manipulated variable signal (115) with the periodic signal (113) further comprising generating a control signal (117) adapted to control the pressure based on a comparison between the manipulated variable signal (115) and the periodic signal (113) for Determining the leakage rate on the basis of the control signal (117). Computer program which is adapted to the method according to Claim 12 or 13th when running on a processor.

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