DE102022205616A1 - Method for determining a filling time of a pressure chamber of a hydraulically actuated friction switching element with pressure fluid - Google Patents

Abstract

The invention relates to a method for determining a filling time t (t) of a pressure chamber of a hydraulically actuated friction switching element with a pressure fluid, an original clearance of the friction switching element being measured (100, 200) and the original clearance by inserting an adjusting element of a predetermined thickness an actual clearance (x) is reduced (101). The drive train (10) according to the invention is characterized in that the filling time t (t) is read out (104) from a characteristic curve (20), the characteristic curve (20) describing the filling time t (t) as a function of the clearance (x). .

Description

The present invention relates to a method for determining a filling time of a pressure chamber of a hydraulically actuated friction switching element with pressurized fluid according to the preamble of claim 1.

It is known in the prior art that the clearance must be adjusted when assembling friction switching elements, such as clutches and brakes for automatic transmissions. The clearance is the path that an actuating piston travels mechanically from the powerlessly closed state to the open state or vice versa. To adjust the clearance, the clearance is usually measured in the pre-assembled state of the friction switching element. Depending on the measured width of the clearance, a so-called adjustment element is then inserted in order to reduce the clearance to a specified level. Adjusting the clearance is necessary to avoid a number of disadvantages, such as a reduced service life, a fluctuation in the drag torque and an increased space requirement.

For example from the DE 10 2005 051 146 A1 In this context, a method and a testing device for testing and determining the clearance of a wheel brake of a motor vehicle are known. A pull rod is passed through a passage in a wheel carrier and mechanically coupled to an expansion lock of the wheel brake. The pull rod is then moved with a defined force along a defined path until the brake pads of the brake shoes of the wheel brake rest securely on the friction surface of the wheel brake. The distance traveled and the force acting on the pull rod are the measured force-distance curve.

The DE 10 2015 225 063 A1 describes a method for determining the clearance of a clutch device, which has a disk pack having outer disks and inner disks, which can be actuated by an actuating element. At least one component that is in the flow of force during an actuation is initially manufactured with an oversize. The actual clearance is then measured and the component with the oversize is machined in such a way that a specified clearance is obtained.

An actuating piston of the friction switching elements mentioned is usually actuated hydraulically, i.e. for actuation of the friction switching element, oil volume must be shifted into the piston chamber, which is done by applying appropriate pressure. In order to complete a switching process as quickly as possible, the piston should reach its end position as quickly as possible and thereby cause the friction torque on the friction switching element to be as large as the torque to be transmitted. It is therefore still common practice for a required filling time to be determined iteratively and continuously during operation of the friction switching element, for example in a transmission, within which the actuating piston overcomes the clearance and causes exactly the required friction torque.

However, the disadvantage of all methods known in the prior art for determining the filling time of the piston chamber is that the exact required filling time is not present right from the start when the automatic transmission containing the friction switching element is delivered, but only in the initial phase of operation of the friction switching element by a Friction switching element actuating control unit is determined precisely as part of a series of control processes. As a result, switching operations of the friction switching element are often not very comfortable in the initial phase.

It is an object of the invention to propose an improved method for determining a filling time of a pressure chamber of a hydraulically actuated friction switching element with pressurized fluid.

This object is achieved according to the invention by the method for determining a filling time of a pressure chamber of a hydraulically actuated friction switching element according to claim 1. Advantageous refinements and further developments of the invention emerge from the dependent claims.

The invention relates to a method for determining a filling time of a pressure chamber of a hydraulically actuated friction switching element with a pressure fluid, wherein an original clearance of the friction switching element is measured and the original clearance is reduced to an actual clearance by inserting an adjusting element of a predetermined thickness.

The method according to the invention is characterized in that the filling time is read from a characteristic curve, the characteristic curve describing the filling time depending on the clearance.

The invention therefore describes a method in the sense of a calibration, in which a hydraulically actuated friction switching element, for example a multi-plate clutch, is measured and its filling time is to be adjusted in such a way that the best possible control in terms of actuation results. Optimal control is understood to mean an actuation that results in the shortest possible switching time of the friction switching element - i.e. the fastest possible one Filling time of the pressure chamber - results in neither too high nor too low a filling pressure. Since the filling pressure determines the torque that can be transmitted, a filling pressure that is too high would lead to a so-called torque surge, while a filling pressure that is too low would lead to an uncontrolled revving of a drive unit. A hydraulically actuated friction switching element has a pressure chamber which can be filled with a hydraulic medium and correspondingly acted upon with a hydraulic pressure. The pressurization causes a piston to be axially displaced in the pressure chamber and exerts pressure on the friction switching element. This in turn leads to an increasing frictional force between the friction partners of the friction switching element, so that increasingly more torque can be transmitted through the friction switching element as the pressure increases.

As is known, a hydraulically actuated friction switching element has a pressure chamber which can be filled with the pressure fluid and correspondingly acted upon with a hydraulic pressure. The pressurization causes a piston to be axially displaced in the pressure chamber and thus begins to exert pressure on the friction switching element after the actual clearance has been overcome. This in turn leads to an increasing frictional force between the friction partners of the friction switching element, so that increasingly more torque can be transmitted via the friction switching element as the pressure increases.

The pressure-related movement of the piston can, for example, be counteracted by one or more return springs, which push the piston back from the friction switching element when the pressure decreases.

The adjusting element is a displacement body that is inserted into the original clearance and displaces volume and distance equally there, i.e. reduces the distance that can be covered by the piston until a frictional torque is generated. By inserting the adjusting element, the original clearance is reduced and now represents the actual clearance that must be overcome during operation of the friction switching element in order to operate the friction switching element. The adjusting element to be used is selected from a large number of adjusting elements, each with a different thickness, for example there can be 20 different gradations of the thickness of the adjusting element. The adjustment element to be used is selected in accordance with the original clearance, with a relatively thick adjustment element being used if the original clearance is large and a comparatively thin adjustment element being used if the initial clearance is small, so that after the adjustment element has been inserted, all friction switching elements are approximately one have the same size of actual clearance, which is between a predeterminable upper limit for the actual clearance and a predeterminable lower limit for the actual clearance. The predeterminable upper limit and the predeterminable lower limit can preferably have a difference of 0.3 mm.

The original clearance is preferably measured during assembly of the friction switching element, in particular measured mechanically.

The clearance describes a distance, namely the distance that the piston in the pressure chamber has to cover from one end position in the pressure chamber to the opposite end position, whereby the friction switching element should not yet be actuated. In other words, the clearance represents the maximum distance that the piston can be away from the friction switching element, whereby the friction switching element should be depressurized. When the piston has overcome the clearance, it comes into contact with the friction switching element. If the piston or the pressure chamber continues to be pressurized, the piston begins to exert pressure on the friction switching element, which corresponds to the beginning of actuation of the friction switching element.

The friction switching element is advantageously actuated continuously.

According to the invention, it is now provided that the filling time is read out from a characteristic curve, the characteristic curve describing the filling time depending on the clearance.

The characteristic curve was advantageously determined experimentally on a series of essentially identical friction switching elements, which, however, have different clearances.

This results in the advantage that the filling time for overcoming the clearance is already known when the friction switching element in the automatic transmission is put into operation for the first time. The automatic transmission therefore offers a comparatively high level of shifting comfort right from the start, which, according to the prior art, can usually only be determined experimentally after a large number of filling processes of the pressure chamber.

This advantage also occurs without any significant additional effort, since after the one-time experimental determination of the filling times and the creation of the characteristic curve based on the series of friction switching elements, there is no further effort arises. Measuring the original clearance is necessary anyway in order to set the actual clearance to the intended level between the predeterminable upper limit and the predeterminable lower limit. Since the thickness of the inserted adjustment element is also known, the actual clearance can be determined based on the data that is already available.

The invention thus makes use of the knowledge that the filling time for identical friction switching elements is significantly influenced by the actual clearance and is essentially independent of other influences and tolerances.

According to a preferred embodiment of the invention, it is provided that the characteristic curve describes a linear relationship.

The characteristic curve is therefore a straight line and describes the relationship between filling time and actual clearance in a simple manner.

According to a further preferred embodiment of the invention, it is provided that the pressure fluid is at least partially conveyed into the pressure chamber under pressure modulation.

The pressure modulation advantageously includes a time-limited overshoot of the filling pressure in order to promote an increased volume flow into the pressure chamber during the overshoot and thus allow the piston to overcome the actual clearance comparatively more quickly. The pressure modulation is advantageously ended before the pressure chamber is completely filled, so that exactly the target pressure is present in the pressure chamber when the piston begins to apply force to the friction partners of the friction switching element.

Despite the pressure modulation and the associated variation in the volume flow, the filling time can be determined very precisely from the characteristic curve.

According to a further preferred embodiment of the invention, it is provided that the adjusting element is designed as a snap ring or as an end plate. Both forms of training are equally suitable for adjusting the actual clearance or for reducing the original clearance. The design as an end plate can preferably be used in a friction switching element designed as a multi-plate clutch, the end plate representing an axially outermost plate of the multi-plate clutch. The thicker it is, the further the original clearance can be reduced. An adjusting element designed as a snap ring can also be used to reduce the original clearance. The snap ring can be used, for example, to axially secure an element of the friction switching element, for example the axially outermost plate or the piston. Depending on how thick the snap ring is, it reduces the original clearance to a greater or lesser extent.

The snap ring and the end lamella can preferably also be used together and at the same time as an adjusting element, for example to reduce a particularly large original clearance.

The adjusting element, i.e. the snap ring or the end plate, can, for example, be available in ten, 15 or 20 different thicknesses.

According to a further preferred embodiment of the invention, it is provided that the actual clearance is stored in an electronic memory of an assembly control computer.

The assembly computer is a higher-level computer assigned to one or more production areas - such as the area of production of the complete automatic transmission - which stores a large number of properties of different assemblies, such as in particular a large number of friction switching elements.

The properties advantageously include at least the actual clearance, a pressure and a volume at which the actual clearance is overcome.

This results in the advantage that a later assembly of a large number of friction switching elements, for example in a large number of automatic transmissions, can be accompanied with information about the properties of the friction switching elements, since the properties of the mounted friction switching elements namely the respective automatic transmission in which a corresponding friction switching element is installed. can be assigned.

According to a particularly preferred embodiment of the invention, it is provided that the friction switching element is mounted in an automatic transmission and the automatic transmission is marked with an assignment which assigns to it the clearance in the electronic memory of the assembly computer.

The assignment is advantageously carried out electronically by assigning the clearance associated with the friction switching element to the data describing the automatic transmission in the assembly computer.

According to a further preferred embodiment of the invention, it is provided that the volume of the pressure chamber is verified experimentally by filling the volume with a hydraulic pressure medium.

Filling the volume of the pressure chamber with the hydraulic pressure medium results in the piston being axially displaced in the pressure chamber and beginning to exert pressure on the friction switching element. This in turn leads to an increasing frictional force between the friction partners of the friction switching element, so that increasingly more torque can be transmitted through the friction switching element as the pressure increases.

The pressure-related movement of the piston can, for example, be counteracted by one or more return springs, which push the piston back from the friction switching element when the pressure decreases.

By now measuring the pressure with which the volume is filled up to the point of the pressure-volume characteristic curve at which the actual clearance is overcome, i.e. up to the bend in the pressure-volume characteristic curve, this can be verified by means of a one-time measurement whether the assigned pressure-volume characteristic reliably describes the friction switching element.

If a deviation in the behavior of the friction switching element from the specific filling time is detected, the friction switching element can also be measured experimentally in a series of measurements. This represents a backup solution for determining the properties of the friction switching element.

According to a further preferred embodiment of the invention, it is provided that the determined filling time is stored in an electronic memory of the assembly control computer.

As a result, the friction switching element can be controlled largely optimally from the start during operation of the automatic transmission.

According to a further preferred embodiment of the invention, it is provided that the determined filling time is stored in an electronic control unit of the automatic transmission.

As a result, the friction switching element can be controlled largely optimally from the start during operation of the automatic transmission.

According to a further preferred embodiment of the invention, it is provided that the characteristic curve is determined based on the filling times and the clearances of a large number of reference friction switching elements.

As has already been described, the reference friction switching elements and the friction switching element to be adjusted are advantageously identical friction switching elements. Thus, the characteristic curve determined once on a large number of reference friction switching elements can be transferred to the friction switching element to be adjusted.

The characteristic curve preferably represents a characteristic curve averaged over all individual measurements.

According to a further preferred embodiment of the invention, it is provided that the pressure-volume characteristic curve is further adapted to the friction switching element during operation of the automatic transmission by additional measurements of the filling time.

This means that a control unit of the automatic transmission continues to record the filling times during operation of the automatic transmission and further improves the control of the friction switching element based on this recorded information. This means that increasing wear of the friction partners of the friction switching element during operation can also be taken into account, which leads to increasing clearance.

The invention is explained below by way of example using the embodiments shown in the figures.

• 1 beispielhaft und schematisch eine mögliche Ausführungsform eines erfindungsgemäßen Verfahrens zum Bestimmen einer Füllzeit eines Druckraums eines hydraulisch aktuierten Reibschaltelements mit einem Druckfluid in Form eines Flussdiagramms,
• 2 beispielhaft und schematisch eine Vielzahl von Messpunkten, die an einer Vielzahl von Referenz-Reibschaltelementen ermittelt wurden und
• 3 beispielhaft und schematisch eine mögliche Ausführungsform eines erfindungsgemäßen Verfahrens zum Bestimmen einer Füllzeit eines Druckraums eines hydraulisch aktuierten Reibschaltelements i mit einem Druckfluid n Form eines weiteren Flussdiagramms.

Show it:

• 1 By way of example and schematically, a possible embodiment of a method according to the invention for determining a filling time of a pressure chamber of a hydraulically actuated friction switching element with a pressure fluid in the form of a flow diagram,
• 2 By way of example and schematically, a large number of measuring points that were determined on a large number of reference friction switching elements and
• 3 By way of example and schematically, a possible embodiment of a method according to the invention for determining a filling time of a pressure chamber of a hydraulically actuated friction switching element i with a pressure fluid n in the form of a further flow diagram.

The same objects, functional units and comparable components are designated with the same reference numerals across the figures. These objects, functional units and comparable components are identical in terms of their technical features, provided that: nothing else emerges explicitly or implicitly from the description.

1 shows by way of example and schematically a possible embodiment of a method according to the invention for determining a filling time t of a pressure chamber of a hydraulically actuated friction switching element with a pressure fluid in the form of a flow chart.

In a first method step 100, an original clearance x of a friction switching element is measured mechanically. The friction switching element is, for example, a multi-plate clutch whose end plate has not yet been inserted. The original clearance x is therefore the clearance without the end slat.

Depending on the result of the measurement of the original clearance, i.e. depending on the size of the clearance x, a suitable end slat is now selected in step 101 and inserted into the original clearance x, which reduces the original clearance x to such an extent that the remaining clearance x, i.e the actual clearance clearance is between a predeterminable upper limit for the actual clearance clearance x and a predeterminable lower limit for the actual clearance clearance x.

The end slat is selected according to its thickness and represents the adjusting element for setting the actual clearance x.

In the following step 102, the actual clearance x is now calculated based on the measured original clearance x and the known thickness of the end lamella.

In method step 103, the actual clearance x is stored in an electronic memory of an assembly control computer.

In step 104, the required filling time t is then read out from a characteristic curve, the characteristic curve describing the filling time t depending on the clearance x.

In step 105, the determined filling time t is stored in an electronic memory of the assembly control computer.

In step 106, the friction shift element is then mounted in an automatic transmission.

At the same time, in step 107, the automatic transmission is marked with an assignment, for example a barcode, which assigns to it the clearance x in the electronic memory of the assembly computer.

Finally, in step 108, the determined filling time is stored in an electronic control unit of the automatic transmission, so that the automatic transmission can actuate the friction switching element comparatively precisely from the start via the control unit.

2 shows, by way of example and schematically, a large number of measuring points 10, 11, 12, 13, 14, 15, 16, 17, which were determined on a large number of reference friction switching elements. Each measuring point 10, 11, 12, 13, 14, 15, 16, 17 assigns a filling time t (y-axis) to the actual clearance x (x-axis) of the respective reference friction switching element. All measuring points 10, 11, 12, 13, 14, 15, 16, 17 lie between a predeterminable upper limit 21 for the actual clearance x and a predeterminable lower limit 22 for the actual clearance x.

As can be seen, the filling time t increases essentially linearly with the actual clearance x. This linear relationship is illustrated by a straight line 20, which represents the characteristic curve 20 determined according to the invention. Since the straight line 20 assigns a filling time t to each clearance in the area between the predeterminable upper limit 21 and the predeterminable lower limit 22, the appropriate filling time t can be easily read out for each friction switching element using the straight line 20.

3 shows by way of example and schematically a possible embodiment of a method according to the invention for determining a filling time t of a pressure chamber of a hydraulically actuated friction switching element with a pressure fluid in the form of a further flow diagram.

In steps 200, a first friction switching element, a second friction switching element and a third friction switching element are mounted and their original clearance x is measured and an adjusting element is inserted.

In step 201, the calculated values of the actual clearances x are stored in an electronic memory of an assembly control computer.

In steps 202, the first friction shift element, the second friction shift element and the third friction shift element are assembled into an automatic transmission.

At the same time, in step 203, the automatic transmission is assigned to the respective clearances x of the first friction-shifting element, the second friction-shifting element and the third friction-shifting element.

In step 204, the volume of the pressure chambers is experimentally verified by filling the volumes with a hydraulic pressure medium.

In step 205, an electronic file is generated which describes the verified clearances x and also assigns them to the automatic transmission.

In step 206, a file that can be read by an electronic control unit of the automatic transmission is generated from the file.

Finally, in step 207, an electronic memory of the control device is flashed using the file that can be read by the control device. By flashing the electronic memory, the determined filling time t is stored in the electronic control unit of the automatic transmission. This means that the automatic transmission can precisely actuate the friction switching element from the start via the control unit.

Reference symbols

10

Measuring point

11

Measuring point

12

Measuring point

13

Measuring point

14

Measuring point

15

Measuring point

16

Measuring point

17

Measuring point

20

Characteristic curve, straight line

21

predetermined upper limit

22

predeterminable lower limit

100

Measuring the original clearance

101

Selecting and inserting an adjustment element

102

Calculating the actual clearance

103

Storing the actual clearance in an electronic memory of an assembly control computer

104

Reading out the filling time t from a characteristic curve

105

Storing the determined filling time t in an electronic memory

106

Mounting the friction shift element in an automatic transmission

107

Marking the automatic transmission with an assignment that assigns it the clearance in the electronic memory of the assembly computer.

108

Storing the determined filling time t in an electronic control unit of the automatic transmission

200

Assembly of a first, second and third friction switching element and measurement of the original clearance in each case

201

Storing the calculated values of the actual clearances in an electronic memory of an assembly control computer

202

Assembly of the first, second and third friction shifting elements in an automatic transmission

203

Assignment of the automatic transmission to the respective clearances of the first, second and third friction switching elements

204

Experimentally verifying the volumes of the pressure chambers by filling the volumes with a hydraulic pressure medium

205

Creating an electronic file that describes the verified air clearances and assigning the file to the automatic transmission

206

Generating a file that can be read by an electronic control unit of the automatic transmission

207

Flashing an electronic memory of the control unit using the file readable by the control unit

x

air clearance

t

Filling time t

QUOTES INCLUDED IN THE DESCRIPTION

This list of 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.

Cited patent literature

• DE 102005051146 A1 [0003]
• DE 102015225063 A1 [0004]

Claims (11)

Method for determining a filling time t (t) of a pressure chamber of a hydraulically actuated friction switching element with a pressure fluid, wherein an original clearance of the friction switching element is measured (100, 200) and wherein the original clearance is reduced to an actual clearance by inserting an adjusting element of a predetermined thickness ( x) is reduced (101), characterized in that the filling time t (t) is read out (104) from a characteristic curve (20), the characteristic curve (20) describing the filling time t (t) depending on the clearance (x). . Procedure according to Claim 1 , characterized in that the characteristic curve (20) describes a linear relationship. Method according to at least one of the Claims 1 and 2 , characterized in that the pressure fluid is at least partially conveyed into the pressure chamber under pressure modulation. Method according to at least one of the Claims 1 until 3 , characterized in that the adjusting element is designed as a snap ring or as an end plate. Method according to at least one of the Claims 1 until 4 , characterized in that the actual clearance (t) is stored in an electronic memory of an assembly control computer (103, 201). Procedure according to Claim 5 , characterized in that the friction switching element is mounted in an automatic transmission (106, 202) and the automatic transmission is marked with an assignment which assigns to it the clearance in the electronic memory of the assembly computer (107, 203). Method according to at least one of the Claims 1 until 6 , characterized in that the volume of the pressure chamber is verified experimentally by filling the volume with the pressure fluid (204). Method according to at least one of the Claims 5 until 7 , characterized in that the determined filling time t (t) is stored in an electronic memory of the assembly control computer (103). Method according to at least one of the Claims 1 until 8th , characterized in that the determined filling time t (t) is stored in an electronic control unit of the automatic transmission (108, 206). Method according to at least one of the Claims 1 until 9 , characterized in that the characteristic curve (20) is determined based on the filling time ten (t) and the clearances (x) of a large number of reference friction switching elements. Method according to at least one of the Claims 1 until 10 , characterized in that the filling time t (t) is further adapted to the friction switching element during operation of the automatic transmission by additional measurements of the filling time t (t).

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