GB2302151A

GB2302151A - A clutch/brake actuating system having induced ventilation

Info

Publication number: GB2302151A
Application number: GB9612549A
Authority: GB
Inventors: Thomas Rammhofer
Original assignee: LuK Getriebe Systeme GmbH
Current assignee: LuK Getriebe Systeme GmbH
Priority date: 1995-06-14
Filing date: 1996-06-14
Publication date: 1997-01-08
Anticipated expiration: 2016-06-14
Also published as: DE19622572A1; GB2302151B; GB9612549D0; DE19622572B4; BR9602787A

Abstract

A clutch/brake actuating system 40 comprises a sender cylinder 50, having a ventilation device 51, mounted at a lower level than a receiver cylinder 53. The cylinders are connected via a tubular transfer section 52 having a cascade shaped path with falling regions 63 and rising regions 62. Air bubbles, due to buoyancy, collect at point A and are transported, when the sender cylinder 50 is actuated via controller (13, fig 1) which receives signals from various sensors, at a first speed in the direction of arrow P to position B. From B, if no further actuation occurs, buoyancy will cause the bubbles to move to position C. The distance between A-C is such that actuation of the sender cylinder 50, against arrow P, will result in the bubbles moving at a second lower speed to point B', thereby preventing the bubbles returning to point A. When a vehicle is, for example, stopping or starting the sender cylinder 50 is operated by the controller (13, fig 1) so that the bubbles may be transported the full length of the transfer section 52 into the sender cylinder 53 where they can be automatically ventilated by the ventilation device 51.

Description

DEVICE AND PROCESS FOR OPERATING TORQUE TRANSFER SYSTEMS The invention relates to a device with a pressurised medium transfer system, such as for example a hydraulic system, more particularly for operating or controlling a torque transfer system or a brake, such as for example a pressure plate or a plate spring or a disengagement bearing eg a friction clutch, with a sender cylinder, a receiver cylinder, as well as a transfer section between sender and receiver cylinders and a ventilation device with a central control or computer unit in signal connection with at least one sensor and/or at least one further electronics unit, and with an actor controllable by the control unit for operating the sender cylinder.

Devices of this kind with hydraulic systems are known for example in vehicles, such as motor vehicles, or in stationary systems. In vehicles hydraulic systems of this kind are used for example in brake installations or torque transfer systems, such as for example, friction clutches.

Clutch units having a control or operation by means of a hydraulic system have as a rule a sender and a receiver cylinder wherein the sender and receiver cylinders are in fluid connection with each other by means of a tubular component part, such as a transfer section. The sender cylinder or position of the sender cylinder piston can be controlled or regulated by a manual or automated operation wherein the output part of the receiver cylinder can act on the clutch directly or indirectly through for example a gear rod linkage and the clutch can thereby be set in a position which can lie between a fully engaged state and fully disengaged state. The clutch can thus be completely engaged or completely disengaged or can be set at an intermediate position. Hydraulic systems for automated control of clutch systems are known for example through DE-OS 401 185 0.

Hydraulic systems can have a sender and a receiver cylinder wherein a ventilation or snifting device can be provided on the sender or receiver cylinder. With these systems an arrangement of the ventilation device can be provided on a hydraulic cylinder, such as a sender cylinder which is set on a higher level viewed in the direction of the buoyancy force or against the gravitational force. It is thereby achieved that gas volumes present or entering the hydraulicfluid-filled device move in the direction of the ventilation device.

The object of the invention is to provide a safe costeffective ventilation of a system of the above kind.

Furthermore the object is to provide a device of the above kind which can be ventilated substantially during normal operation or during normal functioning.

The object of the invention is further to provide a device and process for same as well as a component part in order, with an arrangement of the ventilation device on the hydraulic cylinder which is mounted on a lower level or the hydraulic section has a local maximum and the ventilation device lies on a lower level than this local maximum of the hydraulic line, to reach a substantially independent or induced ventilation of the device. Furthermore with the device according to the invention and the process according to the invention it is to be achieved that the placing of the hydraulic cylinder with ventilation device can be effected at least substantially anywhere wherein the design of the hydraulic line should make it possible to overcome obstacles such as for example other assemblies, in the connection.Thus an obstacle in the path of the hydraulic line can also be overcome or avoided wherein the sender cylinder can be mounted in substantially any position wherein the structural space must however be taken into consideration.

A further object of the invention is to improve the above devices and processes according to the prior art in order to obtain higher functioning reliability and to provide safer operating of the above devices with lower costs.

According to the inventive idea this is achieved in that the transfer section is designed as a substantially tubular component so that it ensures a fluid connection between sender and receiver cylinder and has at least two or more regions wherein at least one region has a rising path and at least another region has a falling path and the actor activates the sender cylinder into a first and second direction, that a transport of the fluid column takes place in different directions along the transfer section at different speeds, that the device is ventilated automatically at least occasionally by means of controlling the control unit.

Furthermore this is achieved according to the inventive idea in that the transfer section is designed as a substantially tubular component part so that it ensures a fluid connection between sender and receiver cylinder and has at least two or more regions wherein at least one region has a rising path and at least another region has a falling path and the device is operated by means of a control process and is automatically ventilated at least temporarily. The control of the sender cylinder is undertaken so that gas volumes are transported in the hydraulic system in the area of a rising region owing to the buoyancy force in the direction of the ventilation device and are transported with the fluid over areas with falling path by means of a controlled sender cylinder lift.

Furthermore it can be advantageous if the sender and receiver cylinders are mounted at least substantially on different levels and the ventilation device is mounted on the hydraulic cylinder which is located on a lower level or is attached there and a ventilation of the device or a transport of gaseous substances is carried out at least over regions of the transfer section against the buoyancy force.

It can be expedient if the hydraulic line between the sender and receiver cylinders ensures a fluid connection and a ventilation or snifting device is mounted on a hydraulic cylinder and the hydraulic line is designed so that a local maximum is present and a ventilation of the device or a transport of gaseous substances is carried out at least over regions of the transfer section against the buoyancy force.

Likewise it is advantageous if the design according to the invention provides that the ventilation device is mounted on the sender cylinder and the sender cylinder with the ventilation device is mounted at least substantially on a lower level than the receiver cylinder without ventilation device.

According to the inventive idea it is advantageous if the transfer section has at least in one section at least two types of regions wherein one first type of regions has a rising path and a second type of regions has a falling path and the regions with rising or falling path are mounted at least substantially alternately or in alternation. The pitches of the individual regions with rising path and with falling path can vary according to requirements. This means that the relevant pitches of the regions with rising and falling paths can be adapted to the relevant existing system or each relevant structural space.

Furthermore it is advantageous with a design according to the invention if the regions of the transfer path which viewed in the direction of the hydraulic cylinder with ventilation device has a rising path overcome an at least substantially lower height difference than the regions with falling path and/or the regions of the transfer section, which viewed in the direction of the hydraulic cylinder with ventilation device have a rising path, extend over at least substantially longer route paths than the regions with falling path.

It can likewise be advantageous if the regions of the transfer path, such as hydraulic line which viewed in the direction of the hydraulic cylinder with ventilation device have a rising path, extend over substantially shorter route paths than the regions with falling path.

It is particularly advantageous if the transfer section is designed as a hydraulic line with a cascade-shaped path with rising and falling regions wherein the areas with rising or falling path at least substantially alternate.

Furthermore it can be expedient if the actor is a controllable operating element which can be controlled by means of the control unit. Furthermore it can be expedient if the actor is an electromotor-driven actor. Similarly the actor can be drivable electromagnetically or hydraulically or the actor can have a drive element, such as an electromotorized, magnetic, electromagnetic or hydraulic drive element.

According to a further inventive idea relating to a process for controlling a torque transfer system with a hydraulic system with a sender and a receiver cylinder and a transfer section, such as a tubular component part, with a control unit and a setting member for controlling the sender cylinder, it is advantageous if the control of the sender cylinder is carried out so that a transport is guaranteed of at least substantially gas volumes inside the fluid-filled hydraulic system in the direction of the hydraulic cylinder with ventilation device wherein the hydraulic cylinder with ventilation device is mounted for example on a lower level than the hydraulic cylinder without ventilation device or however the hydraulic section runs through a local maximum and a ventilation device is mounted below this maximum and the gas volumes have to be transported at least over regions against the effective buoyancy force. With the process according to the invention it can furthermore be advantageous if gas volumes are transported with the fluid inside the fluid-filled hydraulic system within or along the falling regions, viewed in the direction of the hydraulic cylinder, through lift movements of the sender cylinder piston.

It can likewise be advantageous if the displacement of the fluid column caused by the lift of the sender cylinder piston is controlled so that the amount of displacement is greater than the length of a partial stretch of the transfer section with falling path and/or smaller than the length of a partial stretch of the transfer section with rising path.

It can furthermore be expedient if the displacement of the fluid column caused by the lift of the sender cylinder piston is controlled so that the amount of displacement is greater than the length of a stretch with at least two falling regions and at least one rising region mounted inbetween or is greater than n-times a stretch of a falling path plus (n-l)-times a stretch with rising path.

Furthermore it can be advantageous if after a lift movement of the sender cylinder piston for transporting the fluid column and/or gas volumes in the direction of the ventilation device and/or in the opposite direction there follows a time length without lift of the sender cylinder piston. It can thereby be advantageous if this time length is selected in dependence on a mean rising speed of the gas volumes in the fluid. Furthermore it can be advantageous if material properties of the fluid are taken into account when determining the waiting time. More particularly the viscosity, temperature, absorption capacities of gases in the fluid or pressure can be taken into consideration in order to determine the waiting time between two lift movements.

It can likewise be expedient if the amount of speed of the sender cylinder piston and/or the amount of speed of the movement of the fluid column in the direction of the ventilation device is greater than the amount of the speed of the movement of the fluid column in the opposite direction. Furthermore it can be expedient if in operating states or situations with an engaged neutral gear position a temporary deliberate control of the sender cylinder is carried out in order to implement a deliberate transport of gas volumes in the direction of the ventilation device or a ventilation of the hydraulic system.

According to a further inventive idea it can be particularly advantageous if with a transferable torque of a torque transfer system, such as a clutch with a control according to torque matching, controlled according to the torque arising on the motor side, the torque transfer system is deliberately controlled in a working area between the partially engaged state and the fully engaged state in order to achieve through the movement of the sender cylinder piston a deliberate transport of gas volumes in the direction of the ventilation device or a ventilation of the hydraulic system.

According to a further inventive idea it can be particularly advantageous if with torque transfer systems with a control according to torque matching a control of the sender cylinder takes place for the purpose of ventilation in noncritical situations and/or operating states.

Similarly it can be particularly expedient according to a further inventive idea if the starting and/or switch-off process, as well as stationary phases and/or rolling phases in neutral position and/or in situations with torque matching belong to the non-critical situations for carrying out the sender cylinder control for deliberate transport of gas volumes in the direction of the ventilation device or for ventilation and in these situations a control is carried out for deliberate ventilation.

According to a further inventive idea it is advantageous to provide a tubular component part with a first and second connection or connecting area to produce a fluid connection between two hydraulic elements such as for example sender and receiver cylinders, so that the tubular component is comprised of regions with rising and falling paths or is so designed with the regions being at least substantially alternating. It is likewise expedient if by means of the component part a difference in height is bridged and at least in one section of the component the regions with falling path overcome a greater height difference than the regions with rising path.

The invention will now be explained in further detail with reference to the drawings in which: Figure 1 is a schematic diagram of a vehicle; Figure 2 is a block circuit diagram of a transfer section; Figure 3 is a cut-out section of the transfer section; Figure 4 is a path-time diagram; Figure 5 is a cut-out section of a transfer section; Figure 6 shows a transfer section and Figure 7 is a block circuit diagram.

Figure 1 shows a vehicle 1 with a drive machine 2 such as an internal combustion engine or motor. Furthermore a torque transfer system 3 and gearbox 4 are shown in the drive train of the vehicle. In this embodiment the torque transfer system 3 is mounted between the drive unit 2 and gearbox 4 so that a drive torque of the motor can be transferred through the torque transfer system 3 to the gearbox 4 and from the gearbox 4 on the output side to an output shaft 5 and/or an axle 6 mounted on the output side.

The torque transfer system 3 is designed as a clutch, such as a friction clutch, which can be a self-adjusting clutch adjusting itself in response to clutch wear.

The gearbox 4 is designed as a manual transmission wherein however an automatic transmission such as stepped automatic or continuously variable gearing can also be used. The automatic transmission can also be fitted with a torque transfer system mounted on the output side, such as a clutch and/or friction clutch. The torque transfer system can furthermore be fitted as starting clutch or torque converter with bridging clutch and/or safety clutch and/or turning set clutch with deliberately controllable transferable torque.

The torque transfer system 3 has a drive side 7 and output side 8 wherein an adjoining torque is transferred from the drive side 7 to the output side 8.

The control of the torque transfer system is carried out by means of a control unit 13 which can comprise an actor and the control electronics. The actor can consist of a drive motor 12, such as electromotor, wherein the drive motor 12 acts on a sender cylinder 11 through a gearing 21, such as worm gearing, as well as through a ram rod or crank 22. The movement of the ram 22 or sender cylinder piston is detected by a route sensor 14. The route sensor such as clutch route sensor can be for example a potentiometer or an inductive sensor or echo effect sensor or an optical sensor. The sender cylinder 11 is connected to the receiver cylinder 10 through a transfer section 9 such as a hydraulic line.The sender cylinder 10 can be in active connection with a disengagement means 20 wherein the movement of the output part of the sender cylinder can control the disengagement means 20 in order to deliberately control the torque transferable by the clutch 3. Furthermore the sender cylinder can be designed as a central disengagement member and can control the torque transfer system directly or indirectly. The disengagement means controlled by the output part of the sender cylinder can support a disengagement bearing by means of which for example the friction clutch is operated.

With a torque transfer system such as a friction clutch the control of the transferable torque is carried out by a deliberate contact pressure of the clutch disc between the flywheel and pressure plate. Through the position of for example the disengagement means 20 it is possible to deliberately control the force biasing of the pressure plate or friction linings wherein the pressure plate can be moved between two end positions and can be fixed in any setting between the two end positions.

One end position corresponds to a fully engaged clutch position and the other end position corresponds to the disengaged clutch position.

In order to control a transferable torque which is for example less than the momentary arising engine moment, a position of the pressure plate can be controlled for example which lies in an intermediate area between the two end positions. However transferable clutch moments can also be controlled which lie defined above the relevant ensuing momentary engine moment.

A torque transfer system such as a friction clutch is as a rule designed so that the maximum transferable torque lies a certain factor, for example greater than 1.5, above the nominal engine moment. Accordingly with a fully engaged clutch an excess contact pressure prevails since in most operating states the nominal engine moment on the input side does not adjoin the torque transfer system. By means of moment matching, ie deliberate control of the transferable torque through the torque transfer system the transferable torque can be adapted to the adjoining engine moment, wherein a slight excess contact pressure or a slight underpressure can be deliberately used.

Moment matching of the transferable torque has inter alia the advantage that the clutch is substantially closed only so far as conditioned by the momentary ensuing engine moment and a reaction can thus be carried out faster in relation to a further opening or closing of the clutch. Moment matching with a slight excess contact pressure allows transfer of the momentary ensuing engine moment and ensures the damping of torque irregularities which extend beyond the transferable torque of the torque transfer system since with such torque irregularities the torque transfer system begins to slip.

In order to control the torque transfer system signals are used which substantially represent or characterize the operating state of the vehicle and which are dependent on the relevant characteristic parameters of the system. The sensors which detect the operating parameters, indicate and bring about correspondingly dependent signals, are in signal connection with the central control or electronics unit wherein the central control or electronics unit likewise can be in connection with further electronic units, such as eg an electronics unit of an ABS system, of the electronic engine management or anti-slip regulation.

The embodiment of Figure 1 shows that for example a throttle valve sensor 15, engine speed sensor 16 and tacho sensor 17 are used and supply measured values or data to the control unit. Furthermore the manual transmission gear 4 has an operating lever 18 on which is mounted or attached for example a sensor or a sensor system for recognizing the gear and/or switching intent. Furthermore a sensor 23 or a sensor system can be mounted in the area of the gearbox 4 for identifying the actual gear position and/or switching intent. The control unit comprises with its worm gear and crank and sender cylinder 11 also a position sensor 14 which detects directly or indirectly the position of the sender cylinder piston. From the position of the sender cylinder piston it is possible by means of the physical properties and/or characteristic values of the transfer section 9, 10, 20 to determine or calculate the engaged position of the torque transfer system or the torque transferable by the torque transfer system. Similarly a clutch position sensor can be mounted or attached directly on the operating means or for example on the pressure plate.

The control apparatus 13 is in signal connection at least timewise with the sensors or with the other attached electronic units and sends to the motor 12 of the operating device, such as electromotor, for clutch activation or for setting the transferable torque a setting value in dependence on the measured values and/or system input values and/or signals of the attached sensor system and/or of the implemented control or regulating process. To this end a control program is implemented as hard- and/or software in the control process 13. With a drive moment adjoining the operating point and which is determined or calculated from the system input values, a setting position is calculated or allocated to the setting member and a setting value is provided for the electromotor which controls same.The active connection between the sender cylinder 11 and receiver cylinder 10, such as hydraulic line, leads to a movement of the sender cylinder piston leading to a transfer of the movement to the setting means 20 and the clutch being controlled according to the setting value given.

In the embodiment illustrated in Figure 1 with a senderreceiver cylinder system a solution is shown by means of a hydraulic line which in another embodiment can also be designed in a different manner and way.

The transfer behaviour of the hydraulic transfer section 9, 10, 11 is dependent on the actual operating parameters. The fluid column in the hydraulic line can have for example operating parameters which are modified in dependence on temperature, such as eg have a changed volume, compressibility or density as a function of the temperature.

Furthermore the stiffness of the hydraulic system can be changed as a function of the operating parameters, such as for example the absorption capacity of gases, such as air in the hydraulic fluid as a function of temperature or pressure. At the same time the material of the hydraulic system, such as eg the hydraulic line, is also subjected to external influences. This can cause for example a change in volume of the hydraulic lines as a function of the temperature.

With hydraulic systems having a sender and receiver cylinder the appearance of substantially gaseous materials such as for example air into the hydraulic system cannot always be ruled out. Through the entrance of air or another gaseous substance into the hydraulic system, changed conditions can arise for example in relation to the stiffness of the transfer section since the gaseous proportion inside the hydraulic line shows a different mechanical behaviour compared with the fluid. In this connection for example mention is made of the variable compressibility.

Furthermore there is the possibility that when filling the hydraulic system with the hydraulic fluid gas residues can remain in the system which during filling stick for example to the walls of the hydraulic system.

It is equally possible that small amounts of gas can penetrate into the hydraulic system during the operating of the system wherein functional reliability of the system can be maintained at least for a time with slight leakages. A further possibility for gas entering in slight amounts can be a temporary unsealed area caused by the operation but which can occur for example only under quite special operating conditions such as movements of a hydraulic cylinder The amount of gas or gas volumes which have penetrated into the hydraulic system can be removed by a device for ventilating the hydraulic system in order to ensure optimum functioning reliability of the hydraulic system.

In the case of an arrangement of the ventilation or snifting devices in an area on the uppermost level of the hydraulic system in relation to the buoyancy force or gravitational force the amount of gas located in the hydraulic system can move through buoyancy from the relevant local position up to the ventilation device. This movement in the direction of the ventilation device can automatically take place in such an event where the gas bubbles arising in the fluid move relative to the fluid column.

The automatic movement of gas volumes, such as gas bubbles, in the fluid as a result of buoyancy is dependent on the density difference between the density of the fluid and the density of the gas and on the volume of the gas volumes.

With an arrangement of the hydraulic cylinder with the ventilation device substantially at a position on the lower level for example relative to the level of the overall hydraulic system, the movement of the gas volumes to the ventilation device cannot take place automatically owing to the buoyancy force. The gas volumes collect for example at a position of the transfer section with a local maximum level.

With an arrangement of the ventilation device in an area on a lower level, a deliberate displacement or deliberate transport of the gas volumes has to be carried out within and/or with the hydraulic fluid so that a deliberate transport of the gas volumes can also take place against the buoyancy force towards to the ventilation device. This deliberate transport can take place through a deliberate control of the sender cylinder by means of a control process.

Figure 2 shows a block circuit diagram of an embodiment according to the invention wherein only the hydraulic system with torque transfer system is shown and the installation point, such as for example inside a vehicle, is not shown.

The hydraulic system 40 consists of a sender cylinder 50, a ventilation device 51, which can be mounted on the sender cylinder, a transfer section 52, such as a hydraulic line, and a receiver cylinder 53. Through the position of the sender cylinder piston 54 it is possible to control by means of a hydraulic transfer the position of the sender cylinder piston 55. The control of the sender cylinder 50 and sender cylinder piston is carried out by a setting member 56 which is in signal connection with a control or electronics unit.

Furthermore the control or electronics unit 57 can be in connection with further electronics units, such as for example an engine electronics unit and/or a control electronics unit of an anti-blocking system and/or an antislip regulation and/or an electronic driving dynamics control. The control or electronics unit is furthermore in signal connection with sensors which each detect certain operating parameters and from this data determine or calculate the operating state. As sensors for determining the operating state or actual operating point can be used for example temperature sensors and/or speed sensors and/or sensors of a gear recognition unit and/or wheel speed sensors and/or position sensors for detecting the position of the clutch sender cylinder or the throttle valve position or further sensors.

The output part of the receiver cylinder, such as for example piston or crank, controls the torque transfer system 58 directly or indirectly by means of a transfer unit.

The transferable torque which can be transferred by a torque transfer system is determined and controlled for example in a friction clutch by the degree of engagement. In the embodiment of Figure 2 the position of the receiver cylinder piston has an effect on the engagement position of the torque transfer system 58 wherein the engagement position of the torque transfer system can be set and/or fixed between the two end areas or end positions of a fully engaged or fully disengaged state.

The arrangement of the sender cylinder 50 with ventilation device 51 is mounted in the embodiment of Figure 2 at least substantially on a lower level than the receiver cylinder 53.

Between the sender and receiver cylinders is the transfer section 52, such as a hydraulic line, which produces a fluid connection between the two hydraulic cylinders wherein the transfer section is designed so that a difference in level between the hydraulic cylinders is deliberately overcome by the shaping.

The transfer section 52 of the hydraulic system is as shown in Figure 2 fitted in a cascade construction with several substantially similar type sections 59. The substantially similar areas 59 are composed from two regions 62 and 63 wherein the section 62 has a rising path, viewed in the direction of the ventilation device, and the section 63 has a falling path, viewed in the direction of the ventilation device.

If amounts of gas or gas volumes are present in the transfer section which enter into the system for example at an unsealed area of the receiver cylinder, then these gas volumes cannot automatically pass to the ventilation device as a result of the buoyancy force. In this case the gas volumes would collect in the area with the locally highest level and form a larger gas bubble. Such an area for a collection of gas volumes is always in the area of the local maximum between a rising region 62 and a falling region 63.

An arrangement of the hydraulic cylinder with ventilation device on a level which is below the level of the hydraulic system without ventilation device can be necessary for example as a result of the structural space available.

The transfer section 52 with its regions 62 and 63 must be adapted to the overall height difference and to the route difference between the sender and receiver cylinders wherein a deliberate ventilation of the hydraulic system should be possible.

Figure 3 shows a cut-out section of the transfer section 52, such as hydraulic line, with a falling region 63 and a rising region 62. The height difference overcome by the transfer section in the area of the falling path 63 is greater than the height difference h2 in the area of the rising path 62. Furthermore it can be seen that the route stretch of the transfer section in the area of the falling path 63 from A to B is less than the route stretch in the area of the rising path 62 from B to C.

If a gas volume, such as air bubble, is present for example at point A of the transfer section then this gas volume is kept as a result of buoyancy at the locally highest spot A and an automatic transport in the direction of the ventilation device, in the direction of arrow P, is prevented.

If by means of the control device and the control process according to the invention there follows a deliberate lift of the sender cylinder piston and thus a deliberate movement of the fluid column in the direction of arrow P then an air bubble can be transported from position A into position B wherein the transport of the gas volume is carried out with the fluid column and in the falling region against the buoyancy force. If the sender cylinder piston then remains for a certain period of time in a stationary position then the air bubble can be automatically displaced or transported from position B in the direction of position C through the buoyancy force.

The piston stroke of the sender cylinder can also be dimensioned and controlled in at least some operating points so that a gas volume, such as an air bubble, is moved along with the fluid column and for example covers the stretch from A to D or covers a multiple of the stretch from A to D so that for example a stretch is covered by the multiple of a cascade from A to C.

The stretch from B to C is dimensioned so that with a stroke of the sender cylinder piston against the transport direction P, the gas volume, such as air bubble, is moved from position C not beyond position B. By making the length of the area 62 in this way the gas bubble is prevented from moving from area 62 into area 63 and being transported automatically in area 63 in the direction of point A. If now the gas bubble is moved from point C to point B' as a result of a piston stroke of the sender cylinder, then in a following stationary phase the gas bubble can again rise in the direction of position C.

If the gas bubble is located in position C then with a following piston stroke of the sender cylinder piston in direction D a further transport can be carried out into the next cascade of the hydraulic line.

A control of the torque transfer system for deliberate ventilation of a transfer section can take place in the operating points where a control for this purpose encounters no problems, or only a slight or no impairment to the comfort occurs through an adjustment of the torque transfer system. Such operating points are for example starting processes or stopping processes of the vehicle. In such stationary or quasi-stationary operating conditions a deliberate control of the sender cylinder can be carried out in order to undertake a ventilation of the hydraulic system.

With a starting process at least a sender cylinder stroke can take place for example before release for starting the engine. The stroke path can be selected in dependence on the operating state. If for example with an engaged gear the clutch is closed completely or with partial load before the motor is started, then a parking lock is effected which stops the vehicle from rolling away on an incline for example. The controlled stroke path can be dimensioned after detecting the parking lock operating state by means of the control system and position sensors for the gear and clutch position so that the transferable torque is sufficiently great to ensure the vehicle is stationary. If a parking lock has been detected as not active by the control system then the full stroke of the sender cylinder piston can be controlled. A further design can provide that a stroke of the sender cylinder only takes place after neutral gear has been engaged.

During stopping processes when the motor, such as an internal combustion engine, is running, a control of stroke movements is possible so that in the case of control processes with or without creeping of the vehicle the stroke is utilized whereby only a slight or no torque is transferred on the output side before a starting process is initiated not on the driver's side.

With a control process with moment matching it is also possible to carry out a control for ventilation purposes in a driving situation. With a control with moment matching the torque transferable by the torque transfer system is set each time in dependence on the torque arising on the motor side wherein the set moment is as a rule lower than the nominal moment of the internal combustion engine. In an operating point with moment matching the sender cylinder can for example be controlled so that a variation of the momentarily transferable torque takes place wherein the transferable torque does not drop far beyond the ensuing torque or beyond the originally set torque. The controlled transferable torque can be increased in such an operating point to the maximum transferable torque or can fluctuate between the actual value and the maximum value.

The deliberate control of the movement of the sender cylinder piston for transporting gas volumes in the direction of the ventilation device can be carried out by means of a time-controlled processed.

Figure 4 shows a path-time diagram of an embodiment which reproduces the time path of a deliberate control. In phase I there is a deliberate displacement of the gas volumes with the fluid column in the direction of the ventilation device.

In phase II the position of the sender cylinder piston is held at least substantially stable or constant. In this phase a gas volume which is located in the area of point B in Figure 3 can be transported and/or automatically moved in the direction of point C by means of the buoyancy force.

Phase III shows a movement of the sender cylinder piston in the opposite direction. The amount of the speed in phase III is lower in comparison with the speed in phase I. As a result of this lower speed a transport df gas volumes in the hydraulic line against the buoyancy force cannot take place to the same extent as with higher speeds. Thus it can be reached that the gas volumes in the area of point C are not transported back up to point B. Furthermore it is advantageous if after phase III an at least substantially stationary phase IV occurs and gas volumes which were transported in phase III somewhat in the direction of point B can again move in the direction of point C.

The different speeds in phase I and III are distinguished in that the transported amount of gas is a function rising substantially with the speed of the fluid. If the fluid flows very rapidly then gas volumes are carried along and transported with the fluid stream, but if the fluid flows more slowly then the fluid can also flow in part round the gas volumes and transport is diminished.

Figure 5 shows a cut-out section from a transfer sect ion, such as a hydraulic line, wherein the position or spot marked A'' corresponds to the position marked A in Figure 3.

A difference in height is overcome from position A'' to position B'' wherein no rising path follows on from area B''. The hydraulic line can however also be designed so that after a falling path of the hydraulic section, such as for example from B'' to B''' there is an region with rising path wherein the length of the partial stretch with falling path, for example from B'' to B''', is substantially longer than the length of the partial section with rising path, for example from B''' to D'''. Use in the case of hydraulic lines corresponding to a path as shown in Figures 3 and 5 depends each time inter alia on the structural space required.

Figure 6 shows diagrammatically a path of a transfer means, such as hydraulic line 111, from a hydraulic cylinder 110 to a hydraulic cylinder 120 wherein the hydraulic line 111 ensures a fluid connection between these two hydraulic cylinders. In a first region, starting from the hydraulic cylinder 110 up to the local maximum 112, the hydraulic line is designed so that it always has in this section a positive rise wherein also partial sections, for example 113 can be present within this section which have a substantially vertical path or at least substantially bridge a greater height difference. Such a design of a hydraulic stretch can be suitable to by-pass an obstruction in the path between the hydraulic cylinders since the hydraulic cylinders can be placed at different locations.Following the area of the local maximum 112 the hydraulic line 111 is designed so that a cascade line is attached and connects the area 112 to the hydraulic cylinder 120. Such a design of the hydraulic line is necessary for example if an obstruction has to be overcome and the hydraulic line cannot produce the fluid connection between 110 and 120 in a direct way.

The angle 130 between the incline of the hydraulic line 111 and the horizontal 131 can be selected in an area between two and 10 degrees wherein an angle between 3 and 5 degrees is preferably selected.

Figure 7 shows a flow chart for the process for ventilating a pressurised medium section, such as a hydraulic line. The process is started in block 200 wherein this process is repeated after a certain time, such as for example every 10 to 1000 seconds. The process is preferably repeated every 30 to 300 seconds. In block 201 an activation of the sender cylinder piston in the direction of the ventilation opening is carried out by means of the control unit. The fluid column is thereby moved by the amount Ax1 in the direction of the ventilation opening. This activation takes place at a speed vl. Gas amounts or volumes are thereby transported within the fluid at least over a partial stretch to the ventilation opening.

In block 202 there is an operating pause with a time duration of at wherein the gas amounts or volumes rise up either to the ventilation opening or to a local maximum of the pressurised medium stretch, such as hydraulic stretch and collect there where applicable.

In block 203 an activation of the sender cylinder piston in the direction away from the ventilation opening is carried out by means of the control unit. The fluid column is thereby moved by an amount - & 2 in a direction away from the ventilation opening. This activation takes place at a speed v2 which is against the speed v1. The speed v2 is from the amount clearly less than the speed vl. As far as possible there are no or only slight amounts of gas or volumes transported inside the fluid at least over a partial stretch away from the ventilation opening. Such a transport is avoided if the speed v2 is so slight that only few gas bubbles are carried along with the fluid column.

The process ends in block 204.

For ventilation, such as snifting it is necessary in a design of the invention that the clutch is completely engaged. Through this condition it is expedient if snifting is not introduced if the vehicle stands with the gear engaged, the clutch opened and the engine running. With this or other problematical operating points at 200 the process of Figure 7 is not introduced.

The patent claims filed with the application are proposed wordings without prejudice for obtaining wider patent protection. The applicant reserves the right to claim further features disclosed hitherto only in the description and/or drawings.

References used in the sub-claims refer to the further design of the object of the main claim through the features of each sub-claim; they are not to be understood as dispensing with obtaining an independent protection for features of the sub-claims referred to.

The subjects of these sub-claims however also form independent inventions which have a form independent of the subjects of the preceding sub-claims.

The invention is also not restricted to the embodiment of the description. Rather numerous alterations and modifications are possible within the scope of the invention, more particularly those variations, elements and combinations and/or materials which for example are inventive through combination or modification of individual features or elements or process steps contained in the drawings and described in the general description and claims and which through combinable features lead to a new subject or to new process steps or sequences, also insofar as they relate to manufacturing, testing and working processes.

Claims

PATENT CLAIMS

1. Device with pressurised medium transfer system, such as for example a hydraulic system, more particularly for operating or controlling a torque transfer system or a brake, such as for example a friction clutch, with a sender cylinder, a receiver cylinder, a transfer section between sender and receiver cylinders and a ventilation device, with a central control or computer unit in signal connection with at least one sensor and/or at least one further electronics unit, and with an actor controllable by the control unit for operating the sender cylinder, wherein the transfer section is designed substantially as a tubular component so that it ensures a fluid connection between sender and receiver cylinders and has at least two or more regions wherein at least one region has a rising path and at least another region has a declining path and the actor activates the sender cylinder in a first and second direction, and wherein transport of the fluid column is carried out in different directions along the transfer section at different speeds, the device being ventilated at least occasionally automatically by controlling the control unit.

2. Device according to claim 1 characterised in that the sender and receiver cylinders are mounted at least substantially at different levels and the ventilation device is mounted on the hydraulic cylinder which is located on a lower level and ventilation of the device or a transport of gaseous substances is carried out at least over regions of the transfer section against the buoyancy force.

3. Device according to claim 1 characterised in that the hydraulic line between the sender and receiver cylinders ensures a fluid connection and a ventilation device is mounted on a hydraulic cylinder and the hydraulic line is designed so that a local maximum is present and a ventilation of the device or a transport of gaseous substances takes place at least over regions of the transfer section against the buoyancy force.

4. Device according to claims 1 to 3 characterised in that the ventilation device is mounted on the sender cylinder which is mounted at least substantially on the same or lower level than the receiver cylinder without ventilation device.

5. Device, more particularly according to one of claims 1 to 4 characterised in that the transfer section has at least in one section at least two types of regions wherein a first type of regions has a rising path and a second type of regions has a declining path and the regions with rising or falling path are mounted at least alternating or in alternation.

6. Device, more particularly according to claim 5 characterised in that the regions of the transfer section which seen in the direction of the hydraulic cylinder with ventilation device have a rising path, overcome an at least substantially lower height difference than the regions with falling path.

7. Device, more particularly according to claim 5, characterised in that the regions of the transfer section which seen in the direction of the hydraulic cylinder with ventilation device have a rising path, extend over at least substantially longer route paths than the regions with falling path.

8. Device, more particularly according to claim 5, characterised in that the regions of the transfer section which viewed in the direction of the hydraulic cylinders with ventilation device have a rising path, extend over substantially shorter route paths than the regions with falling path.

9. Device, more particularly according to one of claims 1 to 8 characterised in that the transfer section is designed as a hydraulic line with a cascade-shaped path with rising and falling regions.

10. Device according to one of the preceding claims, characterised in that the actor is a controllable operating element which can be controlled by means of the control unit.

11. Device according to one of the preceding claims, characterised in that the actor has a drive element, such as an electromotorized, magnetic, electromagnetic or hydraulic drive element.

12. Process for controlling a device with pressurised medium system, such as a hydraulic system, more particularly for a torque transfer system or a brake with a sender and a receiver cylinder and a transfer section, such as a tubular component, with a control unit and a setting member for controlling the sender cylinder, characterised in that the control of the sender cylinder is carried out so that a transport or displacement of gas volumes takes place within or with the fluid in the hydraulic system in the direction of the hydraulic cylinder with ventilation device, wherein the hydraulic cylinder with ventilation device is mounted on a lower level than the hydraulic cylinder without ventilation device and gas volumes are transported at least over regions against the acting buoyancy force.

13. Process for controlling a hydraulic system, more particularly for a torque transfer system or a brake with a sender and receiver cylinder and a transfer path, such as a tubular component, with a control unit and a setting member for controlling the sender cylinder, characterised in that the control of the sender cylinder is carried out so that a transport or displacement of gas volumes takes place within or with the fluid in the hydraulic system in the direction of the hydraulic cylinder with ventilation device and the ventilation device is mounted on a lower level than the maximum level of the transfer path and gas volumes are transported at least over regions against the acting buoyancy force.

14. Process according to claim 12 or 13 characterised in that gas volumes are transported within or with the fluid in the hydraulic system along the falling regions, viewed in the direction of the hydraulic cylinder, through lift movements of the sender cylinder piston and displacements of the fluid.

15. Process according to one of claims 12 to 14 characterised in that the displacement of the fluid column caused as a result of the lift of the sender cylinder piston is controlled so that the amount of displacement is greater than the length of a partial stretch of the transfer section with falling path and/or smaller than the length of a partial stretch with rising path.

16. Process, more particularly according to one of claims 12 to 14 characterised in that the displacement of the fluid column caused as a result of the lift of the sender cylinder piston is controlled so that the amount of displacement is greater than the length of a stretch with at least two falling regions and at least one rising region mounted inbetween.

17. Process according to one of claims 12 to 16, characterised in that after a lift movement of the sender cylinder piston for transporting the fluid column and/or gas volumes in the direction of the ventilation device or in the opposite direction there follows a time duration without lift of the sender cylinder piston.

18. Process according to one of claims 12 to 17 characterised in that the amount of the speed of the sender cylinder piston lift and/or amount of the speed of movement of the fluid column in the direction of the ventilation device is substantially greater than the amount of speed of movement of the sender cylinder lift or fluid column in the opposite direction.

19. Process, more particularly according to one of claims 12 to 18 characterised in that in the operating states or situations with an engaged neutral gear position a temporary deliberate control of the sender cylinder takes place in order to carry out a deliberate transport of fluid volumes or gas volumes in the direction of the ventilation device or a ventilation of the hydraulic system.

20. Process, more particularly according to one of claims 12 to 19 characterised in that with a controlled transferable torque of the torque transfer system, such as a friction clutch with a control according to torque matching, corresponding to the torque arising on the engine side, the torque transfer system can be deliberately controlled in a working area between a partially engaged state and a substantially completely engaged state, in order to achieve through the movement of the sender cylinder piston a deliberate transport or displacement of fluid or gas volumes in the direction of the ventilation device or a ventilation of the hydraulic system.

21. Process more particularly according to one of claims 12 to 20 characterised in that with torque transfer systems with a control according to torque matching a control of the sender cylinder is carried out for the purpose of ventilation in non-critical situations and/or operating states.

22. Process more particularly according to one of claims 19 to 21 characterised in that the starting or switch off process, as well as stationary phases or rolling phases with neutral position or operating states with torque matching belong to non-critical situations which are part of carrying out a sender cylinder control for deliberate transport at least of gas volumes in the direction of the ventilation device or ventilation and in these situations a control for deliberate ventilation is carried out at least at times.

23. Tubular component, more particularly according to one of the preceding claims, with a first and a second attachment or connecting area for producing a fluid connection between two hydraulic elements, such as for example sender and receiver cylinders, characterised in that the tubular component at least in one section consists of regions with rising and falling path, wherein the arrangement of the regions is at least substantially alternating.

24. Component part according to claim 23, characterised in that by means of the component part a difference in height is bridged and at least in one section of the component the regions with falling path overcome a greater height difference than the regions with rising path.

25. Device with pressurised medium transfer system, substantially as herein described with reference to the accompanying drawings.

26. Process for controlling a device with pressurised medium transfer system, substantially as herein described with reference to the accompanying drawings.

27. Tubular component, more particularly according to one of the preceding claims, with a first and a second attachment or connecting area for producing a fluid connection between two hydraulic elements, such as for example sender and receiver cylinders, substantially as herein described with reference to the accompanying drawings.