WO2004053348A2

WO2004053348A2 - Hydraulic system for actuating a clutch

Info

Publication number: WO2004053348A2
Application number: PCT/DE2003/003977
Authority: WO
Inventors: Robert Fischer; Burkhard Pollak; Gerd Ahnert; Richard Brian Moseley; John Vivian Comfort; Andrew Watkins; Paul Shepherd; Paul Vincent Rouse; David Anthony Harries; Peter Riemer
Original assignee: Luk Lamellen Und Kupplungsbau Beteiligungs Kg
Priority date: 2002-12-06
Filing date: 2003-12-04
Publication date: 2004-06-24
Also published as: AU2003293003A1; DE10394134D2; AU2003293003A8; WO2004053348A3

Abstract

Disclosed is a hydraulic system, particularly for motor vehicles, comprising a master cylinder with a replenishing line, a slave cylinder, and a pressure medium line that connects said slave cylinder. The aim of the invention is to relieve a hydraulic system in a simple manner. Said aim is achieved by connecting the pressure medium line to the replenishing line via a bypass line comprising a bypass valve.

Description

Hydraulic system

The present invention relates to a hydraulic system, in particular for motor vehicles, comprising a master cylinder with a follow-up line, a slave cylinder and a pressure medium line connecting them.

A generic hydraulic system is known for example from DE10049913 A1. Such a hydraulic system can also be used together with a so-called automated manual transmission. In the automated manual transmission, the clutch or several clutches are actuated by a hydraulic system in the case of a double clutch or parallel transmission. Recently, such couplings have been designed such that they are opened, for example, by a built-in plate spring or the like and closed by an external force, which in this case is supplied by the slave cylinder of the hydraulic system. In contrast to those of manually operated vehicle clutches, in which a clutch force has to be exerted for opening, for example via a clutch pedal and a hydraulic system, a corresponding force has to be exerted here for closing the clutch. This can be particularly advantageous in the case of a double clutch transmission, since simultaneous closing of both clutches must be avoided during operation under all circumstances.

In the event of a failure of the elements required for clutch actuation, the situation may now arise in which one clutch or several clutches is or are closed, but can or must be opened for the purpose of a towing process or the like. The respective clutch is opened by relieving the pressure on the hydraulic system, for example by releasing the pressure, for example by relieving the load on the master cylinder.

The present invention is therefore based on the problem of bringing about an easy to implement relief of a hydraulic system. This problem is solved by a hydraulic system, in particular for motor vehicles, comprising a master cylinder with a follow-up line, a slave cylinder and a pressure medium line connecting them, in which the pressure medium line is connected to the follow-up line via a bypass line with a bypass valve. The pressure medium line connects the master cylinder directly to the slave cylinder. The bypass line is branched off from the pressure medium line, so that no possibly disruptive additional actuating elements or the like are present in the pressure medium line for regular operation. The bypass line can be blocked with the valve in one valve position with respect to the after-run line and allows a direct connection of the pressure medium line with the after-run line in another valve position. Via the bypass valve, the pressure medium line can thus be emptied directly into the follow-up line and thus into a follow-up tank. The bypass valve can be any type of valve, it only requires a closed and an open position for the direction of passage. The hydraulic system according to the invention has several further advantages over the prior art. First of all, no electrical energy is required to open the valve or valves in the event of a fault. Since there are no electrical consumers, no electrical energy is consumed, for example, for electrical devices that are on standby, even during normal operation. The hydraulic system can only be depressurized if the driver depresses the brake pedal several times while the internal combustion engine of the motor vehicle is switched off. The system has a safe fallback mode with open clutches as soon as there is no longer a vacuum in the control line. At first glance, this appears to be a disadvantage, since the flow of power between the engine and transmission is interrupted in the event of a fault, meaning that the vehicle can be moved freely when the vehicle is stationary. However, this is not a problem, in particular in the case of an automatic transmission such as a parallel transmission, since such a transmission has an independent parking lock. Devices can also be provided to ensure that the clutches are open when the motor vehicle is to be started. If the motor vehicle is parked with the prime mover not running, the vacuum of the brake booster is maintained for a longer period of time. In this case, it must therefore be ensured that both Clutches are open and it is not a coincidence that there is a defect in one of the actuators. This can be done by suitable electronic monitoring of

Coupling positions can be achieved.

In one embodiment of the invention it is provided that the bypass valve in a first position switches the pressure medium line directly through to the follow-up line and blocks this connection in a second position. In the second position, the pressure medium line is therefore separated from the environment as usual, in the first position there is an immediate emptying of the pressure medium line into the follow-up line and thus a follow-up container arranged thereon.

In a further embodiment of the invention it is provided that the master cylinder can be actuated by an actuator. The actuator can be operated hydraulically, pneumatically or preferably electrically. The actuator is used for the automated actuation of the clutch. Such an actuator is usually provided in conjunction with an automated manual transmission for clutch actuation.

In a further embodiment of the present invention it is provided that the bypass valve can be switched pneumatically. The bypass valve can therefore be switched by an overpressure or a vacuum or a specific course of a pressure. The bypass valve is preferably blocked when the pressure in a control line is below the ambient pressure. As long as there is negative pressure in the control line, the bypass valve closes. If the negative pressure is released in the control line, the bypass valve opens.

In a further embodiment of the invention it is provided that the control line is connected to a vacuum system of a brake booster. During regular operation of a motor vehicle, there is therefore generally a negative pressure in the control line, so that the bypass valve is closed. When the vehicle is at a standstill or when the internal combustion engine is switched off, the vacuum system can be depressurized, usually by repeatedly actuating the brake by actuating the brake pedal. After a certain number of braking spurts it is System depressurized, that is, the vacuum system has assumed the ambient pressure, so that the bypass valve opens.

If there are several hydraulic systems in the motor vehicle, for example in the case of a double clutch, the bypass valves can be connected to a common control line. This means that all hydraulic systems can be depressurized by applying the brakes together.

In an alternative embodiment of the hydraulic system it is provided that the bypass valve can be actuated mechanically. Mechanical actuation is understood here to mean any type of force transmission via a supporting structure, transmission or the like. It is advantageous if the mechanical actuation comprises at least one cable, preferably a Bowden cable. A cable pull is only able to transmit forces in one direction, one pulling direction. No forces are transferred in the other direction. For a Bowden cable, this only applies to a limited extent. Special measures such as B. a freewheel in the direction of thrust, cause the same effect as with a cable. Such a freewheel can be, for example, a bore in which the Bowden cable can move freely in one direction and is fixed in the other direction by a stop element.

In an advantageous embodiment of the invention, a hydraulic system is provided in which the bypass valve can be actuated by an actuating means which is coupled to at least one first actuating means and a second actuating means, each of which can assume at least a first and a second position, wherein at least the bypass valve is open in a combination of the possible positions of the two actuating means and the bypass valve is closed in at least one combination of the possible positions of the two actuating means. In this context, actuating means is understood to mean any form of valve actuating means, for example mechanical, hydraulic, pneumatic or electrical means. The actuating means are each connected to the actuating means; these can be any means, for example cable pulls, Bowden cables, crank disks, articulated gears, electromagnetic elements or the like. The two actuators must have at least a first and a second position, but there can be any number of positions.

It is advantageous if the bypass valve is open in exactly one combination of the possible positions of the two adjusting means and the bypass valve is closed in all other combinations of the possible positions of the two adjusting means. To open the bypass valve, it is therefore deliberately necessary to select exactly one combination from all possible combinations of the positions of the two actuating means. This measure makes it difficult to operate the bypass valve incorrectly.

In a further embodiment of the invention it is provided that the actuating means is a bar and the adjusting means are arranged in such a way that they are coupled to one another by the bar and the bypass valve is arranged between the adjusting means and can be actuated by the bar. The bar can be rotatably attached to the bypass valve, for example, but it is also possible that it can also be moved translationally away from the bypass valve. The bar is connected to the actuating means in such a way that it can actuate the bypass valve in exactly one position of the two actuating means. Here, bars are to be understood as meaning almost any flat shape, for example also rectangles or triangles or any curved surfaces.

The problem mentioned at the outset is also solved by a disengaging device for actuating a clutch, in particular a clutch in the drive train of a motor vehicle between the drive motor and the manual transmission, in which the disengaging device for closing the clutch comprises a partial section which is subjected to thrust when the clutch is closed and that the section includes a buckling bar that can be bent to relieve the section. A partial area in the force curve between a clutch or a release lever and an actuator for actuating the release lever via, for example, a mechanical or hydraulic power transmission link is common to here. At least part of this route is designed as a mechanical power transmission. Here, a buckling bar is understood to be a bar that is subjected to compressive forces and that at a defined point, for example, a joint or the like. If the compressive force exceeds the buckling load of the beam. The buckling load can be as small as desired with a joint that has little spring stiffness. In this case it is advantageous if the joint is pressed against a stop by a joint spring. When the pressure force on the buckling bar is increased, the joint is only pressed more strongly against the stop, the buckling bar as a beam is therefore already buckled in the physical sense, the stop only prevents further buckling. The hinge spring presses the hinge against the stop.

In an advantageous embodiment of the invention it is provided that the buckling rod can be bent over against the force of the articulated spring. The buckling bar can thus be moved against the force of the articulated spring from its stable position in which it is pressed against the stop by the pressure forces acting on the buckling bar. When a position is reached in which both parts of the buckling bar are exactly opposite one another, ie in which the two individual bars are exactly opposite one another, an unstable equilibrium position is reached. If the buckling bar or the joint is moved further away from the stop against the force of the joint spring via this position, the entire device snaps from a point at which the resulting force in the direction of the joint spring is greater than the force of the joint spring The distance between the two outer suspension points of the buckling bar is abruptly shortened. In this way it is achieved that the buckling bar can be used permanently for the transmission of clutch forces and at the same time there is the possibility of permanently preventing this force transmission without damaging the disengaging device.

The problem mentioned at the outset is also solved by a disengaging device for actuating a clutch, in particular a clutch in the drive train of a motor vehicle between the drive motor and manual transmission, comprising a disengaging lever and an actuator connected to the disengaging lever, in which the disengaging lever is additionally connected to a cable. It is advantageous if the release lever can be brought into a position in which the clutch is opened by the cable pull. In a way, the cable pull provides an additional option Actuation of the release lever. It goes without saying that the cable must be effective in the direction of actuation of the release lever.

In an advantageous embodiment of the invention it is provided that the cable comprises a pulley. The block and tackle can consist of one or more fixed and loose rollers in a manner known per se. The reduction of the pulley can be varied by the number of fixed and loose rollers. Bowden cables can be arranged between the pulley and release lever and between the pulley and a handle, foot pedal or the like for actuation. With the help of Bowden cables, it is much easier to lay such a cable in any vehicle.

In a further advantageous embodiment of the invention it is provided that the cable can be fixed in the position in which the clutch is opened. Fixing can be carried out, for example, by a clamping mechanism, a hook for a lever or the like. The definition reliably prevents the clutch from engaging again by spring force, for example a disc spring of the clutch.

The problem mentioned at the outset is also solved by a disengaging device for actuating a clutch, in particular a clutch in the drive train of a motor vehicle between the drive motor and the manual transmission, in which there is also a propellant charge and a piston-cylinder arrangement which is operatively connected to it and which has a mechanical Power transmission is connected to the release device. The propellant charge can be a chemical substance consisting of one or more components, which can release a gas under pressure through a chemical reaction. However, it can also be a compressed gas cartridge, for example, from which a compressed gas can be released. The piston-cylinder arrangement consists in a known manner of a piston which is movably arranged in a cylinder and is sealed from the environment. A pressurized gas line or another closed space, which ensures the pressure transmission between the space in which the propellant charge is arranged and the piston-cylinder arrangement, is operatively connected here. The piston-cylinder arrangement is connected to the release device with a mechanical power transmission. The mechanical power transmission can have gear elements or freewheel elements or the like, so that a mechanical connection only exists if the propellant charge has been triggered or the piston has been pressed into a certain position.

In one embodiment of the invention it is provided that at least one first throttle is arranged between the propellant charge and the piston-cylinder arrangement. Likewise, a first throttle, a second throttle and an expansion space can be arranged between the propellant and the piston-cylinder arrangement. There may also be additional chokes and expansion rooms. In particular, if the propellant can release gas explosively, the arrangement of throttles and at least one expansion space can result in the pressure increase in the cylinder and thus the load on the piston being weakened, so that the pressure increase in the cylinder is not explosive but slower than that ,

For this purpose, the propellant charge is advantageously arranged in a reaction chamber which, by means of a suitable volume, enables the propellant charge to burn off. It is advantageous here if the propellant charge can be triggered by an ignition charge, in particular an electrical ignition charge. The electrical priming charge can in turn be triggered manually by means of a switch or coupled to on-board electronics only under certain conditions, for example when the drive engine is switched off and / or a fault in the clutch actuator system.

In a further advantageous embodiment of the present invention, it is provided that the piston is connected to a toothed rack which is in engagement with a toothed wheel. The gearwheel can, for example, be arranged on the output shaft of an actuator which actuates a clutch via a spindle or the like and, if appropriate, further transmission means. It is advantageous if the toothed rack has a cutout which, when the toothed rack is at rest, releases the engagement with the toothing of the toothed wheel. The gear can rotate freely in this position. Only by moving the toothed rack is it engaged with the toothing of the toothed wheel. The problem mentioned at the outset is also solved by a disengaging device for actuating a clutch, in particular a clutch in the drive train of a motor vehicle between drive motor and manual transmission, comprising a hydraulic system (1) with a master cylinder which is connected to an actuator (4) (17), a slave cylinder and a pressure medium line (15) connecting master and slave cylinders, characterized in that the actuator is mounted on the housing side in a displaceable mounting with a locked position and an unlocked position. In the unlocked position, the actuator is preferably pressed into a position which, by means of the hydraulic system, causes the vehicle clutch to open.

In principle, the actually gear or motor-fixed mounting of the actuator is designed to be displaceable in the direction of action of the actuator. In terms of model, this displaceability can be understood as being in series with the actual actuating function of the actuator, so it basically allows the same actuating function to be carried out as the actual actuator function. The additional displaceability is used for the emergency release of the clutch, therefore only two positions are provided here, a locked working position and an unlocked position, in which the clutch is open regardless of the position of the actuator. The position of the actuator is to be understood as the way by which an actuator, e.g. a spindle between two possible end positions.

In an advantageous embodiment, it is provided that the actuator in the unlocked position is pressed in the pressure direction of the hydraulic system by a spring accumulator arranged between the actuator housing and a gear-fixed bearing point. The pressure direction is the direction in which actuation of the actuator causes an increase in pressure in the hydraulic system. After releasing a lock that holds the actuator housing in the locked position, the entire actuator is pressed by the spring accumulator in the pressure direction of the hydraulic system, so that the clutch is opened regardless of the position of the actuator. In an alternative advantageous embodiment, it is provided that the actuator is pressed in the unlocked position by the vehicle clutch by means of the hydraulic system into a position which causes the vehicle clutch to open. This alternative is used in the case of a clutch which is open in the unloaded state and is closed under the application of force, a so-called "active clutch", since here a relief of the hydraulic system is sufficient to open the clutch.

In a further advantageous embodiment it is provided that the actuator housing is held in the locked position by a locking device. The locking device can e.g. in the form of a ratchet, a displaceable bolt arranged radially to the direction of action of the actuator in connection with a bore, a lever in the manner of a catch hook or the like. Solutions that bring about the locked position of the actuator housing in a powerless rest position and must be actively transferred to a second position that brings about the unlocked position of the actuator housing are preferred, so that the locking device is "fail safe".

The problem mentioned at the outset is also solved by a drive train, in particular for a motor vehicle, comprising a drive motor, a manual transmission and a clutch connecting it, which comprises a disengaging device according to one of the claims directed to a disengaging device. The drive train can further include a drive shaft, a differential, a rear axle and two wheels.

Exemplary embodiments of the invention are explained below with reference to the accompanying drawings. Show:

Figure 1 is a schematic representation of a hydraulic system based on an embodiment of a clutch release device. 2 shows a hydraulic system with pressure relief according to the invention;

3 shows a further embodiment of a hydraulic system with pressure relief according to the invention in a first position; 4 shows a further embodiment of a hydraulic system with pressure relief according to the invention in a second position;

5 shows a further embodiment of a hydraulic system with pressure relief according to the invention in a third position; 6 shows a mechanically actuated bypass valve in section;

7 shows a first embodiment for actuating a vehicle clutch;

8 shows a schematic diagram of a drive train of a motor vehicle;

9 shows a schematic diagram of a disengaging device with an additional cable pull;

10 shows a sketch of a pyrotechnically operated emergency release device; 11 shows a basic illustration of an exemplary embodiment of an emergency release device with a movable actuator bearing;

Fig. 12 is a schematic diagram of another embodiment of an emergency release device with a movable actuator bearing.

Fig. 1 shows a schematic representation of a possible embodiment of a hydraulic system using a clutch release device 3 with a master cylinder 4 and a slave cylinder 5. In the exemplary embodiment shown, a pressure relief valve 2 is installed in a pressure medium line 15 connecting it and separates it into a first line line 11 and a second wiring harness 12 from each other. It goes without saying that, in other exemplary embodiments, the pressure limiting valve 2 can be integrated in the master cylinder 4 or in the slave cylinder 5, and in other hydraulic systems, for example brake systems, power steering systems, and the like, can be integrated in a functional component. Furthermore, a pressure relief valve in each hydraulic line system can advantageously be advantageous as a pressure relief valve and / or as a vibration filter, for example as a so-called “prickle filter”.

The clutch release system 3 actuates the clutch 7 hydraulically

Actuation of the master cylinder 4 by means of an actuating element 14, which can be a foot pedal, an actuator, for example an electrical actuator, or the like. As a result, pressure is built up in the master cylinder 4 by means of a piston rod 13, which builds up pressure in the slave cylinder 5 via the pressure medium line 15 or the second line branch 12, the pressure relief valve 2 and the first line branch 11. As in the example shown, the slave cylinder 5 can be arranged concentrically around the transmission input shaft 10 and axially supported on a transmission housing (not shown) and apply the necessary release force via a release bearing on the clutch 7 or on its release elements such as a plate spring. Further exemplary embodiments can provide a slave cylinder 5, which actuates a releaser via a disengagement mechanism and is arranged outside the clutch bell, this axially acting on the disengagement mechanism by means of a piston, which is accommodated in the slave cylinder housing and is hydraulically connected to the master cylinder. In order to apply the disengagement force, the slave cylinder is attached to the transmission housing, which is not shown here, or to another component fixed to the housing. When the clutch 7 is closed, the transmission input shaft 10 transmits the torque of the internal combustion engine 8 to a transmission (not shown in more detail) and then to the drive wheels of a motor vehicle.

The combustion processes in the internal combustion engine 25 cause the crankshaft 9 to experience depending on the design of the internal combustion engine 8, for example in

Dependence on the number of cylinders, non-uniform loads, which are expressed in axial and / or wobble vibrations and which are transmitted via the disengaging mechanism 6 to the slave cylinder 5, the pressure medium line 15 to the master cylinder 4 and from there via the piston rod 13 to the actuator 14 , In the case of a clutch pedal as an actuator, these vibrations are perceived as unpleasant. In the case of an actuator as an actuator 14, for example, a reduced control accuracy or a shortened service life

Be the result of the vibrations. The pressure relief valve 2 is therefore switched on for damping in the pressure medium line 15 and tuned for damping the vibrations entered by the crankshaft 9. The frequency range of such vibrations is typically 50 to 200 Hz. Figure 2 shows a hydraulic system according to the invention with the possibility of pressure relief. A master cylinder 4, which is connected via a pressure medium line 15 to a slave cylinder 5, also shown only schematically, are shown schematically. The master cylinder 4 is actuated by an actuator 16. The pressure chamber (not shown) of the master cylinder 4 is connected via a follow-up line 17 to a follow-up tank 18 via sniffer bores or sniffer grooves (also not shown) via a follow-up line 17. The structure of a master cylinder is, for example, from the

Known from DE 10049913.

The pressure medium line 15 can be connected directly to the follow-up line 17 via a bypass line 19 and a bypass valve 20. When the bypass valve 20 is closed, an operating pressure necessary for actuating the clutch can prevail in the pressure medium line 15; when the bypass valve 20 is open, pressure equalization between the pressure-binding line 15 can take place directly into the follow-up line 17 and thus into the follow-up tank 18. The pressure compensation is independent of the position of the master cylinder, so that the slave cylinder 5 can be relieved even when the master cylinder 4 is fully actuated. The bypass valve 20 is controlled pneumatically. If there is negative pressure in a control line 21, the bypass valve 20 is closed, if there is no negative pressure in the control line 21, the bypass valve 20 opens. The control line 21 is also connected to the negative pressure side of a conventional brake booster 22. This has a known type and Way via a vacuum line 23, which is generally connected to the intake line of the internal combustion engine and therefore has a vacuum relative to the ambient pressure. The brake booster 22 or the entire brake power system also has a hydraulic brake circuit 24, which is only indicated schematically here, as well as a brake pedal 25. The entire brake booster 22 with all the components arranged directly on it is known per se and is used in practically every one today Motor vehicle used in this form. The control line 21 can have a further control line 26 with which further hydraulic systems such as that shown here can be controlled via further bypass valves 20. In the operation of the motor vehicle, there is a permanent negative pressure in the control line 21, since a negative pressure for operating a negative pressure system 27 of the brake booster 22 is also permanently generated in the negative pressure line 23 when the internal combustion engine is running. The brake booster 22 usually has a reserve container or the like, so that an effect of the brake booster is achieved even when the internal combustion engine is stationary over one or more strokes of the brake pedal. If the internal combustion engine is switched off, there is therefore initially a sufficient negative pressure in the brake booster 22 and thus also in the control line 21, the bypass valve 20 therefore initially does not open and the hydraulic system 1 remains functional, actuation of the master cylinder 4 has a corresponding movement of the Slave cylinder 5 result.

In the event of a fault, for example in the event of a motor failure or a failure of the actuator 16 or the like, the driver actuates the brake pedal 25 several times when the internal combustion engine 8 is switched off, and thus depressurises the brake booster 22. Thus, the ambient pressure is present in the control line 21, the bypass valve 20 opens and relieves the slave cylinder 5 via the bypass line 19 and the follow-up line 17 into the follow-up tank 18, regardless of the current position of the piston of the master cylinder 4. Of course, the present arrangement requires a clutch that is opened, for example, by a plate spring and that is actively closed via the slave cylinder.

When an error occurs, when the automatic shift system is not able to open the one or more clutches of the automatic transmission, the driver of the motor vehicle must first switch off the engine. This can also take place in that the vehicle is braked to a standstill and because the clutch or the clutches cannot be opened, the internal combustion engine 8 is "stalled" by an insufficient speed. For the sake of caution, the driver now switches off the ignition of the internal combustion engine 8 and applies the handbrake or actuates the parking lock of the gearbox. By depressing the clutch pedal several times, usually about five to six times, the negative pressure in the brake booster 22 is consumed. This will open it

Bypass valve 20 and relieves the slave cylinder 4, whereupon the vehicle clutch is opened. If several clutches are present in the vehicle, for example in the case of a double clutch transmission with two parallel drive trains, this process affects both clutches together, since these two clutches can be actuated via a common control line 21 and their own bypass valves 20.

FIG. 3 shows an alternative embodiment of a hydraulic system with mechanical actuation of the bypass valve 20. The hydraulic connections of the bypass valve 20 are not shown here, but essentially correspond to the illustration in FIG. 2. In contrast to the embodiment according to FIG however, the bypass valve 20 is switched not by negative pressure, but by mechanical actuation. The bypass valve 20 has a pressure pin 33 which opens the bypass valve 20 in the pressed-in state and closes the bypass valve 20 in the non-pressed-in state. In the position of the bypass valve 20 shown in FIG. 3, it is therefore closed. The pressure pin 33 is actuated by a bar 30 which is mounted on the pressure pin 33 so that it can be rotated somewhat centrally. 3 is a schematic diagram, the practical configuration of the mounting can be carried out, for example, in the form of a joint (not shown here) or a guide (not shown here) or the like. The bar 30 is connected to a first Bowden cable 31 and a second Bowden cable 32. Both the first Bowden cable 31 and the second Bowden cable 32 are guided, for example, through bores 34 in the beam 30 and equipped with end caps 35, the outer diameter of which is larger than the inner diameter of the bores 34. Both Bowden cables can therefore be in one direction, as shown in FIG. 3 , without exerting any force or torque on the beam 30, are pushed through the bore 34, in the other direction this is only possible until the end caps 35 abut the beam 30, from then on with a further pull on the Bowden cables 31, 32 transmit a force or a torque to the beam 30.

The first Bowden cable 31 is now connected, for example, to a parking brake actuation 36, the second Bowden cable 32 is connected to an emergency clutch release device 37 connected. It can be, for example, a lever or a push button or the like.

FIG. 4 illustrates the effect when the clutch emergency release device 37 alone, but not the parking brake actuation 36, is actuated. In this case, the bar 30 is rotated about the pressure pin 33 of the bypass valve 20, the length of the first Bowden cable 31 is dimensioned such that its end caps 35 do not strike the bar 30. Despite actuation of the clutch emergency release device 37, the bypass valve 20 is therefore not actuated. The analogous effect is achieved when the parking brake actuation 36 is actuated, but the clutch emergency release device 37 is not actuated. In this case, the representation of FIG. 4 can simply be imagined in reverse, the bar 30 is tilted to the other side.

FIG. 5 shows the conditions when actuating both the clutch emergency release device 37 and the parking brake actuation 36. In this case, the pressure pin 33 is actuated and the bypass valve 20 is opened. The beam 30 in connection with the first

Bowden cable 31 and the second Bowden cable 32 and the bypass valve thus act like a mechanically logical "AND". If you disregard the fact that the Bowden cables can also take intermediate positions to the end positions shown here, both Bowden cables can each take two end positions, one tightened

End position as shown, for example, for both Bowden cables in FIG. 5, and a released end position, as shown for example for both Bowden cables in FIG. 1. The effect of the arrangement shown here as a logical “AND” means that the bypass valve 20 is only opened in exactly one combination of the possible combinations of positions here.

By cascading several of the arrangements shown here or, for example, by a spatial structure in which the beam 30 is designed, for example, in the form of an equilateral triangle with three suspension points or a rectangle with four suspension points, more than two input variables can be created, for a triangle, for example, three and link four input variables with each other according to an "AND" link. 6 shows a mechanically actuable bypass valve 20 in section. This comprises a valve housing 38 in which the pressure pin 33 is mounted so that it can move axially. The bypass valve 20 has a first connection 39, with which it can be connected to the pressure medium line 15 of the hydraulic system, and a second connection 40, with which the bypass valve 20 can be connected to the follow-up line 17 of the hydraulic system. The first connection 39 and the second connection 40 are connected to one another by a channel 41 in which the pressure pin 33 is guided. On its side facing the first connection 39, the latter has a valve plate 42 which is pressed onto a valve seat 44 by a valve spring 43. FIG. 6 shows the closed position of the bypass valve 20. In the open position, the valve plate 42 is lifted off the valve seat 44; a gap 45 remains through which hydraulic fluid can flow from the first connection 39 to the second connection 40. The pressure pin 33, the valve housing 38, the valve seat 44 and the like are sealed in a known manner by O-ring seals 46 or the like.

Fig. 7 shows a schematic diagram of an actuating device of a vehicle clutch. It is assumed here that the vehicle clutch is closed by the application of a force F _R , that is to say it is therefore opened, for example, by the spring force of a plate spring or the like. The clutch is thus open in the unloaded idle state and is actively closed. 7 shows a partial route 50 as a basic sketch. This essentially comprises an articulated rod 51, which is provided with a joint 52. The joint 52 causes the buckling rod 51 to buckle at an arbitrarily small force, regardless of its actual resilience to buckling. The joint 52 is now pressed by a joint spring 54 against a stop 49 of a guide 53. The stop 49 prevents the buckling rod 51 from buckling further and, as a guide 53, permits movement in the direction of the force F _R. As soon as the joint 52 is deflected against the force of the joint spring 54 by a force FN, the buckling bar 51 can completely bend, so there is an immense shortening of the length of the buckling bar 51 in the direction of force FR. As soon as the buckling bar 51 is deflected beyond the horizontal 55 shown in dashed lines in FIG. 7, the two-stroke formed by the joint 52 consisting of the Articulated rod 51. The distance between the two ends of the two-bar rod should be chosen larger than the maximum actuation travel at that point. The actuation of the emergency release can be combined, for example, with the actuation of the parking lock. A distinction must be made between the type of parking lock actuation. In the case of park-by-wire, the clutch is also opened when the parking lock is opened in the event of a failure. In the case of a mechanical parking lock, the emergency release is actuated when the parking lock is inserted. This presupposes that the clutch actuators are moved to the open position so that the clutch can be operated again after the parking lock has been released.

Under the basic assumption that part of the actuation path is subject to compression, the previously described mechanism for emergency opening is proposed by replacing the part of the actuation path that is under pressure by a two-part pressure rod with a joint, a spring with a stop and a connection for the emergency release. By pulling on or in the region of the joint, the stable equilibrium position of the compression rod is pulled over an indifferent position into an unstable area, so that the rod double impact snaps through and the part of the section modified in this way can no longer transmit force and the clutch opens Consequently. If the clutch actuator can be moved back to the "clutch open" position, the spring will move the two-bar rod back into its original position when the emergency operation is released and pressure forces can be transferred again. Appropriate selection of the angle α, the rod lengths and the spring can be achieved that the actuation path for the emergency release is small compared to the actuation path of the clutch at a corresponding point on the actuation path and that the force for actuating the emergency release is many times less than the force with which the clutch is actuated.

8 shows a schematic diagram of a drive train 60 of a motor vehicle 56. A four-wheeled vehicle is shown in which a drive motor 57 drives an axle 63 with wheels 64 arranged therein via a clutch 58 and a manual transmission 59 and a drive shaft 61 via a differential 62. The drive train 60 shown is in principle in a vehicle with front-wheel drive and rear-wheel drive identical, only the arrangement of the manual gearbox 59 and downstream drive means change. The principle shown can also apply to one

All-wheel drive vehicle can be used. The clutch 58 is by a

Release bearing 65, which is connected to a release device 66, for example a release lever 67, a hydraulic or mechanical central release device or the like, is actuated.

9 shows a schematic diagram of a release device 66 with an additional cable pull mechanism. A clutch 58 is shown, which is connected in a known manner to a release bearing 65. The release bearing 65 can be actuated by means of a release lever 67. The release lever 67 and the subsequent components such as release bearing 65 and clutch 58 are only shown here in principle. A mechanical central release system can also be used here, for example, which is controlled by means of a lever or the like. The release lever 67 is actuated by an actuator 68, which essentially consists, for example, of a spindle nut 69, a spindle 70 and an electric motor mounted on the housing

71, which may have a reduction gear, for example. Alternatively, a rack and pinion drive or the like can also be used here.

If, for example, the electric motor 71 fails, the release lever 67 remains in its current position, for example in the engaged state. In order to enable the vehicle or the like to be towed, for example, it is necessary to open the clutch 58. In the present exemplary embodiment, this is done by means of a cable 72, which can be guided, for example, via deflection rollers 73, a Bowden cable or the like to any point in the vehicle. A pulley 74, which can consist of one roller or several pairs of rollers, as outlined here, serves to reduce the cable pull

72, it is therefore possible to apply a significantly higher force to relieve the release lever 67 on a pull rope 75 while also having to travel a higher distance. The pull rope 75 can be provided, for example, with a handle, foot lever or the like, not shown here. In the present case, no fixed connection is provided between the spindle nut 69 and the release lever 67; the release lever 67 can lift off the spindle nut 69 in the load direction, that is to say in the release direction. If the pull cable 75 is now pulled, the release lever 67 lifts off the spindle nut 69. To fix the pull rope 75 is, for example, hooked in or fixed in some other way, so that the release lever 67 cannot move back into the engaged position. The entire process is reversible, by releasing the fixation of the traction cable 75, the clutch can be engaged again or the normal operating mode, in which the clutch 58 is operated via the actuator 68, can be returned. So that the cable 72 does not sag, this can be slightly pretensioned, for example, with a spring, not shown here, the spring coming to a stop after a certain spring travel, that is to say when actuated.

The solution shown in FIG. 9 can also be used with a double clutch. In this case, the cable pull 72 is divided into two cable pulls in the manner of a Y, each of the cable pulls acting on a release lever 67. The cables 72 on the two release levers are thus brought together to form a common cable. This has the advantage, among other things, that when the emergency opening is actuated, the driver does not have to know whether he has to open the respective clutch. When the pull cable 75 and thus the cable pull 72 are actuated, both clutches are opened in any case, regardless of the position in which they were previously.

The mechanism shown here works in principle with any clutch release system that has a mechanical transmission over a section. For example, this is also the case with a mechanical central clutch release. In this case, the cable 72 engages the release lever of the mechanical central release.

10 shows an alternative embodiment of an emergency release device 80 for a clutch or the like. It essentially comprises a housing 81 in which the further elements of the device shown below are located. In a Reaction chamber 82 is a one-part or multi-part propellant charge 83 which can be burned or exploded by means of an ignition charge 84 that can be ignited, for example. The propellant charge 83 and the ignition charge 84 can, for example, be designed as a common module that can be introduced into the reaction chamber 82, for example via a screw-on flap or the like, or can be screwed or clamped onto the reaction chamber 82, for example, as a module. The reaction chamber 82 is connected via a throttle 85, an expansion space 87 and a second throttle 86 to a cylinder 88 in which a piston 89 is movably mounted. The throttles 85, 86 and the expansion space 87 serve to reduce the peak pressure generated in the reaction chamber 82, in particular in the case of a rapid explosion of the propellant charge 83, only a comparatively slow and even pressure increase remains in the cylinder 88 from the very rapid pressure increase in the reaction chamber 82 The piston 89 is pressed in the direction of arrow 90 by the pressure increase in the cylinder 88 and drives a gear 92 via a rack 91. The gear 92 can for example be connected to an actuator (not shown here) or the like. Alternatively, instead of a rack 91, the piston 89 can be directly connected to an actuator or the like. Not shown in Fig. 10 are seals or the like. In particular, the piston 89 is here in a known manner, for. B. by means of sealing rings against the cylinder 88. The priming charge 84 can be triggered electrically, for example, but chemical triggering, for example by two-component explosive devices or mechanical triggering with a percussion fuse, is also possible here. Triggering the propellant causes a chemical reaction which builds up a gas pressure in the reaction chamber and thus also in the cylinder 88. An advantage of this solution is that there is an independent energy store in the form of the propellant charge 83 for actuating the emergency release. This is relatively low-maintenance, easy to use and inexpensive to manufacture. The propellant charge 83 is to be designed so that the entire system cannot be damaged. Another advantage is that the entire system cannot be integrated into the actual clutch actuation. Apart from the priming charge 82, the emergency release device 80 presented here works largely without electrical energy, even if the electrical energy supply fails This makes an emergency solution possible. The emergency release device 80 or the triggering of the ignition charge 84 can be carried out, for example, by an automated system of the vehicle, by an independent sensor or manually. For safety reasons, the triggering of the emergency release device 80 should be coupled with a parking brake, so that an emergency solution is only possible when the parking brake is applied.

Both the rack 91 and the gear 92 each have a toothing 94. The rack 91 has a cutout 93, which is introduced, for example, approximately in a semicircle into the rack 91 on the side facing away from the piston 89. Through the cutout 93, the rack 91 and the gear 92 are not in engagement in the position shown in FIG. 10, since the cutout 93 lies in the region of the gear 92. If the piston 89 and thus also the rack 91 are now moved in the direction of arrow 90 after triggering the propellant charge 83, then the cutout 93 is overcome and the toothing 94 of the rack 91 from a certain distance that the rack 91 must have covered the teeth 94 of the gear 92 engaged. In the rest position, as shown in Fig. 10, the gear 92 can thus be freely rotated relative to the rack 91. The rack 91 and the gear 92 are thus brought into engagement only after the propellant charge 83 has been triggered.

The propellant charge 83 can be a substance which consists of one or more components and is capable of a chemical reaction which releases gas in sufficient quantities and under sufficient pressure. Alternatively, a compressed gas container or the like can also be used here, which can be dissolved by the ignition charge 84.

11 shows a basic illustration of an exemplary embodiment of an emergency release device with a movable actuator bearing. The embodiment of FIG. 11 is designed for a clutch that is closed in the unloaded state and must be opened against spring force. The piston 95 of a master cylinder 4 is actuated by an actuator 96. The master cylinder 4 belongs to a hydraulic system, as is shown, for example, with the aid of FIG. 1. The actuator 96 includes an electric motor 97 that drives a spindle 98. The spindle 98 is fixed with an axial bearing 99, which can be a ball bearing, for example. The outer shell of the axial bearing 99 is connected to an actuator housing 100, which is only shown schematically here with regard to its bearing function. The piston 95 comprises a spindle nut 101 which interacts with the spindle 98. If the spindle 98 is rotated by the electric motor 97, the piston 95 is moved by an actuation path 102. The vehicle clutch, not shown here, is opened by the application of force. To open the vehicle clutch, a compressive force must therefore be exerted on the piston 95 and pressure must be applied to the hydraulic system. The actuator housing 100 is accommodated displaceably in the longitudinal direction of the spindle 98 in an actuator bearing 103 which is only indicated schematically in FIG. 11. The actuator 96 has, by means of the actuator bearing 103, a bearing that can be displaced on the housing side. The actuator housing 100 is pressed against a counter bearing 105 by means of a spring accumulator 104. The spring accumulator 104 is supported on the one hand on the actuator housing 100 and on the other hand on a gearbox-fixed bearing point 113. The spring accumulator 104 acts on the actuator housing 100 in the pressure direction of the spindle 98, the spring accumulator 104 thus acts in the pressure direction of the piston 95. A locking device 106, for example, as indicated in FIG and cooperates with a nose 109 of the actuator housing 100, after triggering, for example, a release lever 110, allows the actuator housing 100 to move in the pressure direction of the piston 95 due to the force of the spring accumulator 104. A return spring 111 pulls the lever 107 back into the starting position. The spring accumulator 104 is dimensioned such that its force is greater than the greatest pressure force occurring in the spindle 98 for opening the clutch 7. After the locking device 106 has been released, which can be done electrically, for example, the spring accumulator 104 presses the piston 95 in the hydraulic pressure direction Systems and thereby opens the clutch 7.

The actuator housing 100 and thus the actuator 96 can therefore be brought into two positions. A locked position or working position in which the normal

Function of the actuator 96 is given, and an unlocked position in which the Actuator 96 is brought into a position in which the master cylinder 4 assumes a position for a fully open clutch 7.

After actuation, the spring accumulator 104 can be tensioned again by moving the spindle 98 of the actuator 96 into a position in which the clutch is normally fully open, that is to say in the locked position of the actuator housing. The lug 109 reaches a position as indicated in FIG. 11, that is, it engages around the lever 107 and can be supported again on it, the locking device 106 and thus the entire actuator housing 100 is thus brought back into a locked position. When the release lever 110 is closed and the locking device 106 is locked, the functionality of the master cylinder in connection with the actuator 96 for opening and closing the vehicle clutch is restored. 11 and 12 additionally show an alternative locking device 115 in the form of a ratchet device 112 with a spring-loaded ball 116 which is pressed against an inclined plane. The ball 116 is pulled in order to release the locked position by means of an actuating member 114 in the direction of the inclined plane which is further open with respect to the actuator housing 100.

In the locked position or working position shown in FIG. 11, the spring accumulator 104 presses the nose 109 onto the counter bearing 105. Since the force exerted by the spring accumulator 104 is greater than the counter force exerted by the piston 95 due to the pressure in the hydraulic system 1 the actuator housing 100 in the locked position.

FIG. 12 shows a modification of the exemplary embodiment according to FIG. 11, which is used in a vehicle clutch that is open in the unloaded state. When the hydraulic system is relieved, the clutch is opened by means of a spring accumulator which is present in the vehicle clutch itself. No spring accumulator 104 is therefore necessary here. To do this, the load direction in which the nose 109 and the counter bearing 105 act must be reversed. The direction in which the ratchet 112 acts must also be reversed. The further configuration corresponds to that of the exemplary embodiment in FIG. 11. The counter bearing 105 and the nose 109 are shown in principle in the representations of FIGS. 11 and 12 to clarify the mode of operation. Of course, any device known per se, which knows a first locked position and a second released position, for example bolt mechanisms, bayonet-type mechanisms, catch hooks or the like can be used. The locked position is achieved according to the embodiment of FIG. 11 from the unlocked position of the actuator housing by moving the spindle into a position that corresponds to a vehicle clutch that is as wide open as possible. In this case, the nose 109 encompasses the thrust bearing 105 on the load side, the actuator housing 100 is thus brought back into a position as shown in FIG. 12, so that when a force is exerted from the spindle 98 onto the spindle nut 101, the piston 95 again can be moved in the pressure direction of the hydraulic system.

The locking device 106, 115 can be controlled manually, for example with a Bowden cable, a lever or the like, or automatically by vehicle electronics, electrically, pneumatically or hydraulically. In any case, it must be ensured by a suitable arrangement of the operating elements or by a suitable control that the clutch can only be opened in the permissible operating states.

LIST OF REFERENCES

Hydraulic system

Pressure relief valve

Clutch bearing

Master cylinder

slave cylinder

disengaging mechanism

clutch

Internal combustion engine

crankshaft

Transmission input shaft first wiring harness second wiring harness

piston rod

actuator

Pressure medium line

actuator

trailing cable

An expansion reservoir

bypass line

bypass valve

control line

Brake booster

Vacuum line

brake circuit

brake pedal

Additional control line

Vacuum system

bar

First Bowden cable

Second Bowden cable pushpin

drilling

End caps

Park brake

Kupplungsnotlöseeinrichtung

valve housing

First connection

Second connection

channel

valve disc

valve spring

valve seat

gap

O-ring seal

attack

leg

buckling

joint

guide

joint spring

Horizontal (alpha) angle

motor vehicle

drive motor

clutch

manual transmission

powertrain

drive shaft

differential

axis

bikes

release bearing

declutching release lever

actuator

spindle nut

spindle

electric motor

cable

guide rollers

pulley

rope

emergency release

casing

reaction chamber

propellant

squib

First choke

Second throttle

expansion space

cylinder

piston

arrow

rack

gear

neckline

gearing

piston

actuator

electric motor

spindle

thrust

actuator housing

spindle nut

actuating

actuator bearing 104 spring loaded

105 counter bearing

106 release device

107 levers

108 bearings

109 nose

110 release lever

111 return spring

112 ratchet

113 Gearbox-fixed bearing point

114 actuator

115 alternative locking device

116 bullet

Claims

claims

1. Hydraulic system (1), in particular for motor vehicles, comprising a master cylinder (4) with a follow-up line (17), a slave cylinder (5) and one

5 this connecting pressure medium line (15), characterized in that the

Pressure medium line (15) is connected to the bypass line (17) via a bypass line (19) with a bypass valve (20).

2. Hydraulic system according to the preceding claim, characterized in 0 that the bypass valve (20) in a first position

Connect the pressure medium line (15) directly to the follow-up line (17) and block this connection in a second position.

3. Hydraulic system according to one of the preceding claims, characterized 5, that the master cylinder (4) can be actuated by an actuator (16).

4. Hydraulic system according to one of the preceding claims, characterized in that the bypass valve (20) is pneumatically switchable.

5. Hydraulic system according to the preceding claim, characterized in that the bypass valve (20) blocks when the pressure in a control line (21) is below the ambient pressure.

6. Hydraulic system according to one of the preceding claims, characterized 5, that the control line (21) with a vacuum system (27) one

Brake booster (22) is connected.

7. Hydraulic system according to one of the preceding claims, characterized in that several bypass valves (20) with a common one

$ 0 control line (21) are connected.

8. Hydraulic system according to one of claims 1 to 3, characterized in that the bypass valve (20) can be actuated mechanically.

9. Hydraulic system according to the preceding claim, characterized in that the mechanical actuation comprises at least one cable (30).

10. Hydraulic system according to the preceding claim, characterized in that the at least one cable is a Bowden cable (31, 32).

11. Hydraulic system according to one of the preceding claims, characterized in that the bypass valve (20) can be actuated by an actuating means (30) with at least a first actuating means (31) and a second actuating means (32), each of which has at least one first and can assume a second position, is coupled, the bypass valve (20) being open in at least one combination of the possible positions of the two adjusting means (31, 32) and the in at least one combination of the possible positions of the two adjusting means (31, 32) Bypass valve (20) is closed.

12. Hydraulic system according to the preceding claim, characterized in that the bypass valve (20) is opened in exactly one combination of the possible positions of the two adjusting means (31, 32) and in all other combinations of the possible positions of the two adjusting means (31, 32 ) the bypass valve (20) is closed.

13. Hydraulic system according to the preceding claim, characterized in that the actuating means is a bar (30) and the actuating means (31, 32) are arranged such that they are coupled together by the bar and the bypass valve (20) between the actuating means (31, 32) and can be actuated by the bar (30).

14. Disengaging device for actuating a clutch (58), in particular a clutch (58) in the drive train (60) of a motor vehicle between the drive motor (57) and the manual transmission (59), characterized in that the disengaging device for closing the clutch (58) Partial section (50), which is subjected to thrust when the clutch (58) is closed, and that the partial section (50) comprises an articulated bar (51) which can be folded over to relieve the partial section (50).

15. Release device according to the preceding claim, characterized in that the buckling bar (51) comprises a joint (52).

16. Release device according to the preceding claim, characterized in that the joint (52) is pressed by a joint spring (54) against a stop (49).

17. Release device according to one of the preceding claims, characterized in that the buckling bar (51) can be folded over against the force of the articulated spring (54).

18. Disengaging device for actuating a clutch (58), in particular a clutch (58) in the drive train (60) of a motor vehicle between the drive motor

(57) and manual transmission (59), comprising a release lever (67) and one with the

Release lever (67) connected actuator (68) characterized in that the

Release lever (67) is also connected to a cable (72).

19. Release device according to the preceding claim, characterized in that the release lever (67) by the cable (72) is to be brought into a position in which the clutch (58) is open.

20. Release device according to one of the preceding claims, characterized in that the cable (72) with a plurality of release levers (67), each of which is assigned to a clutch (58), is connected.

21. Release device according to one of the preceding claims, characterized in that the cable pull (72) comprises a pulley block (74).

22. Release device according to one of the preceding claims, characterized in that the cable (72) in the position in which the clutch (58) is open, can be fixed.

23. Release device for actuating a clutch (58), in particular a clutch (58) in the drive train (60) of a motor vehicle between the drive motor

(57) and manual transmission (59), characterized in that there is also a propellant charge (83) and a piston-cylinder arrangement (88, 89) which is operatively connected to the latter and which is connected to the mechanical transmission (91, 92) Disengaging device is connected.

24. Release device according to the preceding claim, characterized in that at least one first throttle (85) is arranged between the propellant charge (83) and the piston-cylinder arrangement (88, 89).

25. Release device according to the preceding claim, characterized in that between the propellant charge (83) and the piston-cylinder arrangement (88, 89) a first throttle (85), a second throttle (86) and between the throttles an expansion space (87) is arranged

26. Release device according to one of the preceding claims, characterized in that the propellant charge (83) is arranged in a reaction chamber (82).

27. Release device according to one of the preceding claims, characterized in that the propellant charge (83) can be triggered by an ignition charge (84).

28. Release device according to one of the preceding claims, characterized in that the ignition charge (84) can be triggered electrically

29. Release device according to one of the preceding claims, characterized in that the piston (89) is connected to a toothed rack (91) which is in engagement with a toothed wheel (92).

30. Release device according to the preceding claim, characterized in that the toothed rack (91) has a cutout (93) which, in the rest position

Rack (91) releases the engagement with the toothing (94) of the gear (92).

31. Disengaging device for actuating a clutch (58), in particular a clutch (58) in the drive train (60) of a motor vehicle between the drive motor (57) and the manual transmission (59), comprising a hydraulic system (1) (1) with a

Master cylinder (4), which is connected to an actuator (96) (4) (17), a slave cylinder (5) and a pressure medium line (15) (15) connecting master and slave cylinders, characterized in that the actuator (96) is mounted on the housing side in a displaceable bearing (103) with a locked position and an unlocked position.

32. Release device according to the preceding claim, characterized in that the actuator (96) in the unlocked position is pressed into a position which, by means of the hydraulic system, causes the vehicle clutch to open.

33. disengaging device according to claim 31 or 32, characterized in that the actuator (96) in the unlocked position by a spring actuator (104) arranged between the actuator housing (100) and a gear-fixed bearing point (113) in the pressure direction of the hydraulic system (1) is pressed.

34. Disengaging device according to claim 31 or 32, characterized in that the actuator (96) in the unlocked position is pressed by the vehicle clutch by means of the hydraulic system into a position which causes the vehicle clutch to open.

35. Release device according to one of the preceding claims, characterized in that the actuator housing (100) is held in the locked position by a locking device (106, 115).

36. Release device according to the preceding claim, characterized in that the locking device comprises a movable lever (107) which cooperates with a nose (109) of the actuator housing (100).

37. Release device according to claim 35, characterized in that the locking device comprises a ratchet (112)

38. Drive train (60) in particular for a motor vehicle, comprising a drive motor (57), a manual transmission (59) and a clutch (58) connecting the same, characterized by a disengaging device according to one of the preceding claims.

39. Drive train according to one of the preceding claims, further comprising a drive shaft (61), a differential (62), a rear axle (63) and two wheels (64).

40. Device with a feature disclosed in the present documents.