Patent Abstract:
A control valve arrangement for controlling a start coupling of an automatic gearbox comprising a clutch control valve ( 3, 37, 41, 48, 49 ) for controlling at least one clutch actuating device ( 4, 40 ) which, during normal operation of the gearbox, converts a supply pressure input (P_V 1,  P_V 2 ) into a clutch actuation pressure (P_K, P_K 1,  P_K 2 ) according to a pre-control pressure or an electric pre-control signal in order to control the clutch actuation device. An activating pressure (P_A) can be supplied to the clutch control valve or directly to the clutch activation device in the event of a discontinuation of the pre-control pressure or pre-control signal according to the engine and gearbox output speed, whereupon the clutch actuation device is maintained in a closed position as long as the above mentioned speed remains above a predetermined limit.

Full Description:
[0001]     This application is a national stage completion of PCT/EP2005/004352 filed Apr. 22, 2005, which claims priority from German Application Serial No. 10 2004 020 569.8 filed Apr. 27, 2004.  
       FIELD OF THE INVENTION  
       [0002]     The invention concerns a control valve arrangement for the control of a start clutch of an automatic transmission of a motor vehicle.  
       BACKGROUND OF THE INVENTION  
       [0003]     In automatic transmissions with automated, wet start clutches, the general practice is to convert a typical mechanical transmission into an emergency operation, for example if following the failure of a transmission control apparatus, which alleviates the failure of power in a transmission in such a manner the start clutch, now unpowered, is caused to disengaging. Especially, in a case of driving in heavy traffic, this strategy can lead to serious results, since the vehicle has become capable of no more than a powerless, forward rolling behavior.  
         [0004]     Engagement of the wet start clutch in such a condition of driving, because of technological safety reasons, is also impossible since the shutdown of power remains in force only because of a hydraulic clutch activation pressure. Insofar as the vehicle&#39;s drive motor stalls itself upon the diminution of the travel velocity with the engaged clutch, there is still a low residual speed at which the important motor driven co-acting aggregates, such as brake action reinforcement or power steering pumping can no longer properly function.  
         [0005]     In a typical automatic transmission with a dry start clutch, during mechanical emergency operation, the clutch is engaged so that the output torque of the vehicle remains in a technological connection with the motor output until the vehicle comes to a standstill. In such a case, it is true that no dangerous, critical conditions of driving exist for the vehicle although, following the standstill, the vehicle can no longer be brought into motion or even pushed into a safer location.  
         [0006]     In accordance with the foregoing, obviously there exists a need for a control apparatus for a start clutch of an automatic transmission of a motor vehicle which, in dependency upon the speed of rotation of the motor and/or the speed of rotation of the output drive of the transmission, the power flow in the drive string is first interrupted when a predetermined threshold speed of rotation of the motor and/or transmission output speed of rotation is understepped. In this way, no stalling of the motor of the vehicle occurs, the auxiliary aggregates remain operable and the driver is still given the advantage of removing himself and his vehicle from a possibly dangerous driving zone. Additionally by way of such a control system, even an induced movement of the vehicle, which is then in standstill, is possible since an otherwise movement blocking, power-flow connection between the motor and the transmission is broken.  
         [0007]     Based on this background, DE 199 43 939 A1 discloses a hydraulic emergency control for a stepless transmission, wherein a dedicated clutch to the transmission becomes separable and engagable according to the speed of rotation of the vehicle motor. Thereby, in the case of a disturbance, a renewed stalling of the drive motor can be avoided upon the understepping of a defined threshold value of rotation speed and as well, a startup upon the overstepping of the threshold is enabled. According to the design of the emergency control, the possibility exists that the speed of rotation related signal can be engendered, for example as (1) a hydraulic pressure, as (2) a pneumatic pressure or as (3) an electrical voltage; any one of which can be functional.  
         [0008]     Additionally, DE 102 38 104 A1 teaches a procedure for controlling an emergency shifting program for an automatic transmission with a start clutch, which is particularly designed to allow a realization of an emergency operation upon the standstill of the vehicle, as well as permitting a by-pass of the lowering of the speed of rotation of the motor to a point below the stalling threshold. In the case of this procedure, provision has been made that the emergency shifting program is controlled by a signal related to the vehicle travel speed and/or to the speed of rotation of the motor, which is computer processed by valve-logic and acts in such a manner that the motor operation is interrupted only in the compression stage in order to prevent the motor from stalling.  
         [0009]     Accordingly, the purpose of the invention is the creation of a control valve arrangement for controlling of a start clutch of an automatic transmission where, during an emergency control operation, the start clutch can be disengaged if the speed of rotation of the motor and/or the output speed of rotation of the transmission, i.e., the travel speed of the vehicle, falls below a predetermined threshold value. The purpose encompasses the fact that this valve arrangement is to be economical in manufacturing costs, simple in design and reliable under emergency conditions.  
       SUMMARY OF THE INVENTION  
       [0010]     The invention is based on a control valve arrangement for controlling a starting clutch of an automatic transmission, where a clutch control valve for controlling at least one clutch activation apparatus which, in the normal operation of the transmission, diverts a provided source of pressure to the direct control of the clutch activation apparatus and does so in relation to a pilot pressure or to an electrical signal.  
         [0011]     Additionally, this control valve arrangement is for the realization of an emergency operation of the transmission. Upon the failure of pilot pressure or electrical signal, an activation pressure can be conducted to the clutch control valve, whereby this valve is held in its engaged position as long as a specified speed of rotation lies above a predetermined speed of rotation threshold. The pilot alarms can be induced by the following, individually or in common: motor speed of rotation; transmission output speed of rotation; motor torque; transmission input torque; transmission input speed of rotation; transmission output torque, and the driving load.  
         [0012]     By way of this valve arrangement, a control apparatus for emergency operation of a vehicle with an automatic transmission can be created, which can be manufactured at low cost and is reliable in its function. The control apparatus would be activated, for example if an electronic transmission control system and/or an electrically controlled clutch control valve dropped out of service. A controlling pressure, which would be related to the speed of rotation of the vehicle&#39;s driving motor and/or to the transmission output speed of rotation, would provide assurance that a start clutch of the automatic transmission remains operative for the transfer of torque through the automatic transmission as long as the driving speed and the speed of rotation of the drive motor do not fall below such a stalling speed of rotation that the driving motor would lose its internal combustion process.  
         [0013]     Insofar as the driving speed, during such an emergency operation, actually drops below such a functional value with an engaged start clutch, the driver would be obliged to contend with stalling of the motor, the control pressure, which is related to the speed of rotation, disengages the start clutch. This start clutch, up to this time, has been transferring the full motor torque. Stalling of the motor is thereby avoided, so that important vehicle components, such as a brake pressure reinforcing way and/or a power steering auxiliary pump, can also be continuously operated.  
         [0014]     In the embodiment of these principles of the invention, the proposal is made that the activation pressure of a self-operating pressure, retention valve can be conducted directly to the clutch activation apparatus by way of an activation valve leading to a clutch control valve, or alternately through a bypass, if available, directly to the clutch activation apparatus. This would take place if a speed of rotation dependent control pressure is applied to the self-activating check valve and this pressure is greater than the applicable pressure threshold value. As this occurs, this pressure threshold value characterizes that the previously mentioned motor speed of rotation, below which the motor will stall.  
         [0015]     According to another component of such a control valve arrangement, provision has been made that a pilot pressure in normal operation, can be exerted on the self-activating check valve and on the activation valve. Deviating therefrom, provision can also be made to the effect that, first, at the self-activating, pressure retention valve and, second, at the activation valve during normal operation, the control pressure, which defines the normal operation or yet, third, during emergency operation at the activation valve, a control pressure is established which defines the emergency operation.  
         [0016]     With regard to the advantageous clutch control valve, notice should be given that it is possible to design this valve, which is capable of governing the pressure means or, in some embodiments, activating a solenoid operator. The defined chosen mode of construction for the self-operating pressure, retention valve is, however, not of decisive importance for the result to be achieved by the invention.  
         [0017]     A pilot pressure controlled clutch control valve advantageously incorporates two axial, successively placed slide valves which, as is the case with all other slide valves here described, are advantageously inserted into a slide valve body of a hydraulic transmission control apparatus to move with axial motion thereby aligning complementary flow ports.  
         [0018]     Belonging to the two slide valves of the pilot pressure controlled clutch control valve, in accord with an advantageous embodiment example, is to be found a shorter slide valve which, on its oppositely situated end surface is pressure-loaded by activation pressure, that is to say, by the pilot pressure, while the pilot pressure can be applied against an axial end face of a longer slide valve.  
         [0019]     According to another embodiment of the control valve arrangement, the slide valve of the activation valve can be subjected to the activation pressure and to the pilot pressure. In addition, provision has been made that the slide valve of the self-operating pressure, retention valve can accept activation and pilot pressures.  
         [0020]     Beyond this, it is a characterization of a control valve arrangement of invented design in that the slide valve of the self-operating pressure, retention valve and the slide valve of the activation valve exhibit on a first axial end, respectively, a control piston against which a reset spring abuts, while the pilot pressure can act upon that second axial end of a control piston, which is remote from the reset spring.  
         [0021]     In a circumstance when pilot pressure fails and a pressure based on speed of rotation exists, which lies below the specified threshold value by way of the above measures, assurance is given that the slide valve of the self-operating pressure, retention valve is pushed so far axially by a reset spring that even a renewed increase of the speed of rotation related pressure is no longer enabled to close the start clutch. From a technological standpoint of safety, this is of exceptional value since the vehicle drive-motor is now in a state of standstill with the start clutch necessarily open. In this operation, the motor, for example, for trial, could be run up to a high rate without the danger that thereby an undesired start of the vehicle would result.  
         [0022]     Further, it could be seen as advantageous if the axial end faces of both slide valves located in the pilot pressure controlled, clutch control valve are subjected to the mentioned pilot pressure. In this condition, provision is made in that the end surface, which is remote from the end surface loaded with the pilot pressure, of the axially longer slide valve of the clutch control valve be subjected to the force of a reset spring.  
         [0023]     A typical reset spring abuts itself on a piston of the axially longer slide valve of the clutch control valve in such a manner that both end faces of the piston can be loaded by the controlled clutch activation pressure.  
         [0024]     In the case of an activation valve, the co-acting reset spring provides assurance that, by a defection of the pilot pressure of the slide valve of this valve, without any auxiliary support, the piston of the valve is pushed into that position where the provided activation pressure from the self-operating pressure, retention valve can be conducted through the clutch control valve, which is now activated by pilot pressure.  
         [0025]     Considering the clutch activation apparatus, it is preferable that this apparatus possess an operative piston in a cylinder, which the piston receives force from an axially aligned, piston-encompassing reset spring. By way of this construction, upon a defection of the pilot pressure, that is to say, upon the failure of another control pressure or a dropout of an electric operative signal, as well as entering a lower state of a control pressure based on speed of rotation, this piston would be so far retracted in its cylinder that a clutch, which has previously been disengaged within the circumstances of emergency operation, remains in the same disengaged state.  
         [0026]     A further embodiment of the invention provides, that the supply pressure, which is delivered to the clutch control valve, possesses the same level of pressure as the activation pressure. If this is the case, it becomes advantageously possible that, first, the same pressure source is being relied upon and, second, the start clutch will be subjected to the same slip-free, clutch-engaging force as is conventionally used in normal operation when the activation pressure is conducted directly (possibly bypassing a clutch control valve) to the clutch activation apparatus.  
         [0027]     In this connection, mention is made that according to another embodiment of the invention, provision could be made so that the activation pressure can be acquired from that very high pressure hydraulic fluid flow, which is employed in normal operation for the clutch slip operation of at least one start clutch.  
         [0028]     Since it can be advantageous that the described self-restraining, operational function of the control valve arrangement acts to prevent a shifted-into, reverse vehicle travel, another embodiment of the invention prevents the enablement of the transmission from performing the reverse travel during an emergency operation.  
         [0029]     For the realization of this controlling function, another provision can be that the end-face of a piston of a slide valve, which piston forms an abutment for the reset spring of the self-operating pressure, retention valve, is loaded with a reversal-prevention pressure, the degree of which pressure is so selected that, in spite of the control pressure, dependent on speed of rotation, exerted on this self-operating pressure, retention valve, any forwarding of the activation pressure is prevented. At the same time, since the pilot pressure or the electrical control signal is no longer being applied on the clutch control valve then, in the emergency operational state in a case of shifted-into reverse travel, the start clutch is disengaged by way of the clutch activation apparatus by the action of the force of the assigned reset spring.  
         [0030]     A special embodiment of an invented design for the control valve arrangement provides that, in normal operation of the transmission, a separate control signal, i.e., a separate control pressure for the activation of the activation valve as well as the self-operating pressure, retention valve is employed, while only the clutch control valve is loaded by the pilot pressure.  
         [0031]     According to this embodiment, it is possible that a conduction of pressure can only be directed against that end face, which is remote from the reset spring of the axially longer, slide valve as well as against the opposite end face of the shorter slide valve of the clutch control valve. Moreover, the self-operating pressure, retention valve as well as the activation valve on their ends, which are remote from the reset springs, are pressurized by that control pressure which is characteristic of normal operation of the transmission. In a case of a defection of this control pressure for realization of the transmission emergency operation, a switching of the activation pressure onto the clutch control valve is possible. Thereby the clutch activation apparatus, upon the defection of the pilot pressure, will be held in its engaged position until the speed of rotation related, control pressure at the self-operating pressure, retention valve drops below the preselected pressure threshold value.  
         [0032]     Another embodiment of the control valve arrangement provides that the clutch control valve and the self-operating pressure, retention valve can be subjected to the pilot pressure, while the activation valve is loaded with a converted starting pressure, which acts upon the reset spring-loaded end of the slide valve of this valve.  
         [0033]     Accordingly, provision is made so that pilot pressure can be applied against that end face, which is remote from the reset spring, of the slide valve of the self-operating pressure, retention valve and to that end face, which is remote from the reset spring of the longer slide valve of the clutch control valve and so that activation pressure can be applied against that end which is remote from the reset spring of the slide valve of the activation valve, as well as a pressure chamber of the activation valve, so that an emergency control pressure can be applied against the end face, which is subjected to the force of the reset spring of the slide valve of the activation valve to bring about the release of an emergency operation of the transmission and so that activation pressure from the activation valve can be diverted to the clutch control valve following a defection of the pilot pressure.  
         [0034]     By way of this construction mode, the clutch activation apparatus is held in its engaged position until the speed of rotation related control pressure at the self-operating pressure, retention valve drops below the predetermined threshold of level of pressure.  
         [0035]     The invention does not limit itself to the activation arrangement for the start clutch. Thus a provision is possible that with the control valve arrangement in accordance with the invention, two mutually separate, controllable start clutches can be present in an emergency operation of the transmission. In the described case which follows during the emergency operation of the transmission, one of the two start clutches is held just so long in its engaged position until the speed of rotation control pressure lies above the specified pressure threshold.  
         [0036]     Thus a control valve arrangement is provided wherein a first pilot pressure of that end surface, which is remote from the reset spring of a spring-loaded, slide valve of a first clutch control valve and a second pilot pressure of that end surface which is remote from the reset spring of a spring-loaded, slide valve of a second clutch control valve, allow both respective clutch control valves to exert pressure upon one of two clutch activation apparatuses with respective one clutch activation pressure and where the two pilot pressures can be directed to one switchover valve by way of which that end surface, which is remote from the reset spring of the slide valve of the activation valve and of the self-operating pressure, retention valve are alternatingly subjected to the higher of the two pilot pressures.  
         [0037]     In accordance with the failure of the pilot pressure, as well as in the presence of a sufficiently high speed of rotation related control pressure on the self-operating pressure, retention valve, the activation pressure from the self-operating pressure, retention valve can be forwarded to a selection valve, by way of which and dependent upon its set position, this pressure can be again forwarded to that end face, which is remote from the reset spring of the shorter slide valve of the first clutch control valve or to that end face, which is remote from the reset spring of the shorter slide valve of the second clutch control valve.  
         [0038]     Thereby a clutch activation apparatus is held in its engaged position until the speed of rotation control pressure understeps the predetermined pressure threshold, while the second clutch activation apparatus is brought into an open-position or, if already open, is continued to be held in that position.  
         [0039]     In the case of such a control valve arrangement, it is possible that provision can be additionally made, to the effect that the reset remote end face of the slide valve in the selection valve can be subjected to the regulated clutch activation pressure of the first clutch control valve so that, under this circumstance, if this controlled clutch activation pressure understeps a predetermined pressure value then the slide valve of the selection valve can be brought into its axial second position in which the activation pressure from this selection valve is directed to that end face, which is remote from the reset spring of the shorter slide valve of the second clutch control valve.  
         [0040]     Accordingly, the shorter slide valve acts upon that end face, which is remote from the reset spring of the spring-loaded slide valve of this second clutch control valve so that a supply pressure is delivered as a clutch activation pressure to the emergency operational positioning, i.e., holding, of the second clutch activation apparatus in the direction of closure of the same.  
         [0041]     Another embodiment of a control valve arrangement, designed according to the invention, emphasizes the actual control function. This is carried out in that two respective clutch activation apparatuses can act upon one of two start clutches where, for the realization of an emergency operation of the transmission that actuation apparatus, i.e., that clutch would be retained in its engaged position, which clutch has been already activated in the engaged direction.  
         [0042]     Provision is made for a control valve arrangement, where a first pilot pressure against that end face, which is remote from the reset spring of the spring-loaded slide valve of a first clutch control valve, as well as a second pilot pressure against that end face, which is remote from a reset spring of a spring-loaded slide valve can be so forwarded, that the two clutch control valves subject one of two clutch activation apparatuses with one clutch activation pressure, so that the two pilot pressures are conducted to a switchover valve, by way of which the end face, which is remote from the reset spring of the slide valve of the activation unit, can be alternately subjected to the pressure of the greater of the two pilot pressures.  
         [0043]     Additionally, this control valve arrangement provides that a speed of rotation related, control pressure can be sent to the slide valve of the self-operating pressure, retention valve that following the failure of the two pilot pressures, as well as in the presence of a predetermined speed of rotation related control pressure at the self-operating pressure, retention valve, the activation pressure from the self-operating pressure, retention valve by way of the activation valve can be forwarded to a selection valve (which lacks a reset spring) by way of the activation pressure, which latter is, in accordance with its setting, applied to that end face, which is remote from the reset spring, of the shorter slide valve of the first clutch control valve or to the end face, which is remote from the reset spring, of the shorter slide valve of the second clutch control valve.  
         [0044]     Further, care has been taken that an end face of the slide valve in the selection valve is subjected to the controlled clutch activation pressure of the first clutch control valve while, at the same time, the other end face is subjected to the controlled clutch, activation pressure of the second clutch, control valve so that, in case of an emergency, failure of the two pilot pressures which were held at the closure pressure of the clutch activation apparatus until the speed of rotation related control pressure at the self-operating, valve understeps the predetermined pressure threshold value.  
         [0045]     As already mentioned, the technological result attributed to the invention is not due to the construction mode of one or more control valves of the control valve arrangement. In this matter, additional embodiments of the invention provide control valve arrangements, which can be equipped with at least one solenoid, proportionally controllable clutch control valve.  
         [0046]     In one embodiment with a solenoid, effective clutch control valve, provision has been made to the effect that the end face, which is remote from the reset spring of the slide valve of the activation valve, as well as the self-operating pressure, retention valve are pressure loaded with that pressure which characterizes a normal operating control pressure, so that clutch activation pressure emanating from the clutch control valve is conducted, without interference, by way of the activation valve to the clutch activation apparatus. Further, the self-operating pressure, retention valve becomes loaded with the speed of rotation related control pressure, whereby, upon the failure of the solenoid clutch valve, as well as upon the failure of the control pressure, which characterizes normal operation for the realization of an emergency operation, an activation pressure from the self-operating pressure, retention valve, by way of the activation valve, can be transferred to the clutch activation apparatus. Thereby the clutch activation apparatus will be held in its engaged position until the speed of rotation, control pressure at the self-operating pressure, retention valve understeps the predetermined pressure threshold.  
         [0047]     A constructive diversion from the embodiment now offers the provision, that the clutch control valve is indeed designed as an solenoid, proportionally controllable valve, however, the control regulates the activation valve for the realization of an emergency operation of the clutch activation apparatus by way of a control pressure, which can be directed upon the spring-loaded side of the slide valve of the activation piston of this activation valve.  
         [0048]     Thus care has been exercised to the effect that the end face, which is remote from the reset spring of the slide valve of the activation valve as well as the self-operating pressure, retention valve, when in normal operation, can be subjected to the controlled clutch, activation pressure from the solenoid clutch, control valve and that the clutch activation pressure, again, in normal operation, which emanates from the clutch control valve, can be directed by way of the activation valve without interference to the clutch activation apparatus, and that for the activation of an emergency operation of the transmission, an emergency control pressure can be applied to the reset spring-loaded, end face of the slide valve of the activation valve.  
         [0049]     This design allows that, after the failure of the solenoid clutch, control valve, the activation pressure from the self-operating pressure, retention valve can be applied, by way of the activation valve, onto the clutch activation apparatus, where the clutch activation apparatus is then held it its engaged position until the speed of rotation, control pressure at the self-operating pressure, retention valve understeps a predetermined pressure threshold.  
         [0050]     Another control valve arrangement for the activation of two start clutches, which also function as emergency activation clutches, provides that in an emergency operation of the transmission, the start clutch is held in its engaged position, which clutch was last activated into that engaged position. This control valve arrangement encompasses two clutch activation valves, which can be solenoidally activated for the purpose of activation-control of two clutch activation apparatuses, one self-operating pressure, retention valve, an activation valve, a selection valve, a switchover valve as well as a pressure conversion control valve.  
         [0051]     In the normal operation of the transmission, provision is made to the effect that a higher controlled, clutch activation pressure present, respectively in one of the two clutch control valves, by way of a switchover valve, acts alternately against that end face of the slide valve which is remote from the reset spring and/or against the activation valve.  
         [0052]     In addition, the controlled clutch, activation pressure of the one clutch control valve can be conducted, by way of a first reversal control valve to a first clutch activation apparatus, as well as to an end face of a slide valve of the selection valve, while the controlled clutch, activation pressure of the second clutch, control valve, by way of a second reversal valve, can be conducted to the second clutch, activation apparatus and, further the second end face of the slide valve at the selection valve can be subjected to this clutch activation pressure.  
         [0053]     Moreover, provision is made that, in a case of failure of the two solenoid clutch control valves, an emergency operation of the transmission is assured by way of a pressure, which is dependent upon the speed of rotation, which so acts upon the self-operating pressure, retention valve with a rotational velocity which is above the predetermined threshold of speed of rotation value in such a manner, that an activation pressure from the self-operating pressure, retention valve can be applied by way of the activation valve onto the selection valve, where this activation pressure can be relayed from the selection valve to one of the two reversal valves.  
         [0054]     Additionally, provision is made that the two reversal valves can be brought into such an operative setting by way of the activation pressure in which setting the activation pressure can be transferred directly to the assigned clutch activation apparatus, whereby the subject clutch activation apparatus is held in its engaged position until the speed of rotation control pressure understeps the predetermined pressure threshold value.  
         [0055]     A further embodiment of this named control valve with two solenoid control valves allows that the selection valve has been so designed, that in an emergency operation of the transmission, specifically that one of the two clutch activation apparatuses is held in an engaged position, which activation apparatus was last set into an engaged position.  
         [0056]     This situation can be further revised in that alternative to the loading of the self-operating pressure, retention valve and the activation valve with the controlled clutch, activation pressure, a control pressure, equal to that which is characteristic to normal operation of the transmission, can be applied to that end face, which is remote from the reset spring of the slide valve of these two valves.  
         [0057]     Considering the design-oriented formulation of the self-operating pressure, retention valve, it could be advantageously assumed that, if this were so constructed that the speed of rotation-related, control pressure could be conveyed to two separate pressure chambers of the self-operating pressure, retention valve, which chambers were separated by way of at least one control piston of the correlated control slide valve.  
         [0058]     In accordance with yet other embodiment of the self-operating pressure, retention valve, provision can be made that the mentioned reversal travel, prevention pressure can easily be directed to the spring-loaded end face of the slide valve of the self-operating pressure, retention valve and that the speed of rotation-related, control pressure can be directed to that pressure chamber of the self-operating pressure, retention valve by way of a one-way valve, which is placed axially, directly beside the pressure space for the acceptance of the reset spring and is located for application with the reversal travel, prevention pressure. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0059]     The invention will now be described, by way of example, with reference to the accompanying drawings in which:  
         [0060]      FIG. 1  is a control valve arrangement with a clutch control valve, wherein a pilot pressure for the control valve is employed as a control pressure for an activation valve as well as for a self-operating, check valve;  
         [0061]      FIG. 2  is a control valve arrangement with clutch control valve with which a separate control pressure for the control of the activation valve is used;  
         [0062]      FIG. 3  is a control valve arrangement with clutch control valve with which a separate control pressure is used for a converted control of the activation valve;  
         [0063]      FIG. 4  is a control valve arrangement with two clutch control valves with which alternate to one another, the pilot pressure for the two control valves are used both as a control pressure for an activation valve and for a self-operating pressure, retention valve, as well as one of two clutch, activation apparatuses, which are held in their engaged position while in an emergency operation of the transmission;  
         [0064]      FIG. 5  is a control valve arrangement, as in  FIG. 4 , in the case of which however, one of two clutch activation apparatuses, in the emergency operation of the transmission, is held in the engaged position, which one clutch activation apparatus had already been placed in its engaged position;  
         [0065]      FIG. 6  is a control valve arrangement with an solenoid clutch valve with which a separate control pressure for the control of the activation valve is used;  
         [0066]      FIG. 7  is a control valve arrangement with an solenoid clutch control valve with which a separate control pressure for inverse control of the activation valve is employed;  
         [0067]      FIG. 8  is a control valve arrangement with two electromagnetic clutch valves with which a separate control pressure for inverse controlling of the activation valve is used, whereby one of two clutch activation apparatuses in an emergency operation of the transmission is held in its engaged position, but wherein the valve was preliminarily placed in its engaged position;  
         [0068]      FIG. 9  is a constructive assembly of a self-operating pressure, retention valve as in an aforementioned control valve arrangement, and  
         [0069]      FIG. 10  is a variation to the self-operating pressure, retention valve in accord with  FIG. 9 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0070]      FIG. 1  displays an assembled and comparatively simple embodiment of a control valve arrangement, according to the invention, and which is of a low manufacturing cost. This control valve arrangement encompasses one self-operating pressure, retention valve  1 , an activation valve  2  for emergency operation, (in the following, designated as “activation valve 2”), a clutch control valve  3  as well as a clutch activation apparatus  4 . The clutch activation apparatus  4  consists of a cylinder  5  in which is to be found a piston  6 . The piston  6  stands within a co-axial helical, reset spring  7  which acts counter to the activation pressure. A pressure application against an end face of the piston  6 , which face is remote from the reset spring  7 , causes the piston  6  to slide in a closing direction so that a clutch of the transmission for torque transfer is likewise engaged.  
         [0071]     The subject clutch (not shown here), but would be known as present to the expert, belongs to an automatic transmission, which can be designed to operate on the basis of a planetary transmission to function as a ratio changing transmission operating in a stepless manner or as a load-shifting, automated simple transmission. In such a case, wherein a control valve arrangement for a double clutch transmission is to be designed then, preferably, two control valves as well as two clutch activation apparatuses should be used, which will be discussed below.  
         [0072]     The named valves, i.e.,  1 ,  2  and  3  are disposed in a smooth cylindrical enclosure (not shown) of a hydraulic control apparatus for the transmission, whereby each valve possesses at least one slide valve, which can be axial movable for opening pressure chambers; for disengaging and/or engaging by hydraulic pressure, and also a helical piston, encompassing reset, spring force.  
         [0073]     In the case of all following presented embodiments, the self-operating pressure, retention valve  1  and the activating valve  2  are generally identically designed. Thus the self-operating pressure, retention valve  1  comprises one slide valve  30 , which is located in a valve boring  36  and is axially movable. The slide valve  30  includes, as part of itself, spaced control pistons namely  20 ,  21  and  22 , whereby the free end face of the control piston  20  is loaded by force from a reset spring  31 . Against the axially opposite, located end face of the slide valve  30 , a pilot pressure P_VST acts, which is introduced into a pressure chamber  38  by way of a feed-in, pressure line  8 .  
         [0074]     Additionally to a pressure chamber  39  on the self-operating pressure, retention valve  1 , located between the control piston  21  and the control piston  22 , a control pressure P_D can be delivered by way of a line  11 , the intensity of the pressure thereof being dependent upon the speed of rotation of the drive motor of the vehicle and/or being dependent upon the speed of rotation of the output shaft of the transmission.  
         [0075]     Further, an activation pressure P_A is delivered to the self-operating pressure, retention valve  1  to a pressure chamber  70  between the control pistons  20  and  21 . The delivery is effected through a line  12  which, when in an emergency operation, takes care that a torque transferring clutch of the transmission remains engaged in accordance with a speed of rotation.  
         [0076]     Finally, there is also placed in the self-operating pressure, retention valve  1 , a pressure chamber  71  which holds within the reset spring  31  which, by way of a line  13 , can be loaded with a reverse travel, prevention pressure P_RV. This arrangement will be further discussed below.  
         [0077]     In regard to the assembly of the activation valve  2 , it must be mentioned that this valve possesses a slide valve  29  with two control pistons  23 ,  24 , which are mutually spaced away from one another and the piston  23  is axially and slidingly inserted into a boring  63  of the slide valve enclosure. In this specific case, the free end face of the control piston  24  can be loaded by the force of a reset spring  32 .  
         [0078]     The pilot pressure P_VST in a pressure chamber  78  is delivered to the axial, oppositely situated end face of the slide valve  29  by way of a line  9 . A line  14  additionally connects the pressure chamber  70  (or  143 ) of the self-operating pressure, retention valve  1  with a pressure chamber  72  of the activation valve  2 , whereby this pressure chamber  72 , by way of the control piston  23 , which is remote from the reset spring  7 , can be engage or made to communicate with a pressure chamber  73  on the activation valve  2 .  
         [0079]     The clutch valve  3  encompasses an axial longer, control slide valve  19  with three control pistons  26 ,  27  and  28 , as well as with an axially shorter, control slide valve  34 , which is axially and slidingly located in borings  64 ,  65  of the slide valve enclosure. Further, in this matter, the axially longer, control slide valve  19  can be loaded on the free end of the control piston  28  by the restoration force of a reset spring  33 .  
         [0080]     The axially shorter, control slide valve  34  includes a slide valve  25 , the end face of which is proximal to the other slide valve  19 , which can be loaded by the pilot pressure P_VST. Correspondingly, this pilot pressure P_VST is available from a pressure chamber  74  on the clutch control valve  3  by way of a line  10 . On the oppositely situated end face of the piston  25 , the activation pressure P_A can be delivered through a line  15 , which is connected with the pressure chamber  73  on the activation valve  2 .  
         [0081]     The axially longer, control slide valve  19  of the clutch control valve  3  possesses, as part of its construction, three control pistons  26 ,  27 ,  28 , where two pistons  26 ,  27  are placed immediately next to one another. The free end face and the oppositely situated end of the axially shorter, control slide valve  34  of the slide valve  26  are likewise subject to the pilot pressure P_VST emanating from the pressure chamber  74  while that end face, which is remote from the reset spring of the control piston  28  communicates with a pressure chamber  75 , which itself is subjected to the pressure from a system source or a supply pressure P_V 1 .  
         [0082]     By way of an appropriate control of the clutch control valve  3 , this pressure chamber  75  can be connected with a neighboring pressure chamber  76  through the pilot pressure P_VST, so that a controlled clutch pressure P_K can function in the pressure chamber  76  through the control piston  28 . By way of a line  16 , the pressure chamber  76  is additionally connected with the cylinder  5  of the clutch activation apparatus  4  as well as with a pressure chamber  77  on the clutch control valve  3 , which also houses the reset spring  33 .  
         [0083]     The method of operation, i.e., the functionality, of the control valve arrangement, according to  FIG. 1 , is outlined below.  
         [0084]     In normal operation, the pilot pressure P_VST is so adjusted in that the slide valve  30  on the self-operating pressure, retention valve  1  is axially pushed against the force of the spring  31  to the extent that the control piston  20  opens a path for the activation pressure P_A from the pressure chamber  70 , through the pressure chamber  143  and the line  12 , to gain access to the pressure chamber  72  of the activation valve  2 .  
         [0085]     Additionally, the pilot pressure P_VST acts in the pressure chamber  78  of the activation valve  2  in such a manner that the slide valve  29  is pushed against the force of the reset spring  32  to take its place so far into the boring  63  that the pressure chamber  73  is separated from the pressure chamber  72 .  
         [0086]     Beyond this, the axially longer, control slide valve  19  of the clutch control valve  3  is loaded with the pilot pressure P_VST through the line  10 ; that a rim of the control piston  28  more or less frees up the pressure chamber  75  on the clutch control valve  3 . In this way, with a dependency on the intensity of the pilot pressure P_VST, a supply pressure P_V 1  is regulated to serve as a clutch activation pressure P_K, with which the clutch activation apparatus  4  can finally be brought into a position for opening or closing the attached clutch. Obviously, it is possible that interposed positions can be adjusted to in which the clutch would be slipwise operated.  
         [0087]     Should it occur, for example, that by a disturbance in the transmission control equipment, the pilot pressure P_VST drops out, or at least reduces itself drastically, then the speed of rotation dependent control pressure P_D at the self-operating pressure, retention valve  1  becomes activated. Insofar as the motor speed of rotation or, alternately, the speed of rotation of the output shaft of the transmission is so high that a stalling of the motor need not be expected, then even this controlling pressure P_D will be so high that this is in a situation where it can hold the slide valve  30  of the self-operating pressure, retention valve  1  in a position in which the activation pressure P_A can be conducted through pressure chambers  70  and  143 , as well as through the line  14  to the pressure chamber  72  of the activation valve  72 .  
         [0088]     The function of the self-operating pressure, retentive valve  1  is extinguished if the speed of rotation related control pressure P_D drops below a predetermined value. This pressure threshold characterizes the stalling speed of rotation of the motor. In this case, the slide valve  30 , by the force of the reset spring  31 , is axially moved in the direction of the pressure chamber  38 , so that the activation pressure supply to the activation valve  2  is interrupted.  
         [0089]     In an emergency operation, the pilot pressure P_VST drops to zero in the pressure chamber  78  of the activation valve  2  or is at least significantly reduced, so that the slide valve  29 , by way of the force of the reset spring  32 , is so displaced in the direction of the pressure chamber  78 , that the pressure chamber  72  and the pressure chamber  73  become bound together. Thereby, the activation pressure P_A is conducted through the line  15  to a pressure chamber  80  on the clutch control valve  3 , at which point this pressure then acts upon the axially shorter, control slide valve  34 . As a result of this, an axial section  35  of the slide valve  34  exerts pressure upon the free end face of the piston  26  of the axially longer, control slide valve  19 , whereby this is axially pushed against the force of the reset spring  33 . For this reason, in spite of the failing pilot pressure P_VST, the connection between the pressure chamber  75  and the pressure chamber  76  is held in the open state.  
         [0090]     By way of this method of operation, it is possible that, even in a case of the failure of the pilot pressure P_VST by way of a line  18 , the pressure chamber  75 ,  76 , as well as the line  16 , a clutch activation pressure P_K, which holds the clutch activation apparatus  4  in its engaged position, can be conducted to the same.  
         [0091]     Should the motor speed of rotation or the transmission speed of rotation drop to such an extent that stalling of the motor must be reckoned with, then too, the related speed of rotation related pressure P_D is correspondingly also lowered. This leads, finally, to a break in the emergency operation of the transmission, since under these circumstances, the force of the reset spring  31  on the self-operating pressure, retention valve  1 , without pressure obstruction, becomes sufficient to push its slide valve  30  so far in an axial direction, that the activation pressure connection between the pressure chamber  70  on the self-operating pressure, retention valve  1  and the pressure line  14  can no longer sustain itself.  
         [0092]     As a result of this, even the shorter, control slide valve  34  becomes, of the clutch control valve  3  is no longer pressurized with the activator pressure P_A, while the longer, control slide  19 , driven by the force of the reset spring  33 , is pushed into such a position, where the connection between the pressure chambers  75 ,  76  are interrupted. Thereby, also the clutch activation pressure in cylinder  5  of the clutch activation apparatus  4  declines to the extent that its piston  6 , driven by the force of the reset spring  7 , is pushed into its open state.  
         [0093]     As is made clear in  FIG. 1 , it is possible that the clutch activation apparatus  4 , upon a resurgence of the speed of rotation related pressure P_D, in accordance with an emergency operation, cannot be immediately brought into its engaged position so that an advantageous safety precaution is made to exist, so that, for example in a repair-shop, the motor speed of rotation may be driven so high for test purposes, without causing an increase of the speed of rotation dependent pressure P_D and, automatically, an adjustment to closure in the automatic transmission might be made.  
         [0094]     Additionally it is obvious that the end face, which is proximal to the reset spring  33  of the control piston  28  of the control slide valve  19 , by way of the pressure chamber  76  and lines  16  and  17  may, likewise, be loaded with the controlled clutch activation pressure P_K, i.e., with the activation pressure P_A.  
         [0095]     Finally,  FIG. 1  shows that, in a case of a selected reverse travel direction, the pressure chamber  71 , which contains the reset spring  31  of the self-operating pressure, retention valve  1  may be subjected to the pressure of a reverse travel protection pressure P_RV where, in a case of a deficiency of the pilot pressure P_VST, the slide valve  30 , by the force of the spring  31  combined with the pressure P_RV will be axially transported so far that the pressure chamber  39  becomes engaged, as well as that the pressure loading of the control piston  21  is provided with the speed of rotation related control pressure P_D. The reverse travel prevention pressure P_RV, when the control pistons  20 ,  21  have equal diameters, can be selected to be greater than the speed of rotation related control pressure P_D.  
         [0096]     The illustrated control valve arrangement in  FIG. 2  differentiates itself from the above explained embodiment, essentially in that in normal operation, the pilot pressure P_VST is exclusively directed to act upon the clutch control valve  3 , while the pressure chamber  38  of the self-operating pressure, retention valve  1  and the pressure chamber  78  of the activation valve  2  are loaded by a control pressure P_NOR, which characterizes normal operation.  
         [0097]     The pressure P_NOR, upon the failure of drastic reduction of the pilot valve P_VST for the realization of the described emergency operation, can be likewise diverted so that when the speed of rotation related control pressure P_D lies above the pressure threshold, the activation pressure P_A, can be forwarded by way of the self-operating pressure, retention valve  1 , the line  14 , the pressure chambers  72 ,  73  of the activation valve  2  and the line  15  at the end face, which is remote from the reset spring  31 , of the control piston  25  of the shorter, control slide valve  34  of the clutch control valve  3 .  
         [0098]     Thereby the possibility exists, as has already been described in connection with  FIG. 1 , the slide valve  34  acts axially on the control slide valve  19 , in the result of which action, the supply pressure P_V 1  can be forwarded by way of the pressure chambers  75 ,  76  as well as by the line  16  to the cylinder  5  of the clutch activation apparatus  4 . In this way, the clutch, which is activated by the clutch activation apparatus  4 , even during a failure or drastic diminution of the pilot pressure P_VST is held engaged so that, in the emergency operation of the transmission, a forward motion of the vehicle can be managed.  
         [0099]     The control valve arrangement, presented in  FIG. 3  as an embodiment example, differentiates itself only comparatively and slightly from the embodiments shown in  FIG. 1  and  FIG. 2 . Thus, in this case, the pilot pressure P_VST can be conducted into the pressure chamber  38  of the self-operating pressure, retention valve  1  as well as into the pressure chamber  74  of the control valve  3 . Additionally, the activation pressure P_A is directed, not only to the pressure chamber  70  at the self-operating pressure, retention valve  1 , but also to the pressure chamber  78 , which is remote from the reset valve at the activation valve  2 . Finally, in order to realize an emergency operation, a control pressure P_NS, which characterizes this particular emergency, can be directed to a pressure chamber  79 , which contains the reset spring  32  of the activation valve  2 .  
         [0100]     Insofar that, because of an operational disturbance, the pilot pressure P_VST drops out or is severely reduced, it is true that by way of a sufficiently higher speed of rotation of the motor or, correspondingly, a higher speed of rotation of the output of the transmission by way of the speed of rotation related control pressure P_D of the control slide valve  30 , then the self-operating pressure, retention valve  1  will be retained specifically in that position, shown in  FIG. 3 . However, the activation pressure P_A, which is also present in the pressure chamber  78  of the activation valve  2 , so acts that its slide valve  29  also remains in the depicted position. Only under such a circumstance which characterizes the emergency operation, a control pressure P_NS becomes active in the pressure chamber  79  of the activation valve  2 , can the slide valve  29  be pushed in the direction of the pressure chamber  78 , so that the pressure chamber  72  is brought into communication with the pressure chamber  73 .  
         [0101]     When this occurs, then the activation pressure P_A of the pressure chamber  73 , by way of the line  15  becomes open to the pressure chamber  80  of the clutch control valve  3 , so that the axially shorter, control slide valve  34  acts in such a manner upon the control piston  26  of the longer, control slide valve  19 , allowing the latter to be axially moved, against the force of the reset spring  33  and the pressure chamber  75  to be bound to the pressure chamber  76 . Now, in an already described manner, the clutch activation pressure P_K communicates over the line  16  to the cylinder  5  of the clutch activation apparatus  4  and, as an ensuing result, this remains in its engaged position until the speed of rotation control pressure P_D understeps the predetermined pressure threshold.  
         [0102]     In the case of the embodiment, illustrated in  FIG. 4 , this is an embodiment of a control valve arrangement designed within the framework of the invention. In total, there are two clutch activation apparatuses  4  and  40 , which are of use for an emergency operation of the transmission. These two apparatuses  4 ,  40  are for two start clutches, for example, provision for a double clutch gear train, wherein the first clutch activation apparatus  4 , oppositely situated the second clutch activation apparatus  40 , is advantageously retained in its engaged state.  
         [0103]     Also, this control valve arrangement includes the self-operating pressure, retention valve  1  and the activation valve  2 , which two valves, by way of a selection valve  42 , for the purpose of relaying the already multiply mentioned activation pressure P_A, bind themselves together in a pressure-technological manner with a first clutch, control valve  3  or a second clutch, control valve  41 .  
         [0104]     Especially noted is the fact that in the functionality of this control valve arrangement, a switch-over valve  43  can be subjected to pressure, by way of a line  45  or as well by a line  61  with two pilot pressures P_VST 1 , P_VST 2 . These two pressures can be delivered over lines  46  or  60  to the pressure chamber  74  or  105  of the longer, control slide valve  19  or  90  of the two clutch, control valves  3  and  41 . The respective immediately larger pilot pressure P_VST 1  or P_VST 2  acts in normal operation of the transmission by way of lines  66  and  67  to act upon the pressure chamber  38  of the self-operating pressure, retention valve  1  and upon the pressure chamber  78  of the activation valve  2 .  
         [0105]     Further,  FIG. 4  clarifies that the activation pressure P_A of the self-operating pressure, retention valve  1  can be continually transferred over the activation valve  2  as well by way of two lines  93 ,  94  to pressure chambers  81 ,  82  of the selection valve  42 . In relation to the selection positioning of a control slide valve  44  of the selection valve  42  in a first operational position, this activation pressure P_A of the pressure chamber  82  and a pressure chamber  83  is directed by selection valve  42  by way of a line  95  to that pressure chamber  80  on the end face, which is remote from the reset spring of the shorter, control slide valve  34  of the first clutch, activation valve  3 . In a second operational positioning of the selection valve  42 , the activation pressure P_A is forwarded through the pressure chamber  81  and a pressure chamber  84  as well as by way of a line  96  to a pressure chamber  91 , which is located in the area of that end face and which is remote from the reset spring of a shorter, control slide valve  92  on the second clutch, control valve  41 .  
         [0106]     Finally, it is a specific design feature of the control valve arrangement, according to  FIG. 4 , that the control slide valve  44  of the selection valve  42  is subjected to the application of a restoration force on one of its end faces, by way of a reset spring  97  and further that the oppositely controlled clutch activation pressure P_K 1  of the first clutch, control valve  3  over a line  68 . The latter pressure emanates from a pressure chamber  85  on the selection valve  42 .  
         [0107]     Giving consideration to the above operational possibilities of the control valve arrangement, according to  FIG. 4 , the following method of functioning is possible.  
         [0108]     In the normal operation of the transmission, at least one of the two pilot pressures P_VST 1  or P_VST 2  acts through the switch-over valve  43  to load the pressure chambers  38  and  78 , respective of the self-operating pressure, retention valve  1  and of the activation valve  2 . In this way, the control slide valve  29  of the activation valve  2  is so positioned that an activation pressure P_A from the self-operating pressure, retention valve  1  cannot be delivered over the line  14  to the selection valve  42 . Additionally, at least one of the two clutch activation apparatuses  4  or  40  are activated by way of the pilot pressure P_VST 1  or P_VST 2  to reach an engaged position.  
         [0109]     To the extent that the two pilot pressures P_VST 1 , P_VSR 2  fail or are drastically reduced, then the control slide valve  29  on the activation valve  2  is pushed so far from the assigned reset spring  32  in the direction of the pressure chamber  78 , that the two pressure chambers  72 ,  73  on the activation valve  2  are bound together in a pressure-technological manner.  
         [0110]     Insofar as the speed of rotation related control pressure P_D, which acts upon the pressure chamber  39  on the self-operating pressure, retention valve  1  is intense enough, then the control slide valve  30  is retained in a position shown in  FIG. 4 , so that the activation pressure P_A of the self-operating pressure, retention valve  1  can be conducted through the line  14  and through the pressure chamber  72  or  73  on the activation valve  2  to the selection valve  42 . The activation pressure P_A thus appears in this way in the pressure chamber  81  of the selection valve  42 .  
         [0111]     In a case of failure of the pilot pressure P_VST 1  to act upon the first clutch control valve  3 , since the control slide valve  44  of the selection valve  42  remains in its depicted position, due to the presence of the still existing clutch activation pressure P_K 1  from the pressure chamber  76  of the first clutch, control valve  3  by way of the line  68  to the pressure chamber  85  on the selection valve  42  in  FIG. 4 . Thus, in this emergency operation, a path is made free for the activation pressure P_A from the pressure chamber  73  of the activation valve  2  though the line  93 , the pressure chamber  82  and through the pressure chamber  83  as well as by way of the line  95  to the pressure chamber  80  on the shorter, control slide valve  34  of the first clutch, control valve  3 .  
         [0112]     In this way, it is possible that the shorter, control slide valve  34  can establish an axial force upon the longer, control slide valve  19  of the first clutch, control valve  3  which force, in spite of failure of the pilot pressure P_VST 1 , will hold this longer, control slide valve  19  in a position open to the pressure chamber  75 . Thus, the supply pressure P_V 1 , by way of the pressure chambers  75 ,  76 , as well as through the line  16  gains access to the cylinder  5  of the first clutch, activation apparatus  4  for the purpose of holding this apparatus in the engaged position.  
         [0113]     By way of an exact fitting design of the diameter of a control piston  69 , which is remote from the reset spring of the control selection valve  42  as well as the restoration force of its reset spring  97 , it is possible that this control valve arrangement, according to  FIG. 4 , can also be constructed to function effectively, so that upon the failure of the two pilot pressures P_VST 1 , P_VST 2 , a control piston  86  of the control slide valve  44  of the selection valve  42  remains in its second shifted position.  
         [0114]     In this second shifted position, the activation pressure P_A of the pressure chamber  73  of the activation valve  2  is conducted through the line  94  to the pressure chamber  81  of the selection valve  42  and from there, by way of the pressure chamber  84  and the line  96  to the pressure chamber  91  of the second clutch control valve  41 . At that location, the shorter, control slide valve  92  acts in the already mentioned manner on the longer, control slide valve  90 , in such a manner that the control piston, which is loaded with a reset valve releases the connection between two pressure chambers  87 ,  88 . There the supply pressure P_V 2  is directed to the cylinder  5  of the second clutch, activation apparatus  40  where, in spite of the failure of the pilot pressure P_VST 2 , this is held just so long in its engaged position until the speed of rotation related control pressure P_D at the pressure chamber  39  of the self-operating pressure, retention valve  1  has fallen below the predetermined threshold pressure.  
         [0115]      FIG. 5  shows a further embodiment of the inventive control valve arrangement, by way of which one of two clutch activation apparatuses  4  and  40 , are held in their engaged position during an emergency operational phase, which was the last position in which they were formerly placed.  
         [0116]     Exhibiting a difference to the control valve arrangement according to  FIG. 4 , in this case it is first provided that a selection valve  47  possesses no reset spring. Additionally, in the case of this selection valve  47 , the two control pistons  69  and  99  at the axial ends of the control slide valve  44  are subjected to the control pressure P_K 1  and P_K 2 . Deviating from the control valve arrangement, according to  FIG. 4 , in this case, the controlled clutch, activation pressure P_K 2  of the second clutch, control valve  41  is directed from its pressure chamber  88 , over a line  98  to the pressure chamber  89  on the end face side of the control piston  99  of the selection valve  47 .  
         [0117]     For the activation of the emergency operation of the transmission, the pilot pressures P_VST 1  and P_VST 2  become inoperable or very much diminished. Additionally, the speed of rotation related control pressure P_D acts upon the pressure chamber  39  on the self-operating pressure, retention valve  1 , with a level of pressure which is high enough to keep the control slide valve  30  of the self-operating pressure, retention valve  1  in the activation mode, as is shown in  FIG. 5 .  
         [0118]     Since both pilot pressure P_VST 1  and P_VST 2  are not enabled to maintain sufficient pressure in the pressure chamber  78  of the activation valve  2 , then its slide valve  29  is displaced in the direction of the pressure chamber  78  by way of the force of the reset spring  32 , so that the pressure chambers  72  and  73  of the activation valve  2  are bound together within the technology of pressure. Thereby, the activation pressure P_A is conducted by way of the self-operating pressure, retention valve  1  and the activation valve  2  to the pressure chamber  81  and  82  of the selection valve  47 . Insofar as the clutch activation valve which, in an immediately prior time, was in its engaged position, was actually the second clutch, activation apparatus  40 , then this acts for the direction of the clutch activation pressure P_K 2  from the pressure chamber  88  of the second clutch, control valve  41  by way of the line  98  to the pressure chamber  89  on the selection valve  47 , so that the control slide valve  44  becomes pushed so far in the direction of the pressure chamber  85 ; that the activation pressure P_A from the pressure chamber  81 , by way of the pressure chamber  84  of the selection valve  47 , is conducted through line  96  to that end face, which is remote from the reset spring of the shorter, control slide valve  92  of the second clutch, control valve  41 .  
         [0119]     As a result of the above, this shorter, control slide valve  92  acts axially on the longer, control piston  90 , whereby this latter is held in an activation position, in which the control piston  89 , which is subjected to the face of a reset spring, hold the flow connection open between the pressure chamber  87  and pressure chamber  88 . In this manner, it is possible, that from the supply pressure P_V 2 , the clutch activation pressure P_K 2  can be formed which, in this emergency operation, now holds engaged, that clutch activation apparatus  40 , which was most recently in the engaged position. This occurs in the same way as in the case of the other control valve arrangements, however, only during that time that the speed of rotation related control pressure P_D lies above the predetermined pressure threshold.  
         [0120]     Due to this knowledge of the described assembly, as well as of the explained functionality, an expert would quickly grasp that when, contrary to the last example, the first clutch, activation apparatus  4  was immediately activated in the engaged position, this being held in the engaged position, due to a failure of the pilot pressures P_VST 1  and P_VST 2 , which brought about the governing emergency operation.  
         [0121]      FIG. 6  clarifies a control valve arrangement, according to the invention, which arrangement is in a comparatively well designed manner and of simple assembly, wherein the advantages which are desired to be attained do not lie in the mode of construction. In the depicted embodiment example, the clutch control valve is not controlled by the influence of a pilot pressure. Rather, the depicted construction includes a solenoid operated clutch control valve  37  which, in response to a warning signal S received through an electrical line  146 , so acts as to provide a proportional clutch activation pressure P_K.  
         [0122]     For the realization of the desired functionality, this control arrangement includes the self-operating pressure, retention valve  1  and the activation valve  2  with slide valves  29  and  30  which, during normal operation, are loaded at their end faces, which are remote from the reset springs  31 ,  32 , by a control pressure P_NOR, which is characteristic of the normal operation. This control pressure P_NOR is introduced to the two valves  1  and  2  through a control pressure line  124  to the end face pressure chambers  38  and  78 .  
         [0123]     Moreover, a speed of rotation related control pressure P_D acts, in the already explained manner, on the centrally located control piston  21  of the self-operating pressure, retention valve  1 . Likewise, with the existing control pressure P_NOR, the activation pressure P_A is also brought upon a pressure chamber  70  between the two control pistons  20  and  21 .  
         [0124]     This activation pressure P_A is conducted through the line  14  to the pressure chamber  72  on the activation valve  2 , which activation valve  2  is engaged during a normal operational condition by way of the piston  23  of the control slide valve  29  against further extension of the pressure. In this operation, two pressure chambers  73  and  102 , which are located between the two control pistons  23  and  24  are bound together in a pressure-technological manner. This action now permits that a clutch activation pressure P_K, which has been generated by the solenoid operating clutch, control valve  37  from a supply pressure P_V, can now be conducted to the cylinder  5  of the clutch activation apparatus  4  through lines  100  and  101 .  
         [0125]     Should the case be that, due to dome defect, the solenoid control valve  37  becomes inoperable, then that pressure P_NOR, which is characteristic of normal operation, is either diverted or so reduced that the control slide valve  29  of the activation valve  2  by the power of the reset spring  32  becomes axially transported in the direction of the pressure chamber  78 . Insofar as the motor or the output speed of the transmission lies above the stalling speed of the motor, then the speed of rotation related control pressure P_D is sufficiently high, so that at the self-operating pressure, retention valve  1  of the control slide valve  30 , in spite of the failure of the pressure P_NOR in the pressure chamber  38 , is still enabled to maintain the position shown in  FIG. 6 .  
         [0126]     Thereby the activation pressure P_A is conducted from the self-operating pressure, retention valve  1  by way of the line  14 , the pressure chambers  72 ,  73  of the activation valve  2  and the pressure line  101  to the clutch activation apparatus  4 . In this way, in spite of the failure of the clutch control valve  37 , the clutch activation apparatus  4  is held as long in the engaged position until the speed of rotation related control pressure P_D lies above a predetermined pressure value and simultaneously above that pressure which represents stalling the motor.  
         [0127]     Since the control piston  24  of the control slide valve  29  of the activation valve  2  in this emergency operational phase has engaged the pressure chamber  102 , it is possible that no hydraulic pressure fluid can escape over the line  100  to the solenoid control valve  37 . Note is made, only in the interests of a complete explanation that even in this above described case of the invention, a reverse travel prohibiting pressure P_RV would be conducted to the pressure chamber  71  of the self-operating pressure, retention valve  1  to bring about the desired effect.  
         [0128]      FIG. 7  shows an embodiment, according to the invention, which is slightly changed from the foregoing, wherein a differentiation is made to the control valve arrangement of  FIG. 6 , in that the pressure chambers  38  and  78  on the self-operating pressure, retention valve  1  or on the activation valve  2  can be pressure loaded through lines  100  and  106  or  107  with the clutch activation pressure P_K which is forwarded from the solenoid control valve  37 .  
         [0129]     Additionally, provision here has been made that even the pressure chamber  103  on the activation valve  2 , which can contain the reset spring  32 , can be subjected to pressure from through a line  104  with a control pressure P_NS, which is characteristic of the emergency condition. Within the control valve arrangement of  FIG. 7 , insofar as the solenoid clutch valve  37  drops out, then also the clutch activation pressure P_K reduces itself in the pressure chambers  38  and  78  as well as  102  and  73 , which has been acting upon the clutch activation pressure P_K.  
         [0130]     At this time, in order to bring the activation valve  2  into its emergency state of operation, the pressure chamber  103 , proximal to the reset spring, is loaded with the control pressure P_NS, whereby the control slide valve  29  is axially pushed so far toward the pressure chamber  78 , that the pressure chambers  72  and  73  become bound to one another. Thereby the path for the activation pressure P_A is made free, which the pressure can now emanate from the pressure chamber  70  of the self-operating pressure, retention valve  1  up to the clutch activation apparatus  4 . The pressure P_A can now hold the clutch activation apparatus in its engaged position until the speed of rotation related control pressure P_D drops below the predetermined pressure threshold value.  
         [0131]     The last embodiment example for a control valve arrangement, designed according to the invention, is shown in  FIG. 8 . In this control valve arrangement, two solenoidally activated clutch, control valves  48 ,  49  are present with which two clutch activation apparatuses  4 ,  40  can activate two clutches (not shown). The belonging control valves are, in this case, so constructed and placed that, in an emergency operation of the transmission, that particular clutch activation apparatus  4  or  40  is continually held in its engaged position until the motor or the transmission out speed of rotation drops under that speed which sustains operation without stalling.  
         [0132]     Additionally to the two clutch control valves  48  and  49 , this control valve arrangement encompasses a self-operating pressure, retention valve  1  and an activation valve  2 , along with a selection valve  51  and two proportional flow solenoid valves  52 ,  53  (hereinafter designated as “conversion valves 52, 53”). The control-technological action of this control valve arrangement will be described by way of a presentation of its normal running condition.  
         [0133]     In the normal operation of the transmission and by way of electrical connections  144  or  145 , the control signal S acts upon the solenoid clutch control valves  48  or  49 , from a transmission control apparatus (not shown), by way of which each proportional flow, solenoid valve  52 ,  53  provides a pressure loading for the displacement of an assigned control slide valve  127  or  128 . Thereby at the respective pressure chamber  125  and/or  126 , existing supply pressure P_V 1  or P_V 2  is converted to a clutch activation pressure, namely P_K 1  and/or P_K 2 .  
         [0134]     In the case of the first solenoid clutch, control valve  48  the immediate clutch activation pressure P_K 1  is conducted over a pressure line  123  to the first conversion valve  52 , from which the valve, this pressure, in the depicted set position, is forwarded over line  118  to the cylinder  5  of the first clutch, activation apparatus  4  so that the piston  6  thereof is, for example, forced into an engaged position.  
         [0135]     Moreover, the clutch activation pressure P_K 1 , through a line  116  is conducted to a switch-over valve  54  and from this, directed to the pressure chamber  38  and/or  78  of the self-operating pressure, retention valve  1  and/or to the activation valve  2 .  
         [0136]     In the case of the second proportional solenoid valve  49 , the clutch activation pressure thereof, namely P_K 2 , is conducted over a line  122  to the second conversion valve  53 , from which this same pressure, in the illustrated set position of the valve, is conducted through a line  120  to the cylinder  5  of the second clutch, activation valve  40 , so that the piston  6  thereof, for example, is placed in an engaged position.  
         [0137]     Moreover, the clutch activation pressure P_K 2  is conducted by way of a line  114  to the already mentioned switch-over valve  54 , from which this pressure is directed to the pressure chamber  38  and/or  78  of the self-operating pressure, retention valve  1  and/or of the activation valve  2 . The switch-over valve  54  forwards only the respective higher of the two clutch activation pressures P_K 1  or P_K 2  to the pressure chamber  38  and/or  78 .  
         [0138]     As an alternative to the above, a control pressure P_NORA can be conducted to the named pressure chambers  38  and/or  78  through the line  124 , which is characteristic of operation in a non-emergency operation.  
         [0139]     In the normal operation of the transmission, the self-operating pressure, retention valve  1  and the activation valve  2  find themselves in that position, shown in  FIG. 8 , so that the activation pressure P_A can actually, by way of the pressure chamber  70  of the self-operating pressure, retention valve  1  and the line  14  to the pressure chamber  72  of the activation valve  2 , the forwarding of which is, however, blocked by the position of the control slide valve  29  of the activation valve  2 . On this account, in normal operation, the two clutch activation apparatuses  4 ,  40  are simultaneously at rest or are alternatively activated.  
         [0140]     In a case of a disturbance, for example, of the transmission control apparatus, the electrically controlled clutch control valves  48 ,  49  do not function. On this account, the control slide valves, respectively,  127  or  128  of these two clutch control valves close the pressure chambers  125  or  126 , so that no clutch control pressure P_K 1  or P_K 2  can be transmitted through the switch-over valve  54  to the pressure chambers  38  and/or  78  of the self-operating pressure, retention valve  1  as well as of the activation valve  2 .  
         [0141]     Alternatively or in addition to the above, in such an emergency operation, the possibly operating control pressure P_NORA is not operative or at least very much reduced, so that the control slide valve  29  of the clutch activation valve  2  will be driven by the force of the reset spring  32  in the direction of the pressure chamber  78 . Thereby, in a case of a sufficiently higher motor or transmission output speed of rotation, the speed of rotation control pressure P_D at the self-pressure pressure, retention valve  1  takes care that the slide valve  30  thereof when, in the shown position of  FIG. 8 , remains unchanged and the activation pressure P_A is communicated to pressure chambers  110 ,  111  by way of the pressure chamber  70 , the line  14  and the now mutually connected pressure chambers  72  and  73 , through a line  119 .  
         [0142]     In a case of normal operation, the clutch activation apparatus  4  is in its activated state and the clutch activation pressure P_K 1  therein, which was delivered from the first clutch, control valve  48 , is then conducted through the first conversion valve  52 , subsequently through the line  118  to reach a pressure chamber  108  of the selection valve  51 , then is free to invest that location, where the pressure chamber  108  is placed in the neighborhood of one of the two end faces of a control slide valve  50 .  
         [0143]     The clutch activation pressure P_K 2  can indeed be transferred from the second clutch, control valve  49  through the conversion valve  53  and the line  120  to a pressure chamber  113  on the exactly oppositely disposed end face of the control slide valve  50  of the selection valve  51  since, in this depicted embodiment, the clutch activation arrangement  40  was finally not activated, whereby the control slide valve  50 , as shown in  FIG. 8 , stands in the depicted shifting position.  
         [0144]     In this emergency operation shifting position of the selection valve  51 , the activation pressure P_A, emitted by the pressure chamber  110  through a pressure chamber  109  and a line  117  to pressure chambers  129 ,  130  of the first conversion valve  52 . Since the pressure chamber  129  is placed in the neighborhood of that end face, which is remote from the reset spring of a control slide valve  135 , then the activation pressure P_A, which has been hereto introduced, pushes the control slide valve  135  against the force of a reset spring  137 , so that pressure chambers  130 ,  131  at the conversion valve  52  become combined. Thereby, the activation pressure P_A becomes available in this emergency operation to the first clutch, activation apparatus  4  through the line  118 . This is then held by the now present pressure P_A in its engaged position, until the speed of rotation related control pressure P_D at the self-operating pressure, retention valve  1  drops below the predetermined pressure threshold.  
         [0145]     Under a circumstance, wherein the second clutch, activation valve  49 , during the normal operation of the transmission was finally active in an emergency operation which follows that the control slide valve  50  of the selection valve  51 , because of the clutch activation pressure P_K 2 , which was formerly active through the line  120  to pressurize the pressure chamber  113  now stands in a shifting position, in which the activation pressure P_A from the pressure chamber  111  can free the path of the pressure into a pressure chamber  112  on the selection valve  51 . By way of a line  121 , this activation pressure P_A then is open to a pressure chamber  132  as well as to a pressure chamber  133  of the second conversion valve  53 .  
         [0146]     Thereby in the emergency operation, no clutch activation pressure P_K 2  is in force at the second conversion valve  53 , a control slide valve  136  is pushed against the force of a reset spring  138 , so that pressure chambers  133 ,  134  of the second conversion valve  53  are pressure-wise, bound together. In this way, the activation pressure P_A is communicated to the cylinder  5  of the second clutch, activation apparatus  40  by way of the pressure line  120 . This apparatus will be held with the activation pressure P_A in its engaged position until the speed of rotation related control pressure P_D at the self-operating pressure, retention valve  1  drops below the predetermined threshold pressure value.  
         [0147]     Finally, with the aid of the  FIGS. 9 and 10 , the explanation is made clear, that the self-operating pressure, retention valve  1  can be extended into further self-operating pressure, retention valve valves  55 ,  56 , wherein three slide pistons  139 ,  140 ,  147  are designed for and mounted on the control slide valve  30 . In the case of the embodiments, it is immaterial as to whether the pilot pressure P_VST or another pressure, such as the control pressure which characterizes normal operation of the transmission, is delivered to the pressure chamber  38 , which is placed in the area of the end face, which is remote from the reset spring of the control slide valve  30 .  
         [0148]     Further, the activation pressure P_A is routed to the self-operating pressure, retention valve  55  or  56 , at the pressure chamber  70 , by way of the line  14  to the activation valve  2  (not shown). Now, the attachment of line  14  to the self-operating pressure, retention valve  55  or  56 , as usual, is done by way of the additional pressure chamber  143 , which is contiguous to the pressure chamber  70 .  
         [0149]     In the case of the embodiment example according to  FIG. 9  and  FIG. 10 , provision is further made in that the speed of rotation related control pressure P_D is directed to two pressure chambers  58  and  59 , which are so placed that each, according to the set position of the control piston  139 , which is remote from the reset spring or the control piston  140 , which is proximal to reset springs  141 ,  142 , can be subjected to this speed of rotation related pressure P_D, which is activation-effective.  
         [0150]     In the case of the embodiment example according to  FIG. 10 , there has been additionally provided in the retention valve  56  for the enhancement of the constructive features of the self-operating pressure, retention valve  55  (as indicated in  FIG. 9 ), the advantage that the already mentioned reverse travel prevention pressure P_RV can also be directed to pressure chamber  62  which contains the reset spring  142  and that the conveyance of the speed of rotation control pressure P_D can be sent to the pressure chamber  59  by way of a one-way valve  57 .  
         [0151]     By way of the last mentioned measure, assurance is given that the reverse travel prevention pressure P_RV cannot act upon the pressure chamber  58  and again, the assurance is provided in that, in a case of purposeful reverse travel in the emergency operation, the clutch, which up to that time has been engaged, is disengaged and thus the forward drive of the vehicle is interrupted for safety reasons.  
         [0152]     The control valve arrangements presented up to this point carry the advantage that the lubrication of a wet start clutch during the slipping normal operation of the transmission is an assured matter. Such a slip-operation is, however, terminated when the start clutch is engaged. This condition is forcefully retained during the emergency operations by way of the presented control valve arrangements, so that no special measures for the lubrication of the clutch need be given consideration.  
         [0153]     In this connection, provision can also be made that the activation pressure P_A in the description of the invention is then taken from that specific supply of hydraulic pressure fluid, which during the normal operation, is used for the slip operation of at least one start clutch.  
       REFERENCE NUMERALS  
       [0000]    
       
           1  self-operating, retention valve (maintains given pressure)  
           2  activation valve  
           3  clutch regulation valve  
           4  clutch activation apparatus  
           5  cylinder  
           6  clutch piston  
           7  reset spring  
           8  line, pilot pressure  
           9  line, pilot pressure  
           10  line, pilot pressure  
           11  line, pressure regulated by speed of rotation  
           12  line to retention valve  1   
           13  line, reverse travel prevention pressure  
           14  connection line, retention valve-activation valve  
           15  connection line, activation valve, clutch regulation valve  
           16  conn. Line, clutch regulation-valve-clutch activation apparatus  
           17  conn. Line, clutch regulation valve-clutch activation apparatus  
           18  line, pressure source  
           19  reset-spring loaded control slide valve in clutch regulation valve  
           20  control piston on control slide valve in retention valve  
           21  control piston on control slide valve in retention valve  
           22  control piston on control slide valve in retention valve  
           23  control piston on control slide valve in activation valve  
           24  control piston on control slide valve in activation valve  
           25  control piston on control slide valve in clutch regulation valve  
           26  control piston on control slide valve in clutch regulation valve  
           27  control piston on control slide valve in clutch regulation valve  
           28  control piston on control slide valve in clutch regulation valve  
           29  control slide valve in activation valve  
           30  control slide valve in self-operating pressure, retention valve  
           31  reset spring in self-operating, retention valve  
           32  reset spring in activation valve  
           33  reset spring in clutch regulation valve  
           34  shorter control slide valve in clutch regulation valve  
           35  axial section on shorter slider of the clutch regulation valve  
           36  valve boring of the self-operating, retention valve  
           37  solenoid operated clutch regulation valve  
           38  pressure chamber at the self-operating, retention valve  
           39  pressure chamber at the self-operating, retention valve  
           40  clutch activation apparatus  
           41  clutch regulation valve  
           42  selection valve  
           43  switch-over valve  
           44  control slide valve in selection valve  
           45  line P_VST 1   
           46  line P_VST 1   
           47  selection valve  
           48  solenoid operated clutch regulation valve  
           49  solenoid operated clutch regulation valve  
           50  control slide valve at selection valve  
           51  selection valve  
           52  proportional flow solenoid valve (conversion of pressure)  
           53  proportional flow solenoid valve (conversion of pressure)  
           54  switch-over valve  
           55  self-operating pressure, retention valve  
           56  self-operating pressure, retention valve  
           57  one way block valve  
           58  pressure chamber for RPM dependent control pressure  
           59  pressure chamber for RPM dependent control pressure  
           60  line P_VST 2   
           61  line P_VST 2   
           62  pressure chamber for reverse travel prevention pressure  
           63  boring for control slide valve in the activation valve  
           64  boring for long control slide valve in the clutch regulation valve  
           65  boring for short control slide valve in the clutch regulation valve  
           66  line for exchange valve-self-operating pressure, retention valve  
           67  line for exchange valve-activation valve  
           68  line for selection valve-clutch regulation valve  
           69  control piston on the selection valve  
           70  pressure chamber on the self-operating pressure, retention valve  
           71  pressure chamber on the self-operating pressure, retention valve  
           72  pressure chamber on the activation valve  
           73  pressure chamber on the activation valve  
           74  pressure chamber on the first clutch regulation valve  
           75  pressure chamber on the clutch regulation valve  
           76  pressure chamber on the clutch regulation valve  
           77  pressure chamber on the clutch regulation valve  
           78  pressure chamber on the activation valve  
           79  pressure chamber on the activation valve  
           80  pressure chamber on the clutch regulation valve  
           81  pressure chamber on the selection valve  
           82  pressure chamber on the selection valve  
           83  pressure chamber on the selection valve  
           84  pressure chamber on the selection valve  
           85  pressure chamber on the selection valve  
           86  control piston on the selection valve  
           87  pressure chamber on the second clutch regulation valve  
           88  pressure chamber on the second clutch regulation valve  
           89  pressure chamber on the second clutch regulation valve  
           90  longer control slide valve on the second clutch regulation valve  
           91  pressure chamber on the second clutch regulation valve  
           92  shorter control slide valve  
           93  line  
           94  line  
           95  line  
           96  line: selection valve to second clutch regulation valve  
           97  reset spring on the selection valve  
           98  line: selection valve to the second clutch regulation valve  
           99  control piston on the selection valve  
           100  line  
           101  line  
           102  pressure chamber on activation valve  
           103  pressure chamber on activation valve  
           104  line for pressure P_NS  
           105  pressure chamber on second clutch regulation valve  
           106  line  
           107  line  
           108  pressure chamber on selection valve  51   
           109  pressure chamber on selection valve  51   
           110  pressure chamber on selection valve  51   
           111  pressure chamber on selection valve  51   
           112  pressure chamber on selection valve  51   
           113  pressure chamber on selection valve  51   
           114  line  
           115  line  
           116  line  
           117  line  
           118  line  
           119  line  
           120  line  
           121  line  
           122  line  
           123  line  
           124  line  
           125  pressure chamber on clutch regulation valve  49   
           126  pressure chamber on clutch regulation valve  48   
           127  control slide valve on clutch regulation valve  49   
           128  control slide valve on clutch regulation valve  48   
           129  pressure chamber on conversion valve  52   
           130  pressure chamber on conversion valve  52   
           131  pressure chamber on conversion valve  52   
           132  pressure chamber on conversion valve  52   
           133  pressure chamber on conversion valve  52   
           134  pressure chamber on conversion valve  52   
           135  control slide valve on conversion valve  52   
           136  control slide valve on conversion valve  53   
           137  reset spring  
           138  reset spring  
           139  control piston  
           140  control piston  
           141  reset spring  
           142  reset spring  
           143  pressure chamber on self-operating pressure, retention valve  
           144  electrical control cable  
           145  electrical control cable  
           146  electrical control cable  
           147  control piston  
          P_A activation pressure  
          P_D speed of rotation dependent control pressure  
          P_K clutch activation pressure  
          P_K 1  clutch activation pressure  
          P_K 2  clutch activation pressure  
          P_NOR normal operational characterizing control pressure  
          P_NORA normal operational characterizing control pressure  
          P_NS emergency operational pressure  
          P_RV reverse travel prevention pressure  
          S electrical pre-signal  
          P_V 1  supply pressure  
          P_V 2  supply pressure  
          P_VST pilot pressure  
          P_VST 1  pilot pressure  
          P_VST 2  pilot pressure

Technology Classification (CPC): 8