Abstract:
A variable displacement pump is disclosed for hydraulic gearbox control systems, in particular a vane pump, having a variable stroke volume and having a pump regulator for outflow pressure regulation, in which the outlet pressure of the pump acts in a compensation chamber and a regulation pressure, which can be set by the pump regulator, acts in a regulation pressure chamber on an adjustable stroke ring, wherein the pressure in the regulation pressure chamber and an additional spring force adjust the stroke ring in the direction of maximum pivoting out. Additionally, a gearbox control system for automatic gearboxes, which has a primary hydraulic circuit for the elements of the gearbox that are relevant to force transmission and a primary pressure regulating valve, which opens a bypass to a secondary hydraulic circuit when the settable primary pressure is exceeded and has an additional pressure-limiting function for the primary pressure if the primary pressure continues to be exceeded, and wherein the secondary hydraulic circuit acts to cool and lubricate the gearbox, and wherein the regulation loop or regulation circuits of the pump regulation system and of the gearbox regulation system can be separated from each other by a switching valve and thus can be connected individually and independently or can be connected together.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a U.S. National Stage of International Application No. PCT/EP2014/064002 filed Jul. 1, 2014, which claims the benefit and priority of German Application No. DE102013107180.5 filed Jul. 8, 2013. The entire disclosure of each of the above applications is incorporated herein by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The invention relates to a variable displacement pump for hydraulic transmission controls, in particular vane pump, with variable stroke volume and with a pump controller for outflow pressure control, in the case of which the outlet pressure of the pump in a compensation chamber and a control pressure, which can be set by the pump controller, in a control pressure chamber act on an adjustable stroke ring, wherein the pressure in the control pressure chamber and an additional spring force move the stroke ring in the direction of maximum swiveling out, i.e. maximum stroke volume, and with a transmission control for automatic transmissions which has, among other things, a primary hydraulic circuit for the elements of the transmission which are relevant to the transmission of force and a primary pressure control valve which, upon reaching or exceeding the settable primary pressure, opens a bypass to a secondary hydraulic circuit and, in the event of further exceeding of the primary pressure, has an additional pressure limiting function for the primary pressure, and wherein the secondary hydraulic circuit serves the purpose of cooling and lubrication of the transmission. 
       BACKGROUND 
       [0003]    Variable displacement pumps for hydraulic transmission controls for automatic transmissions are known. 
         [0004]    There exist, for example, control circuits in which initially only the primary pressure control valve is active and, upon reaching the set primary pressure, the connection to the secondary hydraulic circuit opens and then the pressure acting in the secondary hydraulic circuit is active on the pump controller so that the pump control is adjusted in the direction of a swiveling-back or downward-regulating pump, i.e. the conveying volume becomes smaller. As a result, what is known as a cascade control or arrangement in series of two controller systems, namely of the primary pressure control valve and of the pump controller which can have an influence counter to one another in their control movements or control characteristics, is created, wherein, due to the downstream secondary pressure action, the pump control becomes active with a time delay after the initial adjustment of the primary pressure by the primary pressure control valve ( FIG. 1.1 ). 
         [0005]    Control circuits with a variable displacement pump and an automatic transmission in which a separate control pressure from a control circuit becomes active simultaneously on the pump controller of the variable displacement pump, the primary pressure control valve and, where applicable, a pressure reduction valve in the secondary or lubrication circuit are furthermore known in the prior art. This means that, depending on adjustment, possibly three difference controllers, which are all activated by the same pressure signal variable, intervene simultaneously and thus, depending on their behavior over time, mutually influence one another and can lead to instabilities ( FIG. 1.2 ). 
       SUMMARY 
       [0006]    The object of the invention is therefore to represent a variable displacement pump for hydraulic transmission controls and a transmission control for automatic transmissions which does not have these problems. 
         [0007]    The object is achieved by a variable displacement pump for hydraulic transmission controls, in particular vane pump, with variable stroke volume and with a pump controller for outflow pressure control, in the case of which the outlet pressure of the pump in a compensation chamber and a control pressure, which can be set by the pump controller, in a control pressure chamber act on an adjustable stroke ring, wherein the pressure in the control pressure chamber and an additional spring force move the stroke ring in the direction of maximum swiveling out, i.e. maximum stroke volume, and with a transmission control for automatic transmission which has, among other things, a primary hydraulic circuit for elements of the transmission which are relevant to the transmission of force and a primary pressure control valve which, upon reaching or exceeding the settable primary pressure, opens a bypass to a secondary hydraulic circuit and, in the event of further exceeding of the primary pressure, has an additional pressure limiting function for the primary pressure, wherein the secondary hydraulic circuit serves the purpose of cooling and lubricating the transmission, and wherein the control loops or control circuits of the pump control and the transmission (primary pressure) control can be separated from one another and can thus be connected or interconnected independently and individually by an (additional) shift valve. 
         [0008]    A further variable displacement pump and transmission control are characterized in that a sensing pressure chamber of the primary pressure control valve for the primary pressure can be activated or deactivated with respect to the primary hydraulic circuit via the inflow of the sensing pressure chamber or via the outflow of the sensing pressure chamber by the shift valve ( FIGS. 2 and 3 ). 
         [0009]    A variable displacement pump and transmission control are also preferred in which the secondary hydraulic circuit inflow or the secondary hydraulic circuit connection of the primary pressure control valve can be activated or deactivated by the shift valve ( FIG. 4 ). 
         [0010]    A variable displacement pump and transmission control are furthermore preferred in which the inflow or the connection to the pump controller or to the control pressure chamber from the primary pressure circuit or primary hydraulic circuit can be activated or deactivated by the shift valve ( FIG. 5 ). 
         [0011]    A further variable displacement pump and transmission control are characterized in that the inflow of the sensing pressure chamber of the primary pressure control valve from the primary hydraulic circuit can be activated or deactivated by the valve and the outflow of the sensing pressure chamber is performed via a hydraulic resistance, e.g. a throttle to a tank or oil sump. 
         [0012]    A variable displacement pump and transmission control are also preferred in which the outflow of the sensing pressure chamber to the tank or oil sump can be activated or deactivated by the valve and the inflow of the sensing pressure chamber from the primary hydraulic circuit is performed via a hydraulic resistance, e.g. a throttle. 
         [0013]    A variable displacement pump and transmission control are also preferred in which a control pressure of a control pressure circuit of the transmission control acts on a surface of the control pressure chamber of the pump controller (large surface, spring space, upward regulation) and on the shift valve (spring space surface) in a closing direction ( FIG. 2 , shift valve shifts inflow of the sensing pressure chamber). 
         [0014]    A further variable displacement pump and transmission control are characterized in that the control pressure of the transmission control acts on a surface of the control pressure chamber of the pump controller (large surface, spring space, upward regulation) and on the spring space of the shift valve in an opening direction ( FIG. 3 , outflow of the sensing pressure chamber of the primary pressure control valve). 
         [0015]    A variable displacement pump and transmission control are also preferred in which the control pressure of the transmission control acts on a surface of the control pressure chamber of the pump controller (large surface, spring space, upward regulation) and on the spring space of the shift valve in an opening direction ( FIG. 4 , shift valve shifts inflow to the secondary hydraulic circuit). 
         [0016]    A variable displacement pump and transmission control are furthermore characterized in that a control pressure of the transmission control acts on a surface of the control pressure chamber of the pump controller (large surface, spring space, upward regulation) and on the spring space of the primary pressure valve, and the secondary pressure acts in an opening direction on the shift valve ( FIG. 5 ; shift valve controls inflow from primary hydraulic circuit to the pump controller; pump controller performs reduction with primary pressure). 
         [0017]    A preferred variable displacement pump and transmission control are also characterized in that the shift valve or the shift valves can be actuated hydraulically and/or electrically. 
     
    
     
       DRAWINGS 
         [0018]    The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
           [0019]      FIG. 1.1  shows a variable displacement pump with transmission control according to the prior art. 
           [0020]      FIG. 1.2  shows another variable displacement pump with transmission control according to the prior art. 
           [0021]      FIG. 2  shows a first embodiment according to the invention of a variable displacement pump with transmission control. 
           [0022]      FIG. 3  showed second embodiment according to the invention of a variable displacement pump with transmission control. 
           [0023]      FIG. 4  shows a third embodiment according to the invention of a variable displacement pump with transmission control. 
           [0024]      FIG. 5  shows a fourth embodiment according to the invention of a variable displacement pump with transmission control. 
       
    
    
     DESCRIPTION 
       [0025]    An adjustable vane pump  1  with variable stroke volume and a transmission control for automatic transmissions is represented in  FIG. 1 . Vane pump  1  with variable stroke volume has a displaceable stroke ring  3  which is represented in its maximally deflected position with respect to a rotor  5 . Radially displaceable vanes  7  are arranged in radial slots in rotor  5 . The pressure in what is referred to as a compensation chamber  9  acts on displaceable stroke ring  3  in the direct of a swiveling back of stroke ring  3  up to zero conveyance of the pump, on the opposite side, the pressure in what is referred to as a control pressure chamber  11  acts on displaceable stroke ring  3  on a pressure active surface which is larger than the pressure active surface of the compensation chamber, wherein stroke ring  3  acts by means of a spring  13  additionally in the direction of swiveling out  3 , i.e. in the direction of the maximum stroke volume of vane pump  1 . After switching off the pump and the transmission, spring  13  also acts in the direction of maximum deflection of stroke ring  3  in order to enable an immediate oil supply and a starting of the transmission during starting of the motor vehicle. Compensation chamber  9  is acted upon via a control oil line  15 , represented by dashed lines, with line  17  at the pump outlet, i.e. with the maximum pressure which can be generated by the pump. Control pressure chamber  11  of adjustable vane pump  1  is connected via a control oil line  19  to a control valve  21 , also referred to as a pump controller, wherein the pump controller varies the control pressure in control pressure chamber  11  or in feed line  19  between a pressure from the pump outlet with line  17 , which is fed to control valve  21  via line  23 , and a tank pressure in a tank line  25 . Control valve  21  or the pump controller has a control piston  27  which acts in an opening direction on one side with a spring  29  and the pressure in a chamber which acts on a small pressure active surface  31  of control piston  27  and which is connected via a control line  33  to the pump outlet pressure region so that control piston  27  connects control pressure chamber  11  initially in an unthrottled manner to the pump outlet pressure in line  17 , while the connection of control pressure chamber  11  via control piston  27  to the tank outflow to tank line  25  is shut off. The pressure from a control circuit  49  of the transmission in a control pressure line  37  acts on a large pressure active surface  35  of control valve piston  27 , wherein this control pressure is set or varied by the internal program processes of the automatic transmission. The volume flow of the pump from the pump outlet of line  17  leads to a primary hydraulic circuit  39  of the transmission which supplies all the force-relevant elements such as, for example, hydraulically shiftable clutches, brake straps, synchronization devices for gearwheels or adjustable bevel washers and pressure cylinders, for example, for CVT transmissions. When starting the motor vehicle, primary hydraulic circuit  39  is therefore first supplied via pump outlet line  17  with the pump volume flow until a corresponding primary pressure which is required to activate the above-mentioned transmission elements has built up in primary hydraulic circuit  39 . A primary pressure control valve  41  remains closed until this operating point. Primary pressure control valve  41  has a hydraulic pressure chamber  43  with a control surface on which the primary pressure can act via a control line  47 . On the opposite side, the primary pressure control valve has a hydraulic control surface  45  on which the pressure in control circuit  49  can act and a spring  51  which acts together with the pressure in control circuit  49  in the closing direction on primary pressure control valve  41 . If, in primary hydraulic circuit  39 , the corresponding primary pressure in pressure chamber  43  of the primary pressure control valve is exceeded to such an extent that it can open primary pressure control valve  41  counter to the pressure in control circuit  49  and spring force  51 , a bypass volume flow flows through line  53  to what is referred to as a secondary hydraulic circuit  55  which serves the purpose of cooling and lubricating the corresponding transmission components. The pressure which builds up in said secondary hydraulic circuit  55  in line  57  is also active on pump controller  21  via line  37  and leads, in the case of sufficient volume flow requirement and the corresponding build-ups of pressure caused as a result in the primary and secondary hydraulic circuit, to the pump controller setting a lower control pressure than the pressure at pump outlet  17  in control pressure chamber  13  so that variable displacement pump  1  swivels back in accordance with the only maximally required volume flow requirement. The pressure in control circuit  49  additionally acts on an additional pressure active surface  59  of a pressure reducing valve  63  via which, upon reaching the pressure set there for a lubrication hydraulic circuit  61 , a bypass volume flow to said separate lubrication hydraulic circuit  61  is correspondingly throttled. The pressure set at pressure reducing valve  63  is thus changed by the control circuit pressure. 
         [0026]    The circuit represented here according to the prior art has the (disadvantageous) function that primary hydraulic circuit  39  must first complete the required pressure build-up and only thereafter does primary pressure control valve  41  open the line to secondary hydraulic circuit  55  so that it is only then that a corresponding control pressure acts on pump controller  21  and pump  1  can swivel back correspondingly to the maximally required volume flow which can be quickly exceeded, for example, in the case of a high rotational speed of pump  1 . The pump control itself therefore firstly comes about with a certain time delay and is secondly changed in turn in terms of its actuating variable and possibly disrupted by a potentially opposite control movement of primary pressure control valve  41 . This can lead to long time delays and potentially to instabilities in control at various operating points. 
         [0027]    A different prior art is represented in  FIG. 1.2 . Variable displacement pump  1  with its compensation chamber  9 , its control pressure chamber  11  and additional spring  19  located therein as well as corresponding lines  15  and  17  correspond to the representation in  FIG. 1.1  and should not be mentioned again here in order to avoid repetition. Pump controller  70  itself has a different structure here and is therefore provided with reference number  70 . A control pressure space  72 , in which a corresponding adjustment spring  74  also sets the base position of control piston  76 , is connected by a control pressure line  78  to control circuit  49  and thus to the pressure prevailing in control circuit  49 . Control circuit  49  with its pressure acts as in  FIG. 1.1  again on surface  45  of primary pressure control valve  41  on which, on the other side of the primary pressure control valve piston, the pressure in primary hydraulic circuit  39  acts, as already described in  FIG. 1.1 . Moreover, the pressure from control circuit  49  also acts on pressure reducing valve  63  of lubrication hydraulic circuit  61 . When the corresponding pressure is reached in the control circuit, this leads to the situation in which at least primary pressure control valve  41 , which should open upon the primary pressure being reached, and pump controller  70 , which should also swivel back the stroke volume of pump  1  upon the primary pressure being reached, should intervene substantially simultaneously and may mutually influence one another up to instability. Moreover, the control circuit pressure in control circuit  49  additionally acts, in addition to the lubrication circuit pressure, on pressure reducing valve  63  so that a change and potential disruption of the control circuit pressure by additionally connected consumers can also in turn occur here. The pump outlet pressure from pump outlet line  17  acts on pump controller  70  on a small annular surface  80 , which pump outlet pressure, upon reaching a maximum pressure set at pump controller  70  and set by spring  74  and the control pressure in control pressure chamber  72 , opens a control edge of pump controller  70  to tank outflow  82  and thus an intermediate pressure is set between the pump outlet pressure and the tank pressure in pump control chamber  11 . 
         [0028]      FIG. 2  represents an arrangement according to the invention of a variable displacement pump with a transmission control. An adjustable vane pump  100 , which is represented here with a reverse direction of rotation in comparison to previous  FIGS. 1.1 and 1.2 , has an outlet line  102  via which a compensation chamber  104  can be acted upon with the pump outlet pressure and as a result can move stroke ring  105  of adjustable vane pump  100  correspondingly into the zero position. On the opposite side of stroke ring  105 , a pressure from pump controller  110  acts via a control pressure line  112  in pressure control chamber  106  in the upward regulation direction like upward regulation spring  108 . The control valve or pump controller  110  is represented slightly differently in its structure than in the previous figures. Pump controller  110  is connected by its large piston surface  114  in the pressure space, in which spring  116  which acts on control piston  120  is also arranged, to control circuit  49  of the automatic transmission. The pump outlet pressure, i.e. the maximum high pressure from outlet line  102  of vane pump  100  prevailing in the system acts on an annular surface  118  which is active in the opposite direction and is correspondingly smaller. In the position represented in  FIG. 2  of control piston  120  of pump controller  110 , control pressure chamber  106  of the pump is connected via control line  122 , via first control edge  124  and via control pressure line  112  downstream of pump controller  110  to the pump outlet pressure in line  102  and the pump is thus fully regulated upward. If the force of the outlet pressure on annular surface  118  exceeds the force which is generated by the force from control circuit  49  on piston surface  114  and by the force exerted by spring  116 , control piston  120  moves against spring  116  to the right and thereby opens a second control edge  126  which additionally connects control pressure line  112  to tank  128 . In the case of an automatic transmission, tank  128  is, for example, the oil sump on the base of the automatic transmission. In the case of this return travel of control piston  120 , as described above, the control pressure in control pressure chamber  106  is lowered, and the maximal swiveling out of the pump can be reduced by the high pressure in compensation chamber  104 . Primary hydraulic circuit  130  of the automatic transmission is to be understood in all cases here as a hydraulic resistance consumer. A bypass line  132  leads from the primary hydraulic circuit to a primary pressure control valve  134 . In the case of certain adjustment pressures, primary pressure control valve  134  is able to conduct a bypass volume flow from line  132  into secondary hydraulic circuit  136  which is also represented here symbolically by a hydraulic resistance as a consumer. In this representation, secondary hydraulic circuit  136  and the lubrication circuit are represented in a simplified manner to form a single hydraulic circuit without interconnection of a pressure reducing valve. A shift valve  138  (according to the invention) is additionally arranged in the hydraulic circuit in order to deactivate or activate the function of primary pressure control valve  134 . For this purpose, shift valve  138  is arranged between feed lines  140  and  142  which can correspondingly shut or open it, wherein feed line  142  is guided into a sensing pressure chamber  144  of primary pressure control valve  134 . If shift valve  138  is shifted into its opening position, which occurs, for example, as a result of a lowering of the control pressure in control pressure circuit  49  which acts on a piston surface of shift valve  138  in a control pressure chamber  148  which also contains a corresponding spring  150  in comparison to an annular surface  146  on which the primary circuit pressure is active via feed line  142 , the piston of valve  138  opens the connection between lines  140  and  142  and enables an inflow out of the primary pressure circuit into sensing pressure chamber  144  and thus a pressure build-up in sensing pressure chamber  144  since the outflow out of sensing pressure chamber  144  into a tank  154  or the oil sump of the automatic transmission is limited by a hydraulic resistance  152 , for example, in the form of a throttle. Primary pressure control valve  134  can thus open a control edge  156  to secondary hydraulic circuit  136  and conduct a corresponding bypass volume flow out of primary hydraulic circuit  130  or high-pressure line  102  to secondary hydraulic circuit  136  which is active on piston surface  158  in the pressure space with spring  160  of primary pressure valve  134  also for a secondary pressure build-up in secondary hydraulic circuit  136  and thus for an active secondary pressure force. This means that, in this case, separately shiftable valve  138  makes it possible to initially deactivate primary pressure control valve  134  so that only pump controller  110  of variable displacement pump  1  becomes active with its control circuit until setting of the primary pressure. Only in the event of connection of a shift signal, either as a result of a specific level of the control pressure from control pressure circuit  49  and/or where applicable as a result of an external actuator, not represented here, for example, an electromagnet, after pump controller  110  has adjusted vane pump  100  and reached its operating point, primary pressure control valve  134  is activated and can from then take on an additional control function so that, in the case of changes in the volume flow in the primary or secondary hydraulic circuit, a further control change of pump controller  110  no longer requires any large control movements. Large control jumps and thus any potential stimuli towards instability can thus be limited by decoupling the two control circuits from pump controller  110  and primary pressure control valve  134  during starting of the hydraulic system. 
         [0029]    In  FIG. 3 , both vane pump  100  with its pressure chambers and pump controller  110  as well as primary pressure control valve  134  and primary hydraulic circuit  130 , secondary hydraulic circuit  136  and control circuit  49  are arranged and connected to one another as in  FIG. 2  so that the same reference numbers and the same description of functions apply to these regions apart from the different arrangement of a shift valve  170 . In  FIG. 3 , shift valve  170  is connected between sensing pressure chamber  144  of primary pressure control valve  134  and tank  154  or the oil sump of the transmission. In this case, shift valve  170  is opened by a spring  172  initially in the depressurized state so that an outflow is carried out from primary hydraulic circuit  130  or high-pressure line  102  via a control line  174  out of this high-pressure or primary pressure region via a hydraulic resistance  176 , for example, in the form of a throttle, to sensing pressure chamber  144 . Since the connection in outflow  178  to tank  154  is opened by shift valve  170 , no significant pressure can build up in sensing pressure chamber  144  which can set in motion or trigger the function of primary pressure control valve  134 . Only when shift valve  170  is closed, wherein a corresponding control pressure from control pressure circuit  49  into the pressure space of shift valve  170  with spring  172  counter to the primary pressure which acts on annular surface  173  of shift valve  170  can exceed the corresponding actuating forces, is shift valve  170  closed, and a corresponding build-up of pressure in sensing pressure chamber  144  of primary pressure control valve  134  sets the primary pressure control function in motion. 
         [0030]    A further arrangement according to the invention of a variable displacement pump with a transmission control is represented in  FIG. 4 . Both the interconnection of vane pump  100  with its pump controller  110  and also the fundamental arrangement of primary pressure control valve  134 , of primary hydraulic circuit  130  and of secondary hydraulic circuit  136  in  FIG. 4  are initially identical to those from  FIGS. 2 and 3 . The difference now lies in the fact that sensing pressure chamber  180  of the primary pressure control valve no longer has any outflow so that the primary pressure in primary hydraulic circuit  130  or in high-pressure line  102  can become active directly via an inflow out of primary hydraulic circuit  130  and only damped or delayed by an attenuator valve  182  by inflow and without outflow. In this circuit diagram, a shift valve  184  is connected between outflow  186  of primary pressure control valve  134  to secondary hydraulic circuit  136 . This means that, after the primary pressure set at primary pressure control valve  134  is reached, primary pressure control valve  134  also remains without function as long as valve  184  is closed since, after opening control edge  188 , the primary pressure in line  186  shut off from secondary circuit  136  by valve  184  also becomes active in pressure space  190  with the spring of primary pressure valve  134  and thus primary pressure control valve  134  moves control edge  188  back in the direction of the closing position. Only after opening of valve  184  which occurs in that, in control circuit  49 , the control pressure on the pressure active surface of pressure chamber  192  together with spring  194  counter to the primary pressure on annular surface  196  can open valve  184 , can primary pressure control valve  134  also move into its control position. This means that, in this case too, initially pump controller  110  adjusts the corresponding pressure in primary circuit  130  with vane pump  100  and thereafter, in the case of a corresponding shift signal via shift valve  184 , the second control circuit, namely that of primary pressure control valve  134 , can be interconnected. The advantages and effects correspond to those which were described above in  FIGS. 2 and 3 . 
         [0031]    A further embodiment according to the invention of a variable displacement pump with a transmission control is represented in  FIG. 5  which differs in principle in that here a primary pressure control valve  212  is not initially deactivated during starting of the transmission hydraulics, rather a controller  204  of vane pump  100 . Primary pressure control valve  212  therefore forms the controller for the control circuit which firstly occupies its control position, and thereafter additionally pump controller  204  and thus the adjustment of vane pump  100  can be activated via a shift valve  200 . The linking, i.e. the connection of vane pump  100  itself to pump controller  204  and also the piston or control edge structure of pump controller  204  remain as described above in  FIGS. 2, 3 and 4 . The difference lies in the fact that the inflow is carried out via line  202  to pump controller  204  via shift valve  200  which can thus open or shut off the inflow out of high-pressure line  102  or primary hydraulic circuit  130 . The control pressure from control circuit  49  otherwise acts as in  FIGS. 2, 3 and 4  on large piston surface  206  of pump controller  204  in the spring space of pump controller  204 , but in  FIG. 5  differently to in  FIGS. 2, 3 and 4  directly on piston surface  208  in spring space  210  of primary pressure control valve  212 . Here, sensing pressure chamber  214  also possesses only an inflow out of primary pressure circuit  130  via a corresponding attenuator valve  216 . In this circuit, secondary hydraulic circuit  218  is separated from lubrication hydraulic circuit  220  via a pressure reducing valve  224 . 
         [0032]    In the case of direct connection of existing hydraulic transmission controls with a pressure-controlled pump, the function of the prioritizing distribution of the pump conveying quantity (prior art) can lead to control engineering problems. 
         [0033]    The prioritization of the oil quantity in the transmission generally initially has the function of preventing inadequate supply of the primary hydraulic circuit. All the elements relevant to the transmission of force in the transmission are supplied via this primary hydraulic circuit. The secondary hydraulic circuit supplies the cooling and lubrication in the transmission, i.e. subordinate functions. One aim of the invention is thus to close the secondary hydraulic circuit in the case of small conveying quantities of the pump. 
         [0034]    In known embodiments of prioritization circuits, a primary pressure control valve is used which opens the secondary hydraulic circuit from a specific adjustable primary pressure and closes it again when the primary pressure drops below this pressure level. Mutual influences can arise if this operating point lies too close to the pressure level to be set for the pump. The proposed control systems of the invention solve this conflict. 
         [0035]    The solution which achieves the object therefore lies in limiting the control valve types upstream of the consumers, in particular the valves upstream of the consumers for prioritization of the oil quantity, and separation of the two functions of pressure control and prioritization. The circuits which represent this solution are represented, for example, in  FIGS. 2 to 5 . 
         [0036]    Prioritization in these embodiments means that initially the primary hydraulic circuit quantity, then the secondary hydraulic circuit quantity, and then the final volume flow quantity of the variable displacement pump should be adjusted. The aim of the invention is to separate the control variable actuation for the variable displacement pump and for the transmission hydraulics as consumers from one another. 
         [0037]    In contrast to the corresponding stability problems in the prior art, as described in  FIGS. 1.1 and 1.2 , the inventive solutions presented here lead to a shortening of the length of the control loop by temporary switching off of a control loop and thus to the elimination of disruptive mutual influences on the control circuits, in particular their signal flow. All of the functions and consumers of the transmission can thus represent simple disturbance variables for the “variable displacement pump with control valve” controller unit in contrast to control circuits in which prioritization functions for several control loops are connected. 
         [0038]    According to the invention, the primary pressure control valves in  FIGS. 2 to 5  additionally have the following functions. The control function of the primary pressure control valves is initially activated by the available primary pressure and the primary pressure control valves open a control edge to the secondary hydraulic circuit when a primary pressure level is exceeded. 
         [0039]    From now on, a fixed ratio between primary and secondary pressure is adjusted as a result of the return of the secondary pressure to the primary pressure control valve. The control circuit pressure component additionally comes to bear in the case of the primary pressure control in  FIG. 5 . In the case of a further increase in the primary pressure, a control edge from the primarily hydraulic circuit to the tank is opened, i.e. an additional pressure limiting function comes into force. If the primary pressure control valve is separated by an upstream valve from the primary hydraulic circuit, it only becomes functional when the valve is shifted. 
         [0000]    
       
         
               
             
               
               
             
           
               
                   
               
               
                 List of reference numbers 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 1. 
                 Vane pump 
               
               
                 3. 
                 Stroke ring 
               
               
                 5. 
                 Rotor 
               
               
                 7. 
                 Vane 
               
               
                 9. 
                 Compensation chamber 
               
               
                 11. 
                 Control pressure chamber 
               
               
                 13. 
                 Spring 
               
               
                 15. 
                 Control oil line 
               
               
                 17. 
                 Line 
               
               
                 19. 
                 Control oil line 
               
               
                 21. 
                 Control valve 
               
               
                 23. 
                 Line 
               
               
                 25. 
                 Tank line 
               
               
                 27. 
                 Control piston 
               
               
                 29. 
                 Spring 
               
               
                 31. 
                 Pressure active surface 
               
               
                 33. 
                 Control line 
               
               
                 35. 
                 Pressure active surface 
               
               
                 37. 
                 Control pressure line 
               
               
                 39. 
                 Primary hydraulic circuit 
               
               
                 41. 
                 Primary pressure control valve 
               
               
                 43. 
                 Pressure chamber 
               
               
                 45. 
                 Control surface 
               
               
                 47. 
                 Control line 
               
               
                 49. 
                 Control circuit 
               
               
                 51. 
                 Spring 
               
               
                 53. 
                 Line 
               
               
                 55. 
                 Secondary hydraulic circuit 
               
               
                 57. 
                 Line 
               
               
                 59. 
                 Pressure active surface 
               
               
                 61. 
                 Lubrication hydraulic circuit 
               
               
                 63. 
                 Pressure reducing valve 
               
               
                 70. 
                 Pump controller 
               
               
                 72. 
                 Control pressure space 
               
               
                 74. 
                 Adjustment spring 
               
               
                 76. 
                 Control piston 
               
               
                 78. 
                 Control pressure line 
               
               
                 80. 
                 Annular surface 
               
               
                 82. 
                 Tank outflow 
               
               
                 100. 
                 Vane pump 
               
               
                 102. 
                 Outlet line 
               
               
                 104. 
                 Compensation chamber 
               
               
                 105. 
                 Stroke ring 
               
               
                 106. 
                 Control pressure chamber 
               
               
                 108. 
                 Upward regulation spring 
               
               
                 110. 
                 Pump controller 
               
               
                 112. 
                 Control pressure line 
               
               
                 114. 
                 Piston surface 
               
               
                 116. 
                 Spring 
               
               
                 118. 
                 Annular surface 
               
               
                 120. 
                 Control piston 
               
               
                 122. 
                 Control line 
               
               
                 124. 
                 Control edge 
               
               
                 126. 
                 Control edge 
               
               
                 128. 
                 Tank 
               
               
                 130. 
                 Primary hydraulic circuit 
               
               
                 132. 
                 Bypass line 
               
               
                 134. 
                 Primary pressure control valve 
               
               
                 136. 
                 Secondary hydraulic circuit 
               
               
                 138. 
                 Shift valve 
               
               
                 140. 
                 Feed line 
               
               
                 142. 
                 Feed line, inflow 
               
               
                 144. 
                 Sensing pressure chamber 
               
               
                 146. 
                 Annular surface 
               
               
                 148 
                 Control pressure chamber 
               
               
                 150. 
                 Spring 
               
               
                 152. 
                 Resistance 
               
               
                 154. 
                 Tank 
               
               
                 158. 
                 Piston surface 
               
               
                 160. 
                 Spring 
               
               
                 170. 
                 Shift valve 
               
               
                 172. 
                 Spring 
               
               
                 173. 
                 Annular surface 
               
               
                 174. 
                 Control line 
               
               
                 176. 
                 Resistance 
               
               
                 178. 
                 Outflow 
               
               
                 180. 
                 Sensing pressure chamber 
               
               
                 182. 
                 Attenuator valve 
               
               
                 184. 
                 Shift valve 
               
               
                 186. 
                 Outflow/line 
               
               
                 188. 
                 Control edge 
               
               
                 196. 
                 Annular surface 
               
               
                 200. 
                 Shift valve 
               
               
                 204. 
                 Controller/pump controller 
               
               
                 206. 
                 Piston surface 
               
               
                 208. 
                 Piston surface 
               
               
                 210. 
                 Spring space 
               
               
                 212. 
                 Primary pressure control valve 
               
               
                 214. 
                 Sensing pressure chamber 
               
               
                 216. 
                 Attenuator valve 
               
               
                 218. 
                 Secondary hydraulic circuit 
               
               
                 224. 
                 Pressure reducing valve