Abstract:
A device for processing compressed air for a commercial vehicle is provided. The device includes an inlet connection for connecting a compressor, an air dryer unit, a first solenoid valve for pneumatically shutting off the compressor and blocking a pipe that is connected to the compressor, and a second solenoid valve for controlling a backflow of air to regenerate the air filter unit. Loss of compressed air during regeneration in the pressure in a pipe located between the compressor and a stop valve upstream of the air filter unit is minimized by exciting the first solenoid valve. Different methods for operating the compressed air processing device are also provided.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a U.S. National Phase of PCT International Application No. PCT/EP2006/011031, filed on Nov. 17, 2006, which claims priority under 35 U.S.C. §119 to German Application No. 10 2005 057 004.6, filed Nov. 30, 2005, the entire disclosures of which are expressly incorporated by reference herein. 
     
    
     BACKGROUND AND SUMMARY OF THE INVENTION 
       [0002]    The invention relates to a device for the processing of compressed air for a commercial vehicle, with an inlet connection for connecting a compressor, a ventilation (also referred to as a vent), a compressor control outlet for acting with pressure upon a control inlet of the compressor, an air dryer unit, a pneumatically activatable shut-off valve which follows the inlet connection in the flow direction and which can be transferred from an open to a closed state by the action of pressure, a pneumatically activatable pressure regulating valve which is arranged between an outlet connection of the shut-off valve and the ventilation and which can be transferred from a closed to an open state by the action of pressure, a compressor control device which has a first solenoid valve and via which, in an excited state of the first solenoid valve, compressed air can be supplied to a control inlet of the shut-off valve and to the compressor control outlet, and a second solenoid valve which, in the excited state, allows a backflow of compressed air through the air dryer unit and the pressure regulating valve to the ventilation and via which, in the excited state, a control inlet of the pressure regulating valve can be acted upon with compressed air. 
         [0003]    The invention relates, furthermore, to various methods for operating such a device for the processing of compressed air. 
         [0004]    Devices for the processing of compressed air contain as central components a pressure regulator, an air dryer unit and a multiple-circuit protection valve. In the electronic design of the device for the processing of compressed air, an electronic control is integrated as a further essential component into the device. Compressed air is supplied by a compressor to the device for the processing of compressed air, this compressed air supply being delivered via the air dryer unit and the multiple-circuit protection valve to various consumers of a commercial vehicle, for example to the brake system of the traction vehicle and trailer, to a lift-axle device and to other secondary consumers, as they are known. The multiple-circuit protection valve in this case serves particularly the purposes of controlling the filling sequence of the various consumer circuits and of protecting the various circuits with respect to one another or of topping them up in a suitable way. The pressure regulator is provided in order, when the maximum permissible system pressure is overshot, that is to say in the case of additional compressed air not required, to discharge the surplus compressed air via ventilation. The air dryer unit is provided in order to supply dried and purified air to the consumers and thereby to avoid premature wear of the consumers due to corrosion and comparable processes. 
         [0005]    Since the air dryer unit is laden with moisture and other foreign particles during the operation of the device for the processing of compressed air, it is necessary to regenerate the latter from time to time, either at regular time intervals or when specific preconditions are present, for example a signal from a moisture sensor. The regeneration of the air processing plant then takes place in that air is extracted from the reservoirs previously filled with dry compressed air and flows through the air dryer unit in a direction which is opposite to the flow direction when the system is being filled. Since a flow in such a direction is undesirable outside the regeneration phases, this is prevented by a nonreturn valve which follows the air dryer unit. During the regeneration phases, this nonreturn valve is bypassed by the changeover of a solenoid valve. 
         [0006]    There are various concepts for operating the compressor during the regeneration phases. For example, it is possible to allow the compressor to continue to convey during idling, that is to say to discharge via a ventilation line the air which is delivered by the compressor. Other concepts provide for switching off the compressor during the regeneration phase in order to save energy. To make this possible, the device for the processing of compressed air has provided on it a compressor control outlet, to which a control inlet of the compressor is connected. It is thereby possible to supply compressed air in a directed manner to the control inlet of the compressor in order to switch off the latter. 
         [0007]    WO 02/24506 A1 describes such a concept, in which a switching off of the compressor takes place, with reference to several embodiments. According to one of these embodiments, there is provision, in addition to switching off the compressor, for closing a shut-off valve in the conveying line of the compressor, in order thereby to avoid an unnecessary pressure loss in the conveying line. When the compressor is restarted, a smaller volume consequently has to be brought anew to the desired pressure. However, according to this exemplary embodiment of WO 02/24506 A1, only a pressure breakdown downstream of the shut-off valve is prevented. 
         [0008]    The object on which the invention is based is to make available a device for the processing of compressed air, having improved properties, while, in particular, an unnecessary pressure loss in the compressor line is to be avoided. 
         [0009]    This object is achieved by means of the features of the independent claims. Advantageous embodiments of the invention are specified in the dependent claims. 
         [0010]    The invention builds on the generic device for the processing of compressed air, in that, with the first solenoid valve excited, the pressure in a line between the compressor and the shut-off valve is essentially maintained. Consequently, when compressor operation resumes, the volume which is held under pressure does not have to be filled anew, thus giving rise to a saving of energy and of time. 
         [0011]    This functionality may be implemented particularly in that the first solenoid valve, besides activating the shut-off valve and the control valve, does not assume any further control functions relating to the line between the compressor and the shut-off valve. Hence, besides acting with the pressure upon the compressor control inlet, the first solenoid valve merely activates the shut-off valve, and, in particular, there is no activation of a further valve, via which compressed air could escape from the compressor line. The pressure in the line region upstream of the shut-off valve is therefore maintained when the compressor is switched off. 
         [0012]    It is preferable that the compressor control device has a control valve, that compressed air delivered by the first solenoid valve can be supplied to the compressor control outlet via the control valve, and that, in the absence of compressed air delivered by the first solenoid valve, the control valve connects the compressor control outlet to the ventilation. Since the compressor control device has a solenoid valve and a control valve, the aerating and exhausting ventilation of the control inlets involved can take place reliably and in a controlled way. In particular, although compressed air is supplied to the control inlet of the compressor by the control valve and is delivered directly by the solenoid valve, there is nevertheless no need for ventilation of the control inlet to take place via the solenoid valve, since the control valve can make available a direct connection of the compressor control outlet to the ventilation. 
         [0013]    Furthermore, there may be provision for the shut-off valve to be able to be transferred into its open state by means of a spring force. The shut-off valve is therefore always opened, independently of the conveying pressure of the compressor, when the control inlet of the shut-off valve is not acted upon with compressed air. By such action of pressure upon the control inlet, the shut-off valve can then be closed counter to the spring force. 
         [0014]    It is particularly expedient that a safety valve is provided which limits the pressure in the line between the compressor and the shut-off valve. Since the compressor conveying line is not ventilated upstream of the shut-off valve in the conveying intermission, it is expedient to provide a safety valve, in order thereby to prevent a pressure rise in said line branch. Such a safety valve may be provided inside the device for the processing of compressed air or else be implemented as an external component. As a particular embodiment, a shut-off valve with an integrated safety valve offers complete functionality in terms of maintaining the pressure and affords the required safety, while at the same time having a low outlay in terms of assembly and a small construction space requirement. 
         [0015]    The invention relates, furthermore, to a method for operating a device for the processing of compressed air according to the invention, having the steps: 
         [0016]    transfer of the first solenoid valve into an excited state, 
         [0017]    transfer of the second solenoid valve into an excited state, 
         [0018]    maintaining these states for the purpose of the regeneration of the air dryer unit, a pressure in a line between the compressor and the shut-off valve being essentially maintained, 
         [0019]    transfer of the second solenoid valve into a non-excited state, and 
         [0020]    transfer of the first solenoid valve into a non-excited state. 
         [0021]    According to this method, the regeneration of the air dryer unit in the device for the processing of compressed air is implemented, while at the same time the pressure in the compressor conveying line is maintained. 
         [0022]    Furthermore, however, the invention also makes available a method for operating a device for the processing of compressed air according to the invention, having the following steps: 
         [0023]    transfer of the second solenoid valve into an excited state, and 
         [0024]    maintaining a non-excited state of the first solenoid valve and the excited state of the second solenoid valve for the purpose of regenerating a line between the compressor and the device for the processing of compressed air. 
         [0025]    Thus, moisture and dirt can be removed, as required, from the compressor conveying line, since, in the described switching states of the solenoid valves, the compressor continues to convey in the direction of ventilation. 
         [0026]    The method may expediently be developed in that it is carried out at regular time intervals. 
         [0027]    Alternatively or additionally, however, there may also be provision for the method to be carried out in the presence of one or more conditions. Such events may be given, for example, by the detection of specific measurement values of sensors, for example pressure and/or temperature sensors. 
         [0028]    The invention, then, is explained by way of example by means of particularly preferred embodiments, with reference to the accompanying drawings in which: 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0029]      FIG. 1  shows a circuit diagram of part of a first embodiment of a device for the processing of compressed air according to the invention; 
           [0030]      FIG. 2  shows a circuit diagram of part of a second embodiment of a device for the processing of compressed air according to the invention; 
           [0031]      FIG. 3  shows a circuit diagram of part of a third embodiment of a device for the processing of compressed air according to the invention; 
           [0032]      FIG. 4  shows a circuit diagram of part of a fourth embodiment of a device for the processing of compressed air according to the invention; 
           [0033]      FIG. 5  shows a sectional view of a first embodiment of a shut-off valve; 
           [0034]      FIG. 6  shows a sectional view of a second embodiment of a shut-off valve; 
           [0035]      FIG. 7  shows a sectional view of a third embodiment of a shut-off valve with an integrated safety valve; 
           [0036]      FIG. 8  shows a sectional view of a first embodiment of a safety valve; 
           [0037]      FIG. 9  shows a sectional view of a second embodiment of a safety valve; and 
           [0038]      FIG. 10  shows a sectional view of a third embodiment of a safety valve. 
       
    
    
       [0039]    In the following description of the drawings, the same reference symbols designate identical or comparable components. 
       DETAILED DESCRIPTION 
       [0040]      FIG. 1  shows a circuit diagram of part of a first embodiment of a device for the processing of compressed air according to the invention. The device for the processing of compressed air according to the invention  10  has a compressed air inlet  1  to which compressed air can be supplied from a compressor, not illustrated. Parallel to the compressed air inlet  1 , an external filling connection  12  is provided, via which the compressed air system of the commercial vehicle can be filled, for example in a garage, without the compressor being operated. Furthermore, a ventilation  3  is present. Compressed air passes via the compressed air inlet  1  to an air dryer unit  32  and from there, by way of a nonreturn valve  22 , via a multiple-circuit protection valve device, not illustrated, to compressed air consumers  50 , not illustrated. The nonreturn valve  22  is provided for avoiding a backflow of compressed air from the consumers  50  in the direction of the air dryer unit  32 . However, in order to allow a desirable backflow of dry compressed air from the reservoirs through the air dryer unit  32  for regeneration purposes, a solenoid valve  16  is provided, via which the nonreturn valve  22  can be bypassed in a corresponding switching state. The solenoid valve  16  is connected in series to a nonreturn valve  24  and a throttle  26 . During the conveying phases of the compressor, the nonreturn valve  24  avoids an overflow of compressed air via the solenoid valve  16  to the ventilation  3 . The throttle is provided for limiting the flow velocity in a way which is conducive to regeneration. Upstream of the nonreturn valve  24 , a control line is connected, which leads to a pressure regulating valve  20 . The pressure regulating valve  20  is connected between the inlet side of the air dryer unit  32  and the ventilation  3 . A further solenoid valve  14  is provided. Via this further solenoid valve  14 , a control inlet of a shut-off valve  18  can be acted upon with pressure, the shut-off valve  18  thereby being transferred into a closed position. However, via the solenoid valve  14 , pressure is also supplied to a compressor control outlet  4  via a control valve  44 . The control valve  44  is designed such that, in the absence of the action of pressure by means of the solenoid valve  14 , it connects the compressor control outlet  4  to the ventilation  3 , thereby making available rapid ventilation and therefore a reliable operation of the compressor in terms of the restarting of the latter. Further components of the device for the processing of compressed air  10  illustrated are an electronic control unit  40 , via which the solenoid valves  14 ,  16  can be excited independently. Furthermore, a temperature sensor  34  and heating  36  are connected to the electronic control unit  40 . The electronic control unit  40  has a central plug  42  as an interface with the other vehicle electronics. Moreover, an optional moisture plug  43  is provided, via which a signal from an external moisture sensor, not illustrated, can be read in. This is usually mounted at the lowest point of one of the service brake compressed-air reservoirs. The electronic control unit  40  can activate further components, not illustrated, in particular solenoid valves, and further sensors for monitoring, controlling and regulating the system may be provided, in particular moisture, temperature and pressure sensors. Furthermore, a tire filling valve  30  can be seen, which is connected between the line leading to the consumers  50  and a tire filling connection  28 . The tire filling valve  30  can be actuated, as required, in order to extract compressed air via the tire filling connection  28 . 
         [0041]    The device for the processing of compressed air  10  illustrated operates as follows. During normal conveying operation, the compressor conveys compressed air into the compressed air inlet  1 . The shut-off valve  18  is in its open position illustrated. Compressed air consequently passes through the air dryer unit  32  and via the nonreturn valve  22  and the multiple-circuit protection valve to the consumers  50 . During this normal operation, the air dryer unit  32  is laden with moisture and foreign particles, for example compressor oil and its decomposition products. In order to cause a regeneration of the air dryer unit  32 , the two solenoid valves  14  and  16  are transferred into their position, not illustrated, so that firstly, via the solenoid valve  16 , the regeneration airflow can take place through the nonreturn valve  24 , the throttle  26 , the air dryer unit  32 , the pressure regulating valve  20 , likewise changed over on account of the changeover of the solenoid valve  16 , and the ventilation  3 . In order to avoid a pressure loss from the line connected to the compressor, when the compressor is switched off the shut-off valve  18  is also changed over via the control valve  44  by means of the changeover of the solenoid valve  14  and the action of pressure upon the compressor control outlet  4 , so that said shut-off valve assumes its blocking position. To restart conveying operation after regeneration, the solenoid valves  14  and  16  are transferred into their illustrated positions again, so that the control inlets connected to them are ventilated, and in this case the ventilation of the control inlet of the compressor can take place directly without a bypass via a solenoid valve. 
         [0042]    In addition to normal conveying operation and regeneration operation, the device for the processing of compressed air according to the invention  10  makes it possible to have a further operating mode in which moisture and impurities can be removed from the compressor line. This operating mode can be implemented in that the solenoid valve  16  is changed over, but the solenoid valve  14  remains in its position illustrated. Consequently, the compressor continues to convey, but with reduced load, in the direction of ventilation. The result of this is that moisture and dirt which has accumulated in the conveying line are expelled by means of the compressed air. 
         [0043]      FIG. 2  shows a circuit diagram of part of a second embodiment of a device for the processing of compressed air according to the invention. The device for the processing of compressed air  10 , illustrated here, has, in addition to the device illustrated in  FIG. 1 , a safety valve  38  which is connected between the compressed air inlet  1  and the ventilation  3 . This safety valve  38  limits the pressure in the compressor conveying line, so that, in particular, further conveyance by the compressor after the shut-off valve  18  has been changed over does not lead to an undesirable excessive pressure rise. The safety valve  38  illustrated here is integrated into the device for the processing of compressed air  10 . 
         [0044]      FIG. 3  shows a circuit diagram of part of a third and a fourth embodiment of a device for the processing of compressed air according to the invention. Here, too, a safety valve  38  for pressure limitation is provided, although this is arranged outside the device for the processing of compressed air  10 . 
         [0045]      FIG. 4  shows a circuit diagram of part of a third and a fourth embodiment of a device for the processing of compressed air according to the invention. The embodiment illustrated here likewise has a safety valve  38 . This is integrated into the shut-off valve  18 . For this purpose, the shut-off valve  18  is equipped with a further connection, as compared with the shut-off valves illustrated in  FIGS. 1 to 3 . 
         [0046]      FIG. 5  shows a sectional view of a first embodiment of a shut-off valve. The shut-off valve  18  has an inlet connection  52  and an outlet connection  54 . The inlet connection  52  is connected to the compressor. The outlet connection  54  leads to the air dryer unit. Supported on a valve housing  60  is a spring  62  which drives a valve body  64  by means of the spring force in a direction releasing a valve seat  66 . Furthermore, a control connection  56  and a secondary ventilation  58  are provided. The secondary ventilation is present so that no disturbing pressure directed counter to the switching pressure can build up in the spring space. By the action of pressure upon the control connection  56  and the build-up of pressure caused thereby in a control chamber  68 , the spring  62  can be compressed until the valve seat  66  blocks the connection between the inlet connection  52  and the outlet connection  54 . 
         [0047]      FIG. 6  shows a sectional view of a second embodiment of a shut-off valve. The shut-off valve  18  is similar to the shut-off valve illustrated in  FIG. 5 , although it is not designed as a seat valve, but is equipped with a tappet  70 . 
         [0048]      FIG. 7  shows a sectional view of a third embodiment of a shut-off valve with an integrated safety valve. The shut-off valve illustrated here is based on the shut-off valve according to  FIG. 6 . It has an additional outlet connection  72  which, together with a valve seat  74 , a valve body  76  and a spring  78 , forms a safety valve. When the shut-off valve  18  is closed by the action of pressure upon the control chamber  68 , an excessive pressure at the inlet connection  52  can be broken down via the valve seat  74  and the outlet connection  72 . 
         [0049]      FIG. 8  shows a sectional view of a first embodiment of a safety valve. The safety valve  38  has a valve housing  80  in which a valve body  82  is arranged. The valve body  82  is driven by a compression spring  84  in the direction of a valve seat  88  arranged via a seal  86  in the housing. The force exerted on the valve body  82  by the compression spring  84  can be set via a setscrew  90 . When a pressure prevails at the inlet connection  92  so that the force exerted on the valve body  82  by the compression spring  84  is overshot, the pressure can be broken down via the valve seat  88  and the outlet connection  94 . 
         [0050]      FIG. 9  shows a sectional view of a second embodiment of a safety valve. The safety valve  38  illustrated here is constructed in a similar way to the safety valve illustrated in  FIG. 8 , although it is not designed with a valve body, but, instead, with a diaphragm  98  lying on a supporting plate  96 . The diaphragm  98  is firmly connected on its circumference to the valve housing  80 , and, because of its, elasticity, it can block the valve seat  88  under the compression of the compression spring  84  or release said valve seat. 
         [0051]      FIG. 10  shows a sectional view of a third embodiment of a safety valve. The safety valve  18  illustrated here is designed as a ball valve. A ball  100  sits on a compression spring  84  supported on a setscrew  90  and is pressed onto a valve seat  74  by means of the compression spring  84 . An excessive pressure at the inlet connection  92  can be broken down in that the force acting on the ball  100  by virtue of the pressure compresses the compression spring  84 , with the result that the connection between the inlet connection  92  and the outlet connection  94  is released via the valve seat  88 . 
         [0052]    The features of the invention which are disclosed in the above description, in the drawings and in the claims may be essential both individually and in any desired combination for the implementation of the invention. 
         [0053]    The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof. 
       LIST OF REFERENCE SYMBOLS 
       [0000]    
       
           1  Compressed air inlet 
           3  Ventilation 
           4  Compressor control outlet 
           10  Device for the processing of compressed air 
           12  External filling connection 
           14  First solenoid valve 
           16  Second solenoid valve 
           18  Shut-off valve 
           20  Pressure regulating valve 
           22  Nonreturn valve 
           24  Nonreturn valve 
           26  Throttle 
           28  Tire filling connection 
           30  Tire filling valve 
           32  Air dryer unit 
           34  Temperature sensor 
           36  Heating 
           38  Safety valve 
           40  Electronic control unit 
           42  Central plug 
           43  Moisture plug 
           44  Control valve 
           50  Consumer 
           52  Inlet connection 
           54  Outlet connection 
           56  Control connection 
           58  Secondary ventilation 
           60  Valve housing 
           62  Spring 
           64  Valve body 
           66  Valve seat 
           68  Control chamber 
           70  Tappet 
           72  Outlet connection 
           74  Valve seat 
           76  Valve body 
           78  Spring 
           80  Valve housing 
           82  Valve body 
           84  Compression spring 
           86  Seal 
           88  Valve seat 
           90  Setscrew 
           92  Inlet connection 
           94  Outlet connection 
           96  Supporting plate 
           98  Diaphragm 
           100  Ball