Patent Application
20070290550
The invention is based on an electropneumatic brake system of a rail vehicle, containing a direct action electropneumatic brake device and an indirect action compressed-air brake device according to patent claim 1.
Such an electropneumatic brake system is known, for example, from DE 3803639 Al. In this brake system, a signal which corresponds to the axle load is used in the electronic controller to provide a transmission effector between the brake cylinder request and the brake pressure in the brake cylinder with a load correction. This load signal is applied to a pressure regulator which generates a pilot control pressure of the direct brake as a function of the electric brake pressure request signal of the direct, electronically controlled brake. In contrast, the indirect pneumatic brake comprises a control valve which generates a pilot control pressure of the indirect brake as a function of a main air line pressure. The pilot control pressures of the indirect pneumatic brake and of the electronically controlled, direct brake are subjected to quantity boosting by a relay valve or even two relay valves and are combined by means of a shuttle valve which passes on the larger of the pilot control pressures to a pressure limiting valve in a more or less reliable fashion.
For the indirect pneumatic brake and an emergency brake device, the load signal is used to adjust the pressure limiting valve which limits the brake pressure in the brake cylinder, but only when full braking occurs. Such brake systems have the disadvantage that load correction is not carried out continuously on the service brake and the regulating range is shortened. This fact is represented in the diagram in
The present invention is based on the object of further developing an electropneumatic brake system of the type mentioned at the beginning in such a way that the abovementioned disadvantages are avoided.
This object is achieved according to the invention by means of the features of patent claim 1.
The invention proposes an electropneumatic brake system of a rail vehicle, containing a direct action electropneumatic braking device and an indirect action compressed-air braking device, having at least the following components or modules:
The advantages which can be achieved with this arrangement comprise, in particular, the fact that, on the one hand, load correction is performed continuously on the direct brake device and the regulating range extends over the entire braking request from 0% to 100%, as is apparent in particular from the diagram according to
The measures specified in the subclaims permit advantageous developments and improvements of the invention specified in patent claim 1.
The pressure regulator and the pressure limiting valve, the relay valve, the selection device, the transmission and the actuator device are each particularly preferably accommodated in separate housings which are placed together in a block. This results in a particularly compact design, and in addition the individual functional blocks of the pressure regulator and pressure limiting valve, relay valve, selection device, transmission and the actuating device can be premounted in their respective housing.
According to a further measure, the selection device is formed by a piston diaphragm arrangement, having a first piston diaphragm which is connected in an axially fixed fashion to a first piston rod, and a second piston diaphragm which transmits force only in one direction to the first piston rod, a first pressure chamber which is subjected to the pilot control pressure of the indirect brake being formed between the first piston diaphragm and the second piston diaphragm, and a pressure chamber which is subjected to the maximum pilot control pressure of the direct brake being formed between the second piston diaphragm and a wall of the housing. This arrangement ensures significantly higher reliability compared to the shuttle valve from the prior art in which undefined switched positions cannot be ruled out.
The transmission is preferably formed by a lever linkage, with the first piston rod, a second piston rod which activates the relay valve and with a toggle lever, the first piston rod being coupled to one end of the toggle lever, and the second piston rod being coupled to its other end, and it being possible to set the position of a support, arranged between the coupling points, of the toggle lever as a function of the respective load state of the rail vehicle by means of the actuating device. In particular, the support of the toggle lever can be adjusted by means of a piston of the actuating device, said piston being loaded by a loading pressure.
The relay valve is composed of a double seat valve having an inlet valve which connects a compressed air supply to at least one brake cylinder, and having an outlet valve which connects the at least one brake cylinder to a venting means.
A particularly simple design is obtained if a valve closing body of the outlet valve is formed at the end of the second piston rod which faces away from the toggle lever and said piston rod is connected in an axially fixed fashion to a piston or a piston diaphragm which is loaded by the brake pressure in a direction which opens the outlet valve.
The function of the brake system will become clear through the following description of an exemplary embodiment of the invention.
An exemplary embodiment of the invention is illustrated in the drawing and explained in more detail in the following description. In the drawing:
The rail vehicle has a plurality of bogies, each bogie being controlled separately by a compact control module CCM so that for each bogie it is possible to form an individual brake cylinder pressure for one or more brake cylinders. Consequently, a compact control module CCM which has the following functions is provided per bogie:
An electronic brake control unit CU (not shown in
Brake management is carried out in a superordinate fashion in a gateway unit GU which in addition to the coordination of the brake function also contains the interface with the train control equipment. All the compact control modules CCM are connected to the gateway unit GU via a brake bus CAN within part of a train. The number of compact control modules CCM which can thus be connected and the length of such a segment depends on the configuration of the train. A 2-3-2 segmentation, as is apparent from
The present brake system permits what is referred to as three-level brake management with a “local brake master” in each compact control module CCM, a “segment brake master” per segment and, subordinate to these, which are connected to one another for example via a multi-vehicle bus (MVB), a “train brake master”.
The brake management system has the function of controlling and monitoring all the systems necessary to decelerate the vehicle. These are in particular the electrodynamic brakes which are effective on the sets of drive wheels and are predominantly used for service braking, the direct pneumatic brakes on the carrier axles which are predominantly used to supplement the required braking force in service brakes, the pneumatic brakes on the driven wheel sets and the parking brakes and magnetic rail brakes. The control valve arrangement 4 of the parking brake (not of interest here) and the control valve arrangement 6 of the magnetic rail brake (not of interest here) are illustrated in
The indirect brake device is not controlled but rather only monitored by the brake management system. Said brake device is used in the normal operating mode only for high speed braking, which is carried out purely pneumatically (main air line). When the high-speed brake loop is activated, the brake management system has only a monitoring function.
In the case of emergency braking by means of the electropneumatic safety loop, the respective brake control unit CU brakes additionally in a redundant fashion—this is likewise not a function of the brake management system but rather of the local control unit.
The brake management system for each permanently coupled unit (6 component or 4 component unit) is carried out by a brake computer within a gateway unit GU module, but if said module fails the brake management can be carried out by a second module which is configured for that purpose (master switchover).
If a plurality of units (at maximum two further units) are coupled together to form a train set, a control unit in the leading unit performs superordinate brake management functions for the train set and coordinates the communication between the brake and train control/driver. For example three functions which can be carried out according to requirements and installation location are anchored in the respective gateway units GU and brake control units CU:
Depending on the installation location or configuration, only the required functions are activated. When retrofitting is carried out it is determined which control unit performs leading functions. If a unit with current management functions fails, these functions are taken over by the respective other motor rail unit device which is provided for this purpose (master switchover) The local brake control functions such as actuation of the brake pressure, control of the parking brake, antiskid protection, monitoring and diagnostics of faucets and pressure monitors etc. is preferably not of redundant design.
The communication within a motor rail unit as a permanently coupled unit is carried out via the multi-vehicle bus (MVB). A WT bus is used between the motor rail units, via the coupling. The train brake management system communicates in this way with the segment brake managers of the controlled motor rail units.
The direct action electropneumatic brake system is a microprocessor-controlled, electropneumatic compressed-air brake system with comfortable flexible service brake via an ep pressure regulator 8 in which the electrical commands which are predefined by the electronic control system via a signal line are converted into pneumatic signals, in particular into a pilot control pressure Cv direct for a relay valve 12 connected downstream. A pressure limiting valve 14 which is connected between the e/p pressure regulator 8 and the relay valve 12 limits the pilot control pressure Cv direct of the direct brake to a predefinable maximum pilot control pressure Cv direct max of the direct brake. The antiskid control is carried out here by means of in each case one antiskid valve 16, 18—arranged downstream of the relay valve 12—per wheel set. The emergency brake is implemented by a hard wired emergency brake solenoid valve by bypassing the microprocessor-controlled ep pressure regulator.
The command “brake” and the braking setpoint value are transmitted from the train control unit to the electronic brake control unit (gateway unit GU). The respective brake manager uses this setpoint value to calculate the brake pressure C which corresponds to the braking force and which is passed on as an electric brake request signal to the compact control modules CCM. The electric brake request signal is converted within the brake control modules by means of the ep pressure regulator 8 into a pilot control pressure Cv direct of the direct brake device. This pilot control pressure Cv direct is then converted with power amplification into the pneumatic brake pressure C in a load-dependent standard pressure transducer 20 (shown in cross section in
Apart from the prioritized electrodynamic brake, the direct electropneumatic brake device is used exclusively for service braking. At low velocities, the friction brake takes up the entire braking force in a jolt-free fashion until the stationary state is reached, and then automatically applies the parking brake stage in order to prevent the vehicle from rolling back. The direct action electropneumatic brake device is used for the following functions:
The indirect action compressed-air brake device serves as a fallback level especially when the direct action brake device fails and when UIC vehicles are used for towing away, and ensures the following functions:
In each driver's cab the driver has a time-dependent driver brake valve and an emergency switch button for activating the indirect brake device. The driver can vent the main air line HL in an infinitely variable fashion by means of the driver brake valve, and can thus reduce the pressure from 5 bar (release pressure). The maximum braking level is reached when a reduction of 1.5 bar occurs. A further pressure reduction cannot have any further effect. In the case of high-speed brakes, the main air line HL according to UIC is vented to 0 bar in order to shorten the braking and response times.
The pressure in the main air line HL is held at 5 bar in the normal operating mode by means of a pressure reducing valve and a driver brake valve. The pressure in the main air line HL can also be reduced by activating the emergency switch buttons in the driver's cab and by de-exciting SIFA valves by opening the emergency brake loop, and thus triggering the high-speed braking.
The reduction of pressure in the main air line HL is converted into a pilot control pressure Cv in the control valve 2, said pilot control pressure Cv being fed directly into the compact control module CCM and then being subjected to load correction and power amplification by means of the standard pressure transducer 20. The braking operation can thus be carried out analogously and load-dependently over the entire request range.
High-speed braking can quickly reduce overloading of the working chamber in the control valve 2 (approximation function). Furthermore, a nonreturn valve and a shut-off faucet are provided in order to be able to fill the main air vessel line HB when a vehicle is towed away with an initiation vehicle. In this case, the faucet must be opened. When a vehicle is towed away in the currentless state, i.e. when the high-speed brake loop is not activated, the shut-off faucets of the SIFA valves and the direct brake device must be additionally closed.
In the control valve 2, the control pressure HL (releasing of brakes=5 bar, application=pressure reduction by approximately 0.4 bar, maximum braking force=pressure reduction by 1.5 bar) is converted into a pilot control pressure Cv indirect for the relay valve 12 which is connected downstream. The control valve 2 is UIC-compatible, that is to say there is complete train compatibility. As a result, the UIC braking times and release times and the maximum brake cylinder pressure of 3.8 bar are also possible.
Some of the brake control modules CCM additionally contain the means for actuating the spring loaded brake. This is implemented in the form of a double pulse solenoid valve with additional manual triggering, which prevents the braking force being superimposed on the spring force at the brake cylinder by virtue of its internal circuit. The status of the spring loaded brake is then diagnosed internally by means of a pressure sensor which is connected downstream.
Some of the brake control modules CCM additionally contain the means for actuating the electromagnetic rail brake. This is implemented in the form of a solenoid valve for performing pilot control on a large cross section piston valve with pressure reducing means connected upstream.
Furthermore, the control valve 2, which generates a pilot control pressure Cv indirect of the indirect brake as a function of a main air line pressure PHL of the indirect brake, can also be integrated into the standard pressure transducer 20, which is however not the case in the present exemplary embodiment.
The e/p pressure regulator 8 and the pressure limiting valve 14, the relay valve 12, the selection device 24, the transmission 28 and the actuating device 26 are each accommodated in separate housings 30, 32, 34 which are placed together in a block and which together form the standard pressure transducer 20. The housing 30 which accommodates the e/p pressure regulator 8 and the pressure limiting valve 14 is connected by flanges, for example at the head end, to the housing 32 in which the relay valve 12, the selection device 24 and the transmission 28 are accommodated. The housing 34 which houses the actuating device 26 is also connected by flanges, for example at the bottom end, to the housing 32. In addition, the emergency brake solenoid valve can also be integrated into the block which forms the standard pressure transducer 20.
The e/p pressure regulator 8 (not shown explicitly for reasons of scale) comprises two solenoid valves, an air admission valve and a venting valve. Depending on the setpoint pressure set, either the venting valve connects a regulator port to a venting means or the air admission valve connects the regulator port to a compressed air supply. The pressure limiting valve 14 (likewise not explicitly shown) comprises a valve closing element which is loaded by the pilot control pressure Cv direct to be limited, on the one hand, and by compression springs, on the other, said valve closing element closing the pressure limiting valve 14 if the force resulting from the pilot control pressure Cv direct is larger than the spring force. The design and the method of functioning of such an e/p pressure regulator 8 and of such a pressure limiting valve 14 are otherwise sufficiently known, and for this reason more details will not be given thereon below.
The selection device 24 is formed by a combined piston diaphragm arrangement, having a first piston diaphragm 38 which is connected in an axially fixed fashion to a first piston rod 36, and a second piston diaphragm 40 which transmits force only in one direction to the first piston rod 36, a first pressure chamber 42 which is subjected to the pilot control pressure Cv indirect Of the indirect compressed air brake device being formed between the first piston diaphragm 38 and the second piston diaphragm 40, and a second pressure chamber 44 which is subjected to the maximum pilot control pressure Cv direct max of the direct brake device being formed between the second piston diaphragm 40 and a bottom of the housing 30 which is connected by flanges at the head end. The two piston diaphragms 38, 40 are held at the edges in the housing 32. To be more precise, the second piston diaphragm 40 is fitted onto the end of the first piston rod 36 in an axially movable fashion such that it can only apply compressive forces to the first piston rod 36 but no extension forces. The active surfaces A of the first and second piston diaphragms 38, 40 are preferably of equal size.
The transmission is preferably formed by a lever linkage 28 containing the first piston rod 36 which is preferably arranged vertically, a second piston rod 46 which is also arranged vertically and activates the relay valve 12, and an essentially horizontal toggle lever 48, the first piston rod 36 being coupled to one end of the toggle lever 48, and the second piston rod 46 being coupled to its other end, and it being possible to set the position of a pivot axis 50 which is arranged between the coupling points, assigned to the actuating device 26 and serves as a support for the toggle lever 48 can be set as a function of the respective load state of the rail vehicle by means of the actuating device 26. The pivot axis 50 of the toggle lever 48 can then, for example, be adjusted horizontally by means of a piston 54 of the activating device 26 which is loaded, on the one hand, by the load pressure T which is derived from the respective load and, on the other hand, by a compression spring 52, said adjustment being such that respectively different lever ratios and accordingly also different transmission ratios with respect to vertical movements of the two piston rods 36, 46 occur on the right hand and left hand of the pivot axis 50.
The relay valve 12 includes a double seat valve with a compressed air supply (not shown for reasons of scale) with an inlet valve 56 which connects at least one brake cylinder and with an outlet valve 58 which connects the at least one brake cylinder to a venting means.
The second piston rod 46 activates a valve closing body 60 of the outlet valve 58 which is preferably formed by the end of the second piston rod 46 itself. The valve closing body 60 interacts with a valve seat 62 of the outlet valve 58 on a sleeve 66 which is loaded in the closing direction by a compression spring 64. This sleeve 66 at the same time forms the valve closing body of the inlet valve 56 which, as a result of the effect of the compression spring 64, forms a seal against a valve seat 68 of the inlet valve 56 at the edge of a step in a stepped bore 70 in the housing 32.
If the end 60 of the second piston rod 46 is then lifted off from the valve seat 62 of the outlet valve 58 by downward movement, compressed air can flow from the brake cylinder to the venting means. On the other hand, compressed air from a compressed air supply (also not illustrated for reasons of scale) can continue to flow into the brake cylinder if the valve closing body of the inlet valve 56 in the form of the sleeve 66 is lifted off from the valve seat 68 of the inlet valve 56 at the edge of the stepped bore 70.
Furthermore, the second piston rod 46 is connected in an axially fixed fashion to a third piston diaphragm 72 which is loaded by the brake pressure C in a direction which opens the outlet valve 58. For this purpose, a third pressure chamber 74, in which the brake pressure C is present, is formed between an active surface, facing the outlet valve 58, of the third piston diaphragm 72 which is attached to the edge of the stepped bore 70, and the housing 32.
Against this background, the method of functioning of the standard pressure transducer 20 is as follows:
In response to an electric brake pressure request signal of the direct electropneumatic brake device, the e/p pressure regulator 8 generates a pilot control pressure Cv direct which limits the pressure limiting valve 14 accommodated in the same housing 30 to a predefinable maximum pilot control pressure Cv direct max which is present in the second pressure chamber 44. At the same time, the control valve 2 of the indirect compressed air brake generates a pilot control pressure Cv indirect as a function of the main air line pressure PHL which is dependent on the braking request, said pilot control pressure Cv indirect being applied to the first pressure chamber 42.
This then results in the following force relationship at the first piston rod 36:
Fpiston rod=(Cv direct max. A−Cv indirect. A)+Cv indirect. A (1)
The bracketed expression (Cv direct max. A−Cv indirect. A) describes the force on the second piston diaphragm 40 and the expression Cv indirect.A describes the force acting on the first piston diaphragm 38.
If the pilot control pressure Cv direct max of the direct brake device is then lower than the pilot control pressure Cv indirect of the indirect compressed air brake, the second piston diaphragm 40 is moved upwards relative to the first piston rod 36 owing to the bracketed expression (Cv direct max. A−Cv indirect. A) which is then negative, and consequently cannot apply any force to said piston rod 36. In contrast, the force Cv indirect. A which acts on the first piston diaphragm 38 and is based on the larger pilot control pressure Cv indirect is transmitted to the first piston rod 38 by virtue of the axially fixed connection and ensures that the latter moves downwards. This downward movement is converted by the toggle lever 48 into an upward movement of the second piston rod 46, the magnitude of which movement depends on the position of the pivot axis 50 which is in turn influenced by the load pressure T. Generally the following applies: the larger the load pressure T the larger the lever transmission ratio selected at the toggle lever 48 also has to be in order to generate a sufficient brake pressure C. The upward movement of the second piston rod 46 causes the valve closing body of the inlet valve 56 in the form of the sleeve 66 to lift off from the valve seat 68 of the inlet valve 56, allowing compressed air to flow from the compressed air supply into the brake cylinder in order to build up braking force (increasing the pressure).
However, if the pilot control pressure Cv direct max of the direct brake device is higher than the pilot control pressure Cv indirect of the indirect compressed air brake, the two expressions Cv indirect. A with opposite signs in equation (1) cancel one another out so that the force resulting from the higher pilot control pressure Cv direct max acts on the first piston rod 36 and said piston rod 36 is moved downwards, with this movement already having the consequences described above for the activation of the relay valve 12.
If only the pilot control pressure Cv direct max of the direct brake device is acting and there is no pilot control pressure Cv indirect of the indirect compressed air brake, the first pressure chamber 42 is unpressurized, as a result of which there is no pressure force acting on the first piston diaphragm 38. The activation force for the relay valve 12 is then received by the lever linkage 28 from the second piston diaphragm 40 to which the pilot control pressure Cv direct max of the direct brake device is applied.
When only the pilot control pressure Cv indirect of the indirect compressed air brake is present and the pilot control pressure Cv direct max of the direct brake device has failed, the second piston diaphragm 40 is moved upwards as a consequence of the first pressure chamber 42 to which pressure is applied, without said second piston diaphragm 40 applying a pressure force to the first piston rod 36. Said pressure force is then generated by the first piston diaphragm 38 which is loaded by the pilot control pressure Cv indirect of the indirect compressed air brake.
In order to lower the pressure of the brake pressure C, the pilot control pressure Cv indirect of the indirect compressed air brake and the pilot control pressure Cv direct max of the direct brake device are lowered, with a force which corresponds to the higher of the two pilot control pressures being in turn transmitted to the first piston rod 36. Consequently, there is a reduction in this downward-directed force on the first piston rod 36 counter to which the larger force resulting from the brake pressure C, which continues to be high, at the third piston diaphragm 72 of the second piston rod 46 acts via the toggle lever 48 so that as a result the second piston rod 46 is moved downwards and the valve closing body 60 of the outlet valve 58 lifts off from the assigned valve seat 62 in order to vent the brake cylinder (lower pressure).
Between the positions of the relay valve 12 for increasing pressure and lowering pressure there is a closure position in which the brake pressure C and the respectively active pilot control pressure are balanced with one another in such a way that both the inlet valve 56 and the outlet valve 58 are closed so that the brake pressure C is maintained (maintaining pressure).
1 Brake system
2 Control valve
4 Control valve
6 Control valve
8 e/p pressure regulator
12 Relay valve
14 Pressure limiting valve
16 Antiskid valve
18 Antiskid valve
20 Standard pressure transducer
24 Selection device
26 Actuator device
28 Transmission
30 Housing
32 Housing
34 Housing
36 First piston rod
38 First piston diaphragm
40 Second piston diaphragm
42 First pressure chamber
44 Second pressure chamber
46 Second piston rod
48 Toggle lever
50 Pivot axis
52 Compression spring
54 Piston
56 Inlet valve
58 Outlet valve
60 Valve closing body
62 Valve seat
64 Compression spring
66 Valve closing body
68 Valve seat
70 Stepped bore
72 Third piston diaphragm
74 Third pressure chamber
| Number | Date | Country | Kind |
|---|---|---|---|
| 102004024462.6 | May 2004 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP05/05237 | 5/13/2005 | WO | 7/27/2007 |
