Pneumatic control device for a hydraulic brake

Description

[0001] The present invention relates to a pneumatic control device for a hydrodynamic brake according to the preamble of claim 1. Furthermore, the present invention relates to a hydrodynamic brake with such a pneumatic control device.

[0002] Pneumatic control devices of the type described, for example, in German patent applications DE 10 2019 134 843 A1 and DE 199 29 152 A1, are frequently used in so-called retarders, which can be designed as hydrodynamic or electromagnetic retarders. Such retarders can be used, for example, in buses and trucks above a certain gross vehicle weight as a continuous braking system to ensure braking safety and the availability of braking power while driving. In this context, such retarders are used alongside a service brake system to enable, for example, largely wear-free braking of the vehicle over extended periods, even when driving downhill.

[0003] Hydrodynamic retarders are typically controlled by pneumatic means to determine the magnitude of the braking torque to be generated. Such control devices are known from the prior art. These controls regulate the braking performance, depending on the braking demand of a vehicle, by supplying compressed air to a reservoir filled with the retarder's working fluid.

[0004] To ensure that the corresponding braking torque is available as quickly as possible when the retarder is switched on and / or off, as well as when the braking torque requested by the driver changes, rapid venting and purging of the retarder's pneumatic control circuit, particularly of a reservoir filled with the working fluid, is necessary. Rapid purging of the reservoir is especially important to allow the retarder's braking torque to be switched off as quickly as possible, depending on the situation. To provide rapid venting and purging, known pneumatic control systems, for example, have one or more inlet valves and one or more outlet valves, each with the largest possible opening cross-section and short switching times.

[0005] For example, publication EP 3 819 175 A1 describes a pneumatic control system in which several inlet valves and several outlet valves can be operated in parallel. The individual valves can also be pilot-operated. The parallel connection allows the effective opening cross-section of both the inlet and outlet valves to be increased, thus enabling faster venting. However, this control system still has disadvantages regarding operational reliability.

[0006] In publication EP 1 970 789 A2, one possible solution is described: a control device comprising a pilot stage with one inlet valve and one outlet valve, and a main control stage with two inlet valves and one outlet valve. A physical constriction in a control channel creates a fixed throttling point, which at least passively allows for pressure regulation for venting and purging by the pilot stage. The provided control system enables a type of rapid venting function via the outlet valve of the main control stage, thus reducing venting time. However, the control of the valve providing the rapid venting function is carried out via the pilot stage. The pilot stage uses 2 / 2-way valves, which are subject to a certain probability of failure. Therefore, in the event of a pilot stage failure, the system may be affected.No quick-release function is available, which means that the safe operation of the system is not fully guaranteed.

[0007] Based on the aforementioned prior art, the present invention is therefore based on the objective of further developing at least the venting of a pneumatic control device in such a way that it has a (fail-)safe operating function and / or is as finely controllable as possible and / or enables the shortest possible venting time.

[0008] To solve this problem, a pneumatic control device according to the invention for a hydrodynamic brake is proposed. The pneumatic control device comprises a working pressure port, at least one inlet valve via which a working pressure line leading to the working pressure port can be connected to a vent line connected to a compressed air source, and at least one outlet valve via which the working pressure line is connected to a vent line connected to a vent outlet. The working pressure line is connected to the vent line via at least one quick-release valve. The pneumatic control device according to the invention is characterized in that a safety valve is arranged between the compressed air source and the quick-release valve and is configured to actuate the quick-release valve.

[0009] Furthermore, to solve the above-mentioned problem, a hydrodynamic brake with a pneumatic control device according to the invention is proposed.

[0010] The control device according to the invention enables, for example, a particularly rapid shutdown of a hydrodynamic brake connected to the working pressure connection, such as a retarder. This is achieved by means of at least one rapid venting valve, which allows for the rapid venting of the working pressure prevailing within the working pressure line(s) and thus also within the working pressure connection. The working pressure line is connected, preferably directly, to the venting line leading to the venting outlet via the rapid venting valve. In principle, the control device can also have several rapid venting valves, which can, for example, be connected in parallel and each be controllable via a safety valve or via a common safety valve.

[0011] The safety valve is preferably arranged between the pressure source and the quick-release valve such that pneumatic pilot control of the quick-release valve is enabled by the safety valve. The safety valve is preferably designed, for example, as a solenoid valve or can be activated in some other way. The safety valve is preferably switchable between at least one active position and one inactive position and is thus configured to pilot the quick-release valve. In other words, according to a preferred embodiment, the quick-release valve is pneumatically piloted by means of the safety valve. Furthermore, the safety valve can preferably be switched to at least one intermediate position.

[0012] In the inactive position of the safety valve, preferably at least one outlet of the safety valve is connected (in particular directly) to the vent line, so that the safety valve is configured to vent a pilot channel leading to the quick-release valve as completely as possible. In this inactive position, the pilot channel opens into an inlet of the safety valve. InIn the inactive position of the safety valve, a control input is located on the quick-release valve, which can be pneumatically (pre-)controlled by the safety valve, preferably completely depressurized, so that the quick-release valve is in the most fully open position possible, in which the working pressure line is connected to the vent line via the quick-release valve. In the inactive position of the safety valve, the quick-release valve is preferably also in an inactive, i.e., depressurized, position. Complete rapid venting of the working pressure connection is possible in the inactive position of the quick-release valve.

[0013] In the active position of the safety valve, a flow path is preferably opened between a pressure source-side inlet of the safety valve and a pilot channel-side outlet of the safety valve. The safety valve is thus configured to build up pilot pressure in the pilot channel, and consequently also at the control inlet of the quick-release valve, by means of the pressure source. This pilot pressure switches the quick-release valve into an active position. In the active position of the quick-release valve, venting of the working pressure line is prevented. The quick-release valve is therefore in a closed position, in which at least one valve inlet and one valve outlet are blocked. In the active position of the quick-release valve, pressure build-up in the working pressure line, and thus at the working pressure connection, is therefore possible.

[0014] In a preferred embodiment, the safety valve is designed as a 3 / 2-way valve, in particular as a 3 / 2-way solenoid valve. This design of the safety valve is particularly preferred for pilot control of the quick-release valve. However, other valve designs not mentioned here are also conceivable. In particular, compared to pilot control of a quick-release valve by means of a pilot stage comprising 2 / 2-way valves, as disclosed in EP 1 970 789 A2, the pilot control of the quick-release valve according to the invention offers safety advantages. Specifically, the probability of failure of the quick-release function is reduced, since complete pressure release is ensured in the inactive position of the safety valve. Furthermore, the pilot control is less complex than a pilot stage and requires less installation space.

[0015] In a further preferred embodiment, a controllable throttle or, alternatively, a mechanically piloted valve is arranged between the at least one inlet valve, particularly on the inlet valve outlet side in the working pressure line, and the working pressure connection. In an alternative preferred embodiment, the controllable throttle or the mechanically piloted valve is arranged between the pressure source and the at least one inlet valve, particularly in a pressure supply line. According to these two embodiments, the controllable throttle or the mechanically piloted switching valve can therefore be arranged either in the outlet line, particularly the working pressure line, or in the inlet line, particularly the pressure supply line. If the controllable throttle or the mechanically piloted valve is arranged in the inlet line, it is preferably located upstream of the at least one inlet valve.

[0016] The mechanically piloted (switching) valve is preferably designed as a poppet valve, in particular as a 2 / 2-way valve, and can be switched back and forth between a preferably fully open and a preferably fully closed position. In the closed position, a valve-specific valve body preferably sits on the valve seat and particularly preferably provides a complete seal. Although such a design with a mechanically piloted valve is technically more complex, it can be advantageous because such valves allow for complete sealing of the valve seat, thus avoiding residual leakage, such as occurs with variable and / or controllable throttles.Completely closing the valve has the advantage, for example, that a vehicle's compressor that provides compressed air does not have to run continuously, but can be switched off by closing the valve.

[0017] The controllable throttle can preferably be adjustable between a fully open position and a fully closed position, particularly continuously. In the open position, the controllable throttle preferably has an opening cross-section such that unobstructed passage through the throttle is permitted. The throttle cross-section is preferably as large as the cross-section of the working pressure line, so that no constriction is formed by the throttle in the open position. In the closed position, the controllable throttle is preferably completely closed, so that passage through the throttle is not possible. By providing such a controllable throttle, the probability of failure of the control device is reduced. In other words, a throttle with a variable opening cross-section is required, i.e.,No throttle with a fixed cross-sectional area is provided between the working pressure line and the working pressure port. The variable, i.e., adjustable, throttle has the advantage of shutting off the working pressure line between the at least one inlet valve and the working pressure port during a rapid venting process when the rapid venting valve is in the open position. If, in the event of a malfunction, the at least one inlet valve remains in an active, i.e., at least partially open, switching position, the throttle, which then closes, prevents the compressed air source from remaining connected to the working pressure port via the at least one inlet valve. This prevents, for example, an unwanted braking torque from being applied to a brake system connected to the working pressure port.A particular advantage is that the controllable throttle eliminates the need for additional actuating actuators or pilot valves, allowing the preferred solution of the invention to be implemented in a particularly simple and cost-effective manner. Furthermore, the variable, controllable throttle is robust in its operation, thus increasing overall operational reliability at the device level.

[0018] Such a variable throttle, preferably with a variable opening cross-section, can be designed, for example, by providing a transverse or longitudinal bore in a throttle body. Advantageously, a slidably mounted piston element can be arranged in the transverse or longitudinal bore. By inserting the piston element into the transverse or longitudinal bore, a throttling effect can advantageously be achieved, and in particular, the throttling effect can be increased. Conversely, by moving the piston element out, the throttling effect is preferably reduced. Such a design of the throttle with a variable opening cross-section has the advantage that it can be manufactured in a structurally simple and cost-effective manner.This advantage outweighs even the side effect that, due to a design-related and functionally necessary clearance between the bore wall and the piston element, a marginal annular gap always remains open, resulting in minimal leakage. However, this leakage is tolerable in this throttle design. In particular, this leakage can preferably be compensated for via the other discharge and / or venting options, especially via at least one outlet valve and at least one quick-release valve. For example, with an almost completely closed throttle, there is no control pressure at the outlet.

[0019] It is particularly preferred if the controllable throttle is mechanically connected to the quick-release valve. Such a mechanical connection can be established, for example, by means of a spring and / or a lever linkage to transmit, for example, an opening and / or closing movement of the controllable throttle to the quick-release valve. A pull rod is particularly preferred as the mechanical connection between the throttle and the quick-release valve. Alternatively, a push rod can also be used as the mechanical connection. Alternatively, a coupled rotation or the like can also be used as the mechanical connection. The coupled rotation can preferably be a magnetically coupled rotation. With a magnetically coupled rotation connection, pure rotary and linear motion and / or simultaneous rotary / linear motion can preferably be achieved.The transferable displacement forces and torques are defined by a number of magnets and their arrangement relative to each other.

[0020] In a further preferred embodiment, the quick-release valve has a nominal diameter in the range of 5 to 15 mm, more preferably a nominal diameter in the range of 7 to 15 mm, and particularly preferably in the range of 7 to 9 mm. The term "nominal diameter" also refers, for example, to the opening cross-section of the quick-release valve. In a further preferred embodiment, the quick-release valve has a nominal diameter that is at least twice the nominal diameter of the at least one inlet valve.

[0021] In a further preferred embodiment, the pneumatic control device comprises at least two inlet valves connected in parallel. It is also preferred that the pneumatic control device comprises at least two outlet valves connected in parallel. This ensures particularly precise pressure control of the working pressure at the working pressure port. Furthermore, the valves in such a parallel connection can have a smaller nominal diameter compared to a simple, non-parallel connection, allowing the use of smaller valves. This reduces the required installation space and allows the control device to be more compact overall. The smaller nominal diameter of the respective valves also enables finer pressure control.A parallel connection of inlet and / or exhaust valves also has the advantage of creating redundancy in the control device design, thereby reducing the probability of failure. For example, if an inlet valve fails, its function can be at least partially compensated for by a functioning inlet valve connected in parallel. This allows, for instance, the continued operation of a brake system connected to the working pressure port.

[0022] In a further preferred embodiment of the hydrodynamic brake, it includes a retarder. Such a retarder is preferably integrated into the continuous braking system of a motor vehicle, such as a bus or a truck. Such a retarder can, in principle, be designed as a hydrodynamic or electromagnetic retarder. In the present case, the retarder is particularly preferably designed as a hydrodynamic retarder. A hydrodynamic retarder is preferably a fluid brake, which is particularly preferably acting as a secondary retarder on a driveshaft of a powertrain and is arranged either on a transmission above an output shaft therein or on an axle drive above an input shaft therein. Preferably, such a retarder includes a housing, for example, a torus-shaped one.Preferably, the retarder housing contains a rotatably mounted rotor impeller, attached to the output shaft of the transmission, the driveshaft, or the input shaft of the axle drive, and a stationary stator impeller, also attached to the housing. When the retarder housing is at least partially filled with a working fluid, such as hydraulic oil, during vehicle travel, the rotating rotor impeller forces the fluid outwards and into the stator impeller. Within the stator impeller, the fluid is deflected and returned to the interior of the housing. During this fluid movement, kinetic energy is converted into thermal energy. This energy conversion ultimately decelerates the vehicle.

[0023] The pneumatic control device according to the invention controls or regulates the braking performance depending on the braking requirement of a vehicle by supplying compressed air to a reservoir filled with the working fluid of the retarder.

[0024] If the air pressure introduced into the reservoir via the working pressure port is increased, the amount of working fluid forced into the retarder housing is increased. This also increases the braking torque generated in the retarder. Conversely, if the air pressure in the reservoir is reduced via the working pressure port, working fluid is forced from the retarder housing back into the reservoir due to the resulting overpressure. This effectively reduces the braking torque generated in the retarder.

[0025] It is assumed that the definitions and explanations of the aforementioned terms apply to all aspects described in this description and below, unless otherwise stated. Further details, features, and advantages of the invention will become apparent from the following description of the preferred embodiments in conjunction with the dependent claims. The respective features may be implemented individually or in combination. The invention is not limited to the embodiments. The embodiments are shown schematically in the figures. Identical reference numerals in the individual figures denote identical or functionally equivalent elements, or elements that correspond to each other with respect to their function.

[0026] Details and embodiments of the invention are explained below with reference to schematic drawings only.

[0027] They show: Fig. 1: A pneumatic circuit diagram of a control device according to a first preferred embodiment; Fig. 2: A pneumatic circuit diagram of a control device according to a second preferred embodiment; Fig. 3: A pneumatic circuit diagram of a control device according to a third preferred embodiment; Fig. 4: A pneumatic circuit diagram of a control device according to a fourth preferred embodiment; Fig. 5: A pneumatic circuit diagram of a control device according to a fifth preferred embodiment.

[0028] Fig. 1 Figure 10 shows a pneumatic control device 10 for a hydrodynamic brake (not shown in detail) according to an embodiment of the invention.

[0029] The pneumatic control device 10 comprises according to Fig. 1Two inlet valves 12, 12' (i.e., at least one inlet valve 12, 12') are connected in parallel. In this case, the inlet valves 12, 12' are designed as directly controlled 2 / 2-way solenoid valves. Alternatively, the inlet valves 12, 12' could also be designed as pneumatically piloted 2 / 2-way valves. The inlet valves 12, 12' are closed when de-energized, preventing any flow through them. When energized, the inlet valves 12, 12' are open, allowing the flow of a working fluid through each valve. In Figure 1 The inlet valves 12 and 12' are each shown in a closed position.

[0030] The two inlet valves 12, 12' each have two valve inlets and two valve outlets. One of the valve inlets and one of the valve outlets is sealed, thus acting as a flow restrictor. When the inlet valves 12 are energized, one open valve inlet is connected to a compressed air source 16 via a vent line 14, 14'. In this open valve position, one open valve outlet is also connected to a working pressure line 18, 18'. The working pressure lines 18, 18' have a common junction where they merge to form a single working pressure line 18". The working pressure line 18" leads to a working pressure port 20. A hydrodynamic brake, e.g., a retarder, can be connected to the working pressure port 20.The input pressure of the hydrodynamic brake can be regulated via the working pressure port 20 by means of the control device 10.

[0031] Furthermore, the control device 10 indicates in the case of the Figure 1 at least one exhaust valve 22 opens. In a further embodiment according to Figure 2 The control device 10 can also have two or more outlet valves 22, 22' connected in parallel. In this case, the outlet valves 22, 22' are designed as directly controlled 2 / 2-way solenoid valves. Alternatively, the outlet valves 22, 22' can also be designed as pneumatically piloted 2 / 2-way valves. The outlet valves 22, 22' are closed in the de-energized state, so that no flow is permitted through the respective valve. The outlet valves 22, 22' are open in the energized state, so that a working fluid can flow through the respective valve. Figure 1At least one outlet valve 22, 22' is shown in a closed position. The working pressure line 18" can be fluidically connected to a vent line 24 via this outlet valve 22, 22'. The vent line 24 leads to a vent outlet 26. Complete venting of the control device 10 is possible via the vent outlet 26, for example, to depressurize the working pressure connection 20.

[0032] To ensure the fastest possible venting of the working pressure lines 18, 18', 18" and the working pressure connection 20, the control device 10 has at least one quick-release vent valve 28. The working pressure line 18" is connected to the vent line 24 via the quick-release vent valve 28. According to the invention, a safety valve 30 is arranged between the compressed air source 16 and the quick-release vent valve 28. The safety valve is connected to the pressure source 16 via a 14" vent line on the inlet side. On the outlet side, the safety valve 30 is connected to a pilot valve inlet 32 ​​of the quick-release valve 28 via a pilot pressure line 31. The safety valve 30 is designed as a 3 / 2-way solenoid valve. The quick-release valve 28 is pneumatically piloted by means of the safety valve 30. For this purpose, for example, a [missing information] can be connected to the pilot valve inlet 32 ​​of the quick-release valve 28.a pilot pressure via a closing of the safety valve 30 (in . Figure 1 (the safety valve 30 is shown in an open position) can be set up by which the quick-release valve 28 is opened, i.e., venting, in a state (see Figure 1 ) is brought into a closed state. In the open state shown, the safety valve 30 is connected at one valve outlet to the vent channel 24 via a safety vent channel 34, so that no pressure can build up in the pilot pressure line 31 when the safety valve 30 is open. This prevents an unwanted pressure build-up in the pilot pressure line 31.

[0033] The control device 10 also includes a controllable throttle 36 (see Fig. 3 ) or a mechanical pilot-operated valve 40, in particular a poppet valve (see Fig. 4The controllable throttle 36 or the valve 40 is arranged downstream of the junction of the working pressure line 18" and upstream of the working pressure port 20. The controllable throttle 36 or the mechanically piloted valve 40 is mechanically connected to the quick-release valve 28. Such a mechanical connection 38 is shown schematically by a dashed line.

[0034] Figure 2 differs from Figure 1 simply by providing two parallel outlet valves 22, 22'.

[0035] In the exemplary embodiments of the Figs. 3 to 5 The compressed air source 16 can also be connected to the remaining pneumatic control device 10 via a pressure supply line 21, which is also referred to as the inlet line P. However, this is in contrast to the Fig. 1 and 2 This represents only a modified presentation and no functional or technical change. Due to the relative differences to Fig. 1The ventilation lines 14, 14', 14" also run differently from the pressure source 16 and the pressure supply line 21, although the operation of the differently depicted components and arrangements is otherwise the same in pneumatic terms.

[0036] In alternative embodiments, the controllable throttle (see Fig. 4 ) or the mechanically piloted valve (see Fig. 5 ) also between the pressure source 16 and the at least one inlet valve 12, 12', in particular in the pressure supply line 21. Reference symbol list:

[0037] 10 Pneumatic control device 12, 12' Inlet valve 14, 14', 14" Vent line 16 Compressed air source 18, 18', 18" Working pressure line 20 Working pressure connection 21 Pressure supply line 22, 22' Outlet valve 24 Vent line 26 Vent outlet 28 Rapid vent valve 30 Safety valve 31 Pilot pressure line 32 Pilot valve inlet 34 Safety vent channel 36 Controllable throttle 38 Mechanical connection 40 Mechanically piloted valve

Claims

1. A pneumatic controlling device for a hydrodynamic brake, with a working pressure port (20), at least one inlet valve (12, 12') via which a working pressure line (18, 18', 18") leading to the working pressure port (20) can be connected to an air feed line (14, 14', 14") that is connected to a compressed-air source (16), and at least one outlet valve (22, 22') via which the working pressure line (18, 18', 18") is connected to an air bleed line (24) that is connected to an air bleed exit (26), wherein the working pressure line (18, 18', 18") is connected to the air bleed line (24) via at least one quick air bleed valve (28), characterized in that a safety valve (30) is arranged between the compressed-air source (16) and the quick air bleed valve (28) and is configured to activate the quick air bleed valve (28).

2. The pneumatic controlling device according to claim 1, characterized in that the safety valve (30) is configured as a 3 / 2-way valve, in particular as a 3 / 2-way solenoid switch valve.

3. The pneumatic controlling device according to any one of the preceding claims, characterized in that a controllable throttle (36) or a mechanically pilot-controlled valve (40) is arranged between the at least one inlet valve (12, 12') and the working pressure port (20).

4. The pneumatic controlling device according to claim 1 or 2, characterized in that a controllable throttle (36) or a mechanically pilot-controlled valve (40) is arranged between the pressure source (16) and the at least one inlet valve (12, 12'), in particular in a pressure feed line (21).

5. The pneumatic controlling device according to claim 3 or 4, characterized in that the controllable throttle (36) is mechanically connected to the quick air bleed valve (28).

6. The pneumatic controlling device according to any one of claims 1 to 5, characterized in that the quick air bleed valve (28) is pneumatically pilot-controlled.

7. The pneumatic controlling device according to any one of claims 1 to 6, characterized in that the quick air bleed valve (28) has a nominal width in a range from 5 mm to 15 mm, preferably in a range from 7 mm to 9 mm.

8. The pneumatic controlling device according to any one of claims 1 to 7, characterized in that the pneumatic controlling device (10) comprises at least two inlet valves (12, 12'), which are connected in parallel to one another.

9. The pneumatic controlling device according to any one of claims 1 to 8, characterized in that the pneumatic controlling device (10) comprises at least two outlet valves (22, 22'), which are connected in parallel to one another.

10. A hydrodynamic brake with a pneumatic controlling device (10) according to any one of claims 1 to 9.

11. The hydrodynamic brake according to claim 10, characterized in that the hydrodynamic brake comprises a retarder.