DE10150682B4 - Hydrodynamic braking system with a retarder - Google Patents

Abstract

Hydrodynamic brake system 1.1 with a retarder (1), in particular with a secondary retarder; 1.2 with an external working medium circuit (10); 1.3 the external working medium circuit (10) comprises a loading container (11) which is at least indirectly connected to a feed connection (5) of the retarder (1) in a manner that carries the working medium, for supplying working medium from the loading container (11) into the working space (1.7) of the retarder (1); 1.4 the loading container (11) is pressure-regulated for stepless adjustment of the braking torque of the retarder (1); characterized by the following features: 1.5 an additional quick-loading container (12) is provided for supplying working medium into the working space (1.7) of the retarder (1); 1.6 the quick-charging container (12) is connected to a feed connection of the retarder (1) and / or to the external working medium circuit (10), carrying the working medium; 1.7 the quick-loading container (12) is designed without pressure regulation; 1.8 the stator (1.2) and the rotor (1.1) of the retarder (1.1) are axially displaceable to each other, so that the working space (1.7) of the ...

Description

The invention relates to a hydrodynamic brake system with a retarder, in particular a secondary retarder according to the preamble of claim 1.

Hydrodynamic brake systems with retarders are known. Since the working fluid in the retarder heats up during braking operation, an external working medium circuit is usually provided by a retarder via a heat exchanger in which the heat absorbed by the working fluid is dissipated again, to a Retardereinlass, through which the working fluid back into the working space of the retarder.

It is known that retarder unintentionally apply a braking power in non-braking operation. This is due to the air present in the working space and to the remainder of the working medium remaining in the working space. This is generally referred to as ventilation losses. To keep these losses as low as possible, the working space of the retarder is emptied in non-braking operation completely or down to a certain residual amount of the working medium. As soon as braking operation is required, the working space of the retarder must be refilled as quickly as possible. Only when reaching a predetermined degree of filling the desired braking torque is provided by the retarder. It is therefore desirable that this filling be done very quickly. In particular, when large volumes are to be filled, the filling process takes in known hydrodynamic brake systems with a retarder too long.

In order to minimize ventilation losses in non-braking operation, the rotor and stator of the retarder can be removed from each other in non-braking operation, in particular by axial displacement of the rotor relative to the stator. For example DE 197 04 407 A1 called. This possibility of displacement of rotor and stator to each other requires a larger space of the retarder and a significant increase in the spaces in the retarder. In addition to the rooms with a volume of working medium to be controlled, additional dead spaces are formed here, which absorb an additional dead volume of working medium. These dead spaces must be filled as quickly as possible during the transition from non-braking operation to braking operation. Thus, there is a need for action with regard to a filling speed increase, in particular with regard to the retarders with rotor displacement.

The object of the invention is to present a hydrodynamic brake system with a retarder, wherein the retarder is filled as quickly as possible during the transition from non-braking operation to braking operation.

This object is achieved by a hydrodynamic brake system according to claim 1 and a method for controlling a brake system with a hydrodynamic retarder according to claim 5. The dependent claims describe particularly advantageous embodiments.

The hydrodynamic brake system according to the invention with a retarder comprises an external working medium circuit. In the working medium circuit, a loading container is connected, which is connected at least indirectly Arbeitsmediumführend to a supply terminal of the retarder. Thus, working medium can be guided from the loading container into the working space of the retarder. The hydrodynamic brake system according to the invention further comprises an additional fast-charging container, from which also working medium can be guided into the working space of the retarder. The fast-charging container is connected to a supply connection of the retarder and / or to the external working medium circuit. Due to the design according to the invention, the entire working medium circuit can be performed free of pumps, which is on the one hand favorable and on the other hand a large reaction rate in state change, for example, when changing the braking torque and the degree of filling of the retarder allows.

The external circuit comprises, in particular, a heat exchanger for removing the heat from the working medium, which is supplied to the working medium in the braking operation in the retarder. In this case, the heat exchanger is arranged in the external circuit, in particular behind a throttle element connected to a retarder outlet. Additionally or alternatively, there may also be provided a check valve there. The rapid charging container is advantageously connected to a feed point in the external circuit, wherein the feed point between the retarder and the heat exchanger is located.

Advantageously, a control means, in particular a 3/2-way valve connected to the fast-charging container to activate the fast-charging container. The fast-loading container can be designed as a pressure cylinder with a pressure piston. The pressure cylinder can be filled with working fluid, wherein the pressure piston is displaced during filling by the application of the working medium pressure in one direction, preferably in the direction of the connected 3/2-way valve, in the pressure cylinder. The fast-loading container is then in an "in-focus position". The working medium-facing side of the pressure piston is, upon activation of the printing cylinder, in particular by means of a 3/2 Directional valve, subjected to a control medium, so that the working fluid is pressed due to the displacement force by the action of the pressure piston with the control medium pressure from the pressure cylinder. The control medium can be separated from the working medium in a separate circuit, and it is possible to carry out the activation by means of the same or another medium, for example water is called as the working medium and oil as the control medium.

The inventive method for controlling a brake system with a hydrodynamic retarder comprises the following steps: By means of an external circuit, in which a heat exchanger is connected, the heat supplied to the working medium in the retarder is dissipated. By means of a connected in the external circuit loading container with working fluid volume differences of the working fluid in the external circuit are compensated. By means of a pressure control of the working medium pressure in the loading container, the braking torque of the retarder is controlled in braking mode.

In non-braking operation, the retarder according to the invention completely or emptied to a defined residual working fluid. When activating the retarder, that is the transition from non-braking operation to braking operation, the retarder and / or the external circuit working fluid is supplied from an additional correspondingly connected fast-charging container.

Particularly advantageously, the rapid charging container is recharged during the following after its discharge braking operation, in particular directly with working fluid from the working medium circuit. The inventor has in fact recognized that with skillful selection of the position of the feed point, as described above, the pressure in the feed point during braking operation rapidly increases when the production of the required braking torque of the loading tank trailing working medium, that is, if due to the regulation of the pressure in the load tank working fluid is fed from the loading container in the working medium circuit or in the working space of the retarder. This increase in pressure is exploited to refill the rapid loading container, wherein the volume of discharged into the fast-loading container working medium is tracked due to the pressure control of the loading container in the working fluid circuit, so that adverse effects on the braking torque due to lack of working fluid in the working fluid circuit or in Retarderarbeitsraum be prevented.

The rapid charging container can be controlled by a control valve, in particular a 3/2-way valve.

Advantageously, the rapid loading container is designed as a "pressure compensator" with a pressure piston. If, due to the fact that in the feed point in braking operation, a higher pressure prevails than during the switch-on, the fast-charging container is filled with working fluid during braking operation, the piston is pushed back in the pressure cylinder. When activating the rapid charging container, the working medium is then displaced from the rapid charging container by supplying the opposite side of the piston with a control pressure and fed into the external circuit or into the retarder.

The pressure in the loading container is preferably controlled or regulated by means of a control valve, in particular by means of a proportional valve. It is possible that one or both control valves - control valve for controlling the pressure in the loading container and control valve for controlling the rapid charging container - are controlled by a separate from the working medium control medium. Of course, it is possible to use the same fluid for working medium and control medium.

In order to reduce the ventilation losses of the retarder in non-braking operation, the rotor of the retarder is advantageously removed in non-braking operation from the stator of the retarder, in particular axially displaced relative to the stator. Advantageously, this shift occurs automatically depending on the filling. The rotor is mounted, for example, on a thread, so that it is driven by a relative rotational movement relative to the threaded member from the stator or driven in opposite direction of rotation of the stator.

By completely emptying or by emptying to a defined amount of residual working medium is due to the decreasing hydrodynamic braking torque and the decreasing hydrostatic pressurization of the rotor by working fluid on the side facing away from the stator, the thrust reduced, which moves the rotor towards the stator (filling process) respectively the rotor at a defined axial distance, which may be determined for example by an abutment element, keeps away from the stator (in braking mode). In the request of the braking operation of the retarder is filled, the thrust force on the rotor due to the increasing hydrodynamic braking torque and / or hydrostatic pressure is increased and the rotor to a moved axially defined distance to the stator and held there during the braking operation.

In particular, additional spaces (dead spaces) in the retarder are required for the displacement, which are filled with working medium when the retarder is filled. In a particularly advantageous embodiment of the invention, the volume of the rapid charging container is equal to or approximately equal to the volume of the dead space. In order to bring about a particularly simple and rapid filling of the retarder, the working medium, which is enclosed in the charged fast-loading container in this unregulated supplied to the working space of the retarder, which comprises said dead spaces, at least indirectly. This means that the fast-loading container is free of pressure regulation and the supplied working medium volume is determined solely by the volume displaced from the rapid-loading container. In a preferred embodiment, the fast-loading container is designed as a pressure cylinder, the pressure piston is moved by exposure to a pressurized medium, which control medium may be in a separate control circuit, such that the working fluid is forced out of the rapid loading container. Since the supply of the working medium from the rapid charging container in the retarder is unregulated, the pressurization of the piston can be advantageously triggered by a switching valve, for example 3/2-way valve, which is cheaper compared to, for example, a proportional valve and reliable.

The supply of the working fluid volume, which is necessary for the required braking torque of the retarder, is controlled from the loading container, the pressure of which is advantageously controlled by a proportional valve, as thus a continuous adjustment of the braking torque is possible.

In order to empty the working space of the retarder to a predetermined residual amount or even completely in non-braking operation, it is advantageous that the working medium detected by the rotor is transported through an outlet provided at a defined distance radially to the rotor axis in the rotor housing and the loading container in the external circuit is fed directly or indirectly. In the case of an indirect feed, the working medium transported through the outlet can advantageously be supplied to an atmospherically connected container. The atmospherically connected container is preferably at a geodetically higher level than the loading container and is connected to the loading container in such a way that the working medium drains from this atmospherically connected container into the loading container due to gravity.

To direct a given working medium flow - cooling mass flow - in the non-braking operation through the working space of the retarder, a defined amount of working fluid can be supplied to the retarder and discharged through the outlet in the rotor housing. This cooling is particularly effective in terms of energy expenditure for maintaining this cooling circuit when the external circuit and in particular the line section, which is connected to the outlet in the rotor housing, are free of elements with external energy supply.

The invention will be explained in more detail with reference to an embodiment.

1 shows a control diagram of an embodiment of a hydrodynamic brake system with a retarder;

2 shows an advantageous connection of the fast charging container to the external circuit;

3 shows a differently designed but equally effective connection as in 2 ,

The hydrodynamic brake system includes a retarder 1 with a rotor 1.1 and a stator 1.2 , The rotor 1.1 turns around the rotor axis 1.3 and is in the rotor housing 1.4 arranged while the stator 1.2 in the stator housing 1.6 is arranged. It is the non-braking operation state shown as the rotor 1.1 from the stator 1.2 is axially removed.

At the retarder 1 is an external working medium cycle 10 connected. The working fluid passes through the Retarderauslass in braking mode 6 out, flows through the throttle body 14 and the check valve 15 , is in the heat exchanger 13 cooled and flows over the check valve 20 and the throttle body 21 to the supply connection 5 of the retarder 1 , Then it becomes the workroom again 1.7 supplied to the retarder.

The external circuit 10 further includes a cargo box 11 with working medium, via a line piece 22 , which is preferably arranged perpendicular or nearly vertical, to the feed line 23 connected. The power line 23 is working medium conducting with the supply connection 5 of the retarder 1 connected. In the supply line 23 are the said check valve 20 and the throttle body 21 connected.

The pressure in the loading container 11 is via a control valve 17 , which is preferably designed as a proportional valve set. About the pressure in the loading container 11 is the braking torque of the retarder 1 infinitely variable. The control valve 17 can with a control medium with the pressure pV be acted upon, which is separated from the working medium.

A fast-loading container 12 in the form of a pressure cylinder with a pressure piston is pressure-conducting in the feed point 12.1 to the external working medium circuit 10 connected. The fast loading container 12 is loaded with working medium. At the beginning of a braking operation, one side of the pressure piston is acted upon by means of a control medium with the pressure pV, which is in particular 5-8 bar, by the 3/2-way valve is switched to passage accordingly. By applying the piston in the quick-charge container 12 with the control pressure, the piston is displaced so that the working fluid from the rapid charging container 12 pushed out and into the piping system of the external working medium circuit 10 is fed. This allows a quick filling of the retarder 1 be ensured with working medium.

During the subsequent braking operation, the pressure in the feed point increases 12.1 of the external circuit 10 over the pressure at this point during the switch-on process, so that the fast-charging container 12 automatically refilled because of the loading container 11 Tracking working medium. Thus, the fast loading container 12 brought during braking mode in such a state that it is available for the next start-up phase when braking again.

To prevent too fast working fluid from the working medium circuit in the fast-charging container 12 is discharged at its refilling, which adversely affects a delay of the pressure build-up in the feed point 12.1 could result in a desired increase in the braking torque or even a pressure drop, can be advantageous in the line between fast-charging container 12 and feed point 12.1 a check valve 27 with opening direction in the direction of the feed point 12.1 be provided, which is a line branch with a throttle element 28 is connected in parallel. Such an embodiment is in 2 shown. When unloading the fast loading container 12 will this check valve 27 pressed and a large line cross-section, through the opening cross-section of the check valve 27 and the flow area of the throttle element 28 is determined, is for fast feeding of the working fluid from the fast-charging container 12 in the feed point 12.1 made available. When refilling the quick charge container 12 however, the check valve is 27 closed and the line cross-section, to refill the fast-charging container 12 is available exclusively through the flow cross-section of the throttle element 28 certainly. If the throttle element is designed to be adjustable, then this flow cross-section can optionally be set and, in particular, the refilling time of the quick-charge container 12 depending on the pressure in the feed point 12.1 be set.

Another embodiment according to 3 Provides that in the line between fast-loading containers 12 and feed point 12.1 a check valve with opening direction in the direction of the feed point 12.1 is provided, wherein in the check valve a constantly open minimum cross-section 27.1 is introduced, which takes over the function of the above-mentioned throttle element.

The location of the feed point 12.1 may be selected such that the loading capacity of the rapid loading container 12 essentially only during the period of retarder engagement is available. A preferred location is seen in the flow direction between the Retarderauslass 6 and the heat exchanger 13 ,

The illustrated external working medium circuit 10 further comprises an atmospherically associated container 18 , This is stored at a geodetic higher level than the loading container 11 , In the rotor housing 1.4 is an outlet 1.5 provided by the non-braking operation of the rotating rotor 1.1 recorded working medium from the work area 1.7 of the retarder 1 is transported out. This working medium becomes the atmospherically connected container 18 over the line 25 fed. From there it flows by gravity back into the loading container 11 , Into the pipe between container 18 and loading container 11 is advantageous a check valve 26 switched, which opens due to gravity and with a pressure increase in the loading container 11 closes to a predetermined pressure. In order to prevent that during braking operation with higher pressure acted on working medium via the line 25 in the atmospherically connected container 18 is promoted, is in the lead 25 a check valve 24 provided, which closes in braking mode.

Any type of retarder may be used in the hydrodynamic brake system. For example, primary retarders, secondary retarders, oil-operated retarders, retarders operated with the working medium of the vehicle cooling system (water pump retarder), bearingless retarders (retarders mounted on the fly) and retarders designed with (own) storage may be mentioned.

LIST OF REFERENCE NUMBERS

1

retarder

1.1

rotor

1.2

stator

1.3

rotor axis

1.4

rotor housing

1.5

outlet

1.6

stator

1.7

working space

5

power connection

6

Retarderauslass

10

External working medium circuit

11

loading container

12

Quick loading container

12.1

feed point

13

heat exchangers

14

throttle member

15

check valve

16

3/2-way valve

17

control valve

18

Atmospherically connected container

19

Hydraulic section

20

check valve

21

throttle member

22

line section

23

power line

24

check valve

25

management

26

check valve

27

check valve

27.1

opened minimum cross section

28

throttle element

Claims (13)

Hydrodynamic braking system 1.1 with a retarder ( 1 ), in particular with a secondary retarder; 1.2 with an external working medium circuit ( 10 ); 1.3 the external working medium circuit ( 10 ) comprises a loading container ( 11 ), at least indirectly working medium leading to a feed connection ( 5 ) of the retarder ( 1 ) is connected, for supplying working medium from the loading container ( 11 ) in the working space ( 1.7 ) of the retarder ( 1 ); 1.4 the loading container ( 11 ) is pressure-controlled for stepless adjustment of the braking torque of the retarder ( 1 ); characterized by the following features: 1.5 it is an additional fast-loading container ( 12 ), for supplying working medium into the working space ( 1.7 ) of the retarder ( 1 ); 1.6 the fast-loading container ( 12 ) is working medium leading to a feed connection of the retarder ( 1 ) and / or to the external working medium circuit ( 10 ) connected; 1.7 of the fast-loading containers ( 12 ) is executed free of pressure regulation; 1.8 the stator ( 1.2 ) and the rotor ( 1.1 ) of the retarder ( 1.1 ) are axially displaceable to each other, so that the working space ( 1.7 ) of the retarder ( 1 ) has a caused by the displacement additional in the braking operation with working fluid to be filled dead space; 1.9 the working medium receiving volume of the rapid loading container ( 12 ) is equal to the volume of the dead space. Hydrodynamic brake system according to claim 1, characterized by the following features: 2.1 the external working medium circuit ( 10 ) comprises a heat exchanger ( 13 ) for removing heat from the working medium; 2.2 the heat exchanger ( 13 ) is in the external circuit ( 10 ) behind one at a retarder outlet ( 6 ) connected throttle body ( 14 ) and / or check valve ( 15 ); 2.3 the fast-loading containers ( 12 ) is at a feed point ( 12.1 ) in the external circuit ( 10 ) connected; 2.4 the feed point ( 12.1 ) lies between the retarder outlet ( 6 ) and the heat exchanger ( 13 ). Hydrodynamic braking system according to one of claims 1 or 2, characterized in that the rapid loading container ( 12 ) a control means, such as 3/2-way valve ( 16 ) is activated to activate the quick charge container ( 12 ). Hydrodynamic braking system according to one of claims 1 to 3, characterized in that the rapid loading container ( 12 ) is designed as a pressure cylinder with a pressure piston. Method for controlling a brake system with a hydrodynamic retarder ( 1 ), in particular secondary retarder, comprising the following steps: 5.1 by means of an external working medium circuit ( 10 ) with a heat exchanger ( 13 ), heat is released from the brake system in the retarder ( 1 ) discharged heated working medium; 5.2 by means of an external working medium cycle ( 10 ) connected loading container ( 11 ), volume differences of the working medium in the external working medium cycle ( 10 ), and by means of a pressure control of the working medium pressure in the loading container ( 11 ) the braking torque of the retarder ( 1 ) controlled in braking mode; 5.3 in non-braking mode, the retarder ( 1 ) is emptied completely or to a defined residual working fluid quantity; 5.4 when activating the retarder ( 1 ) - transition from non-braking operation to braking operation - the retarder ( 1 ) and / or the external working medium circuit ( 10 ) Working medium from an additional rapid loading container ( 12 ) fed pressure-regulated; 5.5 in the transition from non-braking operation to braking operation, a dead space volume of the working space ( 1.7 ) is filled with working fluid, which by an axial displacement of the stator ( 1.2 ) and the rotor ( 1.1 ) of the retarder ( 1 ), and 5.6 the working medium receiving volume of the rapid loading container ( 12 ) is equal to the volume of the dead space. Method according to claim 5, characterized in that the rapid loading container ( 12 ) is partially or completely recharged during the following after its discharge braking operation. Method according to one of claims 5 or 6, characterized in that the rapid loading container ( 12 ) by a control valve, such as 3/2-way valve ( 16 ) is controlled. Method according to one of claims 5 to 7, characterized in that the pressure in the loading container ( 11 ) by means of a control valve ( 17 ), such as a proportional valve. Method according to one of claims 5 to 8, characterized in that one or both control valves ( 16 . 17 ) are controlled by a separate from the working medium control medium. Method according to one of claims 8 or 9, characterized in that in non-braking operation, the rotor ( 1.1 ) of the retarder ( 1 ) and the stator ( 1.2 ) of the retarder ( 1 ) are pushed apart axially as by moving the rotor by means of a rotary displacement movement of the rotor on a thread. Method according to one of claims 5 to 10, characterized in that in the non-braking operation of the rotor ( 1.1 ) detected by a working medium at a defined distance radially to the rotor axis ( 1.3 ) in the rotor housing ( 1.4 ) outlet ( 1.5 ) and the loading container ( 11 ) indirectly over an atmospherically connected container at a higher geodetic level ( 18 ) is supplied. Method according to one of claims 5 to 11, characterized in that in non-braking operation, a defined amount of working medium the retarder ( 1 ) and via the outlet ( 1.5 ) is discharged. A method according to claim 12, characterized in that the external working medium circuit ( 10 ) and the outlet ( 1.5 ) connected hydraulic section ( 19 ) are free of external energy supply.

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