SE544940C2 - Method of Controlling a Hydrodynamic Retarder Arrangement, Control arrangement, Hydrodynamic Retarder Arrangement, and Vehicle - Google Patents

Abstract

A method (100) of controlling a hydrodynamic retarder arrangement (10) is disclosed. The retarder arrangement (10) comprises a hydrodynamic retarder (1), an inlet duct (2) connected to an inlet (4) of the hydrodynamic retarder (1), and a pressure increasing arrangement (8) configured to increase fluid pressure (P) in the inlet duct (2) by transferring working fluid to the inlet duct (2) upon activation. The method (100) comprises the steps of initiating (120) or cancelling (140) braking of the hydrodynamic retarder (1), and activating (110, 150) the pressure increasing arrangement (8) in conjunction with the step of initiating (120) or cancelling (140) braking of the hydrodynamic retarder (1). The present disclosure further relates to a computer program, a computer-readable medium (200), a control arrangement (21), a hydrodynamic retarder arrangement (10), and a vehicle (30) comprising a retarder arrangement (10).

Description

Method of Controlling a Hydrodynamic Retarder Arrangement, Control arrangement, Hydrodynamic Retarder Arrangement, and Vehicle TECHNICAL FIELD The present disclosure relates to a method of controlling a hydrodynamic retarder arrangement. The present disclosure further relates to a computer program a computer-readable medium, a control arrangement for a hydrodynamic retarder arrangement, a hydrodynamic retarder arrangement, and a vehicle comprising a hydrodynamic retarder arrangement.

BACKGROUND Retarders are devices used on vehicles to augment or replace some of the functions of primary braking arrangements, such as friction-based braking arrangements. One common type of retarder is hydrodynamic retarders. Such retarders utilize the viscous drag forces of a working fluid in a workspace between a rotor and a stator. The rotor is usually connected to a shaft of the vehicle, such as a shaft of the gearbox of the vehicle, via a retarder transmission. A hydrodynamic retarder arrangement comprises a hydraulic circuit, sometimes referred to as a retarder circuit, comprising components such as hoses and pipes and a radiator configured to dissipate heat generated during braking.

Retarders are capable of providing several advantages. As an example, they are less likely to become overheated in comparison to friction-based braking arrangements, for example when braking a vehicle travelling downhill. Furthermore, when used, retarders lower wear of primary friction-based braking arrangements.

When braking, the workspace of the retarder is filled with a certain volume of working fluid and when the braking is cancelled, the workspace is usually emptied of the working fluid. A problem associated with hydrodynamic retarders is that it imparts significant pressure variations in the hydraulic circuit thereof upon initiation and cancellation of braking. The pressure variations can cause pressures below the ambient pressure which put strain on the hydraulic circuit and can cause hoses to collapse and suck flat. lf one or more hoses is/are sucked flat, the flow through the hose/hoses is obstructed which limits the flow therethrough and consequently the feed of working fluid to the retarder. Moreover, repeated compression of hoses may damage the hoses. ln addition, generally, on today's consumer market, it is an advantage if products, such as vehicle arrangements, comprise different features and functions while the products haveconditions and/or Characteristics suitable for being manufactured and assembled in a cost- efficient manner.

SUMMARY lt is an object of the present invention to overcome, or at least alleviate, at least some of the above-mentioned problems and drawbacks.

According to a first aspect of the invention, the object is achieved by a method of controlling a hydrodynamic retarder arrangement. The retarder arrangement comprises a hydrodynamic retarder configured to brake rotation of a shaft of a vehicle, an inlet duct connected to an inlet of the hydrodynamic retarder, and a pressure increasing arrangement configured to increase fluid pressure in the inlet duct by transferring working fluid to the inlet duct upon activation. The method comprises the steps of: - initiating or cancelling braking of the hydrodynamic retarder, and - activating the pressure increasing arrangement in conjunction with the step of initiating or cancelling braking of the hydrodynamic retarder.

Since the method comprises the step of activating the pressure increasing arrangement in conjunction with the step of initiating or cancelling braking of the hydrodynamic retarder, a method is provided capable of avoiding, or at least alleviating, the problem of pressures below the ambient pressure in a retarder circuit of the retarder arrangement. This is because the fluid pressure in the inlet duct is increased in conjunction with the step of initiating or cancelling braking of the hydrodynamic retarder as a result of the activation of the pressure increasing arrangement.

As a further result thereof, a method is provided capable of lowering strain on the retarder circuit and avoiding compression/collapsing of components thereof in a simple, robust, and efficient manner. Moreover, a method is provided having conditions for ensuring feed of working fluid to the hydrodynamic retarder in a simple, robust, and efficient manner.

Accordingly, a method is provided overcoming, or at least alleviating, at least some of the above-mentioned problems and drawbacks. As a result, the above-mentioned object is achieved. i j-ggpressure increasing arrangement comprises a pump configured to increase fluid pressure in the inlet duct by pumping working fluid to the inlet duct, and wherein the step of activating the pressure increasing arrangement comprises the step of: - initiating operation of the pump.

Thereby, a method is provided capable of lowering strain on the retarder circuit and avoiding compression/collapsing of components thereof in a further simple, robust, and cost efficient manner. Moreover, a method is provided having conditions for ensuring feed of working f|uid to the hydrodynamic retarder in a further simple, robust, and cost efficient manner.

Optionally, the method comprises: - initiating braking of the hydrodynamic retarder, and wherein the step of activating the pressure increasing arrangement is performed prior to the step of initiating braking of the hydrodynamic retarder.

Thereby, a method is provided having further improved conditions for avoiding, or at least alleviating, the problem of pressures below the ambient pressure in the retarder circuit. This is because the step of activating the pressure increasing arrangement is performed prior to the step of initiating braking of the hydrodynamic retarder, and as a consequence thereof, the pressure increasing arrangement starts to increase the pressure in the inlet duct prior to the initiation of braking of the hydrodynamic retarder.

Optionally, the method comprises the step of: - starting rotation of a rotor of the hydrodynamic retarder prior to the step of activating the pressure increasing arrangement.

Thereby, a method is provided having conditions for stabilizing the pressure levels in the retarder circuit prior to the initiation of braking of the retarder.

Optionally, the hydrodynamic retarder comprises a coupling device controllable between an engaged state, in which the coupling device connects the rotor to the shaft, and a disengaged state, in which the coupling device disconnects the rotor from the shaft, and wherein the step of starting rotation of the rotor comprises the step of: - controlling the coupling device to the engaged state.

Thereby, the starting rotation of a rotor is performed in a simple and efficient manner. Moreover, conditions are provided for lowering parasitic losses caused by the retarder arrangement by controlling the coupling device to the disengaged state after a braking event of the hydrodynamic retarder.

Optionally, the method comprises the step of: - deactivating the pressure increasing arrangement after the step of initiating braking of the hydrodynamic retarder.

Thereby, a method is provided having conditions for avoiding too high pressures in the retarder circuit during braking of the hydrodynamic retarder as Well as during cancellation of braking, while avoiding the problem of pressures below the ambient pressure upon initiation or cancelling of braking of the hydrodynamic retarder. This is because pressure peaks usually occur when a braking torque of the hydrodynamic retarder declines, such as upon cancellation of braking with the hydrodynamic retarder. The time in which the braking is cancelled usually cannot be foreseen, because it may be controlled by a driver of the vehicle or a propulsion/travel control system of the vehicle. Accordingly, by deactivating the pressure increasing arrangement after the step of initiating braking of the hydrodynamic retarder, a method is provided having conditions for avoiding too high pressures in the retarder circuit during braking of the hydrodynamic retarder as well as during cancellation of braking of the hydrodynamic retarder. Furthermore, conditions are provided for lowering parasitic losses caused by the retarder arrangement.

Optionally, the method comprises: - cancelling braking of the hydrodynamic retarder, and - activating the pressure increasing arrangement after the step of cancelling braking of the hydrodynamic retarder.

Pressure peaks usually occur when a braking torque of a hydrodynamic retarder declines, such as upon cancellation of braking with the hydrodynamic retarder. Thus, by activating the pressure increasing arrangement after the step of cancelling braking of the hydrodynamic retarder, i.e. by waiting before activating the pressure increasing arrangement, too high pressures can be avoided after the step of cancelling braking of the hydrodynamic retarder. Furthermore, normally, upon cancellation of braking of a hydrodynamic retarder, the workspace is filled with vapor and when a certain speed is reached the workspace is filled with working fluid almost instantaneously and a pressure below ambient occurs for a short time period. However, since the method comprises the step of activating the pressure increasing arrangement after the step of cancelling braking of the hydrodynamic retarder, a method is provided capable of avoiding, or at least alleviating, the problem of pressures below the ambient pressure in the retarder circuit in conjunction with cancellations of braking of the hydrodynamic retarder, while avoiding too high pressures in the retarder circuit during braking and during declines in braking torque of the retarder.

Moreover, the activation of the pressure increasing arrangement after the step of cancelling braking of the hydrodynamic retarder may cool the workspace of the retarder as well as other portions of the retarder arrangement also when there is no rotation of the rotor of the retard er.

Optionally, the method comprises: - cancelling braking of the hydrodynamic retarder, and - activating the pressure increasing arrangement after the step of cancelling braking of the hydrodynamic retarder to circulate working media through a workspace of the retarder.

Thereby, a method is provided capable of cooling the workspace of the retarder, as well as other portions of the retarder arrangement and the working media, in an energy efficient manner. ln some prior art solutions, a rotor of the hydrodynamic retarder is operated, i.e. rotated, so as to cool the retarder after operation. However, by circulating working media through the workspace using the pressure increasing arrangement, the retarder and the workspace thereof can be cooled in a significantly more energy efficient manner as compared to such a solution since the retarder and the workspace thereof can be cooled also When there is no rotation of the rotor of the retarder _ Optionally, the method comprises the step of: - deactivating the pressure increasing arrangement after the step of activating the pressure increasing arrangement.

Thereby, a more energy efficient method is provided capable of reducing parasitic losses caused by the retarder arrangement.

Optionally, the retarder arrangement comprises a brake valve arranged downstream of an outlet of the hydrodynamic retarder, and wherein the step of initiating or cancelling braking of the hydrodynamic retarder comprises the step of: - controlling an opening state of the brake valve.

Thereby, an efficient control of the braking power of the retarder is provided.

According to a second aspect of the invention, the object is achieved by a computer program comprising instructions which, when the program is executed by a computer, cause thecomputer to carry out the method according to some embodiments of the present disclosure. Since the computer program comprises instructions which, when the program is executed by a computer, cause the computer to carry out the method according to some embodiments, a computer program is provided overcoming, or at least alleviating, at least some of the above- mentioned problems and drawbacks. As a result, the above-mentioned object is achieved.

According to a third aspect of the invention, the object is achieved by a computer-readable medium comprising instructions which, when executed by a computer, cause the computer to carry out the method according to some embodiments of the present disclosure. Since the computer-readable medium comprises instructions which, when executed by a computer, cause the computer to carry out the method according to some embodiments, a computer- readable medium is provided overcoming, or at least alleviating, at least some of the above- mentioned problems and drawbacks. As a result, the above-mentioned object is achieved.

According to a fourth aspect of the invention, the object is achieved by a control arrangement for a hydrodynamic retarder arrangement. The retarder arrangement comprises a hydrodynamic retarder configured to brake rotation of a shaft of a vehicle, an inlet duct connected to an inlet of the hydrodynamic retarder, and a pressure increasing arrangement configured to increase fluid pressure in the inlet duct by transferring working fluid to the inlet duct upon activation The control arrangement is configured to: - initiate or cancel braking of the hydrodynamic retarder, and - activate the pressure increasing arrangement in conjunction with an initiation or cancellation of braking of the hydrodynamic retarder.

Since the control arrangement is configured to activate the pressure increasing arrangement in conjunction with an initiation or cancellation of braking of the hydrodynamic retarder, a control arrangement is provided capable of avoiding, or at least alleviating, the problem of pressures below the ambient pressure in a retarder circuit of the retarder arrangement. This is because the fluid pressure in the inlet duct is increased in conjunction with the initiation or cancellation of braking of the hydrodynamic retarder as a result of the activation of the pressure increasing arrangement.

As a further result thereof, a control arrangement is provided capable of lowering strain on the retarder circuit and avoiding compression/collapsing of components thereof in a simple, robust, and efficient manner. Moreover, a control arrangement is provided having conditions for ensuring feed of working fluid to the hydrodynamic retarder in a simple, robust, and efficient manner.

Accordingly, a control arrangement is provided overcoming, or at least alleviating, at least some of the above-mentioned problems and drawbacks. As a result, the above-mentioned object is achieved. lt will be appreciated that the various embodiments described for the method are all combinable with the control arrangement as described herein. That is, the control arrangement according to the fourth aspect of the invention may be configured to perform any one of the method steps of the method according to the first aspect of the invention.

According to a fifth aspect of the invention, the object is achieved by a hydrodynamic retarder arrangement. The retarder arrangement comprises a hydrodynamic retarder configured to brake rotation of a shaft of a vehicle, an inlet duct connected to an inlet of the hydrodynamic retarder, a pressure increasing arrangement configured to increase fluid pressure in the inlet duct by transferring working fluid to the inlet duct upon activation, and a control arrangement. The control arrangement is configured to initiate or cancel braking of the hydrodynamic retarder, and activate the pressure increasing arrangement in conjunction with an initiation or cancellation of braking of the hydrodynamic retarder.

Since the control arrangement of the hydrodynamic retarder arrangement is configured to activate the pressure increasing arrangement in conjunction with an initiation or cancellation of braking of the hydrodynamic retarder, a hydrodynamic retarder arrangement is provided capable of avoiding, or at least alleviating, the problem of pressures below the ambient pressure in a retarder circuit of the hydrodynamic retarder arrangement. This is because the fluid pressure in the inlet duct is increased in conjunction with the initiation or cancellation of braking of the hydrodynamic retarder as a result of the activation of the pressure increasing arrangement.

As a further result thereof, a hydrodynamic retarder arrangement is provided capable of lowering strain on the retarder circuit and avoiding compression/collapsing of components thereof in a simple, robust, and efficient manner. Moreover, a hydrodynamic retarder arrangement is provided having conditions for ensuring feed of working fluid to the hydrodynamic retarder in a simple, robust, and efficient manner.

Accordingly, a hydrodynamic retarder arrangement is provided overcoming, or at least alleviating, at least some of the above-mentioned problems and drawbacks. As a result, the above-mentioned object is achieved. g jšhe pressure increasing arrangement comprises a pump configured to increase fluid pressure in the inlet duct by pumping working fluid to the inlet duct. Thereby, a simple, robust, and efficient pressure increasing arrangement is provided.

Optionally, the pump is an impe||er pump. Thereby, a simple, robust, and efficient pressure increasing arrangement is provided. Moreover, the impe||er pump does not block the fluid path over the impe||er pump and thereby provides more stable pressure levels in the inlet duct as compared to when using a positive displacement pump.

Optionally, the retarder arrangement comprises a retarder circuit, the inlet duct forming part of the retarder circuit, wherein the retarder circuit comprises an expansion tank and a static line connecting the expansion tank to the inlet duct, and wherein the pressure increasing arrangement is configured to increase fluid pressure in the inlet duct by transferring working fluid from the expansion tank to the inlet duct. Thereby, an already existing arrangement of the retarder circuit can be utilized as a source of working fluid for the pump of the pressure increasing arrangement. Thereby, a retarder arrangement is provided having conditions for utilizing available space in an efficient manner as Well as having conditions and characteristics suitable for being manufactured and assembled in a cost-efficient manner.

Optionally, the retarder circuit comprises a deaeration line connecting the expansion tank to a portion of the retarder circuit. Thereby, a retarder arrangement is provided in which the deaeration line can be utilized as a return conduit for working fluid transferred to the retarder circuit by the pressure increasing arrangement. As a further result, even more stable pressure levels can be provided in the retarder circuit. ln addition, improved conditions are provided for operating the retarder circuit in a retarder cooling mode in which working media is circulated through a workspace of the retarder. ln this manner, the retarder can be cooled in an energy efficient manner after a braking event of the hydrodynamic retarder.

Optionally, the retarder circuit comprises a heat exchanger configured to dissipate heat generated by the hydrodynamic retarder, and wherein the portion of the retarder circuit is a portion of the heat exchanger. Thereby, a retarder arrangement is provided having conditions for deairing the heat exchanger in an efficient manner while the deaeration line can be utilized as a return conduit for working fluid transferred to the retarder circuit by the pressure increasing arrangement. Moreover, conditions are provided for deairing the heat exchanger in an efficient manner by activating the pump of the pressure increasing arrangement for short periods of time also when the hydrodynamic retarder is not used for braking. lnaddition, improved conditions are provided for operating the retarder circuit in a retarder cooling mode in which working media is circulated through a workspace of the retarder. ln this manner, the retarder can be cooled in an energy efficient manner after a braking event of the hydrodynamic retarder.

Optionally, the deaeration line comprises a flow restrictor. Thereby, even more stable pressure levels can be provided in the retarder circuit and a suitable pressure increase and deaeration flow can be achieved with regards to the need and the used pump.

Optionally, the deaeration line comprises a valve. Thereby, a retarder arrangement is provided in which fluid pressure in the retarder circuit can be further regulated simply by regulating an opening state of the valve.

Optionally, the control arrangement is configured to control an opening state of the valve to further regulate the fluid pressure in the inlet duct. Thereby, a retarder arrangement is provided capable of obtaining even more stable pressure levels in the retarder circuit.

According to a sixth aspect of the invention, the object is achieved by a vehicle comprising a hydrodynamic retarder arrangement according to some embodiments of the present disclosure.

Since the vehicle comprises hydrodynamic retarder arrangement according to some embodiments, a vehicle is provided overcoming, or at least alleviating, at least some of the above-mentioned problems and drawbacks. As a result, the above-mentioned object is achieved.

Further features of, and advantages with, the present invention will become apparent when studying the appended claims and the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS Various aspects of the invention, including its particular features and advantages, will be readily understood from the example embodiments discussed in the following detailed description and the accompanying drawings, in which: Fig. 1 illustrates a hydrodynamic retarder arrangement according to some embodiments, Fig. 2 illustrates a graph of a portion of a braking event of the retarder arrangement illustrated in Fig. 1, Fig. 3 illustrates a method of controlling a hydrodynamic retarder arrangement according to some embodiments, Fig. 4 illustrates a continuation of the braking event illustrated in Fig. 2, Fig. 5 illustrates hydrodynamic retarder arrangement according to some further embodiments, Fig. 6 illustrates a vehicle according to some embodiments, and Fig. 7 illustrates computer-readable medium.

DETAILED DESCRIPTION Aspects of the present invention will now be described more fully. Like numbers refer to like elements throughout. Well-known functions or constructions will not necessarily be described in detail for brevity and/or clarity.

Fig. 1 illustrates a hydrodynamic retarder arrangement 10 according to some embodiments. The hydrodynamic retarder arrangement 10 is in some places herein referred to as “the retarder arrangement 10” for reasons of brevity and clarity. The retarder arrangement 10 comprises a hydrodynamic retarder 1. The hydrodynamic retarder 1 is configured to brake rotation of a shaft 6 of a vehicle, as is further explained herein. The hydrodynamic retarderis in some places herein referred to as “the retarder 1” for reasons of brevity and clarity.

The retarder 1 comprises a retarder housing 51 with a shovel space 52 and a shovel arrangement 12, 53 arranged in the shovel space 52. The shovel arrangement 12, 53 comprises a shovel-equipped stator 53 and a shovel-equipped rotor 12 together forming a workspace 55. The workspace 55 can also be referred to as a torus. The retarder 1 further comprises an inlet 4 and an outlet 33. Moreover, the retarder 1 comprises a retarder circuit 20 connected to the inlet 4 and to the outlet 33 of the retarder 1. ln more detail, the retarder circuit 20 comprises an inlet duct 2 connected to the inlet 4 of the retarder 1 and an outlet duct 56 connected to the outlet 33 of the retarder 1. The inlet duct 2 thus forms part of the retarder circuit 20. Working fluid is supplied from the inlet duct 2 to the workspace 55 via the inlet 4. The outlet 33 of the retarder 1 is arranged to evacuate working fluid from the workspace 55 to the outlet duct 56 of the retarder circuit 20. The working fluid may also be referred to as working media and may comprise oil or an aqueous mixture, such as coolant. According to the illustrated embodiments, the working fluid is an aqueous mixture, such as coolant. Therefore, the retarder circuit 20 may also be referred to as a “coolant circuit 20”.

The retarder circuit 20 further comprises a brake valve 31. The brake valve 31 is arranged downstream of the outlet 33 of the hydrodynamic retarder 1. The brake valve 31 is arrangedto restrict flow of working fluid through the outlet 33 so as to increase the braking torque of the retarder 1. The wording “outlet duct 56” and “outlet 33” as used herein, may be defined as an outlet channel 56, or a set of outlet channels 56, extending from the workspace 55 to the brake valve 31. The retarder circuit 20 comprises a heat exchanger 3 configured to dissipate heat generated by the hydrodynamic retarder 1. During braking, the working fluid flows through the retarder circuit 20, through the brake valve 31, through the heat exchanger 3, and back to the workspace 55 via the inlet duct According to the illustrated embodiments, the retarder 1 comprises a retarder transmission 60 comprising a set of gear wheels 60', 60”. Furthermore, the retarder 1 comprises a coupling device 14 and an actuator14' mechanically connected to the coupling device 14. The actuator 14' is moveable between an actuated position and an unactuated position to move the coupling device 14 between an engaged state and a disengaged state. The coupling device 14 is configured to, in the engaged state, connect the rotor 12 to the shaft 6 via the retarder transmission 60, and in the disengaged state, disconnect the rotor 12 from the shaft 6. The shaft 6 may be connected to one or more wheels of a vehicle such that the vehicle is braked, i.e. such that a retarding force is applied to the vehicle, when the retarderbrakes rotation of the shaft According to the illustrated embodiments, the retarder transmission 60 comprises a first gear wheel 60' and a second gear wheel 60”. The second gear wheel 60” is arranged on a rotor shaft 61 and the first gear wheel 60' is connectable to the shaft 6 by the coupling device 14. According to the illustrated embodiments, the coupling device 14 is configured to, in the engaged state, connect the first gear wheel 60' of the retarder transmission 60 to the shaft 6. Moreover, the coupling device 14 is configured to, in the disengaged state, disconnect the first gear wheel 60' of the retarder transmission 60 from the shaft 6. Thus, according to the illustrated embodiments, the first gear wheel 60' and a second gear wheel 60” of the retarder transmission 60 will not rotate, or will at least not be driven by the shaft 6, when the coupling device 14 is in the disengaged state. ln the engaged state, the first gear wheel 60' corotates with the shaft 6 so as to drive the rotor 12 via the retarder transmission 60. The coupling device 14 may comprise a dog clutch, a synchronizer, a clutch, or the like.

During operation of the retarder 1, i.e. during rotation of the rotor 12, the retarder 1 pumps working fluid from the inlet duct 2 to the outlet 33, via the workspace 55. The inlet duct 2 and the outlet 33 may each comprise a plurality of parallel channels arranged to supply and evacuate, respectively, working fluid to and from the workspace 55. As an example, the outlet 33, as referred to herein, may be integrated in the shovel-equipped stator 53 and maycomprise one outlet channel portion per shovel of the shovel-equipped stator 53. According to such embodiments, the outlet channel portions may each extend to a common ring- shaped volume arranged in the housing Upon initiation or cancellation of braking of the hydrodynamic retarder 1, the retarder circuit 20, and especially the inlet duct 2, is subjected to significant pressure variations. The pressure variations may cause pressures below a current ambient pressure which put strain on the hydraulic circuit 20 and can cause hoses to suck flat, i.e. collapse. lf one or more hoses is/are sucked flat, the flow through the hose/hoses is obstructed which limits the flow therethrough and consequently the feed of working fluid to the retarder 1. Moreover, repeated compression of hoses of the retarder circuit 20 may damage the hoses of the retarder circuit According to embodiments herein, the retarder arrangement 10 comprises a pressure increasing arrangement 8. The pressure increasing arrangement 8 is configured to increase fluid pressure in the inlet duct 2 by transferring working fluid to the inlet duct 2 upon activation. Moreover, the retarder arrangement 10 comprises a control arrangement 21. The control arrangement 21 is connected to the pressure increasing arrangement 8 and is configured to control operation thereof, i.e. activate and deactivate the pressure increasing arrangement 8. Moreover, according to the illustrated embodiments, the control arrangement 21 is connected to the actuator 14' and is configured to control operation thereof, i.e. is configured to control the actuator 14' between actuated position and an unactuated position in order to move the coupling device 14 between the engaged state and the disengaged state. Furthermore, the control arrangement 21 is connected to the brake valve 31 and is configured to control the opening state of the brake valve 31 so as to initiate and cancel braking of the hydrodynamic retarder 1 and to control a braking torque of the retarder Moreover, according to embodiments herein, the control arrangement 21 is configured to activate the pressure increasing arrangement 8 in conjunction with an initiation or cancellation of braking of the hydrodynamic retarder 1. ln this manner, pressures below the ambient pressure can be avoided in the retarder circuit 20 of the hydrodynamic retarder arrangement 10. This is because the fluid pressure in the inlet duct 2 is increased in conjunction with the initiation or cancellation of braking of the hydrodynamic retarder 1. As a further result thereof, strain on the retarder circuit 20 is lowered and compression/collapsing of components thereof can be avoided in a simple, robust, and efficient manner. Moreover, a hydrodynamic retarder arrangement 10 is provided having conditions for ensuring feed of working fluid to the hydrodynamic retarder 1 in a simple, robust, and efficient manner.According to the illustrated embodiments, the pressure increasing arrangement 8 comprises a pump 9 configured to increase fluid pressure in the in|et duct 2 by pumping working fluid to the in|et duct 2. The pump 9 may be an electrically driven pump 9. According to some embodiments, the pump 9 is a non-positive-displacement pump, such as a non-positive- displacement impe||er pump, for example a centrifugal pump. A non-positive-displacement pump does not block the fluid path over the pump and thereby provides more stable pressure levels in the in|et duct 2 as compared to when using a positive displacement pump because of the free flow path over the pump and because of the fact that a non-positive displacement impe||er pump, such as a centrifugal pump, is capable of producing a continuous flow of coolant as compared to a positive displacement pump, such as a piston pump. The retarder circuit 20 comprises an expansion tank 5 and a static line 7 connecting the expansion tank 5 to a portion 2' of the in|et duct 2. The portion 2' of the in|et duct 2 may also be referred to as a first portion 2' of the retarder circuit 2. The pressure increasing arrangement 8 is configured to increase fluid pressure in the in|et duct 2 by transferring working fluid from the expansion tank 5 to the in|et duct 2. Thus, an in|et 9' of the pump 9 is fluidly connected to the expansion tank 5 and an outlet 9" of the pump 9 is fluidly connected to the portion 2' of the retarder circuit 20. According to the illustrated embodiments, the expansion tank 5 comprises a pressure relief valve 25 configured to open to the surroundings when a pressure inside the expansion tank 5 rises above a threshold pressure. Thus, according to the illustrated embodiments, the retarder circuit 20 is a pressurized retarder circuit 20. Moreover, according to the illustrated embodiments, the pressure relief valve 25 is configured to open to the surroundings when a pressure inside the expansion tank 5 decreases below a second threshold pressure.

Moreover, according to the illustrated embodiments, the retarder circuit 20 comprises a deaeration line 17 connecting the expansion tank 5 to a portion 23 of the retarder circuit 20. The portion 23 of the retarder circuit 20 may also be referred to as a second portion 23 of the retarder circuit 20. According to the illustrated embodiments, the portion 23 of the retarder circuit 9 is a portion of the heat exchanger 3. ln more detail, according to the illustrated embodiments, the portion 23 of the retarder circuit 9 is a portion of an outlet tank of the heat exchanger 3, i.e. a portion downstream of cooling channels of the heat exchanger 3. ln this manner, the heat exchanger 3 can be deaired in an efficient manner while the deaeration line 17 can be utilized as a return conduit for working fluid transferred to the in|et duct 2 by the pressure increasing arrangement 8. Moreover, according to some embodiments, the control arrangement 21 may be provided with a deairing-mode in which the control arrangementoperates the pump 9 so as to cause a flow of working fluid through the heat exchanger 3 andthe deaeration line 17 also when the retarder 1 is inactive, i.e. also when the retarder 1 is not used for braking.

Furthermore, according to the illustrated embodiments, the deaeration line 17 comprises a flow restrictor 27. As indicated in Fig. 1, the flow restrictor 27 may comprise a valve 27. The control arrangement 21 may be configured to control an opening state of the valve 27 to further regulate the fluid pressure in the inlet duct 2. According to such embodiments, the control arrangement may control the valve 27 to a more closed state so as to increase fluid pressure in the inlet duct 2 and may control the valve 27 to a more open state so as to decrease fluid pressure in the inlet duct 2. Moreover, the control arrangement 21 may control the valve 27 to an open state when operating in the deairing-mode. According to further embodiments, the flow restrictor 27 may comprise another type of device or structure, such as a device or structure comprising a flow path with a reduced effective cross sectional area. ln addition, according to some embodiments of the present disclosure, the control arrangement 21 is provided with a retarder cooling mode in which the control arrangement 21 operates the pressure increasing arrangement 8 to circulate working media through the workspace 55 of the retarder 1. The control arrangement 21 may operate in the retarder cooling mode after a braking event of the retarder 1, i.e. after a cancellation of braking of the hydrodynamic retarder 1. The control arrangement 21 may be configured to operate in the retarder cooling mode following a braking event of the retarder 1 when the coupling device 14 is in the disengaged state and/or when a rotational speed of the rotor 12 is zero or close to zero. ln the retarder cooling mode, the control arrangement 21 may operate the pump 9 so as to cause a flow of working fluid through the workspace 55 of the retarder 1, through the heat exchanger 3, the deaeration line 17, the expansion tank 5 and back to the workspace 55 via the static line 7 and the inlet duct As indicated above, the connection 2' between the static line 7 the inlet duct 2' may be referred to as the first portion 2' of the retarder circuit 20 and the connection 23 between the deaeration line 17 the retarder circuit 20 may be referred to as the second portion 23 of the retarder circuit 20. According to the illustrated embodiments, the second portion 23 of the retarder circuit 20 is arranged upstream of the first portion 2' of the retarder circuit 20 relative to an intended flow direction through the retarder circuit 20. ln other words, according to the illustrated embodiments, the second portion 23 is arranged upstream of the first portion 2' relative to an intended flow direction through a circuit section 20” of the retarder circuit 20 between the first and second portions 2', 23 of the retarder circuit 20. As is indicated in Fig. 1, according to some embodiments of the present disclosure, the retarder circuitcomprises a one-way valve 28 arranged in the circuit section 20” of the retarder circuit 20 between the first and second portions 2', 23. According to the illustrated embodiments, the one-way valve 28 is configured to prevent flow of coolant from the first portion 2' towards the second portion 23 through the retarder circuit 20. That is, according to the illustrated embodiments, the one-way valve 28 is configured to prevent flow of coolant through the circuit section 20” in a direction from the first portion 2' towards the second portion 23. ln other words, according to these embodiments, the retarder circuit 20 comprises a one way valve 28 arranged at a location between the connection 2' between the static line 7 the inlet duct 2', i.e. the first portion 2' of the retarder circuit 20 referred to above, and the connection 23 between the deaeration line 17 and the retarder circuit 20, i.e. the second portion 23 of the retarder circuit 20 referred to above, to prevent a reverse flow of working media from the static line 7 to the deaeration line 17 during operation in the retarder cooling mode. According to further embodiments, the retarder circuit 20 may comprise another type of component, structure, and/or routing of ducts to prevent a reverse flow of working media from the static line 7 to the deaeration line 17 during operation in the retarder cooling mode. ln some prior art solutions, a rotor of the hydrodynamic retarder is operated, i.e. rotated, so as to cool the retarder after operation. However, by circulating coolant through the workspace 55 using the pressure increasing arrangement 8, the retarder 1 and the workspace 55 thereof can be cooled in a significantly more energy efficient manner as compared to such a solution. ln embodiments in which the deaeration line 17 comprises a valve 27, the control arrangement 21 may control the valve 27 to an open state when operating in the retarder cooling mode. Likewise, the control arrangement 21 may control the brake valve 31 to an open state when operating in the retarder cooling mode.

Fig. 2 illustrates a graph of a portion of a braking event of the retarder arrangement 1 illustrated in Fig. 1. Therefore, below, simultaneous reference is made to Fig. 1 and Fig. 2. The upper vertical axis in Fig. 2 denotes the rotational speed Rs of the rotor 12 of the retarder 1 and the braking torque Bt of the retarder 1. The lower vertical axis denotes fluid pressure P in the inlet duct 2 of the retarder circuit 20, wherein the full line indicates fluid pressure P according to embodiments of the present disclosure and the dotted line indicates fluid pressure P according to some prior art solutions. The horizontal axes denote time t.

Fig. 3 illustrates a method 100 of controlling a hydrodynamic retarder arrangement 10. The hydrodynamic retarder arrangement 10 may be a retarder arrangement 10 as described with reference to Fig. 1. Moreover, as indicated above, Fig. 2 illustrates a graph of a braking initiation event of the retarder arrangement 1 illustrated in Fig. 1, Therefore, below,simultaneous reference is made to Fig. 1 - Fig. 3. As indicated in Fig. 2 and Fig. 3, according to the illustrated embodiments, the method 100 comprises the step of: - starting 101 rotation of the rotor 12 of the hydrodynamic retarder The rotation of the rotor 12 is started at time t1 as indicated with the dashed vertical line in Fig. 2 provided with the reference sign t1. The rotation of the rotor 12 may be started by controlling the actuator 14' to the actuated position to move the coupling device 14 to the engaged state. ln other words, as indicated in Fig. 3, the step of starting 101 rotation of the rotor 12 may comprise the step of: - controlling 103 the coupling device 14 to the engaged state.

As seen in Fig. 2, the rotational speed of the rotor 12 starts to rise at time t1. Moreover, as seen in Fig. 2, an increase in fluid pressure P in the in|et duct 2 is obtained when the rotor 12 starts to rotate. This is due to the fact that steam is formed in the workspace 55 of the retarder 1 when the rotor 12 starts to rotate. The excess working fluid fed to the retarder circuit 20 via the outlet 33 causes the fluid pressure P to rise in the in|et duct 2 of the retarder circuit As indicated in Fig. 2 and Fig. 3, according to embodiments herein, the method 100 comprises the steps of: - initiating 120 braking of the hydrodynamic retarder 1, and - activating 110 the pressure increasing arrangement 8 in conjunction with the step of initiating 120 braking of the hydrodynamic retarder As can be seen in Fig. 2 and Fig. 3, according to the illustrated embodiments, the step of activating 110 the pressure increasing arrangement 8 is performed prior to the step of initiating 120 braking of the hydrodynamic retarder 1. As a result thereof, the pressure increasing arrangement 8 starts to increase the fluid pressure P in the in|et duct 2 prior to the initiation of braking of the hydrodynamic retarder 1. ln this manner, low fluid pressures P can be further avoided in the in|et duct 2, as is further explained herein.

Moreover, according to the illustrated embodiments, the step of starting 101 rotation of the rotor 12 of the hydrodynamic retarder 1 is performed prior to the step of activating 110 the pressure increasing arrangement As indicated in Fig. 2, the pressure increasing arrangement 8 is activated at time t2 indicated with the dashed vertical line in Fig. 2 provided with the reference sign t2. ln embodiments inwhich the pressure increasing arrangement 8 comprises a pump 9 configured to increase fluid pressure P in the inlet duct 2 by pumping working fluid to the inlet duct 2, the pressure increasing arrangement 8 can be activated by initiating operation of the pump Accordingly, as indicated in Fig. 3, the step of activating 110 the pressure increasing arrangement 8 may comprise the step of: - initiating 112 operation of the pump As seen in Fig. 2, an increase in fluid pressure P in the inlet duct 2 is provided after time t2 as a result of the activation of the pressure increasing arrangement 8. As indicated above, in Fig. 2, the full line indicates fluid pressure P according to embodiments of the present disclosure and the dotted line indicates fluid pressure P according to prior art solutions with no pressure increasing arrangement 8. As can be seen, as a result of the activation of the pressure increasing arrangement 8, a higher fluid pressure P is obtained in the inlet duct 2 after the activation of the pressure increasing arrangement 8 at time t2 than is the case according to the prior art solutions lacking the pressure increasing arrangement 8, i.e. the dotted line.

As indicated in Fig. 2, the braking of the hydrodynamic retarder 1 is initiated at time t3 indicated with the dashed vertical line in Fig. 2 provided with the reference sign t3. According to the illustrated embodiments, the braking of the hydrodynamic retarder 1 is initiated by controlling the brake valve 31 to a closed state. Working fluid is allowed to flow through the brake valve 31 also when the brake valve 31 is in the closed state but with an increased flow resistance. Therefore, the closed state of the brake valve 31, as referred to herein, may also be referred to as a partially closed state, a restricting state, or the like. As a result, the flow of working fluid through the retarder 1 is restricted and a braking torque Bt is applied to the shaft 6 as explained above. As can be seen in Fig. 2, significant drops in fluid pressure P are obtained after the initiation of braking at time t3, in the embodiments according to the present disclosure, i.e. the full line, and in prior art solutions lacking a pressure increasing arrangement 8, i.e. the dotted line. The significant drops in fluid pressure P may be caused by disturbances in a vapour/liquid balance in the workspace 55 of the retarder 1. However, as can be seen in Fig. 2, due to the activation of the pressure increasing arrangement 8 at time t2, the magnitude of the fluid pressure P is higher in the embodiments according to the present disclosure than according to the prior art solutions. ln the lower graph in Fig. 2, ”O” denotes an ambient pressure level. As seen in Fig. 2, according to the prior art solutions, the fluid pressure P in the inlet duct 2 decreases below the ambient pressure level 0. However, according to the present solution, due to the increased pressure level obtained by thepressure increasing arrangement 8, the fluid pressure P in the inlet duct 2 is kept above the ambient pressure 0 during the full braking procedure. ln this manner, strain on components of the retarder arrangement 10 is lowered, as is further explained herein.

As is indicated in Fig. 2 and Fig. 3, the method 100 comprises the step of: - deactivating 130 the pressure increasing arrangement 8 after the step of initiating 120 braking of the hydrodynamic retarder The pressure increasing arrangement 8 may be deactivated by cancelling, i.e. deactivating, operation of the pump 9. ln Fig. 2, the pressure increasing arrangement 8 is deactivated at time t4 indicated with the dashed vertical line in Fig. 2 provided with the reference sign t4. The step of deactivating 130 the pressure increasing arrangement 8 may be performed a predetermined short time after the step of initiating 120 braking of the hydrodynamic retarder 1, such as a few tenths of seconds to a few seconds. As an alternative, or in addition, the step of deactivating 130 the pressure increasing arrangement 8 may be performed when the braking torque Bt of the retarder 1 reaches a predetermined level, or a predetermined short time after the braking torque Bt of the retarder 1 has reached a predetermined level, such as a few tenths of seconds to a few seconds. Pressure peaks usually occur when a braking torque Bt of a hydrodynamic retarder 1 declines, such as upon cancellation of braking with the hydrodynamic retarder 1. The time in which the braking is cancelled usually cannot be foreseen, because it may be controlled by a driver of the vehicle or a propulsion/travel control system of the vehicle. Accordingly, by deactivating the pressure increasing arrangement 8 after the step of initiating 120 braking of the hydrodynamic retarder 1, a method 100 is provided having conditions for avoiding too high pressures in the retarder circuit during braking of the hydrodynamic retarder 1 as well as during cancellation of braking of the hydrodynamic retarder 1. As can be seen in Fig. 2, a slight decrease in fluid pressure P is obtained in the inlet duct 2 after the deactivation of the pressure increasing arrangement 8. Thus, too high pressures in the retarder circuit 20 can be avoided during braking of the hydrodynamic retarder 1 by the deactivation of the pressure increasing arrangement 8. Moreover, excessive pump work of the pressure increasing arrangement 8 can be avoided thus lowering parasitic losses.

Fig. 4 illustrates a continuation of the braking event illustrated in Fig. 2. Therefore, below, simultaneous reference is made to Fig. 1 - Fig. 4. The upper vertical axis in Fig. 2 denotes fluid pressure P in the inlet duct 2 of the retarder circuit 20, wherein the full line indicates fluid pressure P according to embodiments of the present disclosure and the dotted line indicatesfluid pressure P according to some prior art solutions. The lower vertical axis denotes the rotational speed Rs of the rotor 12 of the retarder 1. The horizontal axes denote time t.

As indicated in Fig. 3 and Fig. 4, according to embodiments herein, the method 100 comprises the step of: - cancelling 140 braking of the hydrodynamic retarder The braking of the hydrodynamic retarder 1 may be cancelled by controlling the brake valve 31 to an open state. ln Fig. 4, the braking of the hydrodynamic retarder 1 is cancelled at time t5 indicated with the dashed vertical line in Fig. 4 provided with the reference sign t Moreover, as indicated in Fig. 3 and Fig. 4, according to embodiments herein, the method 100 comprises the step of: - activating 150 the pressure increasing arrangement 8 in conjunction with the step of cancelling 140 braking of the hydrodynamic retarder ln more detail, according to the illustrated embodiments, the step of activating 150 the pressure increasing arrangement 8 is performed after the step of cancelling 140 braking of the hydrodynamic retarder 1. Thereby, too high pressures can be avoided after the cancelling 140 braking of the hydrodynamic retarder 1. Pressure peaks usually occur when a braking torque Bt of a hydrodynamic retarder 1 declines, such as upon cancellation of braking with the hydrodynamic retarder 1, which also can be seen in Fig. 4. Thus, by activating 150 the pressure increasing arrangement 8 after the step of cancelling 140 braking of the hydrodynamic retarder 1, i.e. by waiting before activating the pressure increasing arrangement 8, too high pressures can be avoided after the cancelling 140 braking of the hydrodynamic retarder 1. The step of activating 150 the pressure increasing arrangement 8 may be performed a predetermined time after the step of cancelling 140 braking of the hydrodynamic retarder 1, such as a number of tenths of seconds or a few seconds. As an alternative, or in addition, the step of activating 150 the pressure increasing arrangement 8 may be performed when the braking torque Bt of the retarder 1 declines below a predetermined braking torque Bt, or a predetermined time after the braking torque Bt of the retarder 1 has declined below a predetermined braking torque Bt, such as a few tenths of seconds or a few seconds. As a further alternative, or in addition, the step of activating 150 the pressure increasing arrangement 8 may be performed when the rotational speed Rs of the rotor 12 of the retarder 1 reaches a predetermined rotational speed Rs. As a still further alternative, or in addition, the step of activating 150 the pressure increasing arrangementmay be performed in conjunction with a step of controlling the coupling device 14 to a disengaged state, such as a predetermined time after such a step. ln Fig. 4, the pressure increasing arrangement 8 is activated at time t6 indicated with the dashed vertical line in Fig. 4 provided with the reference sign t6. As can be seen, an increase in fluid pressure P is obtained in the in|et duct 2 as a result of the activation of the pressure increasing arrangement 8 at time t6. Normally, upon cancellation of braking of a hydrodynamic retarder 1, the Workspace 55 of the retarder 1 is filled with vapor and when a certain speed is reached the Workspace 55 is filled with working fluid almost instantaneously and a pressure below a current ambient pressure 0 occurs for a short time period. However, since the method 100 comprises the step of activating 150 the pressure increasing arrangement 8 after the step of cancelling 140 braking of the hydrodynamic retarder 1, a method 100 is provided capable of avoiding, or at least alleviating, the problem of pressures below the ambient pressure 0 in the retarder circuit 20 in conjunction with cancellations of braking of the hydrodynamic retarder 1, while avoiding too high pressures in the retarder circuit 20 during braking and during declines in braking torque of the retarder 1. As seen in Fig. 4, due to the increased pressure level obtained by the pressure increasing arrangement 8, the fluid pressure P in the in|et duct 2 is kept above the ambient pressure 0 during the full braking procedure. ln this manner, strain on components of the retarder arrangement 10 is lowered, as is further explained herein Furthermore, as indicated in Fig. 3 and Fig. 4, according to embodiments herein, the method 100 comprises the step of: - cancelling 140 braking of the hydrodynamic retarder 1, and - activating 155 the pressure increasing arrangement 8 after the step of cancelling 140 braking of the hydrodynamic retarder 1 to circulate working media through a Workspace 55 of the hydrodynamic retarder ln Fig. 4 the step 155 coincides with the step 150. However, the step 155 may be performed at another time than step 150, such as after step 150. According to some embodiments, the step 155 is performed when the rotational speed Rs of the rotor 12 of the retarder 1 reaches a predetermined rotational speed Rs. The predetermined rotational speed Rs may be zero or close to zero. Moreover, according to some embodiments, the step 155 is performed after a step of controlling the coupling device 14 to a disengaged state.

The step of activating 155 the pressure increasing arrangement 8 after the step of cancelling 140 braking of the hydrodynamic retarder 1 to circulate working media through a Workspace55 of the hydrodynamic retarder 1 may also be referred to as an activation of a retarder cooling mode. According to these embodiments, the retarder circuit 20 may comprise a one way valve 28 to ensure an efficient circulation of working media through the workspace 55 during operation of the pressure increasing arrangement 8 in the retarder cooling mode, as is further explained herein.

Moreover, as indicated in Fig. 3 and Fig. 4, according to embodiments herein, the method 100 comprises the step of: - deactivating 160 the pressure increasing arrangement 8 after the step of activating 150, 155 the pressure increasing arrangement ln Fig. 4, the pressure increasing arrangement 8 is deactivated at time t7 indicated with the dashed vertical line in Fig. 4 provided with the reference sign t7. As seen in Fig. 4, a slight decrease in fluid pressure P is obtained as a result of the deactivation of the pressure increasing arrangement 8 after time t7. Due to the deactivation of the pressure increasing arrangement 8, excessive pump work of the pressure increasing arrangement 8 can be avoided.

As understood from the above described, and as is indicated in Fig. 3, the step of initiating 120 or cancelling 140 braking of the hydrodynamic retarder 1 may comprise the step of: - controlling 122, 142 an opening state of the brake valve That is, the step of initiating 120 braking of the hydrodynamic retarder 1 may comprise the step of controlling 122 the opening state of the brake valve 31 to a closed, i.e. restricted, state. Likewise, the step of cancelling 140 braking of the hydrodynamic retarder 1 may comprise the step of controlling 142 the opening state of the brake valve 31 to an open, i.e. non-restricting, state. lt will be appreciated that the various embodiments described for the method 100 are all combinable with the control arrangement 21 as described herein. That is, the control arrangement 21 may be configured to perform any one of the method steps 101, 103, 110, 112, 120, 122, 130, 140,142, 150, 152, 155 and 160 of the method The length between the times t1 - t6, i.e. the time between two successive method steps 101,103,110,112,120,122,130,140,142,150,152,155 and 160 of the method 100 may range from a few tenths of seconds to a number of seconds. As an example, the timebetween two successive method steps 101, 103, 110, 112, 120, 122, 130, 140, 142, 150, 152, 155 and 160 of the method 100 may be within the range of 0.2 seconds to 3 seconds.

Fig. 5 illustrates hydrodynamic retarder arrangement 10 according to some further embodiments. The hydrodynamic retarder arrangement 10 comprises the same features, functions, and advantages as the hydrodynamic retarder arrangement 10 explained with reference to Fig. 1 - Fig. 4, with some exceptions explained below. According to the embodiments i||ustrated in Fig. 5, the hydrodynamic retarder arrangement 10 comprises a retarder circuit 20 forming part of a coo|ant circuit 20', wherein the coo|ant circuit 20' is configured to cool a vehicle component 11. Purely as an example, the vehicle component 11 may be a combustion engine, an electric machine, a propulsion battery, power electronics, a fuel cell, or the like. The coo|ant circuit 20' comprises coo|ant channels, the heat exchanger 3, a bypass line 22 bypassing the heat exchanger 3 and a valve 24 configured to direct coo|ant to the bypass line 22 and/or to the heat exchanger 3. The valve 24 may be a thermostatic valve configured to direct coo|ant to the bypass line 22 and/or to the heat exchanger based on the temperature of coo|ant pumped to the valve 24. As an alternative, or in addition, the valve 24 may be electronically controlled, for example by the control arrangement 21. The coo|ant circuit 20' further comprises a circulation pump 15 configured to circulate coo|ant through the coo|ant circuit 20' so as to cool the vehicle component As seen in Fig. 5, the inlet duct 2 of the hydrodynamic retarder arrangement 10 is connected to the coo|ant circuit 20' at a location downstream of the heat exchanger 3 and the outlet duct 56 is connected to the coo|ant circuit 20' at a location upstream of the heat exchanger 3. Thus, according to the embodiments i||ustrated in Fig 5, the heat exchanger 3 is configured to dissipate heat generated by the vehicle component 11 as well as heat generated by the retarder 1 during operation thereof. Moreover, according to the embodiments i||ustrated in Fig 5, the working fluid of the retarder 1 is coo|ant, i.e. an aqueous mixture.

According to some embodiments of the present disclosure, the inlet duct 2 of the hydrodynamic retarder arrangement 10 may be connected to the coo|ant circuit 20' at a location downstream of the vehicle component 11. According to such embodiments, the pressure increasing arrangement 8 may thus increase fluid pressure in the inlet duct 2 by transferring working fluid to the inlet duct 2 via the circulation pump 15 and the vehicle component 11. The circulation pump 15 may comprise a non-positive displacement impeller pump, such as centrifugal pump. According to such embodiments, the outlet duct 56 may be connected to the coo|ant circuit 20' at a location downstream of the connection of the inlet duct 2 to the coo|ant circuit 20' as in the embodiments i||ustrated in Fig. 5. Moreover,according to some embodiments of the present disclosure, the retarder circuit 20 may be arranged in series with the coolant circuit 20”.

The hydrodynamic retarder arrangement 10 according to the embodiments illustrated in Fig. 5 comprises a control arrangement 21 according to the embodiments explained with reference to Fig. 1 - Fig. 4. Accordingly, the control arrangement 21 may be configured to perform any one of the method steps 101, 103, 110, 112, 120, 122, 130, 140, 142, 150, 152, 155 and 160 of the method 100 on the hydrodynamic retarder arrangement 10 according to the embodiments illustrated in Fig.

Fig. 6 illustrates a vehicle 30 according to some embodiments. The vehicle 30 comprises a propulsion unit 11. The propulsion unit 11 may be a combustion engine or an electric propulsion unit. The vehicle 30 further comprises a hydrodynamic retarder arrangement 10 according to the embodiments illustrated in Fig. 5. According to further embodiments, the vehicle 30 may comprise a hydrodynamic retarder arrangement 10 according to the embodiments illustrated in Fig. 1. The hydrodynamic retarder arrangement 10 is configured to provide a retardation force onto the vehicle 30 via wheels 39 of the vehicle According to the illustrated embodiments, the vehicle 30 is a truck, i.e. a heavy vehicle. However, according to further embodiments, the vehicle 30, as referred to herein, may be another type of manned or unmanned vehicle for land based propulsion such as a lorry, a bus, a construction vehicle, a tractor, a car, or the like.

Fig. 7 illustrates computer-readable medium 200 comprising instructions which, when executed by a computer, cause the computer to carry out the method 100 according to some embodiments illustrated in Fig.

According to some embodiments, the computer-readable medium 200 comprises a computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method 100 according to some embodiments.

One skilled in the art will appreciate that the method 100 of controlling a hydrodynamic retarder arrangement 10 may be implemented by programmed instructions. These programmed instructions are typically constituted by a computer program, which, when it is executed in the control arrangement 21, ensures that the control arrangement 21 carries out the desired control, such as the method steps 101, 103, 110, 112, 120, 122, 130, 140, 142, 150, 152, 155 and 160 described herein. The computer program is usually part of a computerprogram product 200 which comprises a suitable digital storage medium on which the computer program is stored.

The control arrangement 21 may comprise a calculation unit which may take the form of substantially any suitable type of processor circuit or microcomputer, e.g. a circuit for digital signal processing (digital signal processor, DSP), a Central Processing Unit (CPU), a processing unit, a processing circuit, a processor, an Application Specific Integrated Circuit (ASIC), a microprocessor, or other processing logic that may interpret and execute instructions. The herein utilised expression “calculation unit” may represent a processing circuitry comprising a plurality of processing circuits, such as, e.g., any, some or all of the ones mentioned above.

The control arrangement 21 may further comprise a memory unit, wherein the calculation unit may be connected to the memory unit, which may provide the calculation unit with, for example, stored program code and/or stored data which the calculation unit may need to enable it to do calculations. The calculation unit may also be adapted to store partial or final results of calculations in the memory unit. The memory unit may comprise a physical device utilised to store data or programs, i.e., sequences of instructions, on a temporary or permanent basis. According to some embodiments, the memory unit may comprise integrated circuits comprising silicon-based transistors. The memory unit may comprise e.g. a memory card, a flash memory, a USB memory, a hard disc, or another similar volatile or non-volatile storage unit for storing data such as e.g. ROM (Read-Only Memory), PROM (Programmable Read-Only Memory), EPROM (Erasable PROM), EEPROM (Electrically Erasable PROM), etc. in different embodiments.

The control arrangement 21 is connected to components of the hydrodynamic retarder arrangement 10, and/or to components of a vehicle 30 comprising the hydrodynamic retarder arrangement 10, for receiving and/or sending input and output signals. These input and output signals may comprise waveforms, pulses, or other attributes which the input signal receiving devices can detect as information and which can be converted to signals processable by the control arrangement 21. These signals may then be supplied to the calculation unit. One or more output signal sending devices may be arranged to convert calculation results from the calculation unit to output signals for conveying to other parts of the vehicle's control system and/or the component or components for which the signals are intended. Each of the connections to the respective components of the vehicle 30 for receiving and sending input and output signals may take the form of one or more from among a cable, a data bus, e.g. a CAN (controller area network) bus, a MOST (media orientated systems transport) bus or some other bus configuration, or a wireless connection. ln the embodiments illustrated, the hydrodynamic retarder arrangement 10 comprises a control arrangement 21 but might alternatively be implemented wholly or partly in two or more control arrangements or two or more control units.

Control systems in modern vehicles generally comprise a communication bus system consisting of one or more communication buses for connecting a number of electronic control units (ECUs), or controllers, to various components on board the vehicle. Such a control system may comprise a large number of control units and taking care of a specific function may be shared between two or more of them. Vehicles of the type here concerned are therefore often provided with significantly more control arrangements than depicted in Fig.and Fig. 5, as one skilled in the art will surely appreciate.

The computer program product 200 may be provided for instance in the form of a data carrier carrying computer program code for performing at least some of the method steps 101, 103, 110, 112, 120, 122, 130, 140, 142, 150, 152, 155 and 160 according to some embodiments when being loaded into one or more calculation units of the control arrangement 21. The data carrier may be, e.g. a CD ROM disc, as is illustrated in Fig. 7, or a ROM (read-only memory), a PROM (programable read-only memory), an EPROM (erasable PROM), a flash memory, an EEPROM (electrically erasable PROM), a hard disc, a memory stick, an optical storage device, a magnetic storage device or any other appropriate medium such as a disk or tape that may hold machine readable data in a non-transitory manner. The computer program product may furthermore be provided as computer program code on a server and may be downloaded to the control arrangement 21 remotely, e.g., over an lnternet or an intranet connection, or via other wired or wireless communication systems. lt is to be understood that the foregoing is illustrative of various example embodiments and that the invention is defined only by the appended claims. A person skilled in the art will realize that the example embodiments may be modified, and that different features of the example embodiments may be combined to create embodiments other than those described herein, without departing from the scope of the present invention, as defined by the appended claims.

As used herein, the term "comprising" or "comprises" is open-ended, and includes one or more stated features, elements, steps, components, or functions but does not preclude thepresence or addition of one or more other features, elements, steps, components, functions, or groups thereof.

Claims (21)

1. A method (100) of controlling a hydrodynamic retarder arrangement (1 O), wherein the retarder arrangement (10) comprises: - a hydrodynamic retarder (1) configured to brake rotation of a shaft (6) of a vehicle (30), - an inlet duct (2) connected to an inlet (4) of the hydrodynamic retarder (1), and - a pressure increasing arrangement (8) configured to increase fluid pressure (P) in the inlet duct (2) by transferring working fluid to the inlet duct (2) upon activation, wherein the pressure increasing arrangement (8) comprises a pump (9) configured to increase fluid pressure (P) in the inlet duct (2) by pumping working fluid to the inlet duct (2), and wherein the method (100) comprises the steps of: - initiating (120) or cancelling (140) braking of the hydrodynamic retarder (1), and - activating (110, 150) the pressure increasing arrangement (8) in conjunction with the step of initiating (120) or cancelling (140) braking of the hydrodynamic retarder (1 ), and wherein the step of activating (110, 150) the pressure increasing arrangement (8) comprises the step of: - initiating (112, 152) operation of the pump (9). The method (100) according to c|aim 1, wherein the method (100) comprises: - initiating (120) braking of the hydrodynamic retarder (1 ), and wherein the step of activating (110) the pressure increasing arrangement (8) is performed prior to the step of initiating (120) braking of the hydrodynamic retarder (1 ). The method (100) according to c|aim 2, wherein the method (100) comprises the step of: - starting (101) rotation of a rotor (12) of the hydrodynamic retarder (1) prior to the step of activating (110) the pressure increasing arrangement (8). The method (100) according to c|aim 3, wherein the hydrodynamic retarder (1) comprises a coupling device (14) controliable betvveen an engaged state, in which the coupling device (14) connects the rotor (12) to the shaft (6), and a disengaged state, in which the coupling device (14) disconnects the rotor (12) from the shaft (6), and wherein the step of starting (101) rotation of the rotor (12) comprises the step of: - controlling (103) the coupling device (14) to the engaged state. The method (100) according to any one of the claims 2 - 4, wherein the method (100) comprises the step of: - deactivating (130) the pressure increasing arrangement (8) after the step of initiating (120) braking of the hydrodynamic retarder (1 ). The method (100) according to any one of the preceding claims, wherein the method (100) comprises: - cancelling (140) braking of the hydrodynamic retarder (1 ), and - activating (150) the pressure increasing arrangement (8) after the step of cancelling (140) braking of the hydrodynamic retarder (1 ). The method (100) according to any one of the preceding claims, wherein the method (100) comprises: - cancelling (140) braking of the hydrodynamic retarder (1), and - activating (155) the pressure increasing arrangement (8) after the step of cancelling (140) braking of the hydrodynamic retarder (1) to circulate working media through a workspace (55) of the hydrodynamic retarder (1 ). The method (100) according to claim 6 or 7, wherein the method (100) comprises the step of: - deactivating (160) the pressure increasing arrangement (8) after the step of activating (150, 155) the pressure increasing arrangement (8). The method (100) according to any one of the preceding claims, wherein the retarder arrangement (10) comprises a brake valve (31) arranged downstream of an out|et (33) of the hydrodynamic retarder (1), and wherein the step of initiating (120) or cancelling (140) braking of the hydrodynamic retarder (1) comprises the step of: - contro||ing (122, 142) an opening state of the brake valve (31). A computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method (100) according to any one of the claims 1 - A computer-readable medium (200) comprising instructions which, when executed by a computer, cause the computer to carry out the method (100) according to any one of the claims 1 - A control arrangement (21) for a hydrodynamic retarder arrangement (10), wherein the ' *g_\=_§gf;___retarder arrangement (10) comprises: - a hydrodynamic retarder (1) configured to brake rotation of a shaft (6) of a vehicle (30), - an inlet duct (2) connected to an inlet (4) of the hydrodynamic retarder (1), and - a pressure increasing arrangement (8) configured to increase fluid pressure (P) in the inlet duct (2) by transferring working fluid to the inlet duct (2) upon activation, wherein the pressure increasing arrangement (8) comprises a pump (9) configured to increase fluid pressure (P) in the inlet duct (2) by pumping working fluid to the inlet duct (2), and wherein the control arrangement (21) is configured to: - initiate or cancel braking of the hydrodynamic retarder (1), and - activate the pressure increasing arrangement (8) in conjunction with an initiation or cancellation of braking of the hydrodynamic retarder (1), and wherein the control arrangement is configured to activate the pressure increasing arrangement (8) by initiating operation of the pump (9). A hydrodynamic retarder arrangement (10), wherein the arrangement (10) comprises: - a hydrodynamic retarder (1) configured to brake rotation of a shaft (6) of a vehicle (30), - an inlet duct (2) connected to an inlet (4) of the hydrodynamic retarder (1), - a pressure increasing arrangement (8) configured to increase fluid pressure (P) in the inlet duct (2) by transferring working fluid to the inlet duct (2) upon activation, wherein the pressure increasing arrangement (8) comprises a pump (9) configured to increase fluid pressure (P) in the inlet duct (2) by pumping working fluid to the inlet duct (2), and - a control arrangement (21) according to claim Thfls: (9) is an impeller pump. retarder arrangement (10) according to claim 13, wherein the pump Th ej 14, wherein the retarder arrangement (10) comprises a retarder circuit (20), the inlet duct retarder arrangement (10) according to any one of the claims 13 - (2) forming part of the retarder circuit (20), wherein the retarder circuit (20) comprises an expansion tank (5) and a static line (7) connecting the expansion tank (5) to the inlet duct (2), and wherein the pressure increasing arrangement (8) is configured to increase fluid pressure (P) in the inlet duct (2) by transferring working fluid from the expansion tank (5) to the inlet duct (2). ¿;¿,_retarder arrangement (10) according to claim 15, wherein the retarder circuit (20) comprises a deaeration line (17) connecting the expansion tank (5) to a portion (23) of the retarder circuit (20). The circuit (20) comprises a heat exchanger (3) configured to dissipate heat generated by the ggwretarder arrangement (10) according to claim 16, wherein the retarder hydrodynamic retarder (1), and wherein the portion (23) of the retarder circuit (9) is a portion of the heat exchanger (3). The “\\“ jgjjggretarder arrangement (10) according to claim 16 or 17, wherein the deaeration line (17) comprises a flow restrictor (27). i, i... The < gggretarder arrangement (10) according to any one of the claims 16 - 18, wherein the deaeration line (17) comprises a valve (27). The _ arrangement (21) is configured to control an opening state of the valve (27) to further retarder arrangement (10) according to claim 19, wherein the control regulate the fluid pressure (P) in the inlet duct (2). A vehicle (30) comprising a hydrodynamic retarder arrangement (10) according to any one of the claims 15 - 20.