SE2250074A1

SE2250074A1 - A retarder, a transmission, a power train and a vehicle

Info

Publication number: SE2250074A1
Application number: SE2250074A
Authority: SE
Inventors: Kenneth Hammarstedt
Original assignee: Scania Cv Ab
Priority date: 2022-01-28
Filing date: 2022-01-28
Publication date: 2023-07-29
Also published as: SE545857C2; DE102022133653A1; DE102022133653B4

Abstract

A retarder (1) is disclosed. The retarder (1) comprises a reservoir (3) for a working liquid intended to be used for activation of the retarder (1), a working space (5) connected with the reservoir (3) to enable the working fluid to flow between the reservoir (3) and the working space (5) and a compressed air conduct (7) connected to the retarder (5) and arranged to be connected to a compressed air source (9) for compressed air to be provided to the retarder (1) via the compressed air conduct (7) to achieve a flow of at least a portion of the working liquid from the reservoir (3) to the working space (5) by an action of the compressed air within the retarder (1) during activation of the retarder (1). The retarder (1) comprises an air drain conduct (11) connected to the working space (5) for air to flow out from the working space (5) and into the working space (5). The compressed air conduct (7) is connected to the air drain conduct (11) to enable compressed air to enter the air drain conduct (11) during deactivation of the retarder (1). A transmission (21), a power train (27) and a vehicle (25) are also disclosed.

Description

A retarder, a transmission, a power train and a vehicle TECHNICAL FIELD The present disclosure relates to a retarder for a vehicle. Particularly, the present disclosure relates to a hydrodynamic retarder configured to brake a shaft of a transmission in a vehicle.

BACKGROUND Fletarders are devices used in vehicles to augment or replace some of the functions of primary braking arrangements, such as friction-based brakes. One common type of retarders is hydrodynamic retarders. Such retarders utilize the viscous drag forces of a working liquid, which usually is oil, in a work space between a rotor and a stator of the retarder. The rotor is usually connected to a shaft of a transmission of a vehicle, such as a shaft of the gearbox of the vehicle, via a retarder transmission.

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

One problem with some retarders used today is that the working liquid can become contaminated by, for example dust or water, especially when operating in dusty conditions, which is common for trucks. Contaminated working fluid can contribute to wear of the parts of a retarder and has poorer working characteristics comparing to a pure working fluid.

SUMMARY lt is an object of the present disclosure to overcome, or at least alleviate, at least some of the above-mentioned drawbacks and problems. The object is achieved by the subject matter defined according to the independed claims.

According to a first aspect of the disclosure, the object is achieved by a retarder configured to be activated to brake a shaft of a transmission of a vehicle and configured to be deactivated after being activated. Thus, the retarder is arranged to operate in an activation mode for breaking of the shaft and in a deactivation mode when the retarder is deactivated and thereby has no braking effect on the shaft of the transmission.

The retarder comprises: - a reservoir for a working liquid intended to be used for activation of the retarder, 2 - a working space connected with the reservoir to enable the working fluid to flow between the reservoir and the working space and - a compressed air conduct connected to the retarder and arranged to be connected to a compressed air source for compressed air to be provided to the retarder via the compressed air conduct to achieve a flow of at least a portion of the working liquid from the reservoir to the working space by an action of the compressed air within the retarder during activation of the retarder.

The working space is connected with the reservoir, this preferably by a working fluid pipe arranged partly in the reservoir. Thus, the working fluid can flow from the reservoir to the working space during activation of the retarder and to flow back from the working space to the reservoir during deactivation of the retarder.

The compressed air provided to the retarder via the compressed air conduct causes pressure forces acting within the retarder and thereby acting on the working fluid in the reservoir. The retarder may be configured such that the pressure forces created by the compressed air can act directly or indirectly on the working fluid in the reservoir which results in a flow of at least a portion of the working fluid flowing from the reservoir to the working space. This happens during activation of the retarder when the working space is filled in with the working fluid to activate the retarder for breaking. Activation and deactivation of a retarder, i.e. activation and deactivation of parts of the retarder arranged in the working space is a common knowledge and is therefore not described in details herein.

Further, the retarder comprises an air drain conduct connected to the working space for air to flow out from the working space and to flow into the working space. Further, the compressed air conduct is connected to the air drain conduct to enable compressed air to enter the air drain conduct during deactivation of the retarder.

Because the working space of the retarder is connected to the air drain conduct for air to flow out from the working space and into the working space, air can be drained out from the working space during activation of the retarder when working fluid is provided to the working space and thereby filling in the working space. Further, the working space can be filled in with air flowing into the working space via the air drain conduct during deactivation of the retarder when working fluid is removed from the working space. One advantage of draining out air from the working space during activation of the retarder is that a mixing of working fluid with air can be avoided during filling in the working space with the working fluid because the increased pressure in the working space will press out air from the working space. During 3 deactivation of the retarder, the working fluid flows back from the working space to the reservoir. One advantage of enabling air to flow into the working space via the air drain conduct is that the reservoir may be filled in with air during deactivation of the retarder. Thus, the working fluid can be provided to the working space and can be removed from the working space in a smooth manner because negative effect of overpressure or under pressure in the working space can be reduced by the fact that air can flow from the working space and into the working space via the air drain conduct.

Further, since the compressed air conduct is connected to the air drain conduct to enable compressed air to enter the air drain conduct during deactivation of the retarder, clean and compressed air can be provided to the working space during deactivation of the retarder. lf there were no connection between the compressed air conduct and the air drain conduct, ambient air would be sucked into the working space during deactivation of the retarder. Ambient air may contain dust or moisture which may contaminate the working fluid causing negative effects on the working fluid, such as worse working characteristics comparing to pure working fluid. The air drain conduct is preferably provided with a one-way valve to prevent ambient air to enter the air drain conduct. Consequently, one advantage of the present disclosure is that clean compressed air can be provided to the working space during deactivation of the retarder instead of ambient air. Thereby risks for contamination of the working fluid with all the negative effects of that can be reduced. Compressed air that is intended to enter the air drain conduct during deactivation of the retarder may be compressed air used during activation of the retarder or may be a fresh compressed air provided directly from the compressed air source or a combination thereof. Accordingly, an improved retarder is provided having conditions to operate in an improved manner and having conditions for an increased service life. As a result, the above-mentioned object is achieved.

Optionally, the retarder comprises an accumulator connected to the reservoir and connected to the compressed air conduct. The accumulator comprises a movable member, preferably a piston member, arranged inside the accumulator and arranged to be displaced in a first direction by the action of compressed air provided via the compressed air conduct to achieve the flow of at least the portion of the working liquid from the reservoir to the working space during activation of the retarder. Further, the movable member is arranged to be displaced in a second direction opposite to the first direction to remove at least a portion of the compressed air from the accumulator into the compressed air conduct during deactivation of the retarder, this preferably by means of a spring. The movable member arranged inside the accumulator divides the inside volume the accumulator into two sections, namely a 4 compressed air section connected to the compressed air conduct and a working fluid section connected to the reservoir. During operation of the retarder the working fluid section will be filled in with the working fluid. Thus, the movable element is intended to have contact with the working fluid in the working fluid section. Compressed air provided to the accumulator via the compressed air conduct creates pressure within the accumulator acting on the movable member. Compressed air acting on the movable member causes a displacement of the movable member. This displacement causes the working fluid to be pressed out from the accumulator towards the reservoir connected to the accumulator. Thereby, the flow of at least the portion of the working fluid from the reservoir to the working space of the retarder during activation of the retarder is achieved. One advantage of the accumulator with the movable member is that the retarder can be activated quickly and with reduced risks for a contact between the compressed air and the working fluid. Thereby, a yet improved retarder is provided.

Optionally, the retarder comprises a valve arranged in the compressed air conduct and arranged to lead compressed air to the retarder to achieve the flow of at least the portion of the working liquid from the reservoir to the working space during activation of the retarder, and to lead compressed air to the air drain conduct during deactivation of the retarder. Thus, flow of compressed air can be controlled in an improved manner by means of the valve during operation of the retarder. Consequently, a yet improved retarder is provided.

Optionally, the retarder comprises an additional compressed air conduct connected to the compressed air conduct and arranged to lead a portion of compressed air out from the compressed air conduct during deactivation of the retarder. Thus, in case of an overflow of compressed air into the air drain conduct, that may cause overpressure in the working space during deactivation of the retarder, a portion of compressed air can be led out from the compressed air conduct. Thereby, pressure in the retarder can be controlled to achieve balanced conditions contributing to improved operation of the retarder.

Optionally, the additional compressed air conduct is arranged downstream the valve in relation to a compressed air direction of compressed air during deactivation of the retarder. Thus, during deactivation of the retarder, compressed air used during activation of the retarder can be guided into the air drain conduct prior to delivering fresh compressed air from the compressed air source. Consequently, some costs saving can be achieved.

Optionally, the working fluid is oil. Oil is a well-functioning working fluid for retarders.

Optionally, the compressed air source is a Compressor of an air system of the vehicle. Thus, the retarder can be connected to the compressor of an air system of the vehicle and can operate using compressed air from the compressor. Thereby, no additional compressed air source configured just for the retarder is needed.

Optionally, the air system is an air system of a power source of the vehicle. Thus, the air system can, for example, be air system of a combustion engine or a cooling system of a battery driven engine.

According to a second aspect of the disclosure, the object is achieved by a transmission configured to transmit power between a power source of a vehicle and wheels of the vehicle, wherein the transmission comprises a retarder according to any one of the embodiments herein. Because the transmission comprises an improved retarder an improved transmission is provided.

According to a third aspect of the disclosure, the object is achieved by a power train for a vehicle. The power train comprises a power source and a transmission according to any one of the embodiments herein. Because the power train comprises an improved transmission an improved power train is provided.

According to a fourth aspect of the disclosure, the object is achieved by a vehicle comprising a power train according to any one of the embodiments herein. Because the vehicle comprises an improved power train, an improved vehicle is provided.

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 is a schematic illustration of a retarder according to some embodiments, Fig. 2 illustrates a vehicle with a power train comprising transmission with a retarder according to some embodiments.

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 shows a schematic representation of a retarder 1 according to some embodiments. The retarder 1 is configured to be activated to brake a shaft 29 of a transmission 21 of a vehicle 25 and is configured to be deactivated after being activated. The vehicle 25 with the transmission 21 is illustrated in Fig. 3. Activation and deactivation of the retarder 1 is a common knowledge and is therefore not described in details herein.

The retarder 1 comprises: - a reservoir 3 for a working liquid intended to be used for activation of the retarder 1, - a working space 5 connected with the reservoir 3 to enable the working fluid to flow between the reservoir 3 and the working space 5 and - a compressed air conduct 7 connected to the retarder 1 The working space 5 may be connected with the reservoir 3 by a working fluid pipe 2 arranged partly in the reservoir 3 and enabling the working fluid to flow between the reservoir 3 and the working space 5. The reservoir 3 and the working space 5 are arranged as substantially closed containers provided with necessary openings for necessary connections. As illustrated in Fig.1, the reservoir 3 and the working space 5 may have one common wall.

The working fluid is preferably oil.

According to the embodiments illustrated in Fig. 1, the compressed air conduct 7 is connected to a compressed air source 9 for compressed air to be provided to the retarder 1 via the compressed air conduct 7. Compressed air is provided to achieve a flow of at least a portion of the working liquid from the reservoir 3 to the working space 5 by an action of the compressed air within the retarder 1 during activation of the retarder 1.

The compressed air source 9 may be a compressor of an air system of the vehicle 25, such as for example an air system of a power source 23 of the vehicle 25.

The retarder 1 comprises an air drain conduct 11 connected to the working space 5 for air to flow out from the working space 5 and into the working space 5. Thus, air can be drained out from the working space 5 during activation of the retarder 1 when working fluid is provided to the working space 5 from the reservoir 3 and thereby filling in the working space 5. Further, the working space 5 can be filled in with air flowing into the working space 5 via the air drain conduct 11 during deactivation of the retarder 1 when working fluid is removed from the working space 5. The air drain conduct 11 may be a pipe made of metal or plastic or may be a hose adapted for use at the retarder 1.

According to the embodiments i||ustrated in Fig. 1, the retarder 1 comprises an accumulator 13 connected to the reservoir 3 and connected to the compressed air conduct 7. The accumulator is arranged as a substantially closed vessel with openings for connection with the reservoir 3 and with the compressed air conduct 7. The accumulator 13 comprises a movable member 15 arranged inside the accumulator 13. The movable member 15 may be a piston member. The movable member 15 is arranged to be displaced in a first direction d1 by the action of compressed air provided via the compressed air conduct 7 to achieve the flow of at least the portion of the working liquid from the reservoir 3 to the working space 5 during activation of the retarder 1. The movable member 15 is arranged to be displaced in a second direction d2 opposite to the first direction d1 to remove at least a portion of the compressed air from the accumulator 13 into the compressed air conduct 7 during deactivation of the retarder 1, this preferably by means of a spring (not shown).

The movable member 15 arranged inside the accumulator 13 divides the inside volume the accumulator 13 into two sections, namely a compressed air section 4 connected to the compressed air conduct 7 and a working fluid section 6 connected to the reservoir 3. The working fluid section 6 may be connected with the reservoir by a pipe 8. During operation of the retarder 1 the working fluid section 6 will be filled in with the working fluid. Thus, the movable element 15 is intended to have contact with the working fluid in the working fluid section 6. Compressed air provided to the accumulator 13 via the compressed air conduct 7 creates pressure within the accumulator 13, particularly in the compressed air section 4, which pressure acts on the movable member 15. Compressed air acting on the movable member 15 causes a displacement of the movable member 15. This displacement causes the working fluid to be pressed out from the working fluid section 6 of the accumulator 13 towards the reservoir 3 connected to the accumulator 13. Thereby, the flow of at least the 8 portion of the working fluid from the reservoir 3 to the working space 5 of the retarder 1 during activation of the retarder is achieved.

According to some embodiments, the compressed air conduct is connected directly to the retarder 1 i.e. without an accumulator 13. Thus, the retarder 1 can be arranged such that compressed air provided via the compressed air conduct 7 affects the working fluid to move from the reservoir 3 to the working space 5 without using an accumulator. For example, via a part arranged in the reservoir 3.

The compressed air conduct 7 is connected to the air drain conduct 11 to enable compressed air to enter the air drain conduct 11 during deactivation of the retarder 1. The compressed air conduct 7 may be a pipe made of metal or plastic or may be a hose adapted for use at the retarder 1.

Since the compressed air conduct 7 is connected to the air drain 11 conduct to enable compressed air to enter the air drain conduct 11 during deactivation of the retarder 1, clean compressed air can be provided to the working space 5 during deactivation of the retarder 1. lf there were no connection between the compressed air conduct 7 and the air drain conduct 11, ambient air would be sucked into the working space 5 during deactivation of the retarder 1. Ambient air may contain dust or moisture which may contaminate the working fluid causing negative effects on the working fluid, such as worse working characteristics comparing to pure working fluid. The air drain conduct 1 1 is preferably provided with a one- way valve 10 arranged at the end of the air drain conduct 11 downstream a connection 12 with the compressed air conduct 7, in relation to a direction of air out to the atmosphere from the air drain conduct 11, to prevent ambient air to enter the air drain conduct 11.

The retarder 1 may comprise a valve 17 arranged in the compressed air conduct 7 and arranged to lead compressed air to the retarder 1 to achieve the flow of at least the portion of the working liquid from the reservoir 3 to the working space 5 during activation of the retarder 1, and to lead compressed air to the air drain conduct 11 during deactivation of the retarder 1. The valve may be a three-ways valve controlled by a control unit (not shown) to control the flow of compressed air during operation of the retarder.

The retarder 1 may comprise an additional compressed air conduct 19 connected to the compressed air conduct 7 and arranged to lead a portion of compressed air out from the compressed air conduct 7 during deactivation of the retarder 1. Preferably, the additional compressed air conduct 19 is arranged downstream the valve 17 in relation to a compressed 9 air direction ca of compressed air during deactivation of the retarder 1. The additional compressed air conduct 19 is preferably provided with a one-way valve 14 arranged at the end of the additional compressed air conduct 19 downstream a connection 16 with the compressed air conduct 7, in relation to a direction of air out to the atmosphere from the additional compressed air conduct 19, to prevent ambient air to enter the additional compressed air conduct 19.

Fig. 2 illustrates a vehicle 25 with a power train 27 comprising a transmission 21 with a retarder 1 according to some embodiments. The transmission 21 configured to transmit power between a power source 23 of the vehicle 25 and wheels of the vehicle 25.

Claims

1. A retarder (1) configured to be activated to brake a shaft (29) of a transmission (21) of a vehicle (25) and configured to be deactivated after being activated, wherein the retarder (1) comprises: - a reservoir (3) for a working liquid intended to be used for activation of the retarder (1 ), - a working space (5) connected with the reservoir (3) to enable the working fluid to flow between the reservoir (3) and the working space (5) and - a compressed air conduct (7) connected to the retarder (1) and arranged to be connected to a compressed air source (9) for compressed air to be provided to the retarder (1) via the compressed air conduct (7) to achieve a flow of at least a portion of the working liquid from the reservoir (3) to the working space (5) by an action of the compressed air within the retarder (1) during activation of the retarder (1 ), characterized in that the retarder (1) comprises an air drain conduct (11) connected to the working space (5) for air to flow out from the working space (5) and into the working space (5), wherein the compressed air conduct (7) is connected to the air drain conduct (11) to enable compressed air to enter the air drain conduct (11) during deactivation of the retarder (1).

2. The retarder (1) according to claim 1, comprising an accumulator (13) connected to the reservoir (3) and connected to the compressed air conduct (7), wherein the accumulator (13) comprises a movable member (15) arranged inside the accumulator (13) and arranged to be displaced in a first direction (d1) by the action of compressed air provided via the compressed air conduct (7) to achieve the flow of at least the portion of the working liquid from the reservoir (3) to the working space (5) during activation of the retarder (1 ”) and arranged to be displaced in a second direction (d2) opposite to the first direction (d1) to remove at least a portion of the compressed air from the accumulator (13) into the compressed air conduct (7) during deactivation of the retarder (1 ).

3. The retarder (1) according to claim 1 or 2, comprising a valve (17) arranged in the compressed air conduct (7) and arranged to lead compressed air to the retarder (1) to achieve the flow of at least the portion of the working liquid from the reservoir (3) to the working space (5) during activation of the retarder (1), and to lead compressed air to the air drain conduct (11) during deactivation of the retarder (1 ).

4. The retarder (1) according to any of the preceding claims, comprising an additional compressed air conduct (19) connected to the compressed air conduct (7) andarranged to lead a portion of compressed air out from the compressed air conduct (7) during deactivation of the retarder (1 ).

5. The retarder (1) according to claim 3 and 4, wherein the additional compressed air conduct (19) is arranged downstream the valve (17) in relation to a compressed air direction (ca) of compressed air during deactivation of the retarder (1).

6. The retarder (1) according to any of the preceding claims, wherein the working fluid is oil.

7. The retarder (1) according to any of the preceding claims, wherein the compressed air source (9) is a compressor of an air system of the vehicle (25).

8. The retarder (1) according to claim 7, wherein the air system is an air system of a power source (23) of the vehicle (25).

9. A transmission (21) configured to transmit power between a power source (23) of a vehicle (25) and wheels of the vehicle (25), wherein the transmission (21) comprises a retarder (1) according to any one of the claims 1 -

10. A power train (27) for a vehicle (25), wherein the power train (27) comprises a power source (23) and a transmission (21) according to claim

11. A vehicle (25) comprising a power train (27) according to claim 10.