Cooling circuit with retarder

Abstract

The invention relates to a cooling circuit, which is designed to output heat generated by a retarder integrated in the cooling circuit, said cooling circuit comprising:-a toroidal working chamber formed by a stator and a rotor of the retarder,-a heat exchanger, which is designed to control the temperature of a working medium in the cooling circuit,-a working medium tank, which is designed to supply heat to the working medium tank, and-a heat exchanger, which is designed to control the temperature of the working medium in the cooling circuit. A working medium tank in which a majority of the working medium in the cooling circuit can be stored such that at least the working chamber can be substantially emptied,-an inlet channel between the working chamber and the heat exchanger outlet,-an outlet channel between the working chamber and the heat exchanger inlet. According to the invention, a first valve is arranged between the heat exchanger outlet and the inlet channel, and a second valve is arranged between the heat exchanger inlet and the outlet channel.

Description

[0001] The present invention relates to the technical field of brake systems, and in particular to a cooling circuit with a retarder, the cooling circuit being used for coupling in a drive train, and a vehicle with such a cooling circuit.

[0002] Electromobility in the form of purely electric vehicles is becoming increasingly important. The brake systems of commercial vehicles with internal combustion engines, such as buses and / or trucks, are usually equipped with wear-free continuous braking devices. Due to the large moving masses of commercial vehicles, continuous braking systems are highly economical.

[0003] In vehicles with conventional internal combustion engines, such wear-free braking devices are designed as retarders. Retarder is required in particular on long descents with steep gradients to ensure the braking effect of the brake system and to reduce the wear on the service brakes overall. In particular, the requirements of "UNECE R13" must be met in order to obtain type approval.

[0004] The brake system known from DE 20 2019 005 478 U1 comprises a working medium circuit with a cooling system. The cooling system has a radiator and a fluid drive for driving a fan wheel, which are directly integrated into the working medium circuit. In the working medium circuit, an uncontrolled coupling between the heat exchanger and the fluid motor has a negative impact on the function of the retarder.

[0005] DE 10 2020 004 797 A1 discloses an electrically driven vehicle in which an electric motor is operated in a generator mode or a regenerative mode to generate braking power. The braking energy is mainly used to charge the operating battery. However, in certain operating states, such as when the battery is fully charged, the battery is too cold and / or a fault has occurred, the battery may no longer be able to absorb energy or should be prevented from absorbing energy. This requires further braking devices that brake the vehicle as wear-free and controllable as possible. Electric brake resistors can be used here, which can electrically convert the braking power into heat, wherein a temperature-dependent resistor is used.

[0006] The terms "deceleration" or "braking" may encompass different operating conditions: reducing travel speed on a substantially straight and / or flat route, traveling at a constant speed downhill, or an increase in speed less than would be expected from the energy in the vehicle without braking.

[0007] For example, when a braking action is applied, when a braking device or a brake is activated, the speed increases lower and / or slower than when no brake is applied.

[0008] In other words, the braking device and / or the brake are designed to convert a predeterminable energy and / or power output of the moving vehicle into the form of power loss, which is essentially not converted into kinetic energy and / or power. The cooling circuit is provided with a heat exchanger and a pump for cooling.

[0009] DE 10 2021 121 407 A1 discloses a vehicle cooling circuit which is suitable for discharging waste heat from vehicle components such as a retarder. The retarder is coupled to the drive train via a coupling device. When braking by means of a hydraulic retarder is initiated or terminated, the coolant circuit and in particular the inlet line are subject to considerable pressure fluctuations, since the working chamber of the retarder is filled with working medium in each operating state. In order to prevent these pressure fluctuations, a vane pump which can be controlled by means of a control device is provided, which prevents the pressure in the inlet line from falling below the ambient pressure when braking is initiated or terminated.

[0010] The object of the present invention is to propose an alternative cooling circuit for dissipating the heat generated by the retarder.

[0011] This object is achieved according to the invention by the embodiments according to the independent claims. Further advantageous embodiments of the invention can be found in the dependent claims.

[0012] A cooling circuit is proposed, which is provided for dissipating heat generated by a retarder integrated in the cooling circuit, wherein the cooling circuit comprises:

[0013] -Torus formed by the stator and rotor of the retarder The working chamber,

[0014] a heat exchanger which is provided for regulating the temperature of the working medium in the cooling circuit,

[0015] a working medium tank in which a large part of the working medium in the cooling circuit can be stored, so that at least the working chamber can be substantially emptied,

[0016] - an inlet channel between the working chamber and the heat exchanger outlet,

[0017] - An outlet channel between the working chamber and the heat exchanger inlet.

[0018] According to the invention, it is proposed to arrange a first valve between the heat exchanger outlet and inlet channel and to arrange a second valve between the heat exchanger inlet and outlet channel.

[0019] The flow rate through the heat exchanger can be regulated by means of the valve and a non-braking operation and a braking operation of the retarder can be defined for two operating states.

[0020] In a preferred design, the first and second valves can be designed to switch to an open position as soon as the pumping action of the retarder generates a preset working medium pressure, thereby ensuring that the heat exchanger is connected to the working medium circuit only when the retarder is in braking operation.

[0021] In addition, the first and second valves can be designed to switch to the closed position when the retarder is in non-braking operation. This ensures that the heat exchanger remains filled with working medium and has no effect on the non-braking operation, in which the retarder is essentially emptied.

[0022] In a preferred embodiment, the first and second valves can be designed as non-return valves, wherein the spring force of the non-return valves is set in a targeted manner to a pressure, above which the non-return valves switch into the open position.

[0023] Alternatively, the first and second valves can also be designed as pressure-controlled 2 / 2-way valves, wherein the control line for controlling the pressure can be connected at different positions in the working medium circuit. For example, the control line for the second valve is arranged directly at the retarder outlet and the control line for the first valve is arranged directly at the working medium tank. The reaction force can also be a correspondingly designed return spring.

[0024] The working medium tank integrated into the cooling circuit is preferably designed as a pressure tank and can be filled with compressed air. The braking torque of the retarder can be regulated by the pressure controller by pressing the working medium from the working medium tank into the working chamber of the retarder through the rising line in the working medium tank. In this connection, the second valve can prevent the working medium from being pressed into the heat exchanger from the working medium tank at the beginning of the pressure loading, thereby ensuring a rapid build-up of the braking torque.

[0025] Furthermore, it can be provided that the working chamber is connected to the outlet channel via a bypass channel. In non-braking operation, a small amount of working medium flow can also flow through the working chamber via the bypass channel. In order to ensure cooling and lubrication of the retarder, the working medium tank can also be connected to the working chamber via a pump channel having a pump.

[0026] A vehicle having a drive train comprising a drive, a transmission and a retarder is also claimed, the retarder comprising a cooling circuit according to one of the above-mentioned embodiments. The cooling circuit in this embodiment is only provided for cooling the retarder, so that its function can be optimized. The cooling of other vehicle components is decoupled from the cooling of the retarder.

[0027] The drive device is preferably an electric machine.

[0028] The present invention is described below with reference to the accompanying drawings. In the accompanying drawings:

[0029] Figure 1 A drive train with an electric motor and a retarder is shown,

[0030] Figure 2 shows a cooling circuit with a retarder,

[0031] Figure 1 The schematic diagram of a transmission system having an electric motor 1 and a retarder 3 is shown. The transmission 2 is arranged between the electric motor 1 and the retarder 3. The drive wheels of the motor vehicle are coupled to the electric motor 1 and the retarder 3 via the transmission 2. The transmission 2 can be designed as a shiftable transmission, and the retarder 3 can be coupled to the transmission via a switchable coupling device.

[0032] During the braking operation of the retarder, the working medium, i.e. the retarder oil or water mixture, is heated by the braking torque of the retarder 3 and pumped into the cooling circuit 22 by the pumping action of the retarder 3 itself. A heat exchanger 4, such as an oil-air heat exchanger, is arranged in the cooling circuit 22. In addition, it can be provided that the inverter 5 on the electric motor 1 is also coupled to the cooling circuit.

[0033] Figure 2 The cooling circuit 22 or working medium circuit with the retarder 3 is shown in detail. As is known from the prior art, the retarder 3 comprises a rotatably supported rotor shaft 18, on which the rotor 6 is arranged in a rotationally fixed manner, and a stator 7 arranged in the retarder housing. The rotor 6 and the stator 7 form a toroidal working chamber 30. The cooling circuit also comprises a working medium tank or oil tank 20 and channels 8, 9, 11, 12 arranged in the retarder housing between the oil tank 20 and the working chamber 30.

[0034] The cooling circuit 22 also includes a heat exchanger 4, whose heat exchanger inlet 16 is coupled to the outlet channel 9 via a valve 23, here a non-return valve. The non-return valve 23 is designed so that it can open at a pressure higher than a specified pressure. It must be ensured that the non-return valve 23 remains in the closed position in non-braking operation, so that the working medium cannot return to the working chamber of the retarder 1, and can be reliably switched to the open position in braking operation.

[0035] A further valve 24 , which is also a non-return valve, is also arranged in the passage between the heat exchanger outlet 17 and the inlet passage 8 . In addition, an ascending passage 25 branches between the inlet passage 8 and the non-return valve 24 into the oil tank 20 .

[0036] The check valve 24 at the outlet of the heat exchanger 4 is designed to move to an open position starting from a predetermined pressure, wherein only when too much working medium accumulates in the working chamber 30 and the opening limit pressure of the two check valves 23 and 24 is exceeded during the rotor drive process, the oil flows into the oil tank 20 through the heat exchanger 4 by closing the check valve 24 when the retarder is not activated.

[0037] In non-braking operation, the working medium is essentially located in the working medium tank 20 and in the heat exchanger 4 , wherein in non-braking operation the heat exchanger 4 is decoupled from the cooling circuit 22 by means of the valves 23 , 24 .

[0038] When switching to braking operation by applying pressure to the oil tank 20 as is known in the prior art, the oil in the oil tank 20 is pressed into the cooling circuit through the riser channel 25, forming a circulation flow that is guided through the working chamber 30 of the retarder 3. The working medium that has entered the working chamber 30 is pumped out of the working chamber again by the pumping action of the retarder.

[0039] When the retarder operation is activated, i.e. the retarder is in braking operation, a circulation flow is generated, wherein the working medium in the retarder is heated by the braking torque and is pumped into the heat exchanger 4 via the outlet channel 9 by means of the pumping effect of the retarder. After flowing through the heat exchanger 4, the working medium is guided back into the working chamber 30 via the inlet channel 8 at a lower temperature.

[0040] In order to prevent the working medium from flowing back into the heat exchanger, here the oil-air heat exchanger, when the retarder is activated, the non-return valve 24 blocks the heat exchanger outlet 17, thereby ensuring a rapid build-up of the braking torque. Only when the retarder has sufficient pumping power does the working medium pressure increase, so that the two valves 23 and 24 move to the open position.

[0041] When the rotor 6 is driven, the pump is also driven, by means of which the working medium, i.e. oil, is delivered to the working chamber 20 through the pump channel 11. This oil volume flow is very small compared to braking operation, but is very important for cooling, lubrication and reducing idling losses during non-braking operation. This oil volume flow is pumped back into the outlet channel 9 via the bypass 12, wherein only when the pump pressure is large enough, the valves 23 and 24 are opened and the oil is pumped back to the working medium tank via the heat exchanger 4 and the riser channel.

[0042] Reference numerals list

[0043] 1 Electric motor

[0044] 2 Transmission

[0045] 3 Retarder

[0046] 4 Heat exchanger

[0047] 5 Inverter

[0048] 6 Rotor

[0049] 7 Stator

[0050] 8 Entryway

[0051] 9 Exit Channel

[0052] 10 Check valve

[0053] 11 Pump channel with pump

[0054] 12 Bypass

[0055] 13 Measurement location

[0056] 14 Maintaining the measurement position

[0057] 15. Eliminate the foam channel

[0058] 16 Heat exchanger inlet

[0059] 17 Heat exchanger outlet

[0060] 18 Rotor shaft

[0061] 19 Tapered roller bearings

[0062] 20 Working medium box

[0063] 21 Discharge throttle valve

[0064] 22 Cooling cycle

[0065] 23 Check valve

[0066] 24 Check valve

[0067] 25 Ascending Channel

[0068] 26 Profile ventilation

[0069] 27 Sensors

[0070] 28 Proportional valve

[0071] 29 Oil separator

[0072] 30 working chamber

Claims

1. A cooling circuit (22) configured to output heat generated by a retarder (3) integrated in the cooling circuit, wherein: The cooling circuit (22) has: - a toroidal working chamber (30) formed by the stator (7) and the rotor (6) of the retarder (3), a heat exchanger (4) which is provided for regulating the temperature of the working medium in the cooling circuit (22), a working medium tank (20), in which a large part of the working medium in the cooling circuit (22) can be stored, so that at least the working chamber (30) can be substantially emptied, - an inlet channel (8) between the working chamber (30) and the heat exchanger outlet (17), - an outlet channel (9) between the working chamber (30) and the heat exchanger inlet (16), characterized in that A first valve (24) is arranged between the heat exchanger outlet (17) and the inlet channel (8), and a second valve (23) is arranged between the heat exchanger inlet (16) and the outlet channel (9).

2. The cooling circuit (22) according to claim 1, characterized in that The first valve and the second valve (23, 24) are designed such that they are switched into an open position as soon as a pumping action of the retarder generates a predeterminable working medium pressure.

3. The cooling circuit (22) according to claim 1, characterized in that The first valve and the second valve (23, 24) are designed such that in non-braking operation they are switched into a closed position.

4. The cooling circuit (22) according to claim 2 or 3, characterized in that The first valve and the second valve (23, 24) are check valves.

5. The cooling circuit (22) according to claim 2 or 3, characterized in that The first valve and the second valve (23, 24) are pressure-controlled 2 / 2-way valves.

6. The cooling circuit (22) according to claim 1, characterized in that The working medium tank (20) can be acted upon with compressed air.

7. The cooling circuit (22) according to claim 1, characterized in that The working chamber (30) and the outlet channel (9) are connected via a bypass channel (12).

8. The cooling circuit (22) according to claim 1, characterized in that The working medium tank (20) is connected to the working chamber (30) via a pump channel (11) having a pump.

9. A vehicle having a transmission system, the transmission system comprising a drive device (1), a transmission device (2) and a retarder (3), characterized in that: A cooling circuit (22) according to any one of claims 1 to 8 is provided.

10. The vehicle according to claim 9, characterized in that The driving device (1) is an electrical machine.

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