Oil Supply System Of An Automatic Transmission Or Automated Manual Transmission In A Powertrain

Abstract

An oil supply system of an automatic transmission or an automated manual transmission in a power train has an oil pan and a pressure line for supplying elements of the transmission with pressurized oil. A pumping device pumps oil from the oil pan into the pressure line at a supply pressure P.sub.0. A hydrodynamic converter, being a starting element, forms a subsection of the pressure line. A hydrodynamic retarder is disposed in a retarder oil circuit. At least a first switching valve, a second switching valve and a heat exchanger, wherein the heat exchanger is selectively switchable, by way of the switching valves, as a subsection into the pressure line or the retarder oil circuit. A temperature sensor is provided following the pumping device in the direction of flow in order to detect the oil temperature in the pressure line.

Claims

1-9. (canceled)

10. An oil supply system of an automatic transmission or an automated manual transmission in a power train, the oil supply system comprising: an oil pan; a pressure line for supplying elements of the transmission with pressurized oil; a pumping device for pumping oil from said oil pan into said pressure line at a supply pressure P.sub.0; as a starting element, a hydrodynamic converter forming a subsection of said pressure line; a retarder oil circuit with a hydrodynamic retarder; a heat exchanger and switching valves, including at least a first switching valve and a second switching valve, disposed to selectively switch said heat exchanger as a subsection into said pressure line or into said retarder oil circuit; and a temperature sensor disposed to follow said pumping device in a direction of flow and configured to detect an oil temperature of the oil in said pressure line.

11. The oil supply system according to claim 10, wherein said temperature sensor is disposed to follow said hydrodynamic converter in the direction of flow.

12. The oil supply system according to claim 10, wherein said temperature sensor is arranged between said first valve and said heat exchanger.

13. The oil supply system according to claim 10, wherein said valves are disposed in said pressure line and configured to adjust the supply pressure P.sub.0 to different working pressures P.sub.1, P.sub.2, P.sub.3 within sub-sections of said pressure line, wherein P.sub.0>P.sub.1>P.sub.2>P.sub.3.

14. The oil supply system according to claim 10, which comprises a further temperature sensor disposed to measure an oil pan temperature.

15. A method of supplying an automatic transmission or an automated manual transmission with pressurized oil, the method comprising: providing an oil supply system according to claim 10; measuring the oil temperature with the temperature sensor in the pressure line; operating in any of the following modes: in a lockup mode: determining an oil pan temperature; in a converter mode: reducing a transmission input power when a first temperature limit T.sub.max W is exceeded; in a retarder mode or in the braking mode: reducing the retarder power when a second temperature limit T.sub.max R is exceeded.

16. The method according to claim 15, which comprises adapting the first temperature limit T.sub.max W and the second temperature limit T.sub.max R to an operating state of the power train.

17. The method according to claim 15, which comprises determining the oil pan temperature by way of a calculation model.

18. The method according to claim 17, which comprises calibrating, and optionally correcting, the calculation model when the converter is operating in the lockup mode and the heat exchanger is connected into the pressure line by way of the valves.

Description

[0026] The invention is explained in greater detail below by means of diagrams, in which

[0027] FIG. 1 shows a section of an oil supply system of a transmission with a temperature sensor,

[0028] FIG. 2 shows an example of an embodiment of an oil supply system of a transmission.

[0029] FIG. 1 shows a section of an oil supply system of a transmission, from which a particularly advantageous position of the temperature sensor 36a can be seen. The subsection shows all the essential elements which an oil supply system according to the invention for an automatic transmission or an automated manual transmission must have.

[0030] Details that are not shown, such as valves for pressure control or switching or controlling the elements can be taken from FIG. 2, by way of example. FIG. 2 shows an illustrative embodiment, from which it is possible to see all the details which are also described below.

[0031] To supply oil, an oil pumping device 3 is provided, by means of which oil is delivered or pumped into the pressure line 2, 12, 22, 32 via an oil line 30. The oil pressure is controlled in such a way that there is in pressure line section 2 a supply pressure P0, which is controlled by a valve (not shown). The supply pressure P0 is required for shifting the clutches and brakes of a transmission, for example, in order to exercise open-loop and/or closed-loop control over the shifting processes in the transmission.

[0032] Arranged further along the pressure line 2, 12, 22, 32, in pressure line 22, is the hydrodynamic converter 18. In this section of the pressure line, the oil pressure is lower, P2<P0. There is a flow of oil through the converter in all operating states.

[0033] Among the elements shown in the next section illustrated are the heat exchanger 33 and the retarder oil circuit 23. The valves 8 and 9 are embodied as 4/2-way valves. The switching of the valves 8 and 9 means that either the heat exchanger 33 is a subsection of the pressure line or the heat exchanger is integrated into the retarder oil circuit 23, with the result that the braking energy is dissipated by the heat exchanger during the operation of the retarder.

[0034] The temperature sensor 36a is installed between valve 8 and the heat exchanger 33. Thus, in the two switching positions of the valves 8, 9, the oil temperature of the oil can be measured either at the outlet of the converter 18 or of the retarder 19. To optimize the operation of the converter 18 and the retarder 19, different temperature limits may be critical. If the maximum temperature is exceeded, the converter 18 or the retarder 19 must be throttled back. The position of the sensor ahead of the heat exchanger 33 ensures optimum temperature monitoring since the actual process temperature is measured.

[0035] In contrast, the oil temperature in the oil pan is relevant only when the retarder is switched on and off frequently since, during this process, a relatively large amount of heated oil is discharged from the working chamber into the oil pan 1.

[0036] In the lockup mode, the oil in the converter is heated only insignificantly, and therefore the measured temperature at the sensor 36a in the lockup mode corresponds approximately to the oil pan temperature. The measured temperature can be input into a calculation model in order to calculate an oil pan temperature in the converter or retarder mode as well.

[0037] FIG. 2 shows an illustrative embodiment of an oil supply system of a transmission with all the elements, in particular converter 18, retarder 19 and the lubrication points 20.

[0038] The oil supply for the shifting elements 17 branches off from pressure line section 2, wherein the individual shifting elements 17 are supplied with pressurized oil via lines 16 and the switching and control valves 15. The shifting elements 7 (which are not shown specifically here) can be clutches or brakes, the actuation of which is accomplished by means of the pressurized oil.

[0039] Two pumps 3 and 4 are provided here for the purpose of supplying oil. Here, pump 3 is coupled to the engine and embodied as a variable pump. Pump 4 is driven by means of an electric motor 5. The connection and control of the two oil pumps 3, 4 can be embodied in different ways, wherein it is ensured in each circuit that a supply pressure P0 can be set ahead of valve 6 and that an oil volume flow can always pass through the pressure line 2, 12, 22, 32 and valves 7, 8, 9 and 10 to the lubrication points 20 after valve 6.

[0040] Excess pressurized oil which is not required for lubrication 20 can be passed back to the intake side of the first oil pump 3 via the bypass line 42.

[0041] A hydrodynamic converter 18, which is flowed through by or supplied with pressurized oil is furthermore provided as a starting element in the pressure line 2, 12, 22, 32 in both embodiments illustrated. To cool the oil flow, two heat exchangers 21, 33 are provided, wherein one is positioned directly in the pressure line 2, 12, 22, 32 ahead of the converter 18. Another heat exchanger 33 is arranged between valves 8 and 9. This can be switched into the retarder operating circuit 23 to dissipate the waste heat of the retarder in accordance with the operating state of the powertrain.

[0042] To fill the retarder oil circuit 23, a filling line 26, 41, via which the retarder 19 can be supplied with oil from the pressure line 2, 12, 22, 32, branches off from the pressure line 2, 12, 22, 32 in the region of the first working pressure P1.

[0043] In the embodiment, a further heat exchanger 21 is installed ahead of the converter 18 in addition to heat exchanger 33. In this heat exchanger 21, the oil is cooled before it enters converter 18.

[0044] In the non-braking mode of the retarder 19, both heat exchangers 21, 33 are incorporated into the oil circuit at all times, with the result that, even in the converter mode, as little as possible heat is introduced into the oil pan 1 or the oil from the oil pan 1 can be cooled down as quickly as possible. In the braking mode of the retarder 19, only heat exchanger 33 is incorporated into the retarder oil circuit 23. The minimum oil flow is passed exclusively via heat exchanger 21.

[0045] Further details or elements illustrated in FIG. 2 are details which are required for the oil supply system but are not directly relevant to the embodiment according to the invention. No further details of these have been given here since they are widely known to those skilled in the art and the function thereof is apparent from the circuit diagrams. They include, in particular, the check valves 28 or the pressure-limiting valves 28.1, the sensors 36, 37 as well as the valves, filters etc. which are not mentioned.