Hydraulic Supply Arrangement and Control Method

Abstract

Proposed is a hydraulic supply system in an automatic transmission of a vehicle, said hydraulic supply system having a primary hydraulic circuit (I) for supplying the transmission components, having a secondary hydraulic circuit (II) for lubricating and cooling the transmission components and having at least one pump (P) for generating a supply flow rate in the hydraulic circuits (I, II), wherein a detecting device (E) for detecting the current hydraulic fluid volumetric flow rate in the secondary hydraulic circuit (II) for adjusting a minimum supply flow rate of the pump (P) is provided. Furthermore, a method for controlling a pump of a hydraulic supply system in an automatic transmission of a vehicle is proposed, wherein the respectively current hydraulic fluid volumetric flow rate in a secondary hydraulic circuit (II) for lubricating and cooling the transmission components is detected, wherein a volumetric flow rate requirement is determined from a characteristic map relating to the current operating range of the automatic transmission, and wherein the supply flow rate of the pump (P) is controlled as a function of the determined volumetric flow rate requirement.

Claims

1. Hydraulic supply system of an automatic transmission of a vehicle, having a primary hydraulic circuit (I) for supplying the transmission components, having a secondary hydraulic circuit (II) for lubricating and cooling the transmission components and having at least one pump (P), which is designed as a variable capacity pump with a variable supply flow rate and which is provided for generating a supply flow rate in the hydraulic circuits (I, II), characterized in that a detecting device (S) for detecting the current hydraulic fluid volumetric flow rate in the secondary hydraulic circuit (II) for adjusting a minimum supply flow rate of the pump (P) is provided.

2-12. (canceled)

Description

[0019] The present invention will be explained below in more detail with reference to the drawing.

[0020] The single FIGURE of the present invention shows in schematic form a view of a hydraulic supply system according to the invention that includes a hydraulic control method.

[0021] The supply system comprises a primary hydraulic circuit I for supplying the transmission components, such as, for example, the shift elements A, B, C, D, E and a converter clutch WK as well as a parking lock device PS.

[0022] The shift elements A to E are supplied hydraulically by means of the primary hydraulic circuit I, in order to be able to engage or disengage said shift elements. Furthermore, the converter clutch and the parking lock device PS are supplied with hydraulic fluid for engagement or disengagement with the engagement pressure Pein and the disengagement pressure Paus.

[0023] Furthermore, the supply system comprises a secondary hydraulic circuit II that is supplied with hydraulic fluid in order to lubricate and cool the transmission components. In the secondary hydraulic circuit II there is a cooling device K that is supplied from the secondary hydraulic circuit II with a pressure p_zK, which is measured in the direction of flow upstream of the cooler. Then hydraulic fluid is fed from the cooling device K back again to the secondary hydraulic circuit at a pressure p_vK, which is measured downstream of the cooler.

[0024] In order to generate a supply flow rate in the hydraulic circuits I and II, a pump P is provided, to which a pressure p_Saug is fed and which delivers a pressure p_Druck to the hydraulic circuits I, II. A variable capacity pump is provided as the pump P. In order to adjust the supply flow rate at the pump P, a predetermined adjusting pressure p_Verstellpumpe is generated for the hydraulic adjustment of the pump P, and this adjusting pressure is specified, as a function of the determined volumetric flow rate requirement, by means of the electric control unit.

[0025] If the pump cannot be adjusted, for example, due to jamming in the full stroke position, the system pressure valve is used as a pressure relief valve.

[0026] In addition, there is a tertiary hydraulic circuit III in order to feed back any possible transmission-damaging excess into the intake system of the pump P.

[0027] In order to adjust a minimum supply flow rate, it is provided that a detecting device S for detecting the current hydraulic fluid volumetric flow rate in the secondary hydraulic circuit II is provided. The detecting device S comprises, for example, a sensor for detecting the pressure or the volumetric flow rate, wherein the detecting device S is disposed in the direction of flow downstream of the cooling device K in the secondary hydraulic circuit II.

[0028] Thus, a system is proposed for supplying, as required, an automatic transmission with hydraulic fluid or oil in order to hydraulically actuate the shift elements A to E and the converter clutch WK as well as to cool and lubricate the transmission and to reduce hydraulic losses by means of a pump P that can be adjusted in the supply flow rate. In this case the supply volume is adjusted to the demand at each operating point of the transmission operating range, so that the respective minimum volumetric flow rate requirement of the transmission system is achieved, where in this case said requirement may consist preferably of the volumetric flow rates of the leaks, the cooling and lubricating oil requirement as well as the cooling oil requirement of the converter clutch WK. The leaks are the leakage in the primary hydraulic circuit I, the pump leakage, and the leakage of the hydraulic control device as well as the leakage in the course of filling and applying pressure to the shift elements A to E as well as the converter clutch WK.

[0029] In this case the adjustment of the supply flow rate of the pump P is carried out by means of a control system comprising the primary hydraulic circuit I for supplying the shift elements A to E and the actuators as well as the converter clutch WK and the parking lock device PS; of the secondary hydraulic circuit II for supplying the transmission cooling and lubricating systems; and of the tertiary hydraulic circuit III. The detecting device E comprises a sensor for detecting the volumetric flow rate or a defined dependent variable in the secondary hydraulic circuit II.

[0030] In order to control the pump P, an electronic control unit is provided, with which control of the supply flow rate at the pump P is provided, as a function of the detected volumetric flow rate in the secondary hydraulic circuit II, by means of a proportional valve. The current volumetric flow rate requirement, required in the present operating range of the automatic transmission, is determined as a function of a characteristic map. The characteristic map is stored in the transmission control unit.

[0031] In the context of the method according to the present invention, the respectively current hydraulic fluid volumetric flow rate is detected in the secondary hydraulic circuit II, the current volumetric flow rate requirement is determined from the characteristic map, and the supply flow rate of the pump P is controlled. The volumetric flow rate in the secondary hydraulic circuit II can be reduced or switched off at least intermittently, when the determined volumetric flow rate requirement is lower than the volumetric flow rate detected in the secondary hydraulic circuit II. In this way the consumption can be reduced to an even greater extent.

[0032] An insufficient supply in the secondary hydraulic circuit II is detected, when the volumetric flow rate requirement, determined from the characteristic map, is higher than the volumetric flow rate detected in the secondary hydraulic circuit II. When an insufficient supply is detected, a rotational speed limiting or a torque intervention is carried out by means of the transmission control unit according to the invention. The regulation of the pressure in the secondary hydraulic circuit II is carried out, for example, by means of a directly controlled pressure regulator or a precontrolled proportional valve.

LIST OF REFERENCE CHARACTERS

[0033] A shift element or, more specifically, clutch or brake [0034] B shift element or, more specifically, clutch or brake [0035] C shift element or, more specifically, clutch or brake [0036] D shift element or, more specifically, clutch or brake [0037] E shift element or, more specifically, clutch or brake [0038] P pump [0039] PS parking lock device [0040] WK converter clutch [0041] K cooling device [0042] S detecting device [0043] I primary hydraulic circuit [0044] II secondary hydraulic circuit [0045] III tertiary hydraulic circuit [0046] p_aus parking lock pressure for disengagement [0047] p_ein parking lock pressure for engagement [0048] p_Druck pressure on the pressure side of the pump [0049] p_Saug pressure on the suction side of the pump [0050] p_Verstellpumpe pressure for the hydraulic adjustment of the pump [0051] p_zum Kühler pressure in the cooling device [0052] p_vom Kühler pressure downstream of the cooling device