Method for controlling at least one hydraulically operated torque transmission device

Abstract

The invention relates to a method for controlling at least one torque transmission device (D1, D2) by means of a hydraulic system (1), which has a pump unit (7) in which an electronically controlled electric motor (12) drives a pump (13) which delivers a volume flow into a pressure line (10), a system pressure regulating valve (11) arranged between an oil sump (8) and the pressure line (10), a slave cylinder (3, 4) and a control pressure regulating valve (14, 15) which loads the slave cylinder (3, 4) and which has a connection to the pressure line (10) and a connection to the oil sump (8). In order that the pump unit (7) can be designed small and that the at least one torque transmission device (D1, D2) can be actuated efficiently, in the case of unregulated closing of the system pressure regulating valve (11) relative to the oil sump (8) and unregulated complete opening of the control pressure regulating valve (14, 15) relative to the slave cylinder (3, 4), a pressure medium quantity which is predetermined for setting a contact point of the at least one torque transmission device (D1, D2) is delivered to the slave cylinder (3, 4) for actuating the at least one torque transmission device (D1, D2), and after reaching the contact point the system pressure regulating valve (11) and the control pressure regulating valve (14, 15) are operated in a regulated pressure manner until the at least one torque transmission device (D1, D2) is completely actuated.

Description

Technical Field

[0001] This invention relates to a method for controlling at least one hydraulically operated torque transmission device. Hydraulic or conventional powertrains with hydraulically operated torque transmission devices are well known. Background Technology

[0002] Hydraulic units for operating torque transmission devices configured as friction clutches, for example, for operating dual clutches, and methods for controlling said hydraulic units are known from publications WO2015 / 086009 A1 and DE 10 2015 210 877 A1, wherein system pressure is generated by means of a pump unit, and a corresponding driven cylinder is pressure-loaded by means of a pressure regulating valve in relation to the switching state of the pressure regulating valve, and the other driven cylinder is depressurized during staggered switching in order to staggeredly switch the torque transmission device. Summary of the Invention

[0003] The object of this invention is an improvement to a method for hydraulically operating at least one torque transmission device. In particular, the object of this invention is to operate at least one torque transmission device quickly and efficiently with a pump unit that minimizes power consumption.

[0004] The stated objective is achieved through the following themes.

[0005] The proposed method is used to control at least one torque transmission device by means of a hydraulic system. The at least one torque transmission device can be configured as a wet or dry friction clutch or as a brake. In the case of a friction clutch, two clutch components arranged in a manner that allows them to twist relative to each other about the same axis of rotation can be connected to each other by frictional engagement via a hydraulic system, thus enabling operation. In the case of a brake, a fixed brake component and a brake component arranged in a manner that allows them to twist about a axis of rotation can be connected to each other by frictional engagement via a hydraulic system. The at least one torque transmission device can be pressed by a driven cylinder of the hydraulic system from the contact point where torque is transmitted until the maximum transmittable torque is transmitted, thus enabling forced closure. The at least one torque transmission device can be directly connected to a drive unit having an electric motor and an internal combustion engine, or to a powertrain between an internal combustion engine and a transmission acting as a disengaging clutch. Alternatively, the at least one torque transmission device can be designed as a brake for fixing transmission components, such as the ring gear, connecting plate, or sun gear of a planetary gear transmission mechanism, or as a clutch for connecting two transmission components. Two torque transmission devices can, for example, alternately couple two different transmission components to each other and / or brake relative to a fixed housing.

[0006] The hydraulic system includes a pump unit in which an electronically controlled, such as a commutator, electric motor drives the pump. Preferably, a torsionally rigid connection is provided between the rotor of the electric motor and the pump shaft, such that the rotor speed can be correlated one-to-one with the pump speed.

[0007] The pump is configured as a positive displacement pump, such as a gear pump, having a delivery volume that corresponds one-to-one with its rotational speed. The pump delivers a volumetric flow of a pressure medium, such as oil, from a substantially unpressurized oil sump into a pressure line in relation to its rotational speed, thereby generating system pressure in the pressure line. The system pressure can be detected and assessed, for example, by means of a pressure sensor located in the pressure line or the pump.

[0008] In order to control or regulate the system pressure in the pressure line, a system pressure regulating valve, for example configured as a proportional valve, is installed between the oil pan and the pressure line.

[0009] To control the operating pressure applied to the driven cylinder for operating at least one torque transmission device, an operating pressure regulating valve, configured as, for example, a proportional valve, is provided, having a connection to a pressure line and a connection to an oil pan. Pressure sensors can be installed upstream of the driven cylinder and downstream of the operating pressure regulating valve to detect the operating pressure.

[0010] In order to design a pump unit in a compact manner and to operate at least one torque transmission device efficiently and quickly, when the system pressure regulating valve is closed without adjustment relative to the oil pan and the operating pressure regulating valve is fully open without adjustment relative to the driven cylinder, a preset amount of pressure medium for setting the contact point of at least one torque transmission device is supplied to the driven cylinder for operating at least one torque transmission device, and after reaching the contact point, the system pressure regulating valve and the operating pressure regulating valve operate in a pressure regulating manner until at least one torque transmission device is fully operated.

[0011] In at least one hydraulically operated torque transmission device, in order to operate at least one torque transmission device by frictional engagement while it is initially fully disengaged, a relatively large volume of pressure medium, such as hydraulic fluid, is dispensed into the driven cylinder until a contact point is reached. After reaching the contact point, the demand for the volume of pressure medium decreases until at least one torque transmission device is fully closed.

[0012] The amount of pressure medium used to fill the driven cylinder until it reaches the contact point is extracted from the oil pan by means of a so-called filling pulse and delivered to the driven cylinder via a pressure line. Because the system pressure in a compact and economically designed pump unit typically cannot remain constant during the filling pulse, the use of a filling pulse with a preset filling time is excluded under constant volumetric flow conditions. More precisely, the filling pulse, and thus the application of the pressure medium amount, is achieved independently of the system pressure applied to the pressure line. The preset pressure medium amount can be determined, for example, based on the rotational characteristic value of the electric motor and the pump's pressure medium displacement related to the rotation angle. For example, the electric motor can be electronically commutated, and the rotation angle increment used to control the electric motor can be associated with the displacement volume of the pump. For example, the filling pulse of the electric motor can be maintained until the preset pressure medium amount is delivered to the pressure line by the pump according to the detected rotation angle increment.

[0013] According to an advantageous embodiment of the method, the filling pulse can be determined by counting the rotations of the pump. For example, a pump configured as a gear pump can determine the required volume of pressure medium from the rotation of the electric motor rotor and thus the pump shaft. Here, the angular position of the electric motor is known to the control electronics of the pump unit and can be used accordingly as the initial angle of the filling pulse. Here, for example, the angle increments are added from the beginning to the end of the filling pulse to deduce the volume of the filling pulse, such as the preset amount of pressure medium.

[0014] In this way, during the filling pulse, the measured actuation stroke of the driven cylinder piston can be matched with the estimated actuation stroke with sufficient accuracy.

[0015] According to an advantageous embodiment of the hydraulic system and the method for controlling said hydraulic system, two alternately operated torque transmission devices, such as two friction clutches, two brakes, or one friction clutch and one brake, are operated by means of the hydraulic system. Two friction clutches are used, for example, to alternately connect two sub-transmissions of a dual-clutch transmission to a drive unit. Alternatively, the friction clutches and / or brakes can be designed for the alternating switching of a planetary gear transmission mechanism, so as to fix different components of the planetary gear transmission mechanism relative to their housings or connect them to each other to set different gear ratios.

[0016] In a hydraulic system, an operating pressure regulating valve is connected upstream of each driven cylinder designed to operate a torque transmission device. While one driven cylinder is filled with a preset amount of pressure medium to operate the torque transmission device associated with that cylinder, another driven cylinder is completely isolated from its operating pressure regulating valve relative to the pressure line, such that only the driven cylinder to be supplied with the preset amount of pressure medium is filled until the contact point of the torque transmission device to be operated is reached.

[0017] To achieve the reproducible output prerequisites for filling pulses, the electric motor can be shut off for at least a short time before the filling pulse begins. Alternatively or additionally, the system pressure regulating valve and clutch pressure regulating valve can be connected to the oil pan for at least a short time to relieve pressure.

[0018] To remove any remaining fill from the driven cylinder after disconnection, the operating pressure regulating valve can be connected to the oil pan, and the driven cylinder can be completely emptied to disconnect at least one torque transmission device. Here, a return spring for the driven cylinder piston can be provided in the driven cylinder in the opposite direction of operation; this return spring presses the driven cylinder piston to the zero position when the operating pressure regulating valve is connected to the oil pan.

[0019] In a preferred embodiment of the hydraulic system, a check valve may be connected between the pressure line and the driven cylinder, such that the operating pressure applied to the driven cylinder is maintained regardless of the position of the operating pressure regulating valve and thus regardless of the applied system pressure. Therefore, the pump unit can be shut off at least briefly, or the volumetric flow can be delivered to another driven cylinder of another friction clutch in the event of a pressure drop. If a pressure drop below a preset pressure threshold occurs due to, for example, leakage at the operating pressure regulating valve, the dropped operating pressure can be reconfigured by the pump, or in other words, returned to above the pressure threshold.

[0020] For example, after the preset amount of pressure medium is dispensed, and before at least one torque transmission device is fully closed, the system pressure and the operating pressure applied to the driven cylinder can be maintained for at least a short time by adjusting the system pressure regulating valve and the operating pressure regulating valve. Attached Figure Description

[0021] According to Figures 1 to 4 The embodiments shown in the figures illustrate the invention in detail.

[0022] Figure 1 The hydraulic system is shown in a systematic manner.

[0023] Figure 2 It shows the contact pressure with respect to the force of the contact pressure. Figure 1 A graph showing the characteristic curves of the operating volumes of the two torque transmission devices controlled by the hydraulic system.

[0024] Figure 3 It shows the contact pressure with respect to the force of the contact pressure. Figure 1 A graph showing the characteristic curves of the operating stroke of the two torque transmission devices operated by the hydraulic system, and

[0025] Figure 4 Shown by means of Figure 1A time-related status chart of the hydraulic system operating torque transmission device. Detailed Implementation

[0026] Figure 1 The schematic diagram shows a hydraulic system 1 for operating two torque transmission devices D1 and D2, wherein, for example, torque transmission device D1 is configured as a friction clutch and torque transmission device D2 is configured as a brake. The torque transmission devices D1 and D2 are preferably switched alternately by the hydraulic system 1. The torque transmission devices D1 and D2 are preferably loaded by corresponding driven cylinders 3 and 4 by means of operating pressures p(D1) and p(D2) individually controlled by valve blocks 2 of the hydraulic system 1, thereby establishing preset contact pressures at the torque transmission devices D1 and D2 for forming a slipping or adhering frictional engagement. The operating pressures p(D1) and p(D2) are detected by pressure sensors 5 and 6, respectively, and are transmitted to and evaluated by an evaluation and control unit of the hydraulic system 1.

[0027] To provide the corresponding operating pressures p(D1) and p(D2), pump unit 7 draws pressure medium 9 from oil pan 8 and compresses the pressure medium to system pressure p(S) in pressure line 10. System pressure regulating valve 11 is connected between pressure line 10 and oil pan 8 in a switching manner and regulates the system pressure p(S) of pressure line 10.

[0028] Pump unit 7 includes an electronically commutated electric motor 12 that torsionally and thus uniformly drives the pump shaft of pump 13. Pump 13 is configured as a positive displacement pump, such as a gear pump, such that the volume of pressure medium 9 delivered to pressure line 10 is proportional to the rotational speed of the pump shaft. Therefore, given the effective pump volume and the detection speed information of electric motor 12, the amount of pressure medium delivered to pressure line 10 can be determined independently of the system pressure p(S) present in pressure line 10.

[0029] Operating pressure regulating valves 14 and 15, and check valves 16 and 17 connected upstream of the operating pressure regulating valves, are respectively provided between the pressure line 10 and the driven cylinders 3 and 4. The operating pressure regulating valves 14 and 15 regulate the operating pressures p(D1) and p(D2) at the driven cylinders 3 and 4, and have outlet lines 18 and 19 to the oil pan 8 for this purpose, so as to reduce, for example, the applied operating pressures p(D1) and p(D2) to disconnect the torque transmission devices D1 and D2. Here, the driven cylinder pistons 20 and 21 of the driven cylinders 3 and 4 are returned to the zero position, for example by means of a return spring, and the corresponding driven cylinders 3 and 4 are completely emptied.

[0030] With the preferred torque transmission devices D1 and D2 respectively pressed, check valves 16 and 17 maintain corresponding operating pressures p(D1) and p(D2) at the torque transmission devices, so that the torque transmission devices remain closed regardless of the operation of the pump unit 7 or the system pressure p(S) and only need to reconstruct the operating pressures p(D1) and p(D2) that have decreased due to leakage, so that an economical operating mode of the hydraulic system 1 can be designed.

[0031] To close the torque transmission devices D1 and D2, the corresponding driven cylinders 3 and 4 are filled, and the driven cylinder pistons 20 and 21 are moved along the operating stroke. For this purpose, the driven cylinder pistons 20 and 21 are initially filled with a relatively large preset pressure medium at high pump speed and relatively low system pressure p(S) until the corresponding torque transmission devices D1 and D2 reach their contact points, at which point the torque transmission devices begin to transmit torque. Due to wear and the setting process, the contact points change, thus changing the pressure medium volume until the contact points are continuously adjusted.

[0032] When the contact point is exceeded, a significantly smaller amount of pressure medium is required as the operating pressures p(D1) and p(D2) increase.

[0033] Therefore, in order to quickly execute the operation of torque transmission devices D1 and D2, unadjusted filler pulses of a preset number of rotation angle pulses of the rotor of the electric motor are connected to the electric motor 12. These filler pulses, generated by the rotation of the corresponding pump shaft, produce a preset amount of pressure medium for the corresponding driven cylinders 3 and 4, so as to move the driven cylinder pistons 20 and 21 to the contact point. Here, the system pressure regulating valve 11 is fully and unadjusted relative to the pressure line. Furthermore, the operating pressure regulating valves 14 and 15 of the driven cylinders 3 and 4 to be operated are fully and unadjusted relative to the pressure line 10. The operating pressure regulating valves 15 and 14 of the torque transmission devices D2 and D1 not to be operated are fully closed relative to the pressure line 10.

[0034] If the preset pressure medium is dispensed into the driven cylinders 3 and 4, the driven cylinder pistons 20 and 21 are at the contact point, and the system pressure regulating valve 11, the operating pressure regulating valves 14 and 15, and the pump unit 7 operate in an adjustable manner to set the operating pressure p(D1) and p(D2) at the driven cylinder in an adjustable manner. The operating pressure is used to set the torque that can be transmitted via the torque transmission devices D1 and D2 in an adjustable manner until complete frictional engagement.

[0035] It should be understood that the hydraulic system 1 is configured such that the pressure line 10 is air-free during the operation of the torque transmission device.

[0036] Figure 2Figure 22 shows characteristic curves 23 and 24 of pressure p with respect to the pressure medium quantity V of torque transmission devices D1 and D2 with operating pressures p(D1) and p(D2). The operating pressure increases with a small pressure rise by means of a pressure medium quantity V(D1, g) and V(D2, g) preset in relation to the system used, i.e., the clutch or brake, until the contact points T(D1) and T(D2). From the contact points T(D1) and T(D2), the pressure rise increases with a large slope in relation to the system.

[0037] Figure 3 refer to Figure 1 Figure 25 is shown, which has characteristic curves 26 and 27 of the contact pressure F of torque transmission devices D1 and D2 with respect to the operating stroke s of driven cylinder pistons 20 and 21. The contact pressures F(D1) and F(D2) at torque transmission devices D1 and D2 are approximately zero up to the contact points T(D1) and T(D2), and then increase sharply when torque transmission devices D1 and D2 are closed. The contact pressure F(D1) rises more smoothly due to the axial elasticity of torque transmission device D2, which is configured as a friction clutch, and the contact point T(D1) is achieved in a smaller operating stroke than in the case of torque transmission device D2 configured as a brake.

[0038] Figure 4 Referring to the accompanying drawings, Figure 28 shows the performance of hydraulic system 1 and torque transmission device D1 with respect to time t during operation in sub-figures I, II, and III. When operating torque transmission device D2, the performance of hydraulic system 1 remains substantially the same until the point of contact changes.

[0039] Subgraph I shows the actuation stroke s(s) of the control piston of the system pressure regulating valve 11 by means of curve 29 and the actuation stroke s(D1) of the control piston of the actuating pressure regulating valve 14 by means of curve 30.

[0040] Subgraph II shows the system pressure p(S) of pressure line 10 and the operating pressure p(D1) acting on driven cylinder 3 by means of curve 31.

[0041] Subgraph III shows the rotational speed n of the rotor of the electric motor 12 by means of curve 32, thereby showing the rotational speed of the pump shaft of the pump 13.

[0042] At time t1, the electric motor 12 is started by means of a filling pulse and its rotational characteristic value, such as the increment of its electronically commutated rotational angle, is detected. The system pressure regulating valve 11 is completely and unadjusted closed relative to the oil pan 8, the operating pressure regulating valve 15 of the other torque transmission device D2 is completely closed relative to the pressure line 10, and the operating pressure regulating valve 14 is completely and unadjusted open relative to the pressure line 10. In the pressure line 10, the system pressure p(S) rises briefly and begins to fill the driven cylinder 3. The slightly increased operating pressure p(D1) is attributed to the displacement of the driven cylinder piston 20 against the action of the return spring.

[0043] Until the time interval is obtained The filling pulse is maintained on t until the preset pressure medium quantity V(D1,g) is obtained from the sum of the rotation angle pulse of the rotor of electric motor 12 and the known fixed pump volume. Figure 2 Due to the rigid configuration of the pressure pipeline components guiding the pressure medium 9, the entire amount of pressure medium V(D1,g) is pumped into the driven cylinder 3, causing the driven cylinder piston 20 to be at the contact point T(D1) until time t2.

[0044] Subsequently, after a preset time, the system pressure regulating valve 11 and the operating pressure regulating valve 14 operate in a regulating manner from time t3, resulting in an increased system pressure p(S). The increased system pressure sets the increased operating pressure p(D1) at the driven cylinder 3, thereby continuously operating the torque transmission device D1.

[0045] List of reference numerals

[0046] 1. Hydraulic System

[0047] 2 Valve Block

[0048] 3 Driven cylinder

[0049] 4 Driven cylinder

[0050] 5. Pressure sensor

[0051] 6. Pressure sensor

[0052] 7 Pump Unit

[0053] 8 Oil pan

[0054] 9. Pressure medium

[0055] 10. Pressure piping

[0056] 11 System pressure regulating valve

[0057] 12 Electric motors

[0058] 13 pumps

[0059] 14. Operate the pressure regulating valve

[0060] 15. Operate the pressure regulating valve

[0061] 16 Check valve

[0062] 17 Check valve

[0063] 18 Outlet tubing

[0064] 19 Outlet tubing

[0065] 20 Driven cylinder piston

[0066] 21 Driven cylinder piston

[0067] 22 charts

[0068] 23 Characteristic Curves

[0069] 24 Characteristic Curves

[0070] 25 charts

[0071] 26 Characteristic Curves

[0072] 27 Characteristic Curves

[0073] 28 charts

[0074] 29 curves

[0075] 30 curve

[0076] 31 curves

[0077] 32 curves

[0078] D1 Torque Transmission Device

[0079] D2 Torque Transmission Device

[0080] F Contact pressure

[0081] F(D1) Contact pressure

[0082] F(D2) Contact pressure

[0083] n rotational speed

[0084] p pressure

[0085] p(D1) Control pressure

[0086] p(D2) Controlling pressure

[0087] p(S) system pressure

[0088] s control stroke

[0089] s(D1) control stroke

[0090] s(s) control stroke

[0091] T(D1) contact point

[0092] T(D2) contact point

[0093] t time

[0094] time t1

[0095] Time t2

[0096] time t3

[0097] V pressure medium volume

[0098] V(D1, g) is the preset pressure medium volume.

[0099] V(D2, g) is the preset pressure medium volume.

[0100] t time interval

Claims

1. A method for controlling at least one torque transmission device (D1, D2) by means of a hydraulic system (1), the hydraulic system comprising: a pump unit (7) in which an electronically controlled electric motor (12) drives a pump (13) to deliver a volumetric flow into a pressure line (10) in relation to a rotational speed; a system pressure regulating valve (11) disposed between an oil pan (8) and the pressure line (10), the system pressure regulating valve being used to control the system pressure (p(S)) in the pressure line (10); driven cylinders (3, 4) for actuating the at least one torque transmission device (D1, D2); and actuation pressure regulating valves (14, 15) loading the driven cylinders (3, 4) with actuation pressures (p(D1), p(D2)), the actuation pressure regulating valves having a connection to the pressure line (10) and a connection to the oil pan (8), characterized in that, In order to operate the at least one torque transmission device (D1, D2), with the system pressure regulating valve (11) closed unadjusted relative to the oil pan (8) and the operating pressure regulating valve (14, 15) fully open unadjusted relative to the driven cylinder (3, 4), a preset amount of pressure medium (V(D1, g), V(D2, g)) for setting the contact points (T(D1), T(D2)) of the at least one torque transmission device (D1, D2) is supplied to the driven cylinder (3, 4), and after reaching the contact points (T(D1), T(D2)), the system pressure regulating valve (11) and the operating pressure regulating valve (14, 15) operate in a pressure regulating manner until the at least one torque transmission device (D1, D2) is fully operated.

2. The method according to claim 1, characterized in that, Two alternately operated torque transmission devices (D1, D2) are operated by means of the hydraulic system (1), wherein an operating pressure regulating valve (14, 15) is connected upstream of each driven cylinder (3, 4) for operating the torque transmission devices (D1, D2) respectively, and when one driven cylinder (3, 4) is filled with the preset pressure medium (V(D1, g), V(D2, g)), the other driven cylinder (4, 3) is completely separated from the operating pressure regulating valve (15, 14) of the other driven cylinder relative to the pressure line (10).

3. The method according to claim 1, characterized in that, The preset pressure medium quantity (V(D1,g), V(D2,g)) is determined independently of the system pressure (p(S)) applied in the pressure line (10).

4. The method according to claim 3, characterized in that, The preset pressure medium quantity (V(D1,g), V(D2,g)) is obtained based on the rotational characteristic value of the electric motor (12) and the pressure medium displacement of the pump (13) related to the rotation angle.

5. The method according to claim 4, characterized in that, The electric motor (12) is electronically commutated, and the rotation angle increment used to control the electric motor is associated with the displacement volume of the pump (13).

6. The method according to claim 5, characterized in that, The electric motor (12) continues to provide filling pulses until the preset amount of pressure medium (V(D1,g), V(D2,g)) is delivered to the pressure line (10) by the pump (13) according to the number of detected rotation angle increments.

7. The method according to claim 6, characterized in that, Before the filling pulse begins, the electric motor (12) is turned off for at least a short time, and the system pressure regulating valve (11) and the operating pressure regulating valve (14, 15) are connected to the oil pan (8) for at least a short time to eliminate any possible operating pressures (p(D1), p(D2)).

8. The method according to any one of claims 1 to 7, characterized in that, In order to disconnect the at least one torque transmission device (D1, D2), the operating pressure regulating valve (14, 15) is connected to the oil pan (8), and the driven cylinder (3, 4) is completely emptied.

9. The method according to any one of claims 1 to 7, characterized in that, A check valve (16, 17) is connected between the pressure line (10) and the driven cylinder (3, 4), and the pump (13) reconstructs the operating pressure (p(D1), p(D2)) set at the driven cylinder (3, 4) when operating at least one torque transmission device (D1, D2), which is reduced due to leakage.

10. The method according to claim 9, characterized in that, After the preset pressure medium quantity (V(D1,g), V(D2,g)) is measured, before the at least one torque transmission device (D1, D2) is fully closed, the system pressure (p(S)) and the operating pressure (p(D1), p(D2)) applied to the driven cylinder (3, 4) are kept constant for at least a short time by adjusting the system pressure regulating valve (11) and the operating pressure regulating valve (14, 15).

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