Hydraulic circuit for dual-clutch transmission and method for operating the hydraulic circuit

Abstract

A hydraulic circuit for a hybrid dual-clutch transmission for a motor vehicle, comprising a hydraulically operable clutch and at least one pressure valve for adjusting the clutch pressure, wherein the clutch (K0) is a disengaging clutch between an internal combustion engine and a dual-clutch transmission equipped with two other clutches, each of which is associated with a pump actuator having a pump, wherein an electric motor is mounted between the clutch (K0) and the clutches of the dual-clutch transmission, characterized in that the clutch (K0) is pressure-loaded via one of the pump devices associated with the other two clutches and a rotary spool valve disposed in the path from the pump device to the clutch, wherein check valves are respectively installed between the pump device and the rotary spool valve of clutch (K1) and between the pump device and the rotary spool valve of clutch (K2), and a branch to the clutch (K0) is provided between the check valves.

Description

Technical Field

[0001] The present invention relates to a hydraulic circuit for a dual-clutch transmission for a motor vehicle, the hydraulic circuit having a first, a second, and a third hydraulically operable clutch and at least one valve for adjusting the clutch pressure of the first, second, and third clutches.

[0002] The present invention also relates to a method for operating a hydraulic circuit. Background Technology

[0003] Dual-clutch transmissions are known in the field of vehicle transmissions. These transmissions are based on a manual shift transmission with an intermediate shaft configuration in terms of transmission design. First and second sub-transmissions are nested within each other and can be independently connected to a drive unit such as an internal combustion engine via separately associated friction clutches. By interleaving the operation of the two friction clutches, gear shifting is possible without reducing traction.

[0004] There is a current trend towards hybrid drive units, where a first drive unit, such as an internal combustion engine, is combined with an electric motor as a second drive unit. Different design concepts are known for hybridization in dual-clutch transmissions. For example, it is known to place an electric motor between a friction clutch and the internal combustion engine, resulting in a P2 parallel hybrid system. In this case, a friction clutch can be placed between the electric motor and the first drive unit. The drive power of the electric motor can be fed into the first or second transmission via a first or second friction clutch.

[0005] In another implementation, the motor is connected to one of the two sub-transmissions, that is, downstream of the associated friction clutch when viewed in the power flow direction, which is referred to as P2.5 hybrid.

[0006] The clutch is operated by a hydraulic device, for example, described in EP 1 763 643 B1, wherein the hydraulic circuit for the dual-clutch transmission has a central valve that connects the pressure regulating valve to the corresponding clutch in a first position and disengages the pressure regulating valve from the corresponding clutch in a second position.

[0007] Furthermore, a hybrid powertrain is known from DE 10 2010 004 711 B1, wherein a third friction clutch is provided between two friction clutches and a first drive unit.

[0008] All these coupling units, especially the clutch K0 located between the internal combustion engine and the transmission, require high pressure and a system performance that is as unrelated as possible in their respective hydraulic paths for hydraulic actuation. Typically, the required operating pressure, or the hydraulic power required for this, is provided either via a central main pressure pump or, more recently, as needed and more efficiently, by a separate electro-hydraulic pump for each clutch. To apply pressure to all clutches, a system with three pump actuators may therefore be necessary. Such a system consists at least of an electrically operated pump connected to a constant diaphragm downstream. Thus, the clutch torque and pump speed are in a fixed relationship, which is not always advantageous.

[0009] DE 10 2015 214 998A1 describes an operating device. Instead of using separate operating actuators for the clutch assembly and the consumable system, a common fluid pump is used. The fluid pump is capable of operating the working fluid in the first delivery direction for operating the clutch assembly and in the second delivery direction for operating the consumable system.

[0010] Access to one circuit or another circuit is achieved via a switching valve or an OR valve.

[0011] A hydraulic circuit for a hybrid dual-clutch transmission for a motor vehicle is known from DE 10 2020 205 759.1 (not yet published), having a first, second, and third hydraulically operable clutch and at least a first, second, and third pressure control valve for regulating the clutch pressure of the first, second, and third clutches, wherein the first clutch is a disengaging clutch between an internal combustion engine and a dual-clutch transmission equipped with two other clutches, each of which is associated with a pump actuator having a pump, wherein clutch K0 is pressure-loaded via a pressure control valve associated with the other two clutches and one of the pressure control valves associated therewith.

[0012] DE 10 2005 019 516 A1 discloses an apparatus for operating multiple hydraulic shift cylinders, particularly for shifting gears in a dual-clutch transmission, the apparatus comprising: a first spool valve having a control input having a applied control pressure; a system pressure input having a system pressure applied; two outputs and at least one return output, wherein one output is optionally connected to the system pressure input and the other output is connected to the return output depending on the pressure applied at the control input; and a valve device connected to the output of the spool valve, by means of which the shift cylinder can be selectively operated.

[0013] By using a first spool valve, typically configured as a 4 / 3 directional valve, and a valve assembly connected to that spool valve, different and simple feasibility options are available for constructing the device. Summary of the Invention

[0014] The object of this invention is to provide a hydraulic circuit that includes driving clutch K0 via the operating pressure of other clutches and the pump actuators of said other clutches, without the need for additional pump actuators, and also reduces the number of valves.

[0015] The objective is achieved by a hydraulic circuit for a hybrid dual-clutch transmission for motor vehicles, the hydraulic circuit having first, second, and third hydraulically operable clutches and at least one pressure valve for regulating the clutch pressure of the first, second, and third clutches, wherein the first clutch is a disengaging clutch between an internal combustion engine and a dual-clutch transmission with two other clutches, wherein each of the other clutches is associated with a pump actuator having a pump, and wherein an electric motor is installed between the disengaging clutch and the other clutches of the dual-clutch transmission, wherein the clutch is pressure-loaded via one of the pump devices associated with the other two clutches and a rotary spool valve disposed in the path from the pump device to the clutch, wherein check valves are respectively installed between the pump device and the rotary spool valve of the clutch and between the pump device and the rotary spool valve of the clutch, and a branch to clutch K0 is provided between the check valves.

[0016] The proposed hydraulic circuit allows three clutches to be operated as needed with only two pump actuators. The pump actuators used here are advantageously used in dual operation to operate clutch K0. The system consisting of the pump and the electric motor is called a pump actuator.

[0017] It is advantageous to have a switching valve between the branch circuit and the K0 clutch.

[0018] Advantageously, the clutch is pressure-supplied via a pressure supply device for another working clutch.

[0019] In the first embodiment, clutch K0 is supplied with pressure via a pressure supply device for another working clutch. Here, a working clutch is understood as one that is pressurized, closed, and transmits the engine's driving torque. A non-working clutch is understood as an open clutch in the second sub-transmission that does not transmit driving torque.

[0020] Alternatively, the clutch is pressure-supplied via a pressure supply device for another non-operating clutch.

[0021] The objective is achieved by a method for operating a hydraulic circuit in which pressure is applied to three clutches via two pumps.

[0022] Advantageously, the adjustment function is implemented in relation to the pump speed.

[0023] If one or both clutches are temporarily at a lower pressure, the check valve maintains the clutch pressure. Attached Figure Description

[0024] Figure 1 This illustrates one embodiment with the rotary slide valve in the electrically driven position.

[0025] Figure 2 Showing the location of hybrid driving,

[0026] Figure 3a This demonstrates starting the internal combustion engine via K1 in an unadjusted manner during electric driving.

[0027] Figure 3b This demonstrates starting the internal combustion engine via K1 during electric driving, while adjustments are being made.

[0028] Figure 4a This demonstrates starting the internal combustion engine via K2 in an unadjusted manner during electric driving.

[0029] Figure 4b This demonstrates starting the internal combustion engine via K2 during electric driving, while adjustments are being made.

[0030] Figure 5a Indicates the position of the rotary slide valve.

[0031] Figure 5b The top view shows the feasibility of the rotary slide valve.

[0032] Figure 6 An alternative implementation of the rotary slide valve is shown.

[0033] Figure 7a A cross-sectional view of the alternative rotary valve is shown.

[0034] Figure 7b A top view of the alternative rotary valve is shown. Detailed Implementation

[0035] Figure 1 Hydraulic unit 1 is schematically shown. Clutches K1 and K2 are operated by actuators 21 or 22, respectively. Actuators 21 and 22 are hydraulically connected to pump assembly 11 or 12 via pump connections. Pump assemblies 11 and 12 each contain an electrically operated pump 15. The electrically operated pump 15 draws oil from oil tank 4 via filter 16. Pump 15 applies pressure to the pistons in actuators 21 and 2 via lines 1 and 2, thereby operating clutches K1 and K2.

[0036] Oil is pumped back to the oil tank 23 in the pump assemblies 11 and 12 via parallel additional leakage sections and baffles 17. In addition, pressure sensors 18 are respectively installed in the pump assemblies 11 and 12.

[0037] Clutch K0 is also pressurized by pump unit 11 or 12. Actuator 23 is pressurized via line 3 and switching valve 60. Line 3 branches off from lines 1 and 2, with each branch separating from the corresponding line 1 or 2 via check valve 19.

[0038] The rotary slide valve 50 is installed in lines 1 and 2 between the pump units 11 and 12 for clutches K1 and K2 and the corresponding actuators 21 and 22.

[0039] An exemplary rotary spool valve 50 is a valve in which two discs having polished surfaces are in principle housed within a valve body 52 and the discs are pressed against each other by a spring and by a pressure differential.

[0040] The lower disc 52A is securely fixed to or is already part of the valve body 52; the upper disc 53 is connected to the valve shaft 54 ​​and rotates via an adjusting actuator 51. Both discs 52A and 53 contain two through-holes 56 each. Typically, once these through-holes 56 overlap, flow is opened in the rotary slide valve 50. In this embodiment, the upper disc 53 is a quarter circle, which, according to... Figure 5b Either one hole or another hole 56 is covered, or both holes 56 are released. A stop 54 is provided on the lower disk 52A. The adjustment driver 51 is operated via its own control device, or also via a CAN bus, etc.

[0041] Another pump assembly 13, also comprising an electrically driven pump 15, is provided for cooling the clutches. Pump 15 draws oil from the oil pan 4 via a filter 16 and delivers the oil via a pump path 6 to a distributor 5, which then delivers the oil to clutches K1 and K2, as well as clutch K0.

[0042] The hydraulic circuit includes a motor EM mounted at position P2 in the vehicle's drive system. The motor EM is supplied with cooling oil via a pump unit 13 in a parallel path 7 to the distributor 5.

[0043] exist Figure 1 The diagram shows the position of the rotary valve 50 as it would be during pure electric driving. The rotary valve 50 opens toward clutches K1 and K2. This allows pressure to be applied to both clutches, causing the electric motor's drive power to be introduced into the transmission via clutch K1 or K2. The switching valve 60 closes toward clutch K0, thus keeping clutch K0 open. The internal combustion engine is therefore disengaged via clutch K0, and the electric motor drives the vehicle directly via the corresponding clutch K1 or K2. Both clutches K1 and K2 are in pump-actuator mode here, meaning that the clutches can be activated individually by the applied pressure.

[0044] exist Figure 2 The position of the valves used for hybrid driving is shown. The rotary spool valve 50 is again in the position where the pressure from pump units 11 and 12 is applied to the actuators of clutches K1 and K2 via lines 1 and 2. For hybrid driving, switching valve 60 opens and pressure is applied to clutch K0 via line 3. Clutch K0 is pressure-connected to clutches K1 and K2 and can be briefly maintained at that pressure via check valve 19. The pressure in clutch K0 corresponds to the maximum pressure of pump unit 11 or 12. This allows the torque of clutch K0 to be tracked and adjusted.

[0045] exist Figure 3a The diagram shows the valve position when the internal combustion engine is to be started during electric driving with clutch K1 engaged. This requires that the instantaneous pressure applied to the engaged clutch (in this case, clutch K1) is greater than the pressure necessary for engine starting on clutch K0. To achieve this, the engaged clutch K1 is placed in slippage by maintaining a constant clutch pressure, briefly increasing the motor torque, and opening the switching valve 60 toward clutch K0.

[0046] Figure 3b The diagram illustrates engine starting during electric drive using clutch K1. In this case, the pressure of the working clutch K1 is lower than the pressure required for the starter motor at K0. The rotary spool valve 50 is adjusted toward the non-working clutch closing path 2, and this path is used to operate clutch 0 without operating clutch 2. The working clutch K1 is placed in slippage such that the clutch pressure is kept constant and the motor torque is briefly increased. Simultaneously, the switching valve 60 opens and the speed of pump 15 in pump module 12 increases to provide the required pressure.

[0047] Figure 4a and 4b Showing with Figure 3a and 3b Similarly, engine starting occurs when clutch K2 is engaged.

[0048] exist Figure 5a The different positions of the rotary valve are shown. From left to right, the position for engine starting via pump module 12 is shown, where the line to clutch K1 is open. The next position describes engine starting via pump module 11 and the connection to clutch K2. The other two identical positions are for engine starting under electric and hybrid driving conditions, as well as under high load conditions. Figure 5b The flow through the rotary slide valve 50 is shown in the top view. The upper plate covering it is shown here only as a quarter circle. The stop is schematically indicated in a wedge shape on the right side. It can be seen that the flow through the right or left side can be activated alternately, or the flow through both lines can be opened.

[0049] Figure 6 An alternative embodiment is shown, in which an alternative rotary slide valve 50' is applied.

[0050] The rotary spool valve 50' has another stage, which has another disc, which is capable of regulating the flow downstream to the clutch K0 in a branch of the pipeline 3.

[0051] Here, pressure path 3 is guided by the second stage via rotary slide valve 50'.

[0052] See different positions of rotary slide valve 50' Figure 7a Valve body 52 includes an embodiment having another rotary spool layer with discs 52D and 55, as in rotary spool valve 50. Rotatable discs 55 and 53 can only be operated together via valve shaft 54.

[0053] First, from left to right, the following positions are shown where the line to clutch K2 is closed, while the lines to clutches K1 and K0 remain open. In this position, engine starting is performed via the pump assembly 12 of clutch K2. In the next valve position, the line to clutch K1 is closed, while the lines to clutches K2 and K0 remain open. Engine starting is then performed via the pump assembly 11 of clutch K1.

[0054] Another valve position is shown where the line to clutch K0 is closed while the lines to clutches K1 and K2 remain open. In this configuration, electric driving is performed. The final valve position is shown for hybrid driving, where all clutches are open.

[0055] Figure 7b The flow position of the second layer of the rotary slide valve 50' between plate 52D and the upper plate 55 is shown. Both openings 57 are always either both open or both closed.

Claims

1. Hydraulic circuit (1) for a hybrid dual clutch transmission of a motor vehicle, having hydraulically operable clutches K0, K1, K2 and at least one pressure valve (50) for regulating the clutch pressure of the clutches K0, K1, K2, wherein the clutch K0 is a separating clutch between an internal combustion engine and a dual clutch transmission provided with two further clutches K1, K2, wherein the further clutches K1, K2 are each associated with a pump actuator having a pump (15), and wherein between the clutch K0 and the clutches K1, K2 of the dual clutch transmission a motor (EM) is arranged, characterized in that The clutch K0 can be loaded with pressure via one of the pump devices (11, 12) associated with the two further clutches and a rotary slide (50) arranged in the path of the pump devices (11, 12) to the clutches K1, K2, wherein a non-return valve (19) is respectively arranged between the pump device (11) of the clutch K1 and the rotary slide (50) and between the pump device (12) of the clutch K2 and the rotary slide (50), between which a branch to the clutch K0 is arranged, wherein the rotary slide is constructed in two layers and regulates the throughflow to the branch of the clutch K0.

2. The hydraulic circuit (1) according to claim 1, characterized in that A switching valve (60) is arranged between the branch and the clutch K0.

3. The hydraulic circuit (1) according to claim 1, characterized in that, The clutch K0 is supplied with pressure via the pressure supply of the other clutch K1 or K2 which is working.

4. The hydraulic circuit (1) according to claim 1, characterized in that The clutch K0 is supplied with pressure via the pressure supply of the other clutch K1 or K2 which is not working.

5. A method for operating a hydraulic circuit (1) according to claim 1, characterized in that, The three clutches K0, K1, K2 are loaded with pressure by two pumps (15).

6. The method for operating a hydraulic circuit (1) according to claim 5, characterized in that The regulating function takes place in relation to the pump rotational speed.

7. The method for operating a hydraulic circuit (1) according to claim 5, characterized in that If one or both clutches K1, K2 are temporarily at a lower pressure, the non-return valves (8a, 8b) maintain the pressure of the clutch K0.

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