Methods for determining volumetric efficiency, hydraulic systems of motor vehicle powertrains, hybrid power modules, control units, and computer program products.

Abstract

The present invention relates to a method for determining the volumetric efficiency of a hydraulic pump (1) within a hydraulic system (2) of a motor vehicle powertrain (3), wherein the hydraulic system (2) comprises: a speed-controlled and leaking hydraulic pump (1), the pump speed of which can be measured by means of a speed sensor; and a hydraulic cylinder (5) connected to the hydraulic pump (1) via a first hydraulic path (4), the hydraulic cylinder having a hydraulically actuated piston (6) for operating a clutch (7) of the motor vehicle powertrain (3), wherein a pressure sensor (9) is provided in the hydraulic path (4) between the pressure side (8) of the hydraulic pump (1) and the hydraulically actuated piston (6) of the hydraulic cylinder (5) for measuring the hydraulic pressure applied in the hydraulic path (4); and a control unit (10) electrically connected to the pressure sensor (9), the speed sensor and the hydraulic pump (1).

Description

Technical Field

[0001] This invention relates to a method for determining the volumetric efficiency of a hydraulic pump within a hydraulic system of a motor vehicle powertrain. The invention also relates to a hydraulic system comprising: a speed-controlled and leaking hydraulic pump, the pump speed of which can be measured by means of a speed sensor; a hydraulic cylinder connected to the hydraulic pump via a first hydraulic path, the hydraulic cylinder having a hydraulically actuated piston for operating a clutch of the motor vehicle powertrain, wherein a pressure sensor is disposed in the hydraulic path between the pressure side of the hydraulic pump and the hydraulically actuated piston of the hydraulic cylinder for measuring the hydraulic pressure applied in the hydraulic path; and a control unit electrically connected to the pressure sensor, the speed sensor, and the hydraulic pump. The invention further relates to a control unit and a computer program product. Background Technology

[0002] Hybrid vehicle powertrains consist of a combination of an internal combustion engine and an electric motor, and can operate in pure electric mode—for example, in densely populated areas—while maintaining sufficient effective range and availability for long-distance travel. Furthermore, it is feasible to drive the vehicle simultaneously using both the internal combustion engine and the electric motor in specific operating conditions. The electric motor in hybrid vehicles typically replaces the previously common starter used for both the internal combustion engine and the generator, in order to reduce the weight increase of hybrid vehicles relative to vehicles with conventional powertrains.

[0003] As known from EP 0 773 127 A1, DE 100 18 926 A1 and US 2007 / 0175726 A1, a first clutch device can be provided between the internal combustion engine and the electric motor to disconnect the internal combustion engine from the electric motor and the rest of the powertrain of the hybrid vehicle. In pure electric driving, the first clutch device is disengaged and the internal combustion engine is shut off, so that the driving torque of the hybrid vehicle is applied solely by the electric motor.

[0004] To operate such a clutch device in a hybrid vehicle, a hydraulic clutch operating system—also known as a hydraulic disengagement system—is known. More precisely, to operate such a disengagement clutch in a hybrid powertrain, an electric pump actuator (EPA) is also used, which can be used to cool the electric motor, lubricate bearings, and / or hydraulically operate the clutch, wherein, for different hydraulic circulation loops, transmission fluid is preferably used as the hydraulic fluid for hydraulic control tasks.

[0005] The aforementioned pump actuators are typically uncompensated. This means that only 60% to 97% of the fluid volume drawn in at the inlet also leaves the pump again via the outlet. Leaks exist at the pump, through which fluid volume similarly leaves the pump in an indeterminate amount. For reliable cooling of components such as the motor and clutch, and for lubricating bearings, it is essential to determine the volumetric flow rate delivered by the pump through the outlet as accurately as possible. Summary of the Invention

[0006] Therefore, the object of the present invention is to provide a method for determining the volumetric efficiency of a hydraulic pump within a hydraulic system of a motor vehicle powertrain. Furthermore, the object of the present invention is to realize a correspondingly improved hydraulic system, a correspondingly improved hybrid power module, a correspondingly improved control unit, and a correspondingly improved computer program product.

[0007] The objective is achieved by a method for determining the volumetric efficiency of a hydraulic pump within a hydraulic system of a motor vehicle powertrain, wherein the hydraulic system includes: a speed-controlled and leaking hydraulic pump, the pump speed of which can be measured by means of a speed sensor; a hydraulic cylinder connected to the hydraulic pump via a first hydraulic path, the hydraulic cylinder having a hydraulically actuated piston for operating a clutch of the motor vehicle powertrain, wherein a pressure sensor is provided in the hydraulic path between the pressure side of the hydraulic pump and the hydraulically actuated piston of the hydraulic cylinder for measuring the hydraulic pressure applied in the hydraulic path; and a control unit electrically connected to the pressure sensor, the speed sensor, and the hydraulic pump, the method comprising the following steps:

[0008] a) The control unit provides a first control signal to change the hydraulic cylinder from a first operating position to a second operating position by energizing the hydraulic pump and thereby increasing the hydraulic pressure in the hydraulic path, thereby actuating the piston of the hydraulic cylinder.

[0009] b) The hydraulic pressure is measured by the pressure sensor and a signal representing the hydraulic pressure is transmitted to the control unit.

[0010] ba1) compares the measured hydraulic pressure with a first lower pressure threshold stored in the control unit, and

[0011] ba2) When the measured hydraulic pressure is greater than or equal to the first lower pressure threshold,

[0012] ba3) By evaluating the signal provided by the speed sensor, the counting of pump speeds performed by the hydraulic pump begins.

[0013] bb1) The measured hydraulic pressure is compared with a second upper pressure threshold stored in the control unit, and

[0014] bb2) When the measured hydraulic pressure is greater than or equal to the second upper pressure threshold,

[0015] bb3) End the counting of pump revolutions performed by the hydraulic pump.

[0016] c) The ratio ((P2-P1) / n) formed by dividing the difference between the lower pressure threshold and the upper pressure threshold by the obtained pump speed is stored in the control unit, wherein the stored ratio is associated with the volumetric efficiency of the hydraulic pump stored in the control unit, or the stored ratio is used to calculate the volumetric efficiency of the hydraulic pump.

[0017] This achieves the following advantage: during each clutch operation, the current value of the hydraulic pump's volumetric efficiency (pump efficiency) during vehicle operation can be determined. Therefore, it becomes possible to rapidly detect potential changes in the hydraulic pump's volumetric efficiency during vehicle operation and to consider these changes when controlling the hydraulic system, for example, when controlling the pump speed to cool the motor operating in the powertrain. This, for example, allows for optimization of the motor's efficiency through cooling.

[0018] First, the elements of the claimed invention are presented in the order presented, and a particularly preferred design of the invention is described below.

[0019] In the sense of this application, a motor vehicle powertrain is understood as all components that generate power in a motor vehicle to drive the motor vehicle and transmit that power through the wheels to the street.

[0020] In the sense of this application, a motor vehicle refers to a land vehicle that moves by mechanical force and is not connected to a track. Motor vehicles can be selected, for example, from the group consisting of passenger cars (PKW), freight vehicles (LKW), small motorcycles, light motor vehicles, motorcycles, buses (KOM), or tractors.

[0021] Hybrid electric vehicles, also known as hybrid electric vehicles (HEVs), are electric vehicles driven by at least one electric motor and another energy converter, and which extract energy from their electrical storage (Akku) and additionally carried fuel.

[0022] A control unit, as used therein in this invention, is used for one or more technical systems of a motor vehicle, particularly for electrically open-loop control and / or closed-loop control. In particular, the control unit can be configured for open-loop control and / or closed-loop control of one or more hydraulic circulation loops.

[0023] The control unit particularly has wired or wireless signal input terminals for receiving, in particular, electrical signals, such as sensor signals. Furthermore, the control unit also preferably has wired or wireless signal output terminals for transmitting, in particular, electrical signals, for example, to the electric actuators or electric consumers of the motor vehicle.

[0024] The control unit is capable of performing open-loop control operations and / or closed-loop control operations. More particularly preferably, the control unit includes hardware configured to execute software. Preferably, the control unit includes at least one electronic processor for implementing program processes defined in the software.

[0025] The control unit may also have one or more electronic memories in which data contained in signals transmitted to the control unit can be stored and retrieved again. Furthermore, the control unit may have one or more electronic memories in which data can be stored variably and / or immutably.

[0026] The control unit can include multiple control devices, which are spatially separated from each other in the vehicle. These control devices are also called electronic control units (ECUs) or electronic control modules (ECMs) and preferably have electronic microcontrollers for performing computational operations to process data, particularly preferably by means of software. The control devices are preferably networked together, enabling wired and / or wireless data exchange between them. It is also particularly feasible for the control devices to be networked together via a bus system present in the vehicle, such as a CAN bus or LIN bus.

[0027] The clutch device in the sense of this invention has the following basic functions: establishing a releasable, force-fitting and / or form-fitting connection between the clutch input shaft and the clutch output shaft for transmitting torque.

[0028] According to an advantageous design of the invention, the ratio stored in the control unit can be used to determine the required rotational speed of the hydraulic pump, particularly for cooling the motor within the powertrain of a motor vehicle.

[0029] The advantage of this design is that it optimizes motor cooling.

[0030] According to another preferred improvement of the invention, a first operating position of the hydraulic cylinder corresponds to the operating position where the piston is fully inserted, and a second operating position of the hydraulic cylinder corresponds to the operating position where the piston is fully removed.

[0031] The object of the present invention is also achieved by a hydraulic system for a motor vehicle powertrain, wherein the hydraulic system includes: a speed-controlled and leaking hydraulic pump, the pump speed of which can be measured by means of a speed sensor; a hydraulic cylinder connected to the hydraulic pump via a first hydraulic path, the hydraulic cylinder having a hydraulically actuated piston for operating a clutch of the motor vehicle powertrain, wherein a pressure sensor is provided in the hydraulic path between the pressure side of the hydraulic pump and the hydraulically actuated piston of the hydraulic cylinder for measuring the hydraulic pressure applied in the hydraulic path; and a control unit electrically connected to the pressure sensor, the speed sensor and the hydraulic pump, wherein the control device has implementation routines for performing the method of the present invention.

[0032] The objective of this invention is also achieved by a hybrid power module, which includes an electric motor and a hydraulic system.

[0033] In a hybrid powertrain module, the structural and functional components of the hybrid powertrain are spatially and / or structurally combined and pre-configured to enable the hybrid powertrain module to be integrated into the powertrain of a motor vehicle in a particularly simple manner. In particular, an electric motor and a clutch system may be present in the hybrid powertrain module, the clutch system particularly having a disengagement clutch for engaging the electric motor into the powertrain and / or disengaging the electric motor from the powertrain.

[0034] Hybrid power modules can be classified into the following categories, P0-P4, based on the connection point between the electric motor and the powertrain:

[0035] P0: The electric motor is positioned before the internal combustion engine and coupled to the engine, for example, via a belt. In this configuration, the electric motor is sometimes also referred to as a belt-driven starter-generator (RSG).

[0036] P1: The electric motor is mounted directly after the internal combustion engine. This mounting of the electric motor can, for example, be done by fixing it to the crankshaft before engaging the clutch.

[0037] P2: The electric motor is located in the powertrain between the disengagement clutch, commonly referred to as K0, and the starting clutch, but before the vehicle's transmission.

[0038] P3: The electric motor is located in the vehicle's transmission and / or transmission output shaft.

[0039] P4: The electric motor is located at the existing or separate axle, and

[0040] P5: The electric motor is located at or inside the wheel, for example, as a hub motor.

[0041] Preferably, the hybrid power module is configured as a P2 hybrid power module. Attached Figure Description

[0042] Without limiting the general inventive concept, the present invention will be described in detail below with reference to the accompanying drawings.

[0043] The attached diagram shows:

[0044] Figure 1 A schematic block diagram of a motor vehicle with a hybrid power module is shown.

[0045] Figure 2 The hydraulic circuit diagram of the hybrid power module is shown.

[0046] Figure 3 A flowchart is shown for a method of determining the volumetric efficiency of a hydraulic pump within the hydraulic system of a motor vehicle powertrain. Detailed Implementation

[0047] Figure 2 A schematic diagram of a hydraulic system 2 for implementing the method according to the invention is shown. In the illustrated embodiment, the hydraulic system 2 is disposed in a hybrid power module 18 having a motor 17.

[0048] The hydraulic system 2 includes, for example, a hydraulic pump 1 configured as a gear pump with a leakage line not shown in the fluid housing 20, which is connected on one side to a coolant line 21 to provide a speed-controlled volumetric flow. The coolant line 21 carries fluid 23, such as a pressure medium or oil, to a first consumer 22 configured as, for example, a heat exchanger. The fluid 23 is carried to the first consumer 22 for cooling or lubrication purposes.

[0049] On the other side, hydraulic pump 1 is connected to hydraulic path 4. Hydraulic path 4 is used to load hydraulic cylinder 5 and clutch 7. In order to selectively operate the hydraulic cylinder or hydraulic actuator 24 for parking lock 25, a switching valve 26 is provided, such as a dual-way switching valve.

[0050] Therefore, the hydraulic system 1 has a hydraulic cylinder 5 connected to the hydraulic pump 1 via a first hydraulic path 4, the hydraulic cylinder having a hydraulically actuated piston 6 for operating the clutch 7 of the motor vehicle powertrain 3. In the hydraulic path 4, a pressure sensor 9 is provided between the pressure side 8 of the hydraulic pump 1 and the hydraulically actuated piston 6 of the hydraulic cylinder 5 for measuring the hydraulic pressure applied in the hydraulic path 4.

[0051] In the illustrated example, hydraulic pump 1 is configured as an electrically driven reversible pump to deliver fluid 23 in a first rotational direction to coolant line 21 and in a second rotational direction to hydraulic path 4. Hydraulic pump 1 is driven by electric motor 27, which is controlled by control unit 10. Control unit 10 has implementation routines for performing a method for determining the volumetric efficiency of hydraulic pump 1 within hydraulic system 2, which are described below according to... Figure 3 It is further elaborated.

[0052] Therefore, the hydraulic system 2 includes a speed-controlled and leaky hydraulic pump 1, the pump speed of which can be measured by means of a speed sensor. The pressure sensor 9, the speed sensor, and the hydraulic pump 1 are electrically connected to the control unit 10.

[0053] Figure 3 Showing the methods used to determine such as from Figure 2 The method process for improving the volumetric efficiency of hydraulic pump 1 within the hydraulic system 2 of a known motor vehicle powertrain 3.

[0054] To determine the efficiency of hydraulic pump 1 affected by leakage of hydraulic pump 1, the following steps are performed:

[0055] First, a first control signal 11 is provided by the control unit 10 to change the hydraulic cylinder 5 from a first operating position to a second operating position by energizing the hydraulic pump 1 and thereby increasing the hydraulic pressure in the hydraulic path 4, thereby actuating the piston 6 of the hydraulic cylinder 5. The first operating position of the hydraulic cylinder 5 corresponds here to the operating position where the piston 6 is fully engaged, and the second operating position of the hydraulic cylinder 5 corresponds to the operating position where the piston 6 is fully disengaged.

[0056] During the operation of hydraulic pump 1 and the pressure rise in hydraulic path 4, hydraulic pressure 12 is continuously measured by pressure sensor 9 and a signal 13 representing hydraulic pressure 12 is transmitted to control unit 10.

[0057] There, the measured hydraulic pressure 12 is compared with a first lower pressure threshold 14 stored in the control unit 10, wherein when there is a condition that the measured hydraulic pressure 12 is greater than or equal to the first lower pressure threshold 14,

[0058] The pump revolutions performed by hydraulic pump 1 are counted by evaluating the signal provided by the revolution sensor.

[0059] Subsequently, monitoring is performed and the measured hydraulic pressure 12 is compared with a second upper pressure threshold 15 stored in the control unit 10, wherein the counting of pump revolutions performed by the hydraulic pump 1 ends when there is a condition that the measured hydraulic pressure 12 is greater than or equal to the second upper pressure threshold 15.

[0060] Now, the ratio ((p1-p2) / n) formed by dividing the difference between the lower pressure threshold 14 and the upper pressure threshold 15 by the obtained pump speed is stored in the control unit 10, wherein the stored ratio is associated with the volumetric efficiency of the hydraulic pump 1 stored in the control unit 10 or the stored ratio is used to calculate the volumetric efficiency of the hydraulic pump 1.

[0061] The ratio stored in the control unit 10 can now be used to determine the required rotational speed of the hydraulic pump 1, particularly for cooling the motor 17 within the vehicle powertrain 3. The efficiency (ratio) determined in this manner is used to correct the fluid volume for the coolant line 3, which is set in relation to the rotational speed of the hydraulic pump 1.

[0062] This invention is not limited to the embodiments shown in the figures. Therefore, the above description should not be considered limiting but rather explanatory. The following claims should be understood as meaning that the mentioned features exist in at least one embodiment of the invention. This does not exclude the presence of other features. If the claims and the above description define "first" and "second" features, the names are used to distinguish two features of the same type, without specifying a priority order.

[0063] Explanation of reference numerals in the attached figures

[0064] 1. Hydraulic pump

[0065] 2 Hydraulic System

[0066] 3. Motor vehicle powertrain

[0067] 4 Hydraulic path

[0068] 5 hydraulic cylinders

[0069] 6-piston

[0070] 7 clutches

[0071] 8. Pressure side

[0072] 9 pressure sensors

[0073] 10 control units

[0074] 11 Control Signals

[0075] 12 pressure

[0076] 13 signals

[0077] 14 pressure threshold

[0078] 15 pressure threshold

[0079] 17 motors

[0080] 18 hybrid power modules

[0081] 19 motor vehicles

[0082] 20 fluid bottom shell

[0083] 21 Coolant piping

[0084] 22 Consumables

[0085] 23 fluids

[0086] 24 hydraulic actuators

[0087] 25 parking lock

[0088] 26 Switching Valve

[0089] 27. Electric motor.

Claims

1. A method for determining the volumetric efficiency of a hydraulic pump (1) within a hydraulic system (2) of a motor vehicle powertrain (3), The hydraulic system (2) mentioned above includes: A speed-controlled and leaky hydraulic pump (1), the pump speed of which can be measured by means of a speed sensor; and a hydraulic cylinder (5) connected to the hydraulic pump (1) via a first hydraulic path (4), the hydraulic cylinder having a hydraulically actuated piston (6) for operating a clutch (7) of the motor vehicle powertrain (3), wherein a pressure sensor (9) is provided in the first hydraulic path (4) between the pressure side (8) of the hydraulic pump (1) and the hydraulically actuated piston (6) of the hydraulic cylinder (5) for measuring the hydraulic pressure applied in the first hydraulic path (4); and a control unit (10) electrically connected to the pressure sensor (9), the speed sensor and the hydraulic pump (1). The method includes the following steps: a) The control unit (10) provides a first control signal (11) for changing the hydraulic cylinder (5) from a first operating position to a second operating position by energizing the hydraulic pump (1) and the resulting increase in hydraulic pressure in the first hydraulic path (4), thereby actuating the piston (6) of the hydraulic cylinder (5). b) The hydraulic pressure (12) is measured by the pressure sensor (9) and a signal (13) representing the hydraulic pressure (12) is transmitted to the control unit (10). ba1) compares the measured hydraulic pressure (12) with the first lower pressure threshold (14) stored in the control unit (10), and ba2) When the measured hydraulic pressure (12) is greater than or equal to the first lower pressure threshold (14), ba3) By evaluating the signal provided by the speed sensor, the counting of pump speeds performed by the hydraulic pump (1) begins. bb1) The measured hydraulic pressure (12) is compared with the second upper pressure threshold (15) stored in the control unit (10), and bb2) When the measured hydraulic pressure (12) is greater than or equal to the second upper pressure threshold (15), bb3) End the counting of pump revolutions performed by the hydraulic pump (1), c) The ratio ((P1-P2) / n) formed by dividing the difference between the lower pressure threshold (14) and the upper pressure threshold (15) by the obtained pump speed is stored in the control unit (10), wherein the stored ratio is associated with the volumetric efficiency of the hydraulic pump (1) stored in the control unit (10), or the stored ratio is used to calculate the volumetric efficiency of the hydraulic pump (1).

2. The method according to claim 1, Its features are, The ratio stored in the control unit (10) is used to determine the required rotational speed of the hydraulic pump (1).

3. The method according to claim 1 or 2, Its features are, The first operating position of the hydraulic cylinder (5) corresponds to the operating position where the piston (6) is fully moved in, and the second operating position of the hydraulic cylinder (5) corresponds to the operating position where the piston (6) is fully moved out.

4. A hydraulic system (2) for a motor vehicle powertrain (3), wherein the hydraulic system (2) comprises: A speed-controlled and leaky hydraulic pump (1), the pump speed of which can be measured by means of a speed sensor; and a hydraulic cylinder (5) connected to the hydraulic pump (1) via a first hydraulic path (4), the hydraulic cylinder having a hydraulically actuated piston (6) for operating a clutch (7) of the motor vehicle powertrain (3), wherein a pressure sensor (9) is provided in the first hydraulic path (4) between the pressure side (8) of the hydraulic pump (1) and the hydraulically actuated piston (6) of the hydraulic cylinder (5) for measuring the hydraulic pressure applied in the first hydraulic path (4); and a control unit (10) electrically connected to the pressure sensor (9), the speed sensor and the hydraulic pump (1). The control unit (10) is characterized in that it is used to perform the method according to any one of claims 1 to 3.

5. A hybrid power module (18) comprising an electric motor (17) and a hydraulic system (2) according to claim 4.

6. A control unit (10) for controlling a hydraulic system (2) in a motor vehicle powertrain (3), comprising a processor and a memory, the memory containing computer program code, wherein the memory and the computer program code are configured to cause the control unit (10) to perform the method according to any one of claims 1 to 3 by means of the processor.

7. A computer program product stored on a machine-readable medium or a computer data signal expressed by electromagnetic waves, having program code adapted to perform the method according to any one of claims 1 to 3.

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