Method and apparatus for starting an internal combustion engine by means of a belt drive with a belt starter generator in a vehicle

Abstract

Method for starting an internal combustion engine by means of a belt drive with a belt starter generator in a vehicle, in which the belt starter generator (2) is energized to drive a belt (3) of the belt drive (1) and a torque of the belt (3) is transmitted to a crankshaft (10) coupled to the internal combustion engine (7), characterized in that at least one parameter (P) of the belt starter generator (2) is set as a function of temperature for starting the internal combustion engine (7), characterized in that the at least one parameter (P) of the belt starter generator (2) is set as a function of the temperature (Tv) of the internal combustion engine (7) when a difference between the temperature (Tv) of the internal combustion engine (7) and an ambient temperature (TA) of the vehicle exceeds a predetermined difference threshold.

Description

The invention relates to a method for starting an internal combustion engine by means of a belt drive with a belt starter generator in a vehicle, in which the belt starter generator is energized to drive a belt of the belt drive and a torque of the belt is transmitted to a crankshaft coupled to the internal combustion engine, and to a device for carrying out the method. DE 102 46 978 A1 discloses a method for starting a drive unit for a motor vehicle. DE 10 2017 128 817 A1 discloses a method for starting an internal combustion engine using an electric motor. EP 1 289 120 A1 discloses a method for impulse-like increase of the torque of an asynchronous motor for starting an internal combustion engine. From DE 10 2014 207 720 A1 a method for controlling a belt drive for an internal combustion engine is known, in which a pulley generator arranged in drive connection with a crankshaft of the internal combustion engine by means of a belt is controlled by means of a control unit. DE 10 2018 132 398 A1 discloses a method for starting an internal combustion engine using a belt drive and / or a pinion starter in a motor vehicle equipped with a belt-driven starter generator. The belt-driven starter generator is energized to generate torque for starting the internal combustion engine, and the torque applied to a belt of the belt drive is transmitted via the belt to a crankshaft of the internal combustion engine. To start the internal combustion engine, the pinion starter engages a starter ring gear on the primary side of a dual-mass flywheel, thereby setting the crankshaft in rotation. After the internal combustion engine has started, the pinion starter is switched off. On the opposite side of the crankshaft, a pulley decoupler of the belt drive is connected to the crankshaft. The invention is based on the objective of providing a method and a device for starting an internal combustion engine, with which a reliable start of the internal combustion engine is possible in all situations despite cost reduction. The problem is solved by the subject matter of claim 1. In a method for starting an internal combustion engine in a vehicle using a belt drive with a belt-driven starter generator, where the starter generator is energized to drive a belt of the belt drive and the belt's torque is transmitted to a crankshaft coupled to the internal combustion engine, at least one parameter of the starter generator is temperature-dependent for starting the engine. This has the advantage that a key start of the internal combustion engine, which will henceforth be understood as a first start or a cold start, can be performed via the belt drive. A pinion starter can thus be omitted. This reduces the installation space required by the internal combustion engine while simultaneously saving weight. In addition to cost reduction, the bell housing and the ring gear of the dual-mass flywheel are simplified.The latter is particularly true because no power transmission is necessary via this connection. There is also potential for savings in electrical wiring. In a non-inventive manner, at least one parameter of the belt-driven starter generator is adjusted depending on the temperature of the internal combustion engine. This ensures that, at any temperature of the internal combustion engine, a corresponding breakaway torque can be transmitted from the belt drive to the internal combustion engine in order to start it. According to the invention, at least one parameter of the belt-driven starter generator is adjusted as a function of the internal combustion engine temperature when a difference between the temperature of the internal combustion engine and the ambient temperature of the vehicle exceeds a predetermined threshold value. This condition can be easily detected by software. In a further embodiment, at least one parameter of the belt-driven starter generator is variably adjusted, preferably in stages, depending on the respective temperature of the combustion engine. Linear or non-linear relationships between the engine temperature and the ambient temperature can be taken into account. In another embodiment, if the combustion engine temperature falls below a first predetermined temperature, at least one parameter of the belt-driven starter generator is increased or decreased, and if the combustion engine temperature falls below a second predetermined temperature, which is lower than the first predetermined temperature, it is further increased or decreased. Thus, a staged adjustment can be easily implemented. In another embodiment, the belt-driven starter generator is controlled in pulses. This is particularly advantageous at very low internal combustion engine temperatures, as the engine breakaway torque can be overcome quickly and the internal combustion engine can reach operating speed. In another embodiment, the belt-driven starter generator is controlled with an alternating current direction. This ensures reliable starting of the combustion engine and the build-up of its speed. In another embodiment, a predetermined torque, less than the torque required to start the engine, is applied to the belt drive for a defined period of time while the internal combustion engine is stationary. This step can be performed as an adjustment procedure before the actual engine start to ensure that any play in the various components of the belt drive is overcome. By overcoming this play, the entire belt drive is tensioned so that a starting torque for the crankshaft of the internal combustion engine can always be applied under the same conditions. In a further embodiment, a key start of the combustion engine is performed when at least one parameter of the belt-driven starter generator is adjusted based on temperature, while a start-stop system is activated when the first predetermined temperature of the combustion engine is exceeded. The belt drive can thus be used for all combustion engine starting situations provided for in the vehicle. Another aspect of the invention relates to a device for starting an internal combustion engine in a vehicle, comprising a belt drive with a belt-driven starter generator which can be coupled to a crankshaft of the internal combustion engine via a belt, wherein the belt-driven starter generator has a control unit. In this device, the control unit is configured to carry out a method according to at least one feature described in this patent application. The invention allows for numerous embodiments. One of these will be explained in more detail with reference to the figures shown in the drawing. Figure 1 shows an embodiment of a device for carrying out the method according to the invention, Figure 2 shows an embodiment of a belt drive coupled to an internal combustion engine, Figure 3 shows an embodiment of the method according to the invention. Figure 1 shows an embodiment of a device for carrying out the method according to the invention. The device is designed as a belt drive 1 and comprises a belt starter generator 2. The belt starter generator 2 drives a belt 3, which drives an auxiliary unit 5 via a pulley decoupler 4. In the area of ​​the belt starter generator 2, the belt is surrounded by a pendulum tensioner 6, which has tensioning rollers 8 whose positions may be undefined after the internal combustion engine 7 has stopped. In addition to the position of the tensioning rollers 8, free angles in which no torque transmission takes place are also undefined in various components of the belt drive 1. Fig. 2 shows the connection of the belt drive 1 to the internal combustion engine 7. The pulley decoupler 4 is coupled to a crankshaft 10, which engages with a dual-mass flywheel 9 of the internal combustion engine 7. In this case, an air conditioning compressor is used as an auxiliary component 5. Simultaneously, further auxiliary components, a water pump 11 and an oil pump 12, are driven by the belt drive 1. To operate the internal combustion engine 7, the belt-driven starter generator 2 includes a control unit 13, which supplies power to the belt-driven starter generator 2. The control unit 13 is connected to a temperature sensor 14 for measuring the temperature of the internal combustion engine 7 and to an ambient temperature sensor 15 (Fig. 1). An embodiment of the method according to the invention will now be explained with reference to Fig. 3. The method is initialized in block 100. Subsequently, it is checked in block 110 whether the internal combustion engine 7 is switched off, that is, whether the rotational speed nV of the internal combustion engine 7 is zero. If this is the case, an adjustment process JV follows in block 120. In this adjustment process JV, the belt starter generator 2 is briefly energized to generate a torque that is less than the torque required to start the internal combustion engine 7. This torque is transmitted to the belt drive 1, causing the pendulum tensioner 6, as well as other components of the belt drive 1, to assume a defined starting position, thereby overcoming the clearance angles of the components and making the belt drive 1 ready for operation. In the subsequent block 130, it is checked whether the temperature TV of the combustion engine 7 is lower than a first predefined temperature T1. The ambient temperature TA of the vehicle, measured by the ambient temperature sensor 15, can be used as the first predefined temperature T1. If block 130 determines that the temperature TV of the combustion engine 7 is higher than the first predefined temperature T1, the vehicle's start-stop system is activated in block 140. Otherwise, block 150 checks whether the temperature Tv of the combustion engine 7 is lower than a second predefined temperature T2, which is lower than the first predefined temperature T1. If this is not the case, parameters P of the belt-driven starter generator 2 are set in block 160 as a function of the temperature T1.The variable parameters P include the rotational speed of the belt-driven starter generator 2, which is increased to, for example, > 400 rpm before the first injection into the combustion engine 7. Likewise, the starting gradient of the belt-driven starter generator 2 can be reduced to 300 Nm / s, or the maximum permissible torque can be increased. If the temperature Tv of the combustion engine 7 is lower than the second predefined temperature T2, the belt-driven starter generator 2 in block 170 is pulsed, and the current direction can be reversed simultaneously. At the same time, or alternatively, the parameters P of the belt-driven starter generator 2 are readjusted to the predefined temperature T2. This allows the speed of the belt-driven starter generator 2 to be further increased to, for example, > 600 rpm before the first injection. The key start is then performed in block 180. In addition to changing the parameters of the belt-driven starter generator 2, operating parameters of the internal combustion engine 7 can also be varied depending on its engine temperature Tv. These parameters can include the injection speed, throttle angle, or valve position of the internal combustion engine 7 in order to reduce compression forces during the starting process of the internal combustion engine 7. The key start, i.e., the initial start or a cold start of the internal combustion engine, is performed using these temperature-dependent parameters P (Block 180). After the key start is enabled (block 180) or the start-stop system is activated (block 140), block 190 checks whether the internal combustion engine 7 is running, i.e., whether its speed nv ≠ 0. If the internal combustion engine 7 is running, the program is terminated (block 200). If the internal combustion engine 7 is not running, the process returns to block 130. Reference symbol list 1 Belt drive 2 Belt starter generator 3 Belt 4 Pulley decoupler 5 Auxiliary unit 6 Pendulum tensioner 7 Internal combustion engine 8 Tension pulleys 9 Dual-mass flywheel 10 Crankshaft 11 Water pump 12 Oil pump 13 Control unit 14 Temperature sensor 15 Ambient temperature sensor nv Internal combustion engine speed JV Adjustment process Tv Internal combustion engine temperature T1 First preset temperature T2 Second preset temperature TA Ambient temperature P Belt starter generator parameter

Claims

Method for starting an internal combustion engine by means of a belt drive with a belt starter generator in a vehicle, in which the belt starter generator (2) is energized to drive a belt (3) of the belt drive (1) and a torque of the belt (3) is transmitted to a crankshaft (10) coupled to the internal combustion engine (7), characterized in that at least one parameter (P) of the belt starter generator (2) is set as a function of temperature for starting the internal combustion engine (7), characterized in that the at least one parameter (P) of the belt starter generator (2) is set as a function of the temperature (Tv) of the internal combustion engine (7) when a difference between the temperature (Tv) of the internal combustion engine (7) and an ambient temperature (TA) of the vehicle exceeds a predetermined difference threshold. Method according to claim 1, characterized in that, depending on the respective temperature (Tv) of the internal combustion engine (7), the at least one parameter (P) of the belt starter generator (2) is variably, preferably in stages, adjusted. Method according to claim 2, characterized in that if a first predetermined temperature (T1) of the internal combustion engine (7) is undershot, the at least one parameter (P) of the belt starter generator (2) is increased or decreased, and if a second predetermined temperature (T2), which is smaller than the first predetermined temperature (T1), is undershot, it is further increased or decreased. Method according to at least one of the preceding claims, characterized in that the belt starter generator (2) is controlled in a pulse-like manner. Method according to at least one of the preceding claims, characterized in that the belt starter generator (2) is controlled with an alternating current direction. Method according to at least one of the preceding claims, characterized in that a predetermined torque is applied to the belt drive (1) when the internal combustion engine (7) is at a standstill, which is less than the torque required to start the internal combustion engine (7). Method according to at least one of the preceding claims, characterized in that, when the at least one parameter of the belt starter generator (2) is adjusted depending on the temperature, a key start of the internal combustion engine (7) is performed, while when the first predetermined temperature (T1) of the internal combustion engine (7) is exceeded, a start-stop system is activated. Device for starting an internal combustion engine in a vehicle, comprising a belt drive (3) with a belt starter generator (2) which can be coupled to a crankshaft (10) of the internal combustion engine (7) via a belt (3), wherein the belt starter generator can be controlled by a control unit (13), characterized in that the control unit (13) is configured to carry out a method according to at least one of the preceding claims.

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