Parallel start system for starting an internal combustion engine

Description

[0001] The present invention relates to a parallel start system for starting an internal combustion engine. State of the art

[0002] Electrically operated starters are typically used to start internal combustion engines. For larger engines with several tens or hundreds of liters of displacement, such as those found in construction machinery, large tractors, stationary engines, and even marine engines, it is common practice to connect multiple starters in parallel to provide high starting power. In these so-called parallel start systems, several electric starters act simultaneously on the ring gear of the internal combustion engine and can thus jointly provide the required starting power.

[0003] To prevent overloading the starters used at the beginning of the starting phase, the starters can be synchronized by connecting switching contacts in series. At the beginning of the starting process, the engagement relays of all starters are activated simultaneously, and these begin the process of meshing the pinions with the ring gear. The main current for all starters is switched simultaneously only after the last individual starter has engaged.

[0004] However, with a fixed series connection of the individual contacts, a fault in a single starter or in the wiring between the starters will lead to a complete failure of the starting system. The probability of failure of the entire system is thus increased in proportion to the number of starters used. If the excitation coils of the (motor current) switching relays of all individual starters are activated simultaneously, the current consumption in the control path and its switching element (e.g., in the engine control unit) is multiplied.

[0005] DE 10 2005 006 248 A1 discloses a parallel starter system with minimal wiring effort. This system comprises several starters connected in parallel, each with a starter motor and a starting relay. This parallel starter system can be implemented particularly easily and cost-effectively if at least one of the switches includes a power relay that switches the main current path to the associated starter motor, and if the starting relay, power relay, and starter motor are implemented as a single structural unit.

[0006] DE 10 2009 001 690 A1 concerns a parallel start system with several starters and a separate control unit.

[0007] DE 10 2010 030 398 A1 concerns a parallel start system in which, depending on defined operating conditions, all, some, or individual starter motors can be controlled to start the internal combustion engine. A separate starter control unit is provided for this purpose.

[0008] EP 2 923 215 A1 relates to a test unit for testing a dual starter. The test unit has two interfaces for communication with corresponding starter interfaces. Disclosure of the invention

[0009] According to the invention, a parallel start system for starting an internal combustion engine and a method for operating such a system are proposed, having the features of the independent patent claims. Advantageous embodiments are the subject of the dependent claims and the following description.

[0010] The invention utilizes the measure of controlling the parallel operation of several starters not by circuitry, but by information technology. For this purpose, each of the at least two starters of the parallel start system has a logic unit with a data interface, via which the logic units are interconnected for data transmission. A first of the starters then functions as a master, whose logic unit is configured to respond to the receipt of a start request, in particular from a higher-level processing unit such as, for example,the engine control unit to output an engagement request and a cranking request to the logic unit of at least one further starter acting as a slave, wherein the logic unit of the at least one further starter is configured, upon receipt of the engagement request, to control the mechanical actuator, in particular a gearing relay, to move the pinion into the engagement position and, upon receipt of the cranking request, to control the starter motor to rotate the pinion. Although one or the further starter is usually referred to below, the described measures and features preferably apply to all further starters or slaves of the parallel starter system.

[0011] Thanks to the IT parallel connection, a malfunction in a single starter or in the wiring between the starters does not lead to a complete failure of the starting system. Rather, flexible control of the multiple starter system is possible even if a single starter malfunctions. The on-board electrical system is no longer burdened by parallel-connected relays on the control side, because the IT parallel connection loads the higher-level processing unit or the on-board electrical system with a relay coil current, thus reducing the current consumption in the control path. This allows the system to be dimensioned according to a lower output power.

[0012] Furthermore, depending on the implemented operating strategy, the availability of the starting system can be increased even beyond that of a single starter by means of limited redundancy, provided a corresponding "emergency operation" concept is implemented. For example, limited "emergency operation" with, for example, two of three starters can still be enabled.

[0013] Within the scope of the invention, the individual starters of a parallel start system are each equipped with a logic unit (intelligent control electronics) (in particular instead of an electromechanical control relay) which can both trigger the meshing process (toe-in movement) and actuate the main current switch to energize the starter motor.

[0014] The determination of which of the starters is the first starter or master within the meaning of the invention can, for example, be determined after production or only at the installation site, for example by appropriate cabling (the master is the starter that is connected (e.g. as the only one or as the first) to the higher-level processing unit) or connector coding or appropriate configuration, both hardware-wise (e.g. jumpers, DIP switches) and software-wise (so-called end-of-line programming).

[0015] Conveniently, the logic unit of the first of the at least two starters is configured to control the mechanical actuator to move the pinion into the meshing position upon receipt of the start request. In other words, the master also meshes upon receipt of the start request.

[0016] Preferably, the logic unit of the at least one further starter is configured to output an engagement message after the pinion has been successfully moved into the meshing position. This allows the master to easily check when the meshing process of the slave(s) is complete and whether, and which, meshing processes were successful.

[0017] The logic unit of the first starter is expediently configured to issue the cranking request upon receiving an engagement message from the logic unit of the at least one further starter and / or to control its own starter motor to rotate the pinion. In other words, after all slaves have successfully engaged (and preferably also its own successful engagement), the master sends the command to switch the main current (current for the starter motor) to all participating starters (and preferably also switches its own main current), so that the cranking process of the combustion engine can begin in a synchronized manner.

[0018] According to a preferred embodiment, the logic unit of the first starter is configured to issue the cranking request and / or to control the starter motor to rotate the pinion after a predetermined period of time has elapsed following the output of the engagement request. This allows, in particular, the combustion engine to be started even if not all engagement processes could be completed successfully, e.g., due to a so-called tooth-on-tooth position between the pinion and ring gear, or similar. In other words, even after the time has elapsed, the master sends the command to switch the main current (current for the starter motor) to all or only to the engaged starters (and preferably also switches its own main current), so that the cranking process of the combustion engine can begin in a synchronized manner.This second alternative comprises that the logic unit of the first starter is configured to issue the spin request only to the logic unit of the further starters from which it has received a lane-entry message, after the expiration of the predetermined time period after the issuance of the lane-entry request.

[0019] Advantageously, the logic unit of the first starter has a single data interface for receiving the start request, outputting the engagement request, outputting the spin request, and receiving the engagement message. This data interface is thus bidirectional. Such an embodiment requires few additional components.

[0020] Alternatively, however, the logic unit of the first starter can have a first data interface for receiving the start request and a second data interface for outputting the engagement request and the spin request, and for receiving the engagement message. In other words, the first data interface is used for communication with the higher-level processing unit, and the second data interface is used for communication between the starters. The first data interface must be at least unidirectional in order to transmit the start request to the first starter. The second data interface must be bidirectional in order to transmit the engagement request, spin request, and engagement message.

[0021] According to the invention, the data interface is a bus interface, in particular CAN, FlexRay, or LIN. This allows the use of proven interfaces.

[0022] Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings.

[0023] The invention is illustrated schematically in the drawing using exemplary embodiments and is described below with reference to the drawing. Short description of the drawings

[0024] .Figure 1 schematically shows a parallel start system according to a preferred embodiment of the invention. Figure 2 schematically shows a preferred embodiment of a starting method using a parallel start system according to Figure 1 . Embodiment(s) of the invention

[0025] In Figure 1 A parallel start system according to a preferred embodiment of the invention is shown schematically and designated overall by 100.

[0026] The parallel start system 100 is connected to a network 20, for example, the on-board electrical system of a vehicle, and serves to start an internal combustion engine 10. The internal combustion engine 10 has a crankshaft 12 and a ring gear 11 connected thereto in a rotationally fixed manner. To start the internal combustion engine, the ring gear 11 and thus the crankshaft 12 must be set in rotation until a rotational speed sufficient for ignition is reached.

[0027] The network 20 is supplied, for example, by a battery 21, which in the present case supplies a computing unit 23 for controlling the parallel start system 100, for example an engine control unit, the parallel start system 100 and other electrical loads or consumers 24 via a fuse box 22.

[0028] The parallel starter system 100 has a first starter 110 (master) and two further starters 120, 130 (slaves), each having a logic unit 111, 121, 131, a switching / engaging unit 112, 122, 132, a starter motor M and a pinion 113, 123, 133.

[0029] The logic unit 111 of the first starter 110 has a first data interface 111a for communication with the computing unit 23 and a second data interface 111b for communication with the additional starters 120, 130. The logic units 121, 131 of the additional starters, in turn, each have a data interface 121b or 131b for communication with the logic unit 111 of the first starter. Communication between the starters takes place via a bidirectional interface, in particular a CAN interface. For example, communication between the computing unit 23 and the logic unit 111 of the first starter also takes place via a bidirectional interface.

[0030] The respective switching / engaging units 112, 122, and 132 of the starter motors comprise, on the one hand, an actuator for moving the respective pinion 113, 123, 133 into the meshing position shown in the figure, in which the respective pinion is in engagement with the ring gear 11 of the internal combustion engine 10. For this purpose, the respective pinion can be moved horizontally to the right and left along the double arrow in the figure. In the initial position, the respective pinion is disengaged from the ring gear 11 and must first be brought into engagement with the ring gear 11 to start the internal combustion engine.

[0031] Furthermore, the respective switching / engaging unit 112, 122, 132 has a switch, in particular a relay, for energizing the starter motor M. The respective switching / engaging unit is controlled by the associated logic unit.

[0032] An exemplary method according to a preferred embodiment of the invention will be described below with reference to Figure 2 be explained.

[0033] The method begins in a step 201 when a start request occurs in the network 20.

[0034] In a step 202, the start request is transmitted from the computing unit 23 to the first starter 110.

[0035] In a step 203, the start request is checked for plausibility by the logic unit 111 of the first starter 110, wherein, in particular in the event that the start request is considered invalid, an error message can be transmitted back to the computing unit 23, connection 204.

[0036] For example, the plausibility check may comprise at least one check selected from whether an immobilizer is active, whether the drive train is in a startable state, e.g. because the transmission and / or clutch are torque-decoupled and the combustion engine is at a standstill, whether the temperature of the starter is within a permissible range, and whether the vehicle electrical system voltage is within a permissible range.

[0037] However, if the start request is recognized as permissible in step 203, the logic unit 111 of the first starter 110 issues a lane-entry request to the logic units 121, 131 of the other starters in step 205.

[0038] In step 206, the logic units 111, 121, 131 control their respective switching / engaging unit 112, 122, 132 to move the respective pinion 113, 123, 133 into the Figure 1Furthermore, the logic units 121, 131 of the further starters are configured to output a meshing message after the associated pinion 123, 131 has been successfully moved into the meshing position, which is transmitted to the logic unit 111 of the first starter 110.

[0039] In step 207, the logic unit 111 of the first starter 110 monitors the respective meshing processes. If the logic unit 111 receives the meshing message from all other starters, it continues with step 208.

[0040] If the logic unit 111 has not yet received all lane-entry messages, it continues with step 209.

[0041] In step 209, a check is made to determine whether a predefined waiting time, for example, since the entry command was issued or since the start request was received, has already elapsed. If this is not the case, the program returns to step 207. If this is the case, however, the program continues with step 210.

[0042] In both steps 208 and 210, the logic unit 111 of the first starter 110 issues a cranking request to the other starters at its interface 111b and controls its own switching / engaging unit 112 so that the starter motor M is supplied with the main current to rotate the associated pinion. Upon receiving the cranking request, the logic units 121, 131 control the associated switching / engaging units 122, 132 to supply the respective starter motor M with the main current to rotate the associated pinion.

[0043] Thus, a regular start of the internal combustion engine occurs in step 211, whereas an emergency start of the internal combustion engine occurs in step 212. In this context, it can be provided that the logic unit 111 of the first starter 110 issues a cranking request at its interface 111b in step 210 only to those other starters from which an engagement message has been received, for example, in the form of addressed data.

[0044] During such an emergency start, it is preferable that the starters with engagement signaling be operated under increased specific load with a reduced permissible duty cycle to enable a start attempt even in the event of a fault. If a bidirectional interface to the on-board electrical system 20 or the processing unit 23 is used, this fault condition can be reported back to the on-board electrical system 20 or the processing unit 23 to initiate a service procedure as soon as possible.

Claims

1. Parallel starter system (100) for starting an internal combustion engine (10), comprising at least two starters (110, 120, 130), wherein each of the at least two starters (110, 120, 130) comprises: a pinion (113, 123, 133) for meshing with a ring gear (11) of the internal combustion engine (10) to be started, a starter motor (M) for spinning the pinion (113, 123, 133), a mechanical actuator (112, 122, 132) for moving the pinion (113, 123, 133) into an engagement position and a logic unit (111, 121, 131) with a data interface (111a, 111b, 121b, 131b), wherein the logic unit (111, 121, 131) is set up: to actuate the mechanical actuator (112, 122, 132) to move the pinion (113, 123, 133) to the engagement position, and to actuate the starter motor (M) to spin the pinion (113, 123, 133), wherein the logic unit (111) of a first of the at least two starters (110, 120, 130) is arranged to output an engagement request and a spinning request in response to the receipt of a start request, wherein the logic unit (121, 131) of at least one further of the at least two starters (110, 120, 130) is arranged to control the mechanical actuator (112, 122, 132) for moving the pinion (113, 123, 133) into the engagement position in response to receipt of the engagement request and to control the starter motor (M) for spinning the pinion (113, 123, 133) in response to receipt of the spinning request, characterized in that the data interface (111a, 111b, 121b, 131b) is a bus interface.

2. Parallel starter system (100) according to claim 1, wherein the logic unit (121, 131) of the at least one further of the at least two starters (110, 120, 130) is set up to output an engagement message after the pinion (113, 123, 133) has been successfully moved into the engagement position.

3. Parallel starter system (100) according to claim 2, wherein the logic unit (111) of the first of the at least two starters (110, 120, 130) is set up to output the spinning request and / or to control the starter motor (M) to spin the pinion (113) in response to the receipt of a spinning message from the logic unit (121, 131) of the at least one further of the at least two starters (110, 120, 130).

4. Parallel starter system (100) according to any one of the preceding claims, wherein the logic unit (111) of the first of the at least two starters (110, 120, 130) is arranged to output the spinning request and / or to control the starter motor (M) for spinning the pinion (113) after a predetermined period of time has elapsed after outputting the spinning request.

5. Parallel starter system (100) according to claims 3 and 4, wherein the logic unit (111) of the first of the at least two starters (110, 120, 130) is arranged to output the spinning request to the logic unit (121, 131) of the at least one further of the at least two starters (110, 120, 130) from which it has received a spinning request after the predetermined period of time has elapsed after the output of the spinning request.

6. Parallel starter system (100) according to any one of the preceding claims, wherein the logic unit (111) of the first of the at least two starters (110, 120, 130) is arranged to control the mechanical actuator for moving the pinion (113) into the engagement position upon receipt of the start request.

7. Parallel starter system (100) according to any one of the preceding claims, wherein the logic unit (111) of the first of the at least two starters (110, 120, 130) comprises a single data interface for receiving the start request, for outputting the engagement request, for outputting the spinning request and for receiving the engagement message.

8. Parallel starter system (100) according to any one of claims 1 to 6, wherein the logic unit (111) of the first of the at least two starters (110, 120, 130) comprises a first data interface (111a) for receiving the start request and a second data interface (111b) for outputting the engagement request and the spinning request and for receiving the engagement message.

9. Parallel starter system (100) according to any one of the preceding claims, wherein the logic unit (121, 131) of the at least one further one of the at least two starters (110, 120, 130) has a data interface for receiving the engagement request and the spinning request and for outputting the engagement message.

10. Arrangement comprising an internal combustion engine (10) and a parallel starter system (100) according to any one of the preceding claims.

11. Arrangement comprising a computing unit (23), which is set up to output a start request, and a parallel starter system (100) according to any one of claims 1 to 9.