Internal combustion engine starting method and reciprocating piston internal combustion engine comprising such a method

Abstract

The invention relates to an internal combustion engine starting method for a reciprocating piston internal combustion engine having a crankshaft which is set in a rotary movement in a starting direction of rotation by a starter device for starting, and wherein at least one reciprocating piston of the reciprocating piston internal combustion engine is kinematically positively coupled to this crankshaft and is movable back and forth between a top dead centre and a bottom dead centre by means of a rotary movement of this crankshaft, wherein this internal combustion engine starting method comprises the following steps: - detecting a starting request to the reciprocating piston internal combustion engine - supplying the starter device with electrical starting current to drive the crankshaft in the starting direction of rotation - detecting the crankshaft speed, at least in a first crankshaft angle range - interrupting the starting current of the starter device, when the crankshaft speed falls below a crankshaft speed threshold value and thus - turning the crankshaft back against the starting direction of rotation to a starting angle range, this turning back being caused by a movement of the reciprocating piston in the direction from top dead centre to bottom dead centre, - supplying the starter device with electrical starting current and driving the crankshaft in the starting direction of rotation when the crankshaft has reached this starting angle range, - setting the internal combustion engine to fired operation.

Description

[0001] Internal combustion engine starting method and reciprocating piston internal combustion engine with such a method

[0002] The invention relates to an internal combustion engine starting method and to a reciprocating piston internal combustion engine with such a starting method. A starting method for an internal combustion engine and a motor vehicle is known from DE 10 2015 216 154 A1.

[0003] The invention is described below in connection with a motorcycle with a two-cylinder internal combustion engine of reciprocating piston design; this is not to be understood as a limitation of the invention to such an application. The two-cylinder internal combustion engine is designed as an internal combustion engine of reciprocating piston design, which operates according to the Otto combustion process or, more generally, as a four-stroke engine. The so-called strokes of such a four-stroke engine are the intake stroke, compression stroke, power stroke, and exhaust stroke. During the intake and exhaust strokes, the so-called charge or gas exchange takes place, which is controlled by the so-called intake and exhaust valves, respectively. During the compression and power strokes, these valves are, at least largely, closed; here the cylinder, with the piston accommodated therein, forms a type of gas spring (compression, expansion).The two-cylinder internal combustion engine has a crankshaft to deliver drive power; pistons are kinematically coupled to this crankshaft by means of connecting rods, or in other words, an alternating movement of these working pistons leads to a forced rotational movement of this crankshaft.

[0004] To start a two-cylinder internal combustion engine—that is, to transition it from a standstill to firing operation, in which a fuel-air mixture is combusted in the cylinders—the crankshaft is accelerated to a starting speed by an electric starter device. Once the starting speed is reached, combustion of the fuel-air mixture is initiated. When such an internal combustion engine is shut down, combustion is stopped, and the crankshaft, and thus the working pistons in these cylinders, come to a standstill in a random position. During starting, the electric starter device rotates this crankshaft against acceleration resistance, frictional resistance, and gas forces (particularly during the compression stroke).It is known that during a start-up process, in which one of the cylinders and the working piston housed therein executes the compression stroke, this is critical for the start-up process because the working piston is displaced in the cylinder during the compression stroke against the gas forces explained above, as the inlet and exhaust valves are closed. Such a situation leads to a particularly high resistance moment on the crankshaft, which must be overcome by the starter device. If the starter device is to be able to start the combustion engine successfully from any position of the crankshaft, it must be dimensioned for this "maximum fairness". Another option is to provide a decompression device by means of which the exhaust valves are opened during the start-up process in addition to the scheduled valve opening.The two measures mentioned are clearly associated with an increase in weight (maximum dimensioned starter device, decompression device) compared to a solution in which the starter device is not designed to start the combustion engine even in the above-mentioned maximum case.

[0005] Against the background outlined above, it is an object of the invention to provide an efficient internal combustion engine starting method and a reciprocating internal combustion engine equipped with such a method. This object is achieved by an internal combustion engine starting method according to claim 1 and by a reciprocating internal combustion engine according to claim 4, with preferred developments of the invention being the subject of the dependent claims.

[0006] In the sense of the invention, an internal combustion engine starting method is understood to mean a method for moving a reciprocating piston internal combustion engine from standstill (in particular, rotational speed of the crankshaft equal to zero, no combustion of fuel-air mixture in combustion chambers, so-called unfired state) into fired operation (in particular, power output at the crankshaft enabled by output of rotational speed and torque, or operation at an idle speed without power output at the crankshaft).

[0007] Furthermore, the internal combustion engine starting method relates to a reciprocating internal combustion engine that can be operated according to the so-called four-stroke principle, in particular a gasoline or four-stroke engine. The proposed internal combustion engine starting method further relates in particular to a reciprocating internal combustion engine with a small number of cylinders, in particular with a number of cylinders of 4 or fewer, preferably 2 or fewer. The proposed internal combustion engine starting method relates in particular to a reciprocating internal combustion engine with a small number of cylinders, since with such reciprocating internal combustion engines, the problem can arise during starting that a conventional starting method is aborted unsuccessfully (fired operating state is not achieved), in particular due to a high torque requirement on the starter device. The invention counteracts this problem.

[0008] An aborted start-up process can result from the fact that the electric starter, known as the starter device, has to accelerate the crankshaft to a starting speed and at the same time, particularly during the compression stroke, works against the compression in the individual cylinders. In a conventional start-up process, a start-up abort can be caused by current monitoring in the electric starter device. This start-up abort can occur in a conventional start-up process if the electrical current drawn by the starter (starting current) exceeds a threshold value, preferably for a predefined period of time. To prevent damage to components of the starter device in such a case, this starting current is interrupted, and the start-up process is thus aborted.To start the internal combustion engine, such a conventional starting procedure requires a new start command to be generated, particularly by the vehicle user pressing a control element. The proposed internal combustion engine starting procedure avoids such an interruption and the associated repeated pressing of a control element.

[0009] For the purposes of the invention, the fired operation of such a reciprocating internal combustion engine is to be understood as meaning that the reciprocating internal combustion engine is operated in its scheduled mode, in particular according to the Otto or four-stroke principle, wherein in particular a mixture of ambient air and fuel, preferably Otto fuel, (fuel-air mixture) is burned in a so-called power stroke. The energy released from combustion is transferred at least partially by means of a mechanism to the crankshaft of the reciprocating internal combustion engine. This crankshaft serves as the output shaft of the reciprocating internal combustion engine and is designed to deliver drive power in the form of speed and torque. In addition to the power stroke, the reciprocating internal combustion engine preferably has an intake stroke, a compression stroke, and an exhaust stroke in each of these cylinders.In particular, the compression stroke contributes to the problem of start abort, or rather, it can contribute to an increase in the torque requirement on the starter device when accelerating the crankshaft during starting of the reciprocating internal combustion engine.

[0010] The proposed internal combustion engine starting method is preferably applied to a reciprocating internal combustion engine without a decompression lever. For the purposes of the invention, a reciprocating internal combustion engine without a decompression lever is understood to mean an internal combustion engine of reciprocating piston design that does not have a decompression lever or decompression device.In the sense of the invention, a decompression lever or such a decompression device is to be understood as a device by means of which, in the reciprocating piston internal combustion engine, an actuating mechanism of valves, in particular a camshaft, or an actuating device of at least one exhaust valve is acted upon at least temporarily, in particular in a starting phase, so that this at least one exhaust valve does not close (“valve lifter”) or is kept open, at least in phases, in particular during the compression stroke.Further preferably, such a decompression device can cause an additional, particularly small, opening stroke of at least one exhaust valve, particularly during the compression stroke, in order to discharge a portion of the compressed gas in the affected cylinder of the reciprocating internal combustion engine into the exhaust and thus reduce the torque required to start the reciprocating internal combustion engine. A reciprocating internal combustion engine without a decompression lever does not have such a device.

[0011] In contrast, the invention proposes an improved internal combustion engine starting method which enables the reciprocating piston internal combustion engine to be started upon actuation, or during actuation, or by a single actuation of a start control element, and which avoids component overload. Within the meaning of the invention, such a start control element is to be understood as a device for specifying a start request; figuratively speaking, such a start control element is to be understood in particular as a start button, preferably a start switch, and more preferably as an ignition lock or the like. Furthermore, within the meaning of the invention, actuation of the start control element is to be understood as a vehicle driver specifying a start request to the reciprocating piston internal combustion engine by actuating the start control element.Further preferably, the start request persists as long as the start control element is actuated, and further preferably, the start request persists for a predetermined time, which may depend on the reciprocating internal combustion engine or on the boundary conditions of the starting process. Further preferably, it is proposed that the proposed internal combustion engine starting method be executed as long as the start request is maintained, preferably as long as the start request continues, and particularly preferably as long as the start request is active. In particular, by actuating the starting device once, the start request can be maintained, i.e., can be active, until the reciprocating internal combustion engine is switched to fired operation or until a predetermined period of time has elapsed.In particular, by maintaining the start request in this way, it can be achieved that the previously explained reversing of the crankshaft can occur in a start attempt without the starter device having to be actuated several times or again, but that the start attempt is aborted if the reciprocating piston internal combustion engine cannot be started, in particular due to other technical problems.

[0012] The proposed internal combustion engine starting method makes it possible to achieve the objectives of avoiding start-up abort and avoiding high component loads, in particular those component loads which can result from high and long-lasting currents in the starter device for accelerating the crankshaft.

[0013] A reciprocating piston internal combustion engine, such as the subject of the invention, is known from the prior art with regard to its basic mode of operation; however, the invention relates to an improved method for starting such a reciprocating piston internal combustion engine.

[0014] The proposed internal combustion engine starting procedure comprises the following steps:

[0015] - Detecting a start request to the reciprocating piston internal combustion engine

[0016] - Supplying the starter device with electrical starting current to drive the crankshaft in the starting direction

[0017] - Detecting the crankshaft speed, at least in a first crankshaft angle range

[0018] - Interruption of the starting current of the starter device when the crankshaft speed falls below a crankshaft speed threshold and thus

[0019] - turning the crankshaft back against the starting direction of rotation up to a starting angle range, whereby this turning back is caused by a movement of the piston in the direction from the top dead center to the bottom dead center,

[0020] - Supplying the starter device with electrical starting current and driving the crankshaft in the starting direction of rotation when the crankshaft has reached this starting angle range.

[0021] - Putting the internal combustion engine into fired operation.

[0022] For the purposes of the invention, detecting a start request is preferably understood to mean detecting a start request for the reciprocating piston internal combustion engine specified by a user, in particular by actuating a start element. For the purposes of the invention, a start element is understood to mean an actuating device, preferably a start switch. For the purposes of the invention, supplying the starter device with electrical starting current is understood to mean supplying electrical power in the form of electrical voltage and electrical current, so-called starting current, to the starter device. The starter device is preferably designed as a so-called pinion starter, more preferably as a so-called crankshaft starter or crankshaft starter generator or the like.For the purposes of the invention, the starting direction of rotation is to be understood as the direction of rotation of the reciprocating piston internal combustion engine, or of its crankshaft, which corresponds to its planned direction of rotation for delivering drive power.

[0023] For the purposes of the invention, detecting the crankshaft speed in at least a first crankshaft angle range is understood to mean directly or indirectly recording the speed of the crankshaft, whereby this recording can occur over the full rotation of the crankshaft or only in at least one predefined angular range of the crankshaft. Furthermore, directly recording the crankshaft speed is preferably understood to mean that a measuring device is provided on or near the crankshaft, which detects, preferably measures, the speed of the crankshaft. Furthermore, indirectly recording the crankshaft speed is understood to mean indirectly recording it.Furthermore, indirect detection is preferably understood as a detection or measurement of variables which allow a conclusion to be drawn about the crankshaft speed; preferably, such indirect detection takes place on or with the starter device.

[0024] Furthermore, a crankshaft speed threshold is specified for the proposed internal combustion engine starting method. This crankshaft speed threshold depends on the design of the reciprocating internal combustion engine to which the proposed internal combustion engine starting method applies. The crankshaft speed threshold can be understood, in particular, as a limiting speed. Above this limiting speed, spinning of the reciprocating internal combustion engine, or its crankshaft, is possible by means of the starter device. Whereas below this limiting speed, such spinning is not possible or at least less likely.The spinning of the reciprocating piston internal combustion engine is understood in particular to mean that the starter device moves the crankshaft, in particular during the execution of the proposed method, over at least one complete compression stroke of the at least one reciprocating piston in the at least one cylinder in the starting direction of rotation. The crankshaft speed threshold can preferably be determined experimentally, preferably calculated, or more preferably derived from empirical values. Furthermore, it is proposed that when the crankshaft speed reaches or falls below the crankshaft speed threshold, the starting current is interrupted, or that the starter device is no longer supplied with electrical power or is preferably de-energized.In other words, when the crankshaft speed threshold is reached or undershot, the drive torque applied to the crankshaft by the starter device is switched off. As explained, a high load demand occurs on the starter device during movement; at least one reciprocating piston in the so-called compression stroke, with all existing intake and exhaust elements, such as in particular intake and exhaust valves, closed, is approaching its top dead center position (direction of movement from bottom dead center to top dead center). If, in the case described above, the crankshaft speed applied to the crankshaft by the starter device reaches or falls below the crankshaft speed threshold, the proposed crankshaft starting method interrupts the starting current without, however, aborting the process.The proposed interruption of the starting current causes the crankshaft to rotate backward, i.e., in a direction opposite to the starting direction. This movement, opposite to the starting direction, occurs under the action of the gas spring located in one of the cylinders of the reciprocating internal combustion engine, which pushes the reciprocating piston housed in this cylinder back from top to bottom dead center, counter to the direction of movement initially imposed by the starter mechanism.

[0025] Furthermore, this reversing of the crankshaft against the starting direction of rotation is terminated by resupplying the starter device with starting current. This resupply is then initiated when the crankshaft has reached a predefined starting angle range. The starting angle range can be understood as an angular range relative to the angle of rotation of the crankshaft, which is selected such that the starter device is capable of completely rotating the crankshaft starting from this starting angle range.

[0026] The position of the starting angle range depends on the one hand on the design and construction of the reciprocating piston internal combustion engine to which this internal combustion engine starting method is applied, and furthermore it can also depend on the starter device and its design.

[0027] Reaching the starting angle range can be detected directly or indirectly. In this case, indirect detection is understood to mean, in particular, a time- or speed-dependent method with respect to the crankshaft movement, and more preferably, a direct method is understood to mean a determination, in particular a measurement, of the crankshaft rotation angle. It is proposed that the renewed supply of starting current to the starter device preferably takes place in a time- or, preferably, rotation-path-controlled manner. Rotation-path-controlled means that this renewed supply of starting current is initiated when a specific rotational position of the crankshaft is reached or exceeded.In particular, rotational travel control can ensure that the starter device has sufficient rotational travel to accelerate the crankshaft in the starting direction of rotation such that it can be fully rotated and the internal combustion engine can thus be started successfully. In particular, time control enables particularly simple control of the proposed starting method without the need for special monitoring of the crankshaft rotation. Furthermore, it is proposed that the starter current be supplied to the starter device again when a predetermined crankshaft speed is reached or undershot. In particular, such speed control makes it possible to prevent the starting current from being supplied again and the crankshaft from still rotating at high speed against the starting direction of rotation.

[0028] Once the starter device is able to fully rotate the crankshaft from the starting angle range, the crankshaft is accelerated in the starting direction of rotation up to the starting speed by re-supplying the starter device with starting current. Upon reaching or after reaching this starting speed, the reciprocating internal combustion engine is switched to fired operation. Once the reciprocating internal combustion engine has been switched to fired operation, the proposed internal combustion engine starting method is terminated.The proposed internal combustion engine starting method makes it possible, in particular, to use a smaller starter device compared to a conventional starting method, since the starter device does not have to be designed for maximum torque requirements, or it makes it possible to avoid uncomfortable starting behavior of the reciprocating piston internal combustion engine, since there is no start abort due to overloading of the starter device due to an unfavorable starting position of the crankshaft.

[0029] In a preferred embodiment of the invention, the first crankshaft angle range is selected such that it begins at least 60°, relative to a rotational angle of the crankshaft, before the top dead center of at least one reciprocating piston is reached and ends when the top dead center of the reciprocating piston is reached. In particular, the aforementioned angle range describes an angle range of the crankshaft "close" to top dead center with respect to the reciprocating piston. Furthermore, the valve position of at least one exhaust valve is preferably also taken into account, since the compression stroke in particular proves to be critical for the starting behavior of a reciprocating piston internal combustion engine due to the compression work. In particular, by limiting the angle range, simple control of the proposed internal combustion engine starting method is possible.

[0030] In a preferred embodiment of the invention, the interruption of the starting current, i.e. the period from which the supply of starting current is interrupted until the point in time from which the starter device is supplied with starting current again, is time-controlled. In other words, a reversing time period is provided which can be specified, which forms the basis for the internal combustion engine starting method and which elapses between this interruption of the supply of starting current until the starter device is supplied with starting current again. It is further proposed that this reversing time period be greater than 20 milliseconds and less than 250 milliseconds. In particular, a reversing time period in the stated range enables advantageous starting behavior of the reciprocating piston internal combustion engine.Further preferably, the range for turning back the crankshaft rotation angle can be controlled, in which case the starter device is only supplied with starting current again after the supply of starting current to the starter device has been interrupted when the crankshaft has been turned back to a predetermined rotation angle position.

[0031] Furthermore, a reciprocating internal combustion engine is proposed, which has a control unit for executing control methods. This control unit further comprises a memory device configured to store computer-executable instructions. It is proposed that an internal combustion engine starting method in one of the previously explained ways be stored on this memory device in the form of a computer-executable instruction, and wherein the reciprocating internal combustion engine can be controlled by means of the control unit in accordance with this internal combustion engine starting method. In particular, a reciprocating internal combustion engine with a smaller number of cylinders than with four or fewer cylinders, and preferably with two or fewer cylinders, can be started particularly conveniently with the proposed internal combustion engine starting method, thus resulting in an improved reciprocating internal combustion engine.

[0032] In a preferred embodiment of the invention, the reciprocating internal combustion engine is operated at least temporarily using the proposed internal combustion engine starting method. Preferably, the reciprocating internal combustion engine is at least temporarily switched from its unfired state to its fired operation using the proposed internal combustion engine starting method, and is thus started. Individual embodiments and features of the invention are explained in more detail below with reference to the figures. Combinations of features other than those shown in the figures are also possible.

[0033] Fig.1: a schematic partial sectional view of a reciprocating piston internal combustion engine, Fig.2: schematic internal combustion engine starting procedure.

[0034] Figure 1 shows a partial sectional view of a reciprocating piston internal combustion engine, this reciprocating piston internal combustion engine being designed as a two-cylinder boxer engine which is to be started using the proposed internal combustion engine starting method. The two-cylinder boxer engine has a crankshaft 1 which, for delivering drive power, has a regular drive direction of rotation which corresponds to the starting direction of rotation 2. To start this two-cylinder boxer engine, the crankshaft 1 is set into a rotary movement in a starting direction of rotation 2 by the starter device 3. In the two-cylinder boxer engine, two reciprocating pistons are kinematically coupled to the crankshaft 1, with a connecting rod each being provided for this forced coupling, although only the first of these reciprocating pistons 4 and the first of these connecting rods 5 are shown in Figure 1.

[0035] With this forced coupling, the reciprocating piston 4 can be moved back and forth between its top dead center 6 and bottom dead center 7. The combustion chamber 8 of the cylinder 9 shown is shown in the closed state because both the intake valve 10 and the exhaust valve 11 are closed. The reciprocating piston is "just" before top dead center 6, and the position of the crankshaft 1 in relation to top dead center 6 can be expressed via its angle of rotation 12. The gas compressed in the combustion chamber 8 counteracts the acceleration of the crankshaft 1 in the starting direction of rotation 2; at the same time, when accelerating the crankshaft 1, the starter device 3 must also work against the inertia of the crankshaft, as well as components coupled to it, as well as against frictional resistance.With a conventional starting method, these accumulated resistances can be so large that the starting process aborts and the internal combustion engine does not start. Such an aborted start is prevented by the proposed internal combustion engine starting method. If the crankshaft is rotated back past the end of the starting angle range 13 in the opposite direction of rotation 2 and comes to a standstill before the reciprocating piston 4 reaches top dead center 6, the crankshaft is in the starting angle range.

[0036] The internal combustion engine starting method proposes the following steps, in particular to avoid a start abort: - in the first step 101, a start request to the reciprocating piston internal combustion engine is detected, which is specified by means of an operating element, such as a start button;

[0037] - in the second step 102, the starter device is supplied with electrical starting current to drive the crankshaft in the starting direction of rotation;

[0038] - in the third step 103 the crankshaft speed is recorded;

[0039] - in the fourth step 104, the detected crankshaft speed is compared with a crankshaft speed threshold value; if the crankshaft speed falls below this crankshaft speed threshold value, the starting current of the starter device is interrupted;

[0040] - if the starting current was interrupted in the fourth step 104, the crankshaft rotates back in the opposite direction to the starting direction of rotation up to a starting angle range in the fifth step 105, this rotation back being caused by a movement of the reciprocating piston in the direction from the top dead center 6 to the bottom dead center 7;

[0041] - in the sixth step 106, the starter device is again supplied with electrical starting current and then drives the crankshaft from the starting angle range in the starting direction of rotation, the starting angle range being selected depending on the reciprocating internal combustion engine and the starter device such that the starter device is able to rotate the crankshaft in such a way that the reciprocating piston 4 reaches the top dead center 6 and continues to drive the crankshaft 1 in the starting direction of rotation 2 even after the reciprocating piston 4 has reached the top dead center 6,

[0042] - in the seventh step 107, the internal combustion engine is put into fired operation so that the fuel-air mixture is burned in its combustion chambers.

[0043] In other words, there are conventional internal combustion engines with a reciprocating piston design which are developed and built without a decompression device. In such conventional internal combustion engines, particularly those with three or fewer cylinders, an "unfavorable" engine shutdown position can result in the starting system not being able to generate sufficient drive power to overcome the first top dead center in the compression stroke. In such a case, the reciprocating piston of this internal combustion engine, which is in the compression stroke and is in contact with the air spring shortly before reaching its top dead center, and the main relay, which switches the so-called starting current to the electric starter device, switches this starting current off after a certain time, e.g. around 0.1 seconds, for reasons of self-protection - the start sequence is therefore aborted unsuccessfully and a further decompression operation may be necessary.A further start attempt initiated by the user, for example, by pressing a start button, is necessary, which can be perceived as inconvenient. The invention counters this with an improved internal combustion engine start method and a reciprocating piston internal combustion engine with a control unit that uses such a start method. This avoids aborted starts and the high component loads caused by the high and prolonged currents.

[0044] A basic idea of ​​the invention is to detect a stop of the reciprocating internal combustion engine, in particular its crankshaft, based on the very low or nonexistent speed of the crankshaft of the reciprocating internal combustion engine after it has been previously turned by the electric starter device, and to briefly interrupt the supply of starting current to the starting system, in particular the starter device. During this brief interruption, the crankshaft of the reciprocating internal combustion engine rotates back a few degrees, in particular into the starting angle range, due to the continued effective air spring force in the combustion chamber during the compression stroke. This reduces the energy stored in the "air spring."The proposed internal combustion engine starting method then initiates a renewed supply of energy, in particular by means of the starting current, to the starting system with the starter device and can reverse the direction of rotation of the reciprocating internal combustion engine, which at this moment can move opposite to the starting direction of rotation, and accelerate the crankshaft back into the starting direction of rotation, as at the beginning of the proposed starting method. The reciprocating internal combustion engine, or rather the reciprocating piston in the compression stroke, is accelerated again by the crankshaft towards its top dead center. Due to the counterforce, at least initially reduced, by the air spring in the combustion chamber due to the "reverse rotation", the energy of the starting system is sufficient to overcome top dead center, thus subsequently enabling the reciprocating internal combustion engine to be transferred to fired operation without the need to operate a starter control element again.

[0045] Functionally, the proposed internal combustion engine starting method uses a high-resolution speed signal with a 2 millisecond grid of the crankshaft or preferably a similar signal from a crankshaft and / or camshaft sensor, and thus, in a critical case in which the conventional starting method is normally aborted, the proposed starting method detects the impending or already acute engine standstill (standstill of the crankshaft).

[0046] If the condition exists where a minimum speed (crankshaft speed threshold) is undershot or the crankshaft is stationary for "long enough," where "long enough" refers to a so-called temporal debouncing to avoid false detections, this is evaluated as a trigger for interrupting the starting current (see fourth method step 104). Thus, if a critical crankshaft speed condition is detected using the method described above, it is proposed for the proposed internal combustion engine starting method to interrupt the current supply to the starter device, preferably for a predetermined period of time.

[0047] Following this interruption of the power supply to the starter device, the starter device is re-energized after the crankshaft 1 has sufficiently reversed its rotation, thus directly continuing the starting process according to the proposed internal combustion engine starting method without requiring a new user input of a start signal. During this continuation, the start request is sent to the relay that controls the power supply to the starter device.

[0048] The proposed interruption of the power supply to the starter device occurs for a very short switch-off time, since an excessively long switch-off time can lead to the crankshaft rotating back too far and very quickly (moving opposite to the starting direction of rotation), which can increase component loads. The switch-off time, i.e. the determination of the so-called reverse rotation period, can be determined by calculation or experimentally, or both computationally and experimentally. Furthermore, a switch-off time of preferably more than 0.01 seconds and more preferably more than 0.025 seconds and preferably more than 0.04 seconds and preferably less than 0.25 seconds and preferably less than 0.10 seconds and particularly preferably less than 0.05 seconds is to be understood.

[0049] In particular, this switch-off time, or the reversing time period, is divided into an actuation time and a relay time, which the relay requires to restore the current supply. In particular, the actuation time can be at least substantially 0.02 seconds and the relay time can be at least substantially 0.02 to 0.03 seconds. Furthermore, it is proposed that the switch-off time be selected such that the crankshaft rotates, i.e., reverses, preferably by more than 5°, preferably more than 10°, particularly preferably more than 15°, preferably less than 60°, preferably less than 45°, and particularly preferably less than 30° crank angle, counter to the starting direction of rotation 2 during the switch-off time. In particular, such a rotation is sufficient to carry out a complete start of the reciprocating piston internal combustion engine using the proposed internal combustion engine starting method when the starter device is re-energized.

Claims

Claims 1. Internal combustion engine starting method for a reciprocating piston internal combustion engine with a crankshaft (1) which is set into a rotary movement in a starting direction of rotation (2) by a starter device (3) for starting, and wherein at least one reciprocating piston (4) of the reciprocating piston internal combustion engine is kinematically coupled to this crankshaft (1) and can be moved back and forth between a top dead center (6) and a bottom dead center (7) by means of a rotary movement of this crankshaft, this internal combustion engine starting method comprising the following steps: - Detecting a start request (101) to the reciprocating piston internal combustion engine - Supplying the starter device (102) with electrical starting current to drive the crankshaft in the starting direction of rotation - detecting the crankshaft speed (103), at least in a first crankshaft angle range - interrupting the starting current (104) of the starter device when the crankshaft speed falls below a crankshaft speed threshold and thus - turning back (105) the crankshaft (1) against the starting direction of rotation (2) up to a starting angle range, this turning back being caused by a movement of the reciprocating piston (4) in the direction from the top dead center (6) to the bottom dead center (7), - Supplying (106) the starter device (3) with electrical starting current and driving the crankshaft (1) in the starting direction of rotation (2) when the crankshaft (1) has reached this starting angle range. - Putting the internal combustion engine into fired operation (107).

2. Internal combustion engine starting method according to claim 1, characterized in that the first crankshaft angle range is selected such that it begins at least 60°, based on a rotation angle of the crankshaft (1), before reaching the top dead center (6) of the at least one reciprocating piston (4) and ends when reaching the top dead center (6) of the reciprocating piston (4).

3. Internal combustion engine starting method according to one of the preceding claims, characterized in that the starting current of the starter device (3) is interrupted for a reversing time period, that the reversing time period is greater than 0.01 seconds and less than 0.25 seconds.

4. Reciprocating piston internal combustion engine with a control device, wherein the control device has a memory device and wherein an internal combustion engine starting method is stored on this memory device in the form of computer-executable instructions.

5. Reciprocating piston internal combustion engine according to claim 4, characterized in that it is at least temporarily switched from an unfired to a fired operation and thus started using an internal combustion engine starting method according to one of claims 1 to 3.

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