"Working device and method for determining the starting conditions of a working device"

Abstract

A working device with an internal combustion engine (4) and with a starting device for starting the internal combustion engine (4), and with a housing (2), wherein a first electrical component is arranged at a first location within the housing (2) and a second electrical component is arranged at a second location, and with a control unit (28) which is connected to the first electrical component and to the second electrical component, and the control unit (28) detects a first temperature-dependent value of the first electrical component and a second temperature-dependent value of the second electrical component, and determines the starting conditions depending on these values, characterized in that the first component is a first actuator (41) and that the second component is a second actuator (42) or a sensor (40).

Description

[0001] The invention relates to a working device of the type specified in the preamble of claim 1 and to a method for determining the starting conditions of a working device with an internal combustion engine, wherein a control device connected to a first electrical component and to a second electrical component determines a first temperature-dependent measured variable at the first electrical component and a second temperature-dependent measured variable at the second electrical component, and the control device compares the first measured variable with the second measured variable and determines the starting conditions.

[0002] DE 20 2011 000 519 U1 discloses a work tool with an internal combustion engine in which a temperature sensor for measuring the temperature of the internal combustion engine is integrated into a component of the work tool. Together with a temperature sensor for measuring the ambient temperature, the output signals of the temperature sensors are evaluated in a control unit and serve to determine the starting conditions of the internal combustion engine. The temperature sensors used are additional components and require installation space; furthermore, they must be wired to the control unit.

[0003] DE 10 2009 040 321 A1 also discloses a work device with an internal combustion engine, in which only a single temperature sensor is provided for determining cold or warm start conditions. EP 2 246 547 A1 describes an arrangement for controlling an internal combustion engine with two temperature sensors positioned at different locations. A warm-up time for the internal combustion engine is determined from the difference between the signals from both temperature sensors. DE 40 39 598 A1 and DE 100 43 695 A1 each disclose a hot start method for an internal combustion engine, each using a temperature sensor.

[0004] The invention is based on the object of providing the control unit with information for determining the starting conditions of an internal combustion engine of a work device using simple means without additional cabling.

[0005] This object is achieved by a working device having the features of claim 1 and by a method having the features of claim 10.

[0006] It is provided that the control unit detects a first temperature-dependent value of a first electrical component and a second temperature-dependent value of a second electrical component and, depending on these values, determines the starting conditions, in particular cold start or warm start conditions, for starting an internal combustion engine with a starting device, wherein the first component is a first actuator and the second component is a second actuator or a sensor. By using two electrical components and the relative comparison of the temperatures tapped at the electrical components, it can be determined, regardless of the ambient temperature, whether warm start or cold start conditions exist. If the internal combustion engine is switched off for a sufficiently long time, the temperatures of the individual components, including the temperatures of the electrical components evaluated by the control unit, approximate the ambient temperature.In contrast, during operation of the combustion engine, different temperatures arise within the housing of the implement, and thus also different temperatures on the electrical components. Since the components are actuators and / or sensors, which usually have an electrical coil, the resistance of the coil, in particular the ohmic resistance of the coil, changes with the temperature. Therefore, the temperature of the electrical component can be determined indirectly based on the changed electrical operating signals or through measuring pulses, without the need for a specific temperature sensor. The signals recorded by the control unit are evaluated by the control unit, and the starting conditions of the combustion engine are determined. The installation of additional temperature sensors, which are only used to determine temperatures for establishing starting conditions, can thus be eliminated.

[0007] Preferably, a first location, where a first electrical component is located, is thermally closer to the internal combustion engine than a second location, where a different, second electrical component is located. If the internal combustion engine is operated for a sufficiently long time, different temperatures develop within the housing. Locations that are thermally close to the internal combustion engine reach high temperatures. Locations that are thermally further away from the internal combustion engine, on the other hand, reach lower temperatures within the same period of time. Due to the thermal distance between the first location and the second location, the temperature caused by the internal combustion engine at the first location during a period of time will have a different value than the temperature caused by the internal combustion engine at the second location during the same period of time.However, if the combustion engine is switched off for a sufficiently long time, the ambient temperature is established throughout the housing, especially around the electrical components. By comparing the temperature at the first location with the temperature at the second location, the control unit can determine the starting conditions. If the measured temperatures are the same, this indicates a cold start; if the temperatures are different, this indicates a warm start.

[0008] It can also be advantageous if a component at the first location exhibits a different thermal decay behavior than a component at the second location. Due to the different thermal decay behavior of the components at the two locations, the control unit can determine the operating state of the implement and the prevailing starting conditions.

[0009] Advantageously, the housing is spatially divided into a first and a second housing region, and the first electrical component is arranged in the first housing region and the second electrical component in the second housing region. Preferably, the first housing region is thermally separated from the second region. The spatial separation of the housing achieves thermal separation into at least two housing regions in which the temperatures caused by the combustion engine develop differently. The electrical components arranged in the housing regions adopt the temperature in the respective housing region. The different temperatures caused by the combustion engine in the various housing regions lead to different temperature-dependent values ​​in the electrical components.In addition, spatial separation into different housing areas is advantageous in order to protect the electrical components in different housing areas from excessively high temperatures, contamination, mechanical influences, etc.

[0010] In a further development of the invention, the sensor is mounted on the control unit. This allows the sensor to output a temperature value to the control unit directly and without complex cabling, and in particular, to continuously supply a temperature value to the control unit even during operation of the implement.

[0011] The actuator is advantageously a component with an electrical coil, e.g., a solenoid valve, an ignition coil, a generator, an injection valve, or the like. In addition to its actual function as an actuator during operation of the implement, the control unit can receive a temperature-dependent value from the actuator that corresponds to a temperature of the actuator and can be used to determine the starting conditions. According to the invention, the temperature-dependent properties of the components required for operating the implement, such as the solenoid valve, ignition coil, generator, injection valve, and the like, which are actually undesirable for normal operation, are used to determine the temperature based on the temperature-dependent properties of these electrical components. The control unit uses the determined temperature-dependent values ​​to determine which starting conditions exist.

[0012] The sensor is preferably a component such as a pressure sensor, a temperature sensor, or similar. The sensor's primary function is to monitor physical parameters, such as pressure, temperature, or similar, during operation of the internal combustion engine. The physical parameter of a sensor is recorded by the control unit during operation of the implement. In addition, the control unit can also record information from the sensor that serves to detect the temperature level, which can be used to determine the starting conditions. The sensor, which is already required for the operation of the internal combustion engine, thus takes on a dual function. During the start-up of the internal combustion engine, the sensor serves as an information source for the control unit to determine the starting conditions.

[0013] In a further embodiment, a third electrical component is arranged at a third location within the housing, wherein the third electrical component is an actuator. By using three electrical components, measurement reliability is increased by having three measuring points. This allows the starting conditions to be determined more reliably. By arranging the three electrical components at three locations within the housing, environmental influences, such as sunlight, which could distort the measurement results, can be reduced.

[0014] For a method for determining the starting conditions of a work device with an internal combustion engine, it is provided that a control unit connected to a first electrical component and a second electrical component determines a first temperature-dependent measured variable at the first electrical component and a second temperature-dependent measured variable at the second electrical component. The control unit compares the first measured variable with the second measured variable and determines the starting conditions. The control unit determines the first measured variable at a first actuator and the second measured variable at a second actuator or at a sensor. In a special embodiment, the control unit converts the first measured variable into a first comparison variable and the second measured variable into a second comparison variable. A value table with a correlation between the comparison variable and the measured variable can advantageously be used for this purpose.To obtain intermediate values ​​between two measured variables stored in the table, the control unit can perform a linear interpolation. The first reference variable can also be directly compared with the second reference variable to determine the prevailing starting conditions. Temperatures derived from the measured variables are particularly suitable as a reference variable.

[0015] The measured variables are advantageously determined during the start-up process of the work equipment. During the start-up process, electrical energy is generated to operate the electrical components so that the components can be controlled by the control unit. The temperature is advantageously determined indirectly by the control unit from the temperature-dependent operating variables of the electrical components so that, after comparing the temperatures, a statement can be made about the start-up conditions. The temperature-dependent measured variable is advantageously correlated with the temperature-dependent value of the electrical component. The start-up conditions are preferably determined and evaluated before the combustion engine starts up. The determined start-up conditions can thus be used to make suitable settings on the combustion engine for the start. The temperature-dependent measured variable is preferably measured on the actuator before the actuator is put into operation.This avoids any possible influences on the measured value caused by the operation of the actuator.

[0016] The actuator for determining the temperature-dependent measured variable is preferably supplied with a measuring current, whereby a smaller current is used to determine the measured variable than the minimum current required to operate the actuator. This means that the actuator is not activated when determining the measured variable, but serves only as a measuring transmitter or sensor at that moment. This allows the temperature-dependent measured variable to be determined without, for example, the actuator switching.

[0017] Advantageously, the control unit determines a temperature-dependent resistance, particularly an internal resistance or an ohmic resistance, at a coil located in the actuator. By using temperature-sensitive electrical components, such as a coil, a temperature-dependent measured variable can be precisely determined within a measurement tolerance. This allows the starting conditions to be precisely predicted. It can also be advantageous to evaluate a temperature-dependent measured variable in a circuit located in the actuator.

[0018] In a further embodiment, the control unit records at least part of the temporal change in a magnetic field of a coil arranged in the actuator and uses this to generate the measured variable. By exploiting the transient, temperature-dependent behavior of the coil arranged in the actuator, conclusions can be drawn about the temperature of the actuator. For example, the temporal progression of the buildup or decay of the magnetic field, which is particularly temperature-dependent, can be read by the control unit. Using the resulting information about the actuator's temperature, the control unit determines the starting conditions.

[0019] Embodiments of the invention are explained below with reference to the drawings. They show: Fig. 1 a schematic section through a chainsaw with an internal combustion engine, Fig. 2 a schematic representation of a fuel system for an internal combustion engine, Fig. 3 a schematic representation of an internal combustion engine with components used to start the internal combustion engine, Fig. 4 and Fig. 5 a schematic representation of the arrangement of electrical components on an internal combustion engine, Fig. 6 a diagram schematically showing the temperature curve of two electrical components with the same thermal decay behavior, Fig. 7 a diagram schematically showing the temperature curve of two electrical components with different thermal decay behavior.

[0020] Fig. Figure 1 shows, as an exemplary embodiment, a chainsaw 1 powered by an internal combustion engine 4. The invention can also be used in other tools with an internal combustion engine 4, for example, in a brush cutter, power cutter, lawn mower, shredder, harvester, vacuum / blower, hedge trimmer, or the like. In the exemplary embodiment, the internal combustion engine 4 is designed as a two-stroke engine. The internal combustion engine 4 can also be a four-stroke engine.

[0021] The chainsaw 1 comprises a housing 2 that houses the internal combustion engine 4. A handle 3 is attached to the housing 2. A throttle lever 5 and a throttle lock 6 are pivotally mounted on the handle 3. The speed of the internal combustion engine 4 can be controlled with the throttle lever 6.

[0022] On the side of the housing 2 opposite the handle 3, a guide rail 7 is arranged. A saw chain 8 rotates on the guide rail 7 as a tool, which is driven by a drive pinion 30 (not shown). Fig. 3) is driven by the combustion engine 4.

[0023] The internal combustion engine 4 has a cylinder 12 and a crankcase 13 in which a crankshaft 31 is rotatably mounted. The crankshaft 31 is driven via a connecting rod 21 by a piston 19, which defines a combustion chamber 14 in the cylinder 12. During operation, the internal combustion engine 4 draws in combustion air. The combustion air flows through an air filter 9 into an intake duct 17, the opening of which is controlled by the piston 19. The intake duct 17 has a carburetor 10. In the carburetor 10, fuel is added to the combustion air, controlled by a partially electrically regulated fuel system 45, thereby creating an ignitable fuel / air mixture in the combustion chamber 14. To control the flow of combustion air, the carburetor 10 has a pivoting throttle element 11. The throttle lever 5 of the implement acts on the throttle element 11. The position of the throttle lever 5 influences and controls the position of the throttle element 11.Depending on the operating condition, for example full load operation, partial load operation, idle operation, starting process, the throttle element 11 assumes a different position.

[0024] The combustion air, enriched with fuel via the intake port 17 and the carburetor 10 to form an ignitable fuel / air mixture, first flows into the crankcase 13 and then, via transfer ports not shown in detail, into the combustion chamber 14. A spark plug 15 arranged on the cylinder 12 extends at least partially into the combustion chamber 14. The spark plug 15 ignites the fuel / air mixture in the combustion chamber 14. The exhaust gases produced by the combustion flow to the outside via an exhaust silencer 22.

[0025] Fig. Figure 2 schematically shows the fuel system 45 for forming the fuel / air mixture in the intake port 17. A venturi 18 is formed in the intake port 17, in which the combustion air is accelerated, creating a vacuum, particularly in the narrowest cross-section of the venturi 18. This vacuum draws fuel in via a main nozzle path 44 of the fuel system 45. The fuel is fed into the intake port 17 via a main nozzle 57 arranged in the region of the narrowest cross-section of the venturi 18.

[0026] The fuel is first pumped from a fuel tank 46 via a fuel pre-feed pump 47 and a pressure-controlled control valve 48 into a control chamber 49. A control diaphragm 50 separates the control chamber 49 from a compensator, with approximately the same static pressure in the compensator as the static pressure in the intake duct 17 outside the venturi 18, particularly after the air filter 9. The pressure-controlled control valve 48 opens as soon as the control diaphragm 50 is displaced towards the control chamber 49 due to the outflow of fuel from the control chamber 49.

[0027] The fuel flow in a fuel channel 51 leading from the control chamber 49 is adjustable by an electrically controllable fuel valve 43. The electrically controllable fuel valve 43 is electrically controlled by a control unit 28 via a valve cable 52.

[0028] The fuel channel 51 branches downstream of the fuel valve 43 into the main nozzle path 44 and an idle path 54. The idle path 54 feeds fuel into the intake channel 17 via an idle chamber 55 and several idle nozzles 56 opening into the intake channel 17 within the pivoting range of the throttle element 11. Accordingly, fuel can be mixed with the combustion air via both the main nozzle 57 and the idle nozzles 56. The fuel delivery is determined by the intake vacuum in the venturi 18 and the opening position of the electric fuel valve 43.

[0029] When the internal combustion engine 4 is started, the fuel / air mixture is adjusted to a different ratio depending on the starting conditions, namely whether cold start or warm start conditions exist. Under cold start conditions, the control unit 28 adjusts a rich fuel / air mixture—in contrast to warm start conditions. To this end, the control unit 28 uses the electric fuel valve 43 to regulate the amount of fuel flowing into the intake port 17 of the carburetor 10. The control unit 28 determines, for example, the time at which the fuel valve 43 opens and closes, as well as the duration of the open or closed fuel valve 43. As a result, the fuel valve 43 can be used to adjust how lean or rich the fuel / air mixture supplied to the combustion chamber 14 becomes.

[0030] If the internal combustion engine 4 is to be started, it must first be determined whether cold or warm start conditions exist. Warm start conditions exist when the temperature of the internal combustion engine 4 exceeds a certain limit temperature. Typically, this limit temperature is above the ambient temperature. Warm start conditions exist when the internal combustion engine 4 has already been in operation for at least a certain period of time before starting, and the temperature of the internal combustion engine 4 is therefore elevated. If the temperature of the internal combustion engine 4 is below the limit temperature, cold start conditions exist.

[0031] According to the invention, the temperature of the combustion engine 4 must be determined before starting, i.e. during pulling and before the first ignition spark, and during the starting process, and communicated to the control unit 28. Fig. 3 is intended to explain how electrical energy is generated before starting and during the starting process and how the control unit 28 can behave during starting and the starting process.

[0032] In Fig. 3 schematically shows an operational internal combustion engine 4. A mechanically or electrically designed starter device 23 is arranged on the crankshaft 31. The starter device 23 rotates the crankshaft 31 and moves a flywheel 25 mounted on the crankshaft 31, a connecting rod 21 with the piston 19, and a first part of a centrifugal clutch 29. The flywheel 25 carries magnets 27 which, when the flywheel 25 rotates, induce a voltage at an ignition module 26. The ignition module 26 is electrically connected to the control unit 28 and to other electrical components such as actuators and sensors, and supplies them with electrical energy. The spark plug 15, a coil connected to the spark plug 15, such as an ignition coil 24, or similar electrical components are referred to as actuators or sensors.

[0033] The control unit 28 controls various functions required for the operation of the implement. Before and during the start-up process, the control unit 28 decides whether warm start or cold start conditions exist. Therefore, the control unit 28 is electrically connected to the actuators and sensors. As soon as electrical energy is available, the control unit 28 can not only control the electric fuel valve 43 during the start-up process, but can also, for example, influence the timing of the ignition spark of the spark plug 15 and thus take the measures required for a warm start or a cold start. To do this, however, the control unit must know whether cold start or warm start conditions exist; the following explains how the control unit determines the start conditions in the exemplary embodiment.

[0034] The Fig. Figure 4 shows a schematic arrangement of the electrical components in the implement. The control unit 28, supplied with electrical energy from the ignition module 26, is connected to the electrical components via cable 16. The electrical components include actuators, for example, the electric fuel valve 43, and sensors, for example, a pressure sensor 32 or a temperature sensor 20. In their basic function, the actuators respond to commands from the control unit 28. The sensors provide the control unit with information, for example, measured values ​​or measured variables. In the present exemplary embodiment, the control unit 28 can also control the actuators in such a way that the actuators provide information, for example, values ​​such as measured values ​​or measured variables. In this case, the actuators operate like sensors and thus perform a dual function.The sensors also have a dual function, as the sensors typically have a different task during operation than during the start-up process, where the sensors are used to determine the start conditions.

[0035] The actuators are supplied with a measuring current determined by the control unit 28. The current is typically significantly smaller, for example, an order of magnitude smaller than the current required to operate the actuator. Depending on the temperature of the actuator, its coil will have a certain resistance, which causes a voltage drop. The voltage drop is recorded by the control unit 28 and, as a measured value or measured variable, corresponds to a certain temperature. This temperature-dependent value of the actuator allows a statement to be made about the state of the actuator, in particular how warm the actuator is. By comparing the temperature-related measured variables of at least two electrical components, i.e. either by two actuators or by an actuator and a sensor, the control unit 28 determines which starting conditions exist. A relative comparison of the measured variables is sufficient, without the need to determine the absolute temperature.

[0036] If control unit 28 determines that the temperatures at the two measured components are approximately equal, this indicates that cold start conditions exist. If control unit 28 determines that the temperatures at the two measured components differ from each other, this indicates that warm start conditions exist.

[0037] Since the different temperatures of the two measured components are to be interpreted as an indication of the starting conditions, it must be ensured that the two components have different temperatures during operation of the implement. This is achieved by selecting the locations at which the electrical components are arranged in the implement. Electrical components that are located close to the combustion engine 4, which is hot during operation, heat up to a higher temperature than electrical components that are further away from the hot combustion engine 4 and thus heat up less over the same period of time, i.e. are colder. The following is an exemplary embodiment of the location at which electrical components can be arranged that can be used by the control unit to determine the starting conditions.

[0038] The pressure sensor 32 is expediently arranged on the intake port 17; in the exemplary embodiment, the pressure sensor 32 is mounted close to the cylinder. Another pressure sensor can be arranged in the crankcase 13. The temperature at the pressure sensor 32 is relatively high due to its proximity to the combustion engine 4.

[0039] The electric fuel valve 43 is located on the carburetor 10. The temperature at the carburetor 10 is significantly lower than the temperature of the combustion engine 4 itself, even during operation.

[0040] The ignition module 26 is located on the flywheel 25, for example, on the fan wheel. The temperature at the ignition module 26 should therefore be below the temperature of the combustion engine 4 during operation. It should be noted that the ignition module 26 can heat up during operation due to its own heat, which means that the temperature at the ignition module 26 is influenced not only by its location in the implement but also by its own operating temperature. This can also be used to determine the starting conditions.

[0041] In the exemplary embodiment, a temperature sensor 20 is arranged in the control unit 28. The control unit 28 can be installed close to the ignition module 26, e.g., on its circuit board, or, as in the exemplary embodiment, at a distance from the ignition module 26. During operation of the internal combustion engine 4, the temperature sensor 20 measures the temperature of the control unit 28. Even with electronic components such as the control unit 28, it should be noted that the temperature of the control unit 28 is not only caused by the internal combustion engine 4, but also by the inherent heat generated during operation. The temperature sensor 20 can also be arranged at a different location, for example, on the cylinder 12, on the carburetor 10, on the crankcase 13, on the outside of the housing 2, or the like.

[0042] Fig. 5 shows similar to Fig. 4 shows the layout of the electrical components. In addition, Fig. 5 shows that the electrical components can be arranged in different housing areas 35, 36, 37 within the housing 2. In the exemplary embodiment, a first housing area 35 is thermally influenced directly by the cylinder 12. During operation of the internal combustion engine 4, it can be assumed that the first housing area 35 is heated significantly by the cylinder 12 and is therefore hot. The first housing area 35 is thermally separated from a second housing area 36 and a third housing area 37 by an insulator 38. The carburetor 10 is arranged in the second housing area 36. The insulator 38 can be made of an epoxy resin, which has an insulating effect. During operation of the internal combustion engine 4, the temperature of the carburetor 10 in the second housing area 36 is significantly below the temperature of the cylinder 12.Due to the insulator 38, the temperature of the second housing region 36 is significantly lower than the temperature of the first housing region 35 during operation of the internal combustion engine 4. During operation of the internal combustion engine 4, the temperature in the second housing region 36 is only slightly above the ambient temperature. The second housing region 36 can therefore be classified as cold.

[0043] The control unit 28 is located in the third housing area. The second housing area 36 can be structurally separated from the third housing area 37 by a heat conductor 39, for example, an aluminum sheet. The temperature in the third housing area 37 is such that the functionality of the control unit 28 is not impaired. Typically, the temperature in the third housing area 37 is only slightly above the ambient temperature, even during operation of the internal combustion engine 4. The third housing area 37 can also be classified as cold.

[0044] In addition to the absolute temperature differences between the housing areas 35, 36, 37 during operation of the internal combustion engine 4, the thermal decay behavior after a hot internal combustion engine 4 is shut down can also vary in the housing areas 35, 36, 37. The thermal decay behavior is influenced, on the one hand, by the insulator 38. On the other hand, the thermal decay behavior is influenced by the spatial distance of the electrical components from the internal combustion engine 4. Conclusions about the starting conditions can be drawn not only from the temperature at the electrical components, but also from the thermal decay behavior of the electrical components. This is explained below.

[0045] The Fig. 6 and Fig. 7 schematically show a possible temperature profile at different locations on the implement under different operating conditions. Fig. 6, the thermal decay behavior at the evaluated locations is identical, but the absolute temperatures during operation of the combustion engine 4 differ.

[0046] The time course is plotted on the x-axis with continuous time t. At start time t1, the combustion engine 4 is started. At stop time t2, the combustion engine 4 is switched off. The measurement time t3 indicates the time of a possible restart of the combustion engine 4. The temperature is plotted on the y-axis. T U indicates the ambient temperature. A maximum temperature T A1 of the first actuator 41 indicates the asymptotically achievable temperature of a first actuator 41, which can be reached at the first actuator 41 during sufficiently long operation of the combustion engine 4. A maximum temperature T A2of the second actuator 42 indicates the temperature of a second actuator 42 or a sensor 40, which can be reached with a sufficiently long operating time of the combustion engine 4. The function with the solid line indicates a temperature T 41 at the first actuator 41 as a function of time t. The dashed function indicates a temperature T 42 at the second actuator 42 or at the sensor 40 as a function of time t.

[0047] Before the start time t1 of the engine start, the temperature T 41 of the first actuator 41 and the temperature T 42 of the second actuator 42 is identical to the ambient temperature T U After the engine starts, the temperature T 41 of the first actuator 41 and the temperature T 42 of the second actuator 42. If the combustion engine 4 is operated for a sufficiently long time, the temperature T 41 of the first actuator 41 asymptotically the maximum temperature T A1of the first actuator 41. Likewise, the temperature T 42 of the second actuator 42 asymptotically the maximum temperature T A2 of the second actuator 42. In this example, the maximum temperature T A1 of the first actuator 41 is greater than the maximum temperature T A2 of the second actuator 42; accordingly, the temperature of the T 41 first actuator 41 is greater than the temperature T 42 of the second actuator 42 with a sufficiently long operating time of the combustion engine 4.

[0048] At stop time t2, the combustion engine 4 is switched off. Both the temperature T 41 of the first actuator 41 as well as the temperature T 42 of the second actuator 42. The difference temperature ΔT, which corresponds to the temperature difference of the temperature T 41 of the first actuator 41 minus the temperature T 42 of the second actuator42 ΔT = T 41 - T 42 corresponds to, when cooling the temperature T 41of the first actuator 41 and the temperature T 42 of the second actuator 42 is lower.

[0049] At the measuring time t3 of a possible restart of the combustion engine 4, the control unit reads the temperature T 41 of the first actuator 41 and the temperature T 42of the second actuator 42, calculates the temperature difference ΔT, and decides whether the temperature difference |ΔT| is greater than a freely selectable parameter a stored in the control unit 28, or whether the temperature difference |ΔT| is less than or equal to the selected parameter a. If the temperature difference |ΔT| is greater than the parameter a, then warm start conditions exist. If the temperature difference |ΔT| is less than or equal to the parameter a, then cold start conditions exist. The parameter a can be a directly specified, limit temperature; alternatively, it is also possible to specify, for example, a limit value for the ohmic resistance of the component as parameter a, so that the control unit does not evaluate the temperature itself, but only the values ​​of the ohmic resistances, e.g., of the actuators 41, 42, which change with temperature.In the control unit 28, any variable of an actuator or sensor that changes with temperature can be evaluated; in the control unit 28, only a change in the monitored variable resulting from the temperature is evaluated, without the temperature itself having to be determined. The parameter a is selected according to the variable to be evaluated. The monitored variable can be, for example, the ohmic resistance of a coil, the current flowing through a coil at a constant measuring voltage, the voltage drop across the coil at a constant measuring current, a change in the inductance or capacitance of an actuator or sensor, or corresponding temperature-dependent variables.

[0050] In the diagram after Fig. 6, the combustion engine 4 is not restarted at the measurement time t3. If the duration of the measurement is sufficiently long without restarting the combustion engine 4, the temperature T 41 of the first actuator 41 and the temperature T 42of the second actuator 42 asymptotically to the ambient temperature T U to.

[0051] Fig. Figure 7 shows another exemplary embodiment with a temperature profile at various locations within the implement with different thermal decay behaviors. Time t is again plotted on the x-axis, with the engine being started at start time t1, shut down at stop time t2, and a measurement being taken at measurement time t3 to determine whether warm-start or cold-start conditions exist.

[0052] The y-axis again represents the temperature T, with T U the ambient temperature. The maximum temperature T A1 of the first actuator and the maximum temperature T A2of the second actuator correspond to the asymptotically achievable temperatures at the two locations with a sufficiently long operating time of the combustion engine 4. The solid line corresponds to the temperature curve of the temperature T 41 of the first actuator 41 as a function of time. The dashed line corresponds to the temperature curve of the temperature T 42 of the second actuator 42 or the sensor 40 as a function of time t.

[0053] Before the start time t1 of the engine start, the ambient temperature T prevails at both the first actuator 41 and the second actuator 42 or sensor 40. U . Accordingly, the temperature T 41 of the first actuator 41 is identical to the ambient temperature T U and the temperature T 42 of the second actuator is identical to the ambient temperature T U After the start time t1 of the combustion engine 4, the temperature T 41 of the first actuator 41 and the temperature T 42of the second actuator 42. Due to the different thermal decay behavior, the temperature T 41 of the first actuator 41 increases more than the temperature T 42 of the second actuator 42. The gradient of the temperature change as a function of time t of the temperature T 41 of the first actuator 41 is greater than the gradient of the temperature change as a function of time t of the temperature T 42 of the second actuator 42.

[0054] After a sufficiently long operating time of the combustion engine 4, both the temperature T 41 of the first actuator 41 as well as the temperature T 42 of the second actuator 42 the asymptotic limit of the maximum temperature T A1 of the first actuator 41 or the maximum temperature of the second actuator T A2 on; T applies A1 = T A2The maximum temperature at time t2 is about 120°C. Due to the different thermal decay behavior, the temperature T 41 of the first actuator 41 the asymptotic limit of the maximum temperature T A1 of the first actuator 41 faster than the temperature T 42 of the second actuator 42 the asymptotic limit of the maximum temperature T A2 of the second actuator 42.

[0055] At the stop time t2 of the engine stop, both the temperature T 41 of the first actuator 41 as well as the temperature T 42 of the second actuator 42. Due to the different thermal decay behavior, the temperature gradient as a function of time t of the temperature T 42 of the second actuator 42 is smaller than the gradient of the temperature as a function of time t of the temperature T 41 of the first actor 41.

[0056] At the measuring time t3 in the example, the temperature difference ΔT between temperature T 41 of the first actuator 41 and temperature T 42 of the second actuator 42 ΔT = T 41 -T 42 measured. The control unit 28 calculates the temperature difference ΔT and determines whether this |ΔT| is greater than a freely selectable parameter b or |ΔT| is less than or equal to the selected parameter b. If the temperature difference |ΔT| is greater than the parameter b, then warm start conditions exist. If the temperature difference |ΔT| is less than or equal to the parameter b, then cold start conditions exist. It is important that the control unit 28 takes into account the time difference between the measurement time and the engine stop time t3 - t2 when evaluating the temperature difference ΔT. Alternatively, the control unit 28 can also calculate the temperature gradient as a function of time t at the measurement time t3 of the temperature of the second actuator T42 and the temperature of the first actuator T 41 evaluate and compare. If the difference in the gradients of temperature T 42 of the second actuator 42 and the temperature T 41 of the first actuator 41 is greater than a freely selectable parameter c, which is also stored in the control unit 28, then warm start conditions exist; if the value is less than or equal to the parameter c, then cold start conditions exist.

[0057] In the diagram shown in Fig. 7, the combustion engine 4 is not restarted at the measuring time t3. Both the temperature T 42 of the second actuator 42 as well as the temperature T 41 of the first actuator 41 approach the ambient temperature T with a sufficiently long waiting time U to.

[0058] The Fig. 6 and Fig. 7 represent idealized, i.e. schematic, working conditions of the electrical components. In reality, a mixed form of the temperature behavior of the electrical components from the Fig. 6 and Fig. 7; the components will therefore have different absolute operating temperatures as well as different thermal decay behavior.

[0059] Before measuring the temperatures of the electrical components, the control unit 28 can also first calibrate the measured variables, in particular by setting them to zero. After calibration, the control unit can measure the temperatures of the electrical components using the calibrated measured variables.

[0060] The parameters b and c can also be a directly specified temperature representing a limit value; alternatively, it is also possible to specify a limit value for the ohmic resistance of the component as parameter b or c, for example, so that the control unit does not evaluate the temperature itself, but only the values ​​of the ohmic resistances that change with temperature, e.g. of the actuators 41, 42. In the control unit 28, any variable of an actuator or sensor that changes as a function of temperature can be evaluated; in the control unit 28, only a change in the monitored variable resulting from the temperature is then evaluated, without the temperature itself having to be determined. The parameter b or c is selected according to the variable to be evaluated. The monitored variable can, for example,the ohmic resistance of a coil, the current flowing through a coil at the same measuring voltage, the voltage drop across the coil at a constant measuring current, a change in the inductance or capacitance of an actuator or sensor or corresponding temperature-dependent quantities.

Claims

[1] A working device with an internal combustion engine (4) and with a starting device for starting the internal combustion engine (4), and with a housing (2), wherein a first electrical component is arranged at a first location within the housing (2) and a second electrical component is arranged at a second location, and with a control unit (28) which is connected to the first electrical component and to the second electrical component, and the control unit (28) detects a first temperature-dependent value of the first electrical component and a second temperature-dependent value of the second electrical component, and determines the starting conditions depending on these values, characterized by that the first component is a first actuator (41), and that the second component is a second actuator (42) or a sensor (40). [2] Working device according to claim 1, characterized bythat the first electrical component is located at a location that is thermally closer to the combustion engine (4) than the second electrical component at a different location. [3] Working device according to claim 1 or 2, characterized by that the thermal decay behavior at the first location is different from that at the second location. [4] Working device according to one of claims 1 to 3, characterized by that the housing (2) is spatially separated into a first housing area (35) and a second housing area (36), and that the first electrical component is arranged in the first housing area (35) and the second electrical component is arranged in the second housing area (36). [5] Working device according to claim 4, characterized by that the first housing area (35) is thermally separated from the second housing area (36). [6] Working device according to one of claims 1 to 5, characterized by that the sensor (40) is arranged on the control unit (28). [7] Working device according to one of claims 1 to 6, characterized by that the first or second actuator (41, 42) is a solenoid valve, an ignition coil, a generator, an injection valve or similar component. [8] Working device according to one of claims 1 to 7, characterized by that the sensor (40) is a pressure sensor (32), a temperature sensor (20) or similar component. [9] Working device according to one of claims 1 to 8, characterized by that a third electrical component is arranged at a third location within the housing (2), wherein the third electrical component is an actuator (40, 41). [10] Method for determining the starting conditions of a working device with an internal combustion engine (4), wherein a control unit (28) connected to a first electrical component and to a second electrical component determines a first temperature-dependent measured variable at the first electrical component and a second temperature-dependent measured variable at the second electrical component, wherein the control unit (28) compares the first measured variable with the second measured variable and determines the starting conditions, characterized by that the control unit (28) determines the first measured variable at a first actuator (41), and that the control unit (28) determines the second measured variable at a second actuator (42) or at a sensor (40). [11] Method according to claim 10, characterized by that the measured values ​​are determined during the start-up process of the work device. [12] Method according to claim 10 or 11, characterized bythat the actuator (41, 42) is supplied with a current for determining the measured variable, wherein a smaller current is used to determine the measured variable than the current minimum required to operate the actuator (41, 42). [13] Method according to one of claims 10 to 12, characterized by that the control unit (28) determines a temperature-dependent resistance at a coil arranged in the actuator (41, 42). [14] Method according to one of claims 10 to 13, characterized by that the control unit (28) at least partially records the temporal change of a magnetic field of a coil arranged in the actuator and forms the measured variable therefrom.

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