Engine system with switched motor

Abstract

Motor system comprising a switched motor and a switching device for exciting the motor, wherein the motor system has at least one disturbance oscillation (1) with a disturbance frequency (fE), wherein the switching device can excite the motor at switching times (4) which depend on a controllable switching frequency (fS), wherein the switching frequency (fS) of the switching device is controlled depending on a power requirement to be achieved for the motor, wherein the switching times (4) of the switching device are additionally controlled depending on at least one disturbance frequency (fE) of the motor system, characterized in that the switching device has a timing device which starts a time measurement at each switching time (4) and compares a time measured by the timing device with times of amplitude maxima or amplitude minima of a subsequent integer and / or half-integer multiple of the disturbance frequency (fE),and the switching device delays or advances the next switching time (4) based on the measured time of the timing instrument to a time of the nearest half-integer multiple of the respective disturbance frequency (fE) or delays or advances it to a time other than an integer multiple of the respective disturbance frequency (fE).

Description

[0001] The invention relates to a motor system. This motor system comprises a switched motor and a switching device for exciting the motor. Furthermore, the motor system includes at least one disturbance oscillation with a specific disturbance frequency, wherein the switching device can excite the motor at switching times that depend on a controllable switching frequency. The switching frequency of the switching device is controlled according to the power demand to be achieved by the motor.

[0002] The motor system of the type described above can utilize both electric motors, particularly reluctance motors, and internal combustion engines. The motor is excited in pulses, specifically at each switching point. These switching points are conventionally spaced according to the switching frequency, which depends on the motor's power requirement or the power demands placed upon it. In conventional operation, the switching points are simply adapted to the switching frequency and the power demands placed on the motor, resulting in power-dependent excitation.

[0003] In particular, the invention relates to motor systems used in household technology, e.g. in stationary, hand-held or automated kitchen appliances or cleaning devices, such as vacuum cleaners.

[0004] In such motor systems, disturbances frequently occur. In particular, at least one disturbance is a natural frequency of the motor. Furthermore, disturbances can also be transmitted to the motor from an external source at a disturbance frequency. Such externally generated vibrations often originate from a second motor system, for example, in an automated vacuum cleaner (robot vacuum) with more than one motor for suction and movement, or in a device with cooling, e.g., from a cooling fan. These disturbances cause, in particular, increased material stress and higher noise levels, which should be avoided as they impair the service life and user comfort.

[0005] To reduce noise generation and material stress, numerous strategies for motor noise reduction exist in the prior art. These are grouped into passive and active solutions. Passive solutions primarily involve damping elements. Active solutions include, in particular, active noise cancellation (ANC) measures.

[0006] It has proven disadvantageous that passive solutions require a large amount of installation space and, in particular, restrict the handling and use of motor systems. Furthermore, active solutions have the disadvantage of being very complex, requiring additional installation space, and usually also additional sensors.

[0007] The invention is based on the objective of improving the motor system of the known type in such a way that it has a long service life and a high level of user comfort, in particular by reducing noise generation and material stress.

[0008] The problem is solved according to the invention by the features of claim 1. By additionally regulating the switching times of the switching device as dependent on at least one disturbance frequency of the motor system, the switching times, or the excitation of the motor, can advantageously be used systematically to influence the disturbance oscillation in the motor system. In particular, the switching times can deviate slightly from the power-dependent switching frequency, so that the switching times are adapted to at least one disturbance frequency, and in particular at least to the natural frequency of the motor. Preferably, the power output of the motor is not affected, or only slightly, and in particular to an extent that is not relevant for the respective application of the motor system. This results in a particularly advantageous compromise between smooth running, noise generation, material stress, and power output.

[0009] This is based on the understanding that as soon as the motor is excited by the switching device, the disturbance oscillation in the motor system is influenced. This influence corresponds to an excitation of the disturbance oscillation's amplitude and is measurable in the motor system. Measurements on a motor system in which the switching points are controlled solely based on power, i.e., independently of the switching frequency and the motor's disturbance frequency, have shown that this excitation of the disturbance oscillation sometimes fails to occur, is weaker, or is particularly strong. The reason is that the motor is excited in the same direction with every excitation. If the disturbance oscillation oscillates in the same direction as the excitation at the switching point, constructive interference occurs; otherwise, destructive interference occurs. Accordingly, the disturbance oscillation is either amplified or attenuated during excitation.

[0010] In particular, the interfering oscillation is the motor's natural oscillation. This natural oscillation begins, in particular, with the first excitation of the motor by the switching device. Since the motor preferably oscillates at its natural frequency, the type of interference in this case is determined, in particular, by the switching point(s) of the respective excitation.

[0011] If the switching point falls within an integer multiple of the motor system's interference frequency, constructive interference occurs, and the amplitude of the interference oscillation is significantly increased. Conversely, if the switching point falls within a half-integer multiple of the interference frequency, destructive interference occurs, and the amplitude of the interference oscillation is reduced.

[0012] According to the invention, the switching points are therefore controlled, in addition to the power-dependent switching frequency of the motor system, in such a way that the power requirements for the motor are met almost unchanged. The disturbance frequency can be either the motor's natural frequency or an externally acting vibration. In particular, several disturbance frequencies occur in the motor system, e.g., both the motor's natural frequency and a vibration generated by a second motor system, which is transmitted to the motor of the first motor system. In this case, the switching points can advantageously be optimized for a specific disturbance frequency. Furthermore, in the case of multiple disturbance frequencies, the switching points can be adjusted to each disturbance frequency as a compromise by adjusting the switching points accordingly.The suggestion is only permitted within certain time-based release periods or at defined time-based release points.

[0013] In an advantageous embodiment of the invention, the switching device includes a timing device. In particular, the timing device starts a time measurement at each switching time and compares the measured time with the times of the following integer and / or half-integer multiples of at least one disturbance frequency.

[0014] Particularly when at least one disturbance frequency is known, the current phase information of the respective disturbance oscillation can be determined by measuring the time. The switching points can then be adjusted to the disturbance frequency based on this determined phase information. This approach is especially advantageous when the disturbance oscillation to be influenced is the motor's natural oscillation, since the motor's natural oscillation begins with the initial excitation of the motor.

[0015] The timing device is in particular either already present in existing motor systems and can be easily adapted to the motor system requirements according to the invention, or it can advantageously be retrofitted into an existing or to-be-manufactured motor system without major design changes.

[0016] The disturbance vibration can be further determined, in particular, by the switching device incorporating a vibration measuring device that detects a current disturbance vibration and determines its current disturbance frequency and / or amplitude and / or phase information. This vibration measuring device is particularly advantageous for vibrations that are transmitted to the motor from external sources and whose phase information cannot be determined mathematically or by means of a time measurement.

[0017] The natural frequency of the motor is primarily determined by its mechanical design and is generally the same for all motors of a given device model in series production. If significant variations occur within a production run due to manufacturing processes, the natural frequency can also be determined once during production. This determination can be carried out, for example, by a simple mechanical excitation similar to the principle of a tuning fork.

[0018] In particular, the motor of the motor system is a switched electric motor, especially a reluctance motor. Advantageously, a current is impressed into the electric motor at the controlled switching points to excite the motor. The electric motor is particularly advantageous for the motor system according to the invention because it exhibits a fast and constant excitation response, and the switching points can therefore be easily matched to or set against the motor's natural frequency.

[0019] In a further advantageous embodiment of the motor system, the motor is an internal combustion engine, and the switching points are the ignition points of the internal combustion engine. Here, the ignition points are preferably adjusted via adjustable ignition angles of the internal combustion engine. In practice, the internal combustion engine has the advantage that the effect achievable by the embodiment according to the invention is greater. The internal combustion engine has, in particular, more oscillating masses than, for example, an electric motor, which is why the vibration amplitudes of the internal combustion engine are generally also greater than those of a comparable electric motor. The effect of the switching points, which are specifically tuned to the natural frequency of the engine, is therefore potentially greater in the internal combustion engine.

[0020] Further advantageous embodiments of the invention will become apparent from the following description of the figures and the dependent subclaims.

[0021] It shows: Fig. 1 An exemplary illustration of the relationship between a switching frequency of a switching device and a natural oscillation of a motor in a motor system.

[0022] In the various figures of the drawing, identical parts are always labelled with the same reference symbols.

[0023] The following description claims that the invention is not limited to the exemplary embodiments and not to all or several features of the described combinations of features; rather, each individual partial feature of the exemplary embodiment(s) is also significant for the subject matter of the invention, independent of all other partial features described in connection therewith, both on its own and in combination with any features of another exemplary embodiment.

[0024] Fig. Figure 1 illustrates the relationship between the switching frequency of a switching device and the natural oscillation of a motor in a motor system. The motor system comprises a switched motor and a switching device for exciting the motor. Furthermore, the motor exhibits at least one disturbance oscillation 1 with a period t. E the interference frequency f E on. In particular, the interference frequency f corresponds to E according to the frequency formula, the reciprocal of the oscillation period 1 / t E . In the Fig. In the embodiment shown in Figure 1, the motor system exhibits a disturbance oscillation 1 which corresponds to the natural frequency of the motor.

[0025] The motor system oscillates with the disturbance oscillation 1, whereby the amplitude 3 of this disturbance oscillation 1 should preferably be kept low because of the noise generation and material stress it causes.

[0026] The switching device can excite the motor in the motor system at switching times 4, which depend on a controllable oscillation period ts of the switching frequency fs. According to the frequency formula, the switching frequency fs corresponds to the reciprocal of the oscillation period 1 / t. S In particular, as in Fig. Figure 1 shows that when the motor is excited, there is an interference between the excitation and the disturbance oscillation 1 or the natural frequency of the motor.

[0027] According to the invention, the switching times 4 of the switching device are additionally dependent on the disturbance frequency f. E regulated. Fig. Figure 1 shows examples of possible design factors according to which criteria the switching times 4 are adjusted to the disturbance frequency f E or the natural frequency of the motor system can be adjusted, and how the switching points 4 accordingly affect the disturbance oscillation 1 of the motor system, in particular the amplitude 3 of the disturbance oscillation 1.

[0028] Particularly advantageously, using the embodiment according to the invention, the switching times 4 can be differentiated temporally from the switching frequency fs and from at least one disturbance frequency f. E The switching frequency fs is controlled depending on the motor system so that the power requirements for the motor are met almost unchanged. The switching frequency fs depends on the power demand to be achieved by the motor. The switching points 4 simultaneously have a beneficial effect on the respective disturbance oscillation 1 of the motor system. The influence on at least one disturbance oscillation 1 of the motor system can be used to constructively amplify or destructively reduce the respective amplitude 3 of the disturbance oscillation 1 of the motor system.

[0029] As an alternative to the embodiment in Fig. 1. At least one disturbance oscillation 1 can be transmitted to the motor additionally or exclusively by external vibrations. Preferably, the switching points 4 in this case depend on at least one disturbance oscillation 1, each with a disturbance frequency f. E regulated. In the Fig. The example shown does not depict an externally acting disturbance oscillation 1.

[0030] In a particular embodiment of the invention, the switching device includes a frequency storage unit. Advantageously, one or more interference frequencies f are stored in the frequency storage unit. EThis means that at least one oscillation pattern of a disturbance oscillation 1 in the motor system is known, thus eliminating the need for real-time measurement of the respective disturbance oscillation 1. The switching points 4 can therefore be advantageously determined based on the power demand to be achieved by the motor, i.e., based on the switching frequency 1 / ts and based on at least one disturbance frequency f. E , are regulated or determined in advance.

[0031] A possible interference frequency f EThe natural frequency of a motor, in particular, is determined primarily by its mechanical design and is fundamentally the same for all motor systems or devices in a series. Therefore, the natural frequency can be determined once for an entire series of devices or, alternatively, for each individual device and / or device type. The natural frequency can be determined, for example, by a simple mechanical excitation based on the principle of a tuning fork.

[0032] In a particular embodiment of the motor system, the switching device includes a timing device. This timing device initiates a time measurement, especially at each switching point 4. The measured time is expediently combined by the timing device with the points in time of a subsequent integer and / or half-integer multiple of at least one disturbance frequency f. E compared.

[0033] In particular, an amplitude maximum of the respective disturbance oscillation 1 occurs at the integer multiple of the disturbance frequency f. E on, where an amplitude minimum of the respective disturbance oscillation 1 occurs at the half-integer multiple of the disturbance frequency f E occurs.

[0034] Especially if at least one interfering frequency f E If the phase information is known and at least one aspect of it is available, the current phase information can be determined using the timing device. This design is particularly advantageous if the at least one disturbance frequency f E The natural frequency of the motor is the frequency at which the motor begins to oscillate with the first excitation.

[0035] The timing device is in particular either already present in existing motor systems and can be easily adapted to the motor system requirements according to the invention, or it can advantageously be retrofitted into an existing or to-be-manufactured motor system without major design changes.

[0036] In an advantageous embodiment of the invention, the switching times 4 are controlled by the switching device using at least one disturbance frequency f. E compares with the switching frequency fs and depends on a ratio between the respective disturbance frequency f E and the switching frequency fs and / or phase information of the respective interference frequency f E regulates.

[0037] Especially when the phase information and / or interference frequency f ESince the frequency and / or amplitude 3 of the disturbance oscillation 1 cannot be mathematically determined by a time measurement or otherwise, an advantageous embodiment of the invention presents itself in which the switching device comprises a vibration measuring device. The vibration measuring device expediently detects a current disturbance oscillation 1 and determines its current disturbance frequency f. E and / or amplitude 3 and / or phase information.

[0038] In Fig. Figure 1 shows a time course on the T-axis and the magnitude of an excitation 6 of the disturbance oscillation 1 of the motor system on the A-axis. From the Fig. 1. It is evident that the interference frequency f E or natural frequency and the switching frequency fs do not exhibit any phase shift relative to each other, since the excitation 6 by the switching times 4 significantly determines the course of the disturbance oscillation 1 or the natural oscillation of the motor.

[0039] Depending on the specific case and the performance requirements placed on the motor, the switching points 4 must be adjusted. This results in various advantageous application scenarios and configurations for the motor system. The switching points 4 should be oriented as closely as possible to the performance-dependent switching frequency fs to achieve an optimal compromise between power delivery, material stress, smooth running, and comfort.

[0040] In particular, the switching points 4, as in the second section 8 and third section 9 of Fig. 1 shown, regulated such that the motor at a switching time 4 not equal to an integer multiple of the disturbance frequency f E or is excited at its natural frequency. In particular, the switching device delays the next switching point 4 to a time other than an integer multiple of the respective disturbance frequency f. E, or shifts the next switching time 4 to a time not equal to an integer multiple of the respective interference frequency f E before.

[0041] This design advantageously reduces the maximum peak amplitude of the respective disturbance oscillation 1 of the motor system. This minimum requirement can also be interpreted as prohibiting excitation of the motor at an integer multiple of one or more disturbance frequencies f. E This expression is used in particular when a direct controlled excitation occurs at a time that is a half-integer multiple of the respective disturbance frequency f. E This is not possible. This is particularly the case if the performance losses would fall below the level required for the application of the motor system. This design is used especially when the respective interference frequency f Ebelow 150% of the switching frequency fs. Furthermore, this design is used to create an advantageous compromise when the number of disturbance oscillations is 1 and their respective disturbance frequencies are f. E a direct excitation of a half-integer multiple of a selected disturbance frequency f E not possible without another disturbance oscillation 1 being amplified beyond a permissible level by this excitation.

[0042] Especially if the respective interference frequency f E If the switching frequency fs of the motor system and the switching frequency required for the power demand are within the same order of magnitude, the switching times 4, according to the third section 9, are preferably used. Fig. 1, brought forward. Section 9 shows the effect of switching point 4 shortly after a half-integer multiple of the disturbance frequency f. Eof the motor system on the disturbance oscillation 1 of the motor system. By advancing the switching points 4, a constructive excitation 6 of the amplitude 3 of the respective disturbance oscillation 1 is not excluded, however, advantageous damping occurs compared to that described in the first section 7 according to Fig. Case 1 as shown. In the first section 7 according to Fig. Figure 1 shows the effect of the excitation 6 on the disturbance oscillation 1 when the switching time 4 is an integer multiple of the respective disturbance frequency f. E falls.

[0043] A destructive excitation 6 of at least one disturbance oscillation 1 can be particularly advantageous, as described in the second section 8 according to Fig. As shown in 1, this occurs when the switching times 4 are regulated such that the motor only operates at a half-integer multiple of the disturbance frequency f. Eor is excited by the motor's natural frequency. This configuration is particularly possible if the disturbance frequency f E the motor's frequency is much higher than the switching frequency fs, preferably when the disturbance frequency f E The switching frequency fs is at least twice as high. Advantageously, the switching device delays the next switching point 4 to a time at the following half-integer multiple of the respective disturbance frequency f. E .

[0044] In a preferred embodiment of the invention, the switching device delays the next switching time 4 to a time at the nearest half-integer multiple of the respective disturbance frequency f. Eor advances the next switching point 4 to a point in time at the nearest half-integer multiple. In particular, this implementation, whereby the switching point 4 is always adjusted to the nearest half-integer multiple, is used when the disturbance frequency lies in a range of 150% to less than 200% of the switching frequency fs. Advantageously, this allows the switching point to be shifted from the power-dependent switching frequency fs to the nearest amplitude minimum of the respective disturbance oscillation 1, thereby particularly effectively damping the respective disturbance oscillation 1 and simultaneously minimizing the power losses compared to a switching point 4 at the switching frequency fs.

[0045] In particular, if a switching time shift as described above would lead to power losses that would affect the respective power requirement of the motor beyond a permissible level, in an alternative embodiment the switching device can shift the next switching time 4 to a time at the following half-integer multiple of an overtone of the respective disturbance frequency f. E delay or bring forward.

[0046] In particular, the motor of the motor system is a switched electric motor. Fig. Figure 1 illustrates the invention using a particularly preferred embodiment, according to which the electric motor is a reluctance motor. Preferably, a current is impressed into the electric motor at the controlled switching times 4 to excite the motor. For illustrative purposes, in Fig. 1 the impressed current via a mechanical response of the motor system, i.e. a disturbance oscillation 1, in particular the natural oscillation of the motor, is depicted.

[0047] The electric motor is particularly advantageous for the motor system according to the invention, since it has a fast and constant excitation behavior and thus the switching frequency fs can easily be adjusted to the disturbance frequency f. E the engine system can be adjusted or determined.

[0048] In a further advantageous embodiment of the motor system, the motor is an internal combustion engine, and the switching points are ignition points of the internal combustion engine. Here, the ignition points are preferably controlled and adjusted via an adjustable ignition angle of the internal combustion engine. The internal combustion engine has, in particular, a larger oscillating mass than, for example, an electric motor, which is why the amplitudes 3 of the disturbance oscillation 1 are generally also larger in the internal combustion engine than in a comparable electric motor. The effect of the switching points 4, which are specifically tuned to the disturbance oscillation 1 of the motor system, is therefore greater in the internal combustion engine.

[0049] The invention is not limited to the embodiments illustrated and described, but also encompasses all embodiments that have the same effect within the meaning of the invention. It is expressly emphasized that the embodiments are not limited to all features in combination; rather, each individual feature can also have inventive significance independently of all other features. Furthermore, the invention is not yet limited to the combination of features defined in claims 1 and 8, but can also be defined by any other combination of specific features from all disclosed individual features. This means that, in principle, virtually any individual feature of claims 1 and 8 can be omitted or replaced by at least one individual feature disclosed elsewhere in the application. Reference symbol list 1. Disturbing oscillation f EInterference frequency t E Oscillation period of the disturbance frequency 3 Amplitude of the disturbance oscillation 4 Switching point fs switching frequency ts Oscillation period of the switching frequency 6 Suggestion 7 First Section 8 Second Section 9 Third Section T Time course axis A amplitude axis

Claims

[1] Motor system comprising a switched motor and a switching device for exciting the motor, wherein the motor system has at least one disturbance oscillation (1) with a disturbance frequency (f) E ) has, wherein the switching device can excite the motor at switching times (4) which depend on a controllable switching frequency (fs), wherein the switching frequency (fs) of the switching device is controlled depending on a power requirement to be achieved for the motor, characterized by , that the switching times (4) of the switching device are additionally dependent on at least one disturbance frequency (f E ) of the engine system are regulated. [2] Motor system according to claim 1, characterized by , that at least one disturbance vibration (1) is a natural vibration of the motor or is transmitted to the motor by external vibrations. [3] Motor system according to claim 1 or 2, characterized bythat the switching device has a frequency memory in which one or more interference frequencies (f E ) are stored. [4] Motor system according to any one of claims 1 to 3, characterized by , that the switching device includes a timing device which starts a time measurement at each switching time (4) and compares the measured time with the times of the following integer and / or half-integer multiples of at least one disturbance frequency (f E ) compares. [5] Motor system according to any one of claims 1 to 4, characterized by that the switching device has at least one interference frequency (f E ) compares with the switching frequency (fs) and the switching times (4) depend on a ratio between the respective disturbance frequency (f E ) and the switching frequency (fs) and / or phase information of the respective interference frequency (f E ) regulates. [6] Motor system according to any one of claims 1 to 5, characterized bythat the switching device has a vibration measuring device which detects a current disturbance vibration (1) and its current disturbance frequency (f E ) and / or amplitude (3) and / or phase information determined. [7] Motor system according to any one of claims 1 to 6, characterized by , that the switching device sets the next switching time (4) to a time of the following half-integer multiple of the respective disturbance frequency (f E ) delayed. [8] Motor system according to any one of claims 1 to 6, characterized by , that the switching device sets the next switching time (4) to a time of the nearest half-integer multiple of the respective disturbance frequency (f E ) delays or brings forward. [9] Motor system according to any one of claims 1 to 6, characterized by , that the switching device sets the next switching time (4) to a time other than an integer multiple of the respective disturbance frequency (fE ) delays or brings forward. [10] Motor system according to any one of claims 1 to 6, characterized by , that the switching device sets the next switching time (4) to a time of the following half-integer multiple of an overtone of the respective disturbance frequency (f E ) delays or brings forward. [11] Motor system according to any one of claims 1 to 10, characterized by , that the motor is a switched electric motor, in particular a switched reluctance motor and a current is impressed to excite the electric motor at the regulated switching times (4). [12] Motor system according to any one of claims 1 to 11, characterized by , that the engine is an internal combustion engine and the switching points (4) are ignition points of the internal combustion engine, wherein the ignition points are regulated and adjusted via adjustable ignition angles of the internal combustion engine.

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