DE102018125710A1 - DC brush motor for driving a compressor, compressed air generation and method for operating a DC brush motor - Google Patents

Abstract

The invention relates to a direct current brush motor for driving a compressor, in particular compressed air generation with a compressor and a direct current brush motor, preferably for an air suspension system, a brake system or the like. The DC brush motor has a stator and a rotor, each with a plurality of pole pairs. The rotor can be supplied with current via a commutator and a brush arrangement with a plurality of brushes. The direct current brush motor also has a switching device, which is connected to the brush arrangement in a control manner, for switching an energization of one of the brushes.

Description

The invention relates to a direct current brush motor according to the preamble of claim 1 for driving a compressor, compressed air generation with a compressor and the direct current brush motor and a method for operating a direct current brush motor according to the preamble of claim 13.

A DC brush motor mentioned at the outset typically has a stator, a rotor, a commutator and a number of brushes and is operated with direct current. The stator is generally immobile and regularly has a hollow cylinder to which main poles of the plurality of pole pairs mentioned at the outset, which are assigned to the stator, are attached. The main poles are used to generate a magnetic field and include, for example, series-connected DC-fed main pole windings, also called excitation windings or permanent magnets.

Typically, a rotatably mounted rotor is arranged in the stator, which comprises one or more coils, which are located in the magnetic field of the stator and which form the plurality of pole pairs mentioned at the outset associated with the rotor. Often the coils of the rotor are wrapped around an iron core called an anchor.

The coils of the rotor are electrically connected to the commutator mentioned at the beginning, which is generally designed to convert an AC voltage into a DC voltage. This happens because a commutator in motor operation always reverses the polarity of the voltage induced in the coils when the direction of the induced voltage changes. The direct voltage generated in motor operation in this way is typically speed-dependent. As a rule, a commutator in motor operation is energized by brushing the brush arrangement mentioned at the beginning, for example metal or carbon brushes. A brush represents a sliding contact, which is typically pressed mechanically onto the commutator via a spring in order to establish an electrically conductive connection during operation. If a rotor is energized via a commutator, the magnetic field generated in the coils of the rotor interacts with the magnetic field of the stator, so that the rotatably mounted rotor rotates in the stator. The polarity reversal caused by the commutator ensures that the torque of the rotor always acts in the same direction.

Examples of a DC brush motor are a permanent magnet DC brush motor in which the stator magnetic field is generated by a permanent magnet and an electrically excited DC brush motor in which the stator magnetic field is generated by an electromagnet. An electrically excited DC brush motor includes a series machine, a shunt machine, a separately excited machine and a compound machine. The latter is also called a double-lock motor.

DC brushed motors are used today in many areas, particularly in a vehicle as a starter motor or as a component of a compressed air supply for a vehicle, due to their comparatively high efficiency, generally uninterrupted torque output and emission-free engine operation.

In DE 10 2012 024 400 A1 a limitation of an operating current of an electric motor is described. In particular, a compressor for generating compressed air, in particular for a compressed air supply system of a vehicle, is described. The vehicle has an electric motor in the form of a brushed DC electric motor BDC electric motor and a compressor, in particular a two-stage compressor with at least a first and a second compressor stage, which can be driven by the electric motor. The electric motor can be controlled by means of an electronic control module of a control device while limiting an operating current of the electric motor.

However, it is regularly problematic that comparatively high current gradients can occur with comparatively high load requirements, in particular when switching on and when switching off a DC brush motor. For example, a brief start-up current peak that occurs when a DC brush motor is switched on can have a negative effect on an electrical system of a vehicle. It is therefore desirable to reliably avoid the occurrence of large current gradients in the operation of a DC brush motor.

In DE 10 2012 214 122 A1 describes an electric starter motor for a starting device, which has excitation windings in the stator and armature windings in the rotating armature, which can be energized with brushes via a commutation device. The starter motor described can be operated either with a maximum number of poles or with a reduced number of poles. The in DE 10 2012 214 122 A1 The starter motor described is designed as a series motor and is not operated in continuous operation, but rather for a limited time during a vehicle's starting process.

A direct current brush motor can still be improved, in particular with regard to the limitation of an operating current and / or further running parameters of the direct current brush motor, in particular if it is to be operated in continuous operation.

At this point, the invention sets an object of which it is to provide an improved DC brush motor, an improved compressed air generation and an improved method for operating a DC brush motor.

According to the invention the object is achieved by a DC brush motor according to claim 1.

The DC brush motor according to the invention is designed to drive a compressor. In particular in the context of compressed air generation with a compressor and the DC brush motor, preferably for an air suspension system, a brake system or the like.

The invention is based on a DC brush motor of the type mentioned at the beginning. This has a stator and a rotor, each with a plurality of pole pairs. The rotor can be energized via a commutator and a brush arrangement with a plurality of brushes. The direct current brush motor also has a switching device, which is connected to the brush arrangement in a control manner, for switching an energization of one of the brushes.

According to the invention, the switching device is integrated in an operating circuit of the DC brushed motor which can be controlled by the latter. The operating circuit is designed according to the invention to control running states of the motor, the operating circuit for the running state monitoring a running parameter determining the power consumption and / or power output of the motor, and controlling the switching device as a function of the running parameter, in such a way that the current supply is supplied by the switching device the brush can be switched when the running parameter reaches a threshold value.

This reliably prevents large current gradients from occurring, particularly when the DC brush motor according to the invention is switched on and off.

The invention also leads to compressed air generation according to claim 12, preferably for an air suspension system, a brake system or the like of a vehicle, with a compressor and a DC brush motor according to the invention.

With regard to the method, the above-mentioned object is achieved by a method of claim 13 for operating a DC brush motor, in particular for operating compressed air generation with a compressor and a DC brush motor, preferably for operating an air suspension system, a brake system or the like Vehicle.

The method is based on the use of a direct current brush motor, which has a stator and a rotor, each with a plurality of pole pairs. The rotor can be energized with a plurality of brushes via a commutator and a brush arrangement. The direct current brush motor furthermore has a switching device, which is connected to the brush arrangement in a control manner, for switching a current supply to a brush, the switching device being integrated in an operating circuit of the direct current brush motor which can be controlled by the latter.

• - die Betriebsschaltung Laufzustände des Motors steuert,
• - die Betriebsschaltung für den Laufzustand einen die Leistungsaufnahme- und/oder Leistungsabgabe des Motors bestimmenden Laufparameter überwacht, und
• - in Abhängigkeit von dem Laufparameter die Schalteinrichtung ansteuert, wobei

die derart angesteuerte Schalteinrichtung die Bestromung der Bürste schaltet, wenn der Laufparameter einen Schwellwert erreicht.According to the invention, the method is characterized in that

• - the operating circuit controls the running conditions of the engine,
• - The operating circuit for the running condition monitors a running parameter determining the power consumption and / or power output of the engine, and
• - Controls the switching device depending on the running parameter, wherein

the switching device controlled in this way switches the current supply to the brush when the running parameter reaches a threshold value.

This reliably prevents large current gradients from occurring, particularly when the DC brush motor according to the invention is switched on and off.

The invention is based on the consideration that it is fundamentally advantageous to drive a compressor with a DC brush motor. However, the inventors have recognized that it can happen that a compressor driven with a DC brushed motor can have comparatively high currents due to its power consumption, for example when switching on or off, but also when operating under different load conditions. The invention is now based on the knowledge that a higher-pole DC brush motor, which has a stator and a rotor, each with a plurality of pole pairs, can increase a power density compared to a DC brush motor with only one pole pair. The size and weight can advantageously be reduced with the same power density.

The invention is further based on the knowledge that a direct current brush motor with a plurality of pole pairs with a changed characteristic can also run with a reduced number of brushes. This means that a commutator in this running state with a reduced power density is not energized with all the brushes of a brush arrangement, but only with a comparatively smaller number of brushes. If only an energization of brushes of a brush arrangement is switched by means of a switching device, advantageously all brushes, even those that are not energized, can remain in contact with the commutator and do not have to be mechanically detached from it in order to energize the commutator by one of the Interrupt brushing.

The inventors have furthermore recognized that there are different running states when driving a compressor with a DC brush motor, and that it can be advantageous to energize a different number of brushes of a brush arrangement in each case in the different running states. The invention is further based on the knowledge that it can be advantageous if a direct current brush motor is supplied with current in different running states with different numbers of brushes of a brush arrangement.

The invention is based on the consideration that it is advantageous to monitor a running parameter determining the power consumption and / or power output of the motor by means of an operating circuit - preferably transiently - over time and the number of energized brushes of the brush arrangement on the basis of the monitored To determine running parameters in a corresponding running state of the engine. It has turned out to be a suitable criterion to define a threshold value for a running parameter and to switch on the energization of a brush of the brush arrangement when the threshold value is reached. To switch the brush, the operating circuit controls the switching device as a function of the monitored running parameter, by means of which the current supply to the brush can be switched when the monitored running parameter reaches a threshold value. The switching device is advantageously integrated into the operating circuit provided anyway, so that basically no changes need to be made to a DC brushed motor itself.

Advantageous developments of the invention can be found in the subclaims and specify in particular advantageous possibilities for realizing the concept explained above in the context of the task and with regard to further advantages.

The DC brushed motor according to the invention can advantageously be operated with only one voltage source. This avoids the use of additional components, such as an additional battery, additional lines and connections, in a vehicle. The concept described thus enables cost savings, in particular compared to today's CSS solution, by eliminating the need for an additional housing and connectors.

A running state can relate to any state in the motor operation of the direct-current brush motor and is in particular not only limited to a motor start. Advantageously, the current supply to a brush of the brush arrangement can be switched as a function of a monitored running parameter at any time during motor operation, in order to adapt current supply to the DC brush motor and to specifically manipulate a running parameter.

The direct current brush motor is preferably a permanent magnet direct current brush motor, that is to say a permanently excited direct current brush motor, in which the stator magnetic field is generated by a permanent magnet.

The compressor is usually controlled by a compressor relay and driven by the permanent magnet DC brush motor. Advantageously and preferably, however, there is no conventional mechanical relay.

A compressor driven by a DC brushed motor usually runs continuously and especially not in a start-stop operation. The running conditions of a DC brushed motor for driving a compressor thus extend in part over a comparatively long period of time, for example continuous operation with a constant load. The running states preferably include at least one engine start, one engine endurance run, and one engine stop.

In certain running conditions, it can be advantageous if the power density of a multi-pole DC brush motor is reduced by reducing the number of brushes with current in a brush arrangement. For example, it can be advantageous to energize a DC brush motor in the continuous motor operation with all existing brushes and in the motor start and stop with a reduced number of brushes. This means that it can be advantageous to energize individual brushes temporarily or over a longer period of time switch off. Motor operation with a reduced number of brushes can advantageously reduce a running parameter determining a power consumption of the motor, which for example represents a starting current, or a running parameter determining a power output of the motor, which represents a speed, for example. The number of energized brushes is preferably less than or equal to the number of poles of the plurality of pole pairs and is, in particular, at least two energized brushes.

The operating circuit is preferably designed to transiently monitor a running parameter that determines the power consumption and / or power output of the engine for a running state. Advantageously, a running parameter is thus monitored transiently over time for a running state during motor operation of the DC brush motor. For example, the operating circuit can query a monitored running parameter at regular or at randomly defined time intervals.

One of the running states is preferably a motor start and the running parameter is a starting parameter, in particular a starting current and / or gradient. The operating circuit is preferably designed to monitor the start-up parameter and to control the switching device as a function of the start-up parameter.

It is preferably switched on using two brushes. This means that only one pair of poles is preferably energized when the motor is started. After the motor has started, the remaining brushes are preferably switched on step by step or together depending on the monitored start-up parameter, i. H. energized. In this way, a starting current or a starting current characteristic can advantageously be set in a controlled manner and starting current peaks which are too high can be avoided. It is then also advantageously possible to use smaller line cross sections for compressor supply lines.

One of the running states is preferably a continuous motor run and the running parameter is a continuous running parameter, in particular a rotational speed. The operating circuit is preferably designed to monitor the endurance parameter and to control the switching device as a function of the endurance parameter.

As mentioned at the beginning, a DC voltage generated in motor operation is typically speed-dependent. If different load conditions occur during motor operation, it may be advantageous to lower or increase a speed of the DC brushed motor, for example, depending on a load. When the speed is reduced, the current is preferably switched off by one or more brushes. By operating the motor with a reduced number of brushes, a rotational speed of the direct current brush motor can be reduced in accordance with the number of brushes with current, the voltage provided and the torque demanded.

One of the running states is preferably a motor stopping and the running parameter is a stopping parameter, in particular a rotational speed. The operating circuit is preferably designed to monitor the runout parameter and to control the switching device as a function of the runout parameter. For example, a direct current brush motor can be brought to a standstill in a controlled manner by switching off brushes of the brush arrangement depending on the monitored run-down parameter, step by step or several brushes together.

Preferably, the DC brush motor comprises two pairs of poles, i.e. H. four poles and four brushes. However, it can also be advantageous to use a larger number of pole pairs, for example three pole pairs and correspondingly six brushes.

In a preferred development, the operating circuit is designed to control the switching device in such a way that the current supply to individual brushes of the brush arrangement is switched in stages depending on the running parameter.

An energization of individual brushes is preferably switched on or off in succession. The number of stages then corresponds to the number of brushes switched on or off. However, it can also be advantageous if the current supply to several brushes is switched on or off together. In this case, the switching of the energization of the brushes in stages comprises fewer stages, for example only one stage between the energization of two brushes during an engine start and the energization of four brushes during an engine continuous operation. By gradually switching the current supply to the brushes of a brush arrangement, a starting current or a switching-off current characteristic can be set in a controlled manner, or a speed of the DC brush motor can be specifically increased or decreased and thus set. The concept described advantageously allows, in addition to a starting current / switch-off current characteristic which can be set in stages, also to influence a rotational speed of a direct current brush motor in stages without the need to fundamentally change the general structure of a direct current brush motor itself.

• - die Schalteinrichtung die Bestromung einer Bürste abschaltet, wenn der Laufparameter einen Schwellwert überschreitet und/oder
• - die Bestromung einer Bürste einschaltet, wenn der Laufparameter einen Schwellwert unterschreitet. Die Betriebsschaltung ist also vorzugsweise ausgebildet, die Schalteinrichtung derart anzusteuern, dass diese die Bestromung einer Bürste abschaltet, wenn der Schwellwert überschritten wird und/oder einschaltet, wenn der Schwellwert unterschritten wird.

The dependence of the control of the switching device on the running parameter preferably includes that

• - The switching device switches off the current supply to a brush when the running parameter exceeds a threshold value and / or
• - switches on the current supply to a brush when the running parameter falls below a threshold value. The operating circuit is therefore preferably designed to control the switching device in such a way that it switches off the current supply to a brush when the threshold value is exceeded and / or switches on when the threshold value is undershot.

The number of energized brushes can therefore advantageously be selected as a function of the monitored running parameter; in particular, the number of energized brushes can be selected by defining a threshold value for the running parameter. If the threshold value is exceeded or undershot, the number of brushes supplied with current can then be changed during motor operation. A threshold value offers a particularly suitable criterion. However, it can also be advantageous to choose the number of brushes that are energized as a function of a further additional or alternative criterion.

The dependence of the control of the switching device on the running parameter preferably includes the fact that the number of brushes of the brush arrangement which are energized in a lukewarm state depends on the monitored running parameter.

In a preferred development, the switching device has electronic switching elements. The switching elements preferably have at least one electrically conductive switching state in which one or more brushes are supplied with current during operation and in an electrically non-conductive switching state in which the current supply to one or more brushes is interrupted. The electronic switching elements of the switching device can preferably be controlled by the operating circuit. In each case one switching element is preferably assigned to exactly one brush of the brush arrangement and switches an energization of this assigned brush. The brushes can then advantageously be switched independently of one another. The switching contacts can particularly preferably be controlled independently of one another by the operating circuit. However, it can also be advantageous if several brushes can be switched together with one switching element. For example, only one switching element can be provided in a switching device, which is designed to switch between a reduced number of energized brushes and a full number of energized brushes.

The switching elements are preferably installed as semiconductor switches on a circuit board of the operating circuit. The semiconductor switches can advantageously be comparatively inexpensive, unprotected semiconductors, since it is not necessary to take external cabling errors into account. The semiconductor switches are preferably metal-oxide-semiconductor field-effect transistors.

The dependence of the control of the switching device on the running parameter preferably includes the fact that the running parameter is limited, in particular reduced, by high-frequency clocking of the semiconductor switches. Advantageously, for. B. two semiconductor switches, each of which switch the current supply to a corresponding brush, can influence a starting current gradient, for example, by means of fast clocking. During a motor start-up, the starting current is preferably limited or even reduced. After the motor has started, the remaining brushes can then be switched on via further semiconductor switches. Advantageously, the starting current gradient can be set during a motor start-up by a pulsed control and two further compressor speeds can be represented by a static control of the other semiconductor switches.

In a preferred development, the switching device is designed to control a brush of the brush arrangement in a time-controlled manner. The switching device preferably comprises a time control logic which is installed together with switching elements of the switching device on a circuit board of the operating circuit. A time-controlled activation of the brushes represents a comparatively simple way of activation. A time-controlled activation of the brushes can advantageously dispense with a current measurement for activation. It is also conceivable that only selected brushes of the brush arrangement are controlled in a time-controlled manner. The timing logic is preferably an integral part of the circuit board on which the switching elements are installed.

In a further development, the switching device is designed to receive a control signal from an operatively connected control unit that is superior to the DC brush motor. The switching device is preferably designed to switch the current supply to the brush as a function of the control signal received. A number of energized brushes of the brush arrangement can advantageously be determined by the higher-level control device independently of the operating circuit by means of a control signal. Brushes can therefore be switched on or off by means of a corresponding control signal.

• 1: eine schematische Darstellung eines Gleichstrom-Bürstenmotors;
• 2: eine schematische Darstellung einer Verschaltung einzelner Bürsten bei einem vier-poligen Gleichstrom-Bürstenmotor;
• 3: ein elektrisches Ersatzschaltbild eines vier-poligen Gleichstrom-Bürstenmotors mit vier Bürsten;
• 4: eine mögliche Beschaltung der Bürsten eines vier-poligen Gleichstrom-Bürstenmotors;
• 5: zeigt einen Rotor, der als zwölf-nutiger Anker mit zwölf Einzelspulen, welche die Ankerwicklungen bilden, aufgebaut ist.

Embodiments of the invention will now be described below with reference to the drawing. This is not necessarily to show the embodiments to scale, rather the drawing, where useful for explanation, is carried out in a schematic and / or slightly distorted form. With regard to additions to the teachings which can be seen directly from the drawing, reference is made to the relevant prior art. It should be taken into account here that various modifications and changes regarding the form and the detail of an embodiment can be made without departing from the general idea of the invention. The features of the invention disclosed in the description, in the drawing and in the claims can be essential for the development of the invention both individually and in any combination. In addition, all combinations of at least two of the features disclosed in the description, the drawing and / or the claims fall within the scope of the invention. The general idea of the invention is not limited to the exact form or detail of the preferred embodiment shown and described below, or is limited to an object that would be limited compared to the object claimed in the claims. For the specified design ranges, values within the stated limits should also be disclosed as limit values and can be used and claimed as required. Further advantages, features and details of the invention result from the following description of the preferred embodiments and from the drawing; this shows in:

• 1 : a schematic representation of a DC brush motor;
• 2nd : A schematic representation of an interconnection of individual brushes in a four-pole DC brush motor;
• 3rd : an electrical equivalent circuit diagram of a four-pole DC brush motor with four brushes;
• 4th : a possible wiring of the brushes of a four-pole DC brush motor;
• 5 : shows a rotor that is constructed as a twelve-slot armature with twelve individual coils that form the armature windings.

In 1 is a schematic representation of a DC brush motor 100 shown. The DC brush motor 100 is preferably provided for driving a compressor (not shown), in particular as a component of compressed air generation with a compressor and a DC brush motor, preferably for an air suspension system, a brake system or the like. The DC brush motor shown 100 is a permanent magnet DC brush motor.

The DC brush motor 100 has a stator 102 and a rotor 104 with two pairs of poles each. In an embodiment not shown here, the DC brush motor has more than two pole pairs, two or three pole pairs being generally preferred. The rotor 104 is in the stator 102 rotatably mounted.

The rotor 104 is about a commutator 106 and a brush assembly 108 with a plurality of brushes 109.n , energizable. In the embodiment shown, the brushes 109.n realized as carbon brushes, each mechanically connected to the commutator via a spring 106 be pressed. The brushes 109.n are therefore permanently in contact with the commutator 106 . In an embodiment not shown here, the brushes are metal brushes.

The DC brush motor 100 also has one with the brush assembly 108 tax-related switching device 110 for switching current supply to one of the brushes 109.n on.

Typically, compressors for vehicle air suspensions driven with a DC brush motor have a power consumption of 180 W to 400 W, with a starting current of up to 120 A. Such a short-term starting current peak can have a negative impact on the electrical system of a vehicle Compressor supply circuit or cause a voltage drop via compressor supply lines at the starting torque and thus affect the ability of the compressor to start.

For example, in the case of a weakened starter battery, it may happen that a DC brushed motor cannot compensate for a steep rise in current when a compressor is switched on. This can lead to a brief undervoltage in a vehicle, which in turn can lead to malfunctions in other vehicle systems. If the compressor is switched off via a relay, for example, the sudden reduction in power consumption by approx. 25 A - 30 A with a weak battery can have an undesirable influence on the vehicle electrical system. Such an influence can affect a short-term overvoltage, which in turn can lead to malfunctions in other systems in a vehicle.

A voltage drop ΔU across compressor supply lines with the line resistance R _{line is} calculated $$\Delta \text{U}={\text{R}}_{\text{management}}\times {\text{I.}}_{\text{Start}}.$$

With a high starting current I _{start there} is a high voltage drop, which can reduce the starting ability of the compressor. To compensate for a voltage drop, it is advantageous to use appropriate line cross sections for compressor supply lines.

Nowadays, typically two-pole DC brush motors, e.g. H. with exactly one pole pair.

In order to set an inrush current or an inrush current characteristic, a CSS (compressor soft start) control is generally used, in particular to bring about a soft start. Current limitation using CSS, however, requires a highly dynamically switchable element and a highly dynamic measurement of a compressor current and is therefore associated with a comparatively high technical outlay. A speed setting using CSS has so far not been used due to increased requirements for cooling and switching elements, for example.

According to the concept of the invention it is now provided, as shown here, that the switching device 110 in an operating circuit 112 of the DC brush motor 100 controllable integrated by this. The switching device 110 has electronic switching elements 114 on, which are semiconductor switches in the embodiment shown.

The operating circuit 112 is trained running conditions of the engine 100 to control. The running conditions can include, for example, an engine start, an engine endurance run, and an engine stop. The operating circuit 112 the power consumption and / or power output of the engine is also designed for at least one of the running conditions 100 determining running parameters, to monitor and depending on the running parameters the switching device 110 head for.

The operating circuit 112 is designed according to the concept of the invention, the switching device 110 to be controlled such that by means of the switching device 110 energizing the brush 109.n is switchable when the running parameter reaches a threshold value.

This reliably prevents large current gradients from occurring, particularly when the DC brush motor according to the invention is switched on and off.

In particular, the operating circuit controls 112 the switching device 110 in operation such that the switching device 110 the energization of a brush 109.n switches off if the threshold value is exceeded and / or switches on if the threshold value is undershot. The number of brushes that are energized in a tepid state 109.n the brush order 108 depends on the monitored running parameter. In particular, the energization of individual brushes 109.n the brush arrangement 108 switched in stages depending on the monitored running parameter.

Even with a reduced number of brushes 109.n the DC brush motor described here can run with two pairs of poles. Advantageously, motor operation with a reduced number of brushes 109.n , a speed of the DC brush motor 100 or a start-up or discharge current characteristic through a flexible choice of the number of brushes supplied with current 109.n , targeted and controlled.

2nd shows a schematic representation of an interconnection of individual brushes 209.1 , 209.2 , 209.3 , 209.4 with a four-pole DC brush motor 200 . The DC brush motor 200 includes a switching device 210 with four switching elements 214.1 , 214.2 , 214.3 , 214.4 . The switching elements 214.1 and 214.2 are independent of each other and from the switching elements 214.3 and 214.4 switchable, whereas the switching elements 214.3 and 214.4 only together via a button 215 but regardless of the switching elements 214.1 and 214.2 are switchable.

The switching elements 214.1 , 214.2 , 214.3 , 214.4 each have a closed, electrically conductive switching state in which a brush 209.1 , 209.2 , 209.3 , 209.4 can be supplied with current and an open, electrically non-conductive switching state in which the current supply to a brush is interrupted. The electronic switching elements 214.1 , 214.2 , 214.3 , 214.4 the switching device 210 can be controlled by an operating circuit (not shown). In the embodiment shown is a switching element 214.1 , 214.2 , 214.3 , 214.4 exactly one brush 209.1 , 209.2 , 209.3 , 209.4 assigned and switches an energization of this assigned brush 209.1 , 209.2 , 209.3 , 209.4 . The switching elements are via connecting cables 211.1 and 211.2 with a power supply 213 , for example a car battery. In particular, the switching elements 214.2 and 214 . 4 with the positive pole of the power supply 213 connected and are subjected to a positive voltage during operation. The switching elements 214.1 and 214.3 are with the negative pole of the power supply 213 connected and are subjected to a negative voltage during operation.

One of the switching elements is over one of the lines 216.1 , 216.2 , 216.3 , 216.4 each with one of the brushes 209.1 , 209.2 , 209.3 , 209.4 electrically connected. If there is a switching element 216.1 , 216.2 , 216.3 , 216.4 is in the conductive state and is supplied with voltage by the voltage supply, the corresponding brush is energized. Because the switching elements 214.2 and 214 . 4 A positive voltage is applied to the brushes during operation 209.2 and 209.4 applied with a positive voltage. The brushes are made accordingly 209.1 and 209.3 subjected to a negative voltage during operation.

The brushes 209.1 , 209.2 , 209.3 , 209.4 are in contact with a commutator 206 of the DC brush motor 200 in such a way that along the circumference of the commutator 206 a brush with a positive voltage follows a brush with a negative voltage. If the brushes 209.1 , 209.2 , 209.3 , 209.4 are energized, a rotor is placed over the commutator 206 and energized the energized brushes. The rotor 204 is rotatably mounted in a stator (not shown). The stator is immobile and has a hollow cylinder on which a permanent magnet 203 attached, which generates a static stator magnetic field in which the rotor 204 is arranged. In the DC brush motor shown 200 accordingly, it is a permanent magnet DC brush motor 200 .

The DC brush motor 200 can with a full number of brushes 209.1 , 209.2 , 209.3 , 209.4 , ie with four brushes, or with a reduced number of brushes 209.1 , 209.2 , 209 3 209.4 , ie less than four but at least two of the brushes 209.1 , 209.2 , 209.3 , 209.4 operate. Even with a reduced number of brushes 209.1 , 209.2 , 209 3 209.4 remains the DC brush motor 200 executable with changed characteristics and reduced power density. So if necessary, for. B. depending on a monitored running parameter, a running parameter, for example a starting current or a speed, in a corresponding running state of the DC brushed motor 200 can be set.

For that in 3rd shown electrical equivalent circuit diagram of a four-pole direct current brush motor, for example, a dependence of a starting current on a number of energized brushes can be considered arithmetically. The model calculations described below are based on a model of a rotor 300 based on that as a twelve-slot anchor with twelve individual coils 304 , the armature windings. The rotor 300 should in this example model with a maximum of four brushes 309.1 , 309.2 , 309.3 , 309.4 can be energized.

The resistance of such a single _coil R _coil can be assumed here, for example, as R _coil = 66.67 mOhm and the brush and _choke resistors together as R _brush + R _choke = 50 mOhm. For the details of the calculation of the total resistance, please refer to the description of the 5 referred; for calculating the indicated below starting currents I _start Ohm's Law was used.

In the event that the rotor 300 in this example model with two brushes 309.1 , 309.2 is energized, the starting current I _start = 48 A, at a voltage of 12 V and a total resistance of 250 mOhm.

In the event that the rotor 300 in this example model with three brushes, for example 309.1 , 309.2 , 309.3 or 309.1 , 309.2 , 309.4 is energized, the starting current I _start = 68 A, at a voltage of 12 V and a total resistance of 175 mOhm.

In the event that the rotor in this example model 300 with four brushes 309.1 , 309.2 , 309.3 , 309.4 is energized, the starting current I _start = 120 A, at a voltage of 12 V and a total resistance of 100 mOhm.

This exemplary mathematical consideration of the dependency of the starting current on the number of energized brushes using the example of a four-pole DC brush motor therefore shows that a starting current, by reducing the number of energized brushes to two or three energized brushes, compared to a motor start with four energized brushes can be significantly reduced - in the present example model from 120A to 68A with three brushes (well below 75%) or 48A with two brushes (well below 50%). This exemplary calculation of the dependency of the starting current on the number energized brushes - here using the example of a four-pole DC brush motor - illustrates that a starting current can be reduced disproportionately compared to the number of brushes by reducing the number of energized brushes.

4th shows an example of a possible wiring of the brushes 409.1 , 409.2 , 409.3 , 409.4 a four-pole DC brush motor 400 .

The DC brush motor 400 includes a commutator 406 , a rotor, a stator (both not shown) and a switching device with three switching elements 414.1 , 414.2 , 414.3 . With the switching element 414.1 the energization of the brushes 409.1 and 409.2 switch on and off together. The brush 409.2 is preferably permanently on ground. In a not shown here Embodiment is in addition to the switching elements 414.1 , 414.2 , 414.3 a fourth switching element is provided with which all brushes 409.1 , 409.2 , 409.3 , 409.4 can be switched on and off together.

With the switching element 414.3 the brush can be energized 409.3 switch on and off, so by switching this switching element 414.3 in a motor operation of the DC brush motor 400 with three energized brushes 409.1 , 409.2 , 409.3 can be changed if the switching element 414.2 in the non-conductive switching state and the brush 409.4 is therefore switched off. In a running state of the DC brush motor 400 in which the switching element 414.3 is in the conductive switching state, by switching the switching element 414.2 in a conductive switching state, in a running state with four energized brushes 409.1 , 409.2 , 409.3 , 409.4 change.

The brushes 409.1 , 409.2 , 409.3 , 409.4 are in electrically conductive contact with the commutator 406 , which corresponds to the switching of the current supply by the switching elements 414.1 , 414.2 , 414.3 with a different number of brushes 409.1 , 409.2 , 409.3 , 409.4 can be energized.

The switching device of the in 4th DC brush motor shown 400 includes timing logic 418 which together with switching elements 414.1 , 414.2 , 414.3 the switching device on a circuit board of the operating circuit (not shown) of the DC brushed motor 400 is installed. The timing logic 418 is with a power supply 421 connected. Using the timing logic 418 can brush 409.1 , 409.2 , 409.3 , 409.4 individually or in groups via the switching elements 414.1 , 414.2 , 414.3 can be controlled time-controlled. A timed control of the brushes 409.1 , 409.2 , 409.3 , 409.4 represents a comparatively simple possibility of control, in which, for example, a current measurement for control can be omitted. For example, the brushes can be timed in such a way that when the DC brush motor is switched on 400 first two of the brushes 409.1 , 409.2 , 409.3 , 409.4 be energized and with a time delay of 100 ms, then a third and a fourth brush are switched in succession. To switch off all brushes together 409.1 , 409.2 , 409.3 , 409.4 can then be interrupted collectively. During a continuous motor run, two of the brushes can then be energized 409.1 , 409.2 , 409.3 , 409.4 be switched off, for example to bring about a speed reduction.

The DC brush motor shown 400 is still with a DC brush motor 400 parent control unit 420 actively connected, e.g. B. wireless, but preferably electrically via a control line 422 . The control device can provide a control signal automatically or by manually entering a user and a filter 419 are transmitted to the switching device. The switching device is designed, the energization of the brushes 409.1 , 409.2 , 409.3 , 409.4 to switch depending on the control signal received. In addition to a circuit for energizing the brushes 409.1 , 409.2 , 409.3 , 409.4 can therefore by one of the higher-level control unit 420 provided control signal energizing the brushes 409.1 , 409.2 , 409.3 , 409.4 be switched. By the higher-level control unit 418 can therefore independently of an operating circuit (not shown) by a control signal a number of energized brushes 409.1 , 409.2 , 409.3 , 409.4 can be determined, for example, to set a starting current or a speed.

5 shows a rotor 500 that as a twelve-groove anchor 502 with twelve individual coils 504 , the armature windings. The individual coils 504 are electrically conductive with electrical connections 508 connected to a commutator. In the illustration shown are brushes 506.1 , 506.2 , 506.3 , 506.4 with one of the electrical connections 508 of the commutator mechanically and electrically conductive in contact.

In a), b) and c) are different, - also with regard to 3rd discussed - Variants of energizing the rotor 500 shown, each in the number of energized brushes 506.1 , 506.2 , 506.3 , 506.4 differentiate.

When current is switched on, a current through the armature windings is limited only by their ohmic resistance. The total resistance R _total results from the electrical connection of the individual coils with the resistor R _coil, ie the corresponding series and parallel connections of the individual coil resistors R _coil , and the number of parallel armature branches through which current flows.

In a) the rotor 500 with two brushes 506.1 , 506.2 energized and the energization of the brushes 506.3 , 506.4 is switched off. Such a current supply can be suitable, for example, to limit a starting current during a motor start-up - as exemplified by 3rd was explained - or to bring about a speed reduction during a continuous engine run. Current flows here via two armature branches - in this case the total resistance results according to the general rules and the example model above from R _total = (R _spool * R _coil ) / (3 * R _coil + 9 * R _coil ) + 2 * 50 mOhm = 2.25 * R _coil + 100 mOhm.

In b) the rotor 500 over three brushes 506.1 , 506.2 , 506.3 energized and energizing the brush 506.4 is switched off. Here, too, the current flows through two armature branches. In this case, the total resistance results according to the general rules and the example model above, from R _total = 3 * R _coil / 2 + 50/2 mOhm + 50 mOhm = 1.5 * R _coil + 75 mOhm.

In c) the rotor 500 over all four brushes 506.1 , 506.2 , 506.3 , 506.4 energized. The current flow then takes place via four armature branches. In this case, the total resistance results according to the general rules and the example model above from R _total = 3 * R _coil / 4 + 50/2 mOhm + 50/2 mOhm = 0.75 * R _coil + 50 mOhm.

Reference list

100

DC brush motor

102

stator

104

rotor

106

commutator

108

Brush arrangement

109.n

Majority of brushes

110

Switching device

112

Operating circuit

114

electronic switching elements

200

DC brush motor

203

Permanent magnet

204

rotor

206

commutator

209.1, 209.2, 209.3, 209.4

to brush

210

Switching device

211.1, 211.2

Connecting cables

213

Power supply

214.1, 214.2, 214.3, 214.4

electronic switching elements

215

Button

216.1, 216.2, 216.3, 216.4

cables

300

rotor

304

twelve individual coils

309.1, 309.2, 309.3, 309.4

to brush

400

DC brush motor

406

commutator

409.1, 409.2, 409.3, 409.4

to brush

414.1, 414.2, 414.3

Switching elements

418

Timing logic

419

filter

420

higher-level control unit

421

Power supply

422

Control line

500

rotor

502

twelve-groove anchor

504

twelve individual coils

506.1, 506.2, 506.3, 506.4

Brushes 508 electrical connections of the commutator

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 102012024400 A1 [0007]
• DE 102012214122 A1 [0009]

Claims (13)

DC brush motor (100) for driving a compressor, in particular compressed air generation with a compressor and a DC brush motor, preferably for an air suspension system, a brake system or the like.Air pressure pickup of a vehicle, the DC brush motor having: - a stator (102 ) and a rotor (104), each with a plurality of pole pairs, the rotor (104) being able to be supplied with current via a commutator (106) and a brush arrangement (108) with a plurality of brushes (109.n), - one with of the brush arrangement (108) control-connected switching device (110) for switching an energization of one of the brushes (109.n), characterized in that - the switching device (110) in an operating circuit (112) of the DC brushed motor (100) controllably integrated by the latter is, wherein - the operating circuit (112) is designed to control running states of the engine (100), the operating circuit for the running state a Le The operating parameters determining the power consumption and / or power output of the motor are monitored and the switching device is controlled as a function of the running parameter such that - by means of the switching device (110) the current supply to the brush can be switched when the running parameter reaches a threshold value. DC brush motor (100) after Claim 1 , wherein the running state is a motor start and the running parameter is a starting parameter, in particular a starting current and / or gradient, the operating circuit (112) being designed to monitor the starting parameter and to control the switching device (110) as a function of the starting parameter. DC brush motor (100) after Claim 1 or 2nd , wherein the running state is a continuous motor run and the running parameter is a continuous running parameter, in particular a speed, the operating circuit (112) being designed to monitor the continuous running parameter and to control the switching device (110) as a function of the continuous running parameter. DC brush motor (100) according to at least one of the Claims 1 to 3rd The running state is a motor stopping and the running parameter is a stopping parameter, in particular a rotational speed, the operating circuit (112) being designed to monitor the stopping parameter and to control the switching device (110) as a function of the stopping parameter. DC brush motor (100) according to at least one of the Claims 1 to 4th The operating circuit (112) is designed to control the switching device (110) in such a way that the current supply to individual brushes of the brush arrangement is switched in stages depending on the running parameter. DC brush motor (100) according to at least one of the Claims 1 to 5 , the dependency comprising that - the switching device (110) switches off the current supply to a brush (109.n) when the running parameter exceeds a threshold value and / or - switches on the current supply to a brush (109.n) when the running parameter sets a threshold value falls below. DC brush motor (100) according to at least one of the Claims 1 to 6 The dependency comprises that the number of brushes (109.n) of the brush arrangement (108) which are energized in a lukewarm state depends on the monitored running parameter. DC brush motor (100) according to at least one of the Claims 1 to 7 The switching device (110) has electronic switching elements (114) and the switching elements (114) are installed as semiconductor switches on a circuit board of the operating circuit (112). DC brush motor after Claim 8 , the dependency comprising that the running parameter is limited, in particular reduced, by high-frequency clocking of the semiconductor switches. DC brush motor according to at least one of the Claims 1 to 9 , wherein the switching device is designed to control a brush of the brush arrangement in a time-controlled manner, in particular as timing control logic, is installed together with switching elements of the switching device on a circuit board of the operating circuit. DC brush motor according to at least one of the Claims 1 to 10th , wherein the switching device is designed to receive a control signal from an operatively connected control device which is superior to the DC brush motor, in particular to switch the current supply to the brush as a function of the received control signal. Compressed air generation, preferably for an air suspension system, a brake system or the like. Compressed air consumer of a vehicle, with a compressor and a DC brush motor, the DC brush motor according to at least one of the Claims 1 to 11 is trained. Method for operating a DC brush motor, in particular for operating compressed air generation with a compressor and a DC brush motor, preferably for operating an air suspension system, a brake system or the like.Air pressure pickup of a vehicle, the DC brush motor comprising: - a stator and one Rotor with a plurality of pairs of poles each, wherein - the rotor can be energized with a plurality of brushes via a commutator and a brush arrangement, - a switching device which is connected to the brush arrangement for switching the energization of a brush, wherein - the switching device in an operating circuit of the DC brush motor is controllably integrated by the latter, the method being characterized in that - the operating circuit controls running states of the engine, - the operating circuit for the running state exercises a running parameter which determines the power consumption and / or power output of the engine rwacht, and - depending on the running parameter controls the switching device, the switching device controlled in this way switches the energization of the brush when the running parameter reaches a threshold value.

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