FR2770945A1 - DEVICE FOR STARTING AN ENGINE - Google Patents

Abstract

Device for starting a motor, with a limiting system (26) which limits an intensity (Im) of the motor current and / or its power to a first maximum value, characterized in that a circuit is provided for start pulses (18b) which deactivates the limitation system (26) for an interval of time from the moment of starting of the engine (10).

Description

State of the art

  The invention relates to a device for starting

  engine rage, with a limiting system that limits

  motor intensity and / or power at a first value

their maximum.

  Document DE 42 10 213 Ai already discloses a system which is used to control a constant current servo motor.

  continued in motor vehicles. To ensure that the adjustment element can be moved from its final position at any time by the motor, there is in the connection between the control system and the positive supply voltage a

  electrically conductive link, bridging the regulator

  voltage lator, with a connection system. If an engine starting current is detected, the

  connection short-circuits the voltage regulator.

  However, the protection system also remains

  activated in this operating case.

Advantages of the invention

  The device used to start a mo-

  tor includes a limitation of the motor intensity and / or

  the power to a first maximum value. It is characterized

  due to the fact that there is provided a circuit of pulses of

  marrage which disables the limitation from the moment the engine starts for a certain time. The

  brief deactivation of the limitation allows you to have an in-

  voltage up to the short-circuit current of the motor and thus ensures the starting of the motor. The couple

  initial detachment of the engine which is a function of the tolerances

  manufacturing rances and which varies according to the duration of

  engine life is surely exceeded. In case of mechanical loads

  ques high, for example in case of icing of a blower motor, the brief removal of the limitation increases the

  probability of starting the engine. Appropriate sizing

  Owing to the time interval guarantees protection of the motor and the electronic circuits of the motor against overloads in the critical case where the motor crashes. In this case the fact that the engine is in normal operation or

  is stopped by a protection system, plays no role.

  If the motor is supplied with a relative setpoint

  You can use the deflection pulse circuit.

  marrage to generate for a brief instant a higher set value which ensures the starting of the engine. The starting pulse circuit can be realized either under

  the form of an autonomous circuit or integrate it into the circuit

  cooked electronic regulation. We can lower the current

  short-circuit in the event of a fault, since it must no longer guarantee

  shot starting the engine. This has a particularly positive effect on the design of power semiconductors. According to an appropriate development, it is expected that the starting pulse circuit limits the intensity of the motor current and / or the power to a second maximum value. We can choose this second maximum value of

  so that on the one hand is ensured the start-up of the mo-

  on the other hand that neither the engine nor the electro-

  engine nicks are not overloaded. The electronic circuit of the engine is designed according to this

second maximum value.

  According to an advantageous configuration, a

  setpoint which is brought to an intensity regulator

  of the motor or of the motor voltage at a threshold for

  complete the start-up time. The setpoint value available for regulation is used for the input pulse start-up pulse circuit, to identify the activation

  market. We can do without an additional device in this case.

  mental signal detection. According to another configuration

  tion we operate a signal from an operating element which

  controls the motor. The variations of the signals which are

  taken by the user lead directly to an ac-

  activation of the starting pulse circuit.

  According to other appropriate developments,

  uses a measurement of the engine speed, motor voltage or motor current to determine when to start. These quantities are also already available to the regulator, so that there is no need to

  additional signal detection. Depending on a configuration, an activa-

  tion of the limitation to determine the start time.

  When there is a limitation of a motor size, the circuit

  cooked start pulses removes it for a specified period. The starting pulse circuit is not

  only activated if necessary.

  According to another configuration, the time interval can be defined at 1 (I beforehand. The fixing

  on a given quantity simplifies the construction of the cir-

  cooked starting pulses. As a rule it is enough

  to have a time interval that is based on values ex-

  perimentales, to achieve a safe starting of the engine.

  According to appropriate developments the interval

  of time depends on a measurement of the speed of rotation of the mo-

  motor voltage or motor current. A variable time interval takes into account the different load cases of the corresponding motor and processes

  respective startup. The sizes mentioned provided-

  feels indications as to whether the engine has already reached full speed. If this is the case, it is no longer necessary to have a deactivation for the continuation of the operation.

  of the limiting device. In other cases we leave ar-

  river for a longer time, for example a higher intensity at the engine. For example in the case where fan motors are frosted, it is necessary to count on a start-up in the case of a sufficiently long command

higher power.

  3 (According to an advantageous configuration, the time interval depends on the amount of energy that is supplied to the motor. In this way we can be sure that the motor and the

  engine electronics are not stressed

  excessive lesson, when the quantity of energy brought in, allows the

  maximum, is chosen accordingly.

  The invention is characterized in that a starting pulse circuit is provided which deactivates the limitation system for a time interval from the instant of starting the engine. According to other characteristics of the invention: - the starting pulse circuit limits the intensity of the motor and / or its power to a second maximum value; - the starting pulse circuit delivers from the instant of starting for a time interval a control signal to a final stage which exerts an influence on the motor intensity and / or on the motor voltage; - a setpoint brought to a motor intensity or voltage regulator is compared to a threshold value for determining. the instant of start-up;

  - a signal from an operating element which uses

  controls the engine to determine the instant of starting; - the intensity of the motor is used to determine the instant of starting and / or the time interval; - an activation of the limiting device is used to determine the instant of starting; - the interval of can be defined beforehand

time.

  Drawings The present invention will be described below in more detail from several embodiments, shown in the accompanying drawings, in which:

  - Figures 1, 2 and 5 show diagrams by example blocks

  possible ples of realization and - Figures 3 and 4 show possible sequences of

  characteristic limitation curves.

  Description of the exemplary embodiment.

  3 () A connection of a motor 10 is connected to the pale more than one supply voltage. The motor voltage Um falls on the motor 10. An intensity Im of the current flows via a motor adjustment device 12 to ground. The engine adjustment device 12 consists of a

  resistance series 16, with respect to which is mounted in pa-

  turns on a starting pulse circuit 18a.

  According to FIG. 2, the intensity Im of the motor flows via a terminal stage 20 towards ground. From

  a setpoint 14 and a real value 24 a

  regulator 22 which includes a limiting device 26, forms a control signal for the final stage 20. The regulator 22 can be bypassed by the starting pulse circuit 18b. Figure 3 shows the evolution over time

  of a characteristic curve of limitation 26. Beginning

  erasing by a starting instant Ts we have a second value

  G2 which is valid until time Ti for an in-

  tervalle of time T. From the instant T1 a first maximum value G1 is active. Possible sequences of the first maximum value and the second maximum value Gl, G2a, G2b as a function of the motor intensity Im and the motor voltage Um are shown in FIG. 4. The first

  maximum value G1 increases linearly, up to

  dye an engine current Im which is not exceeded. A first evolution of the second maximum value G2a is obtained by a translation of the first maximum value Gi upwards with a constant intensity Im of the motor. A second possible evolution of the second maximum value G2b

  consists of a limitation of the motor intensity Im.

  Another exemplary embodiment has been represented.

  of the invention in FIG. 5. The regulator 22 is constituted

  killed in the form of an analog regulator of the voltage of the

  Um motor, to which limitation 26 is superimposed.

  The characteristic curve of the limiting device

  tation 26 could for example take the route shown

  in FIG. 4 of the first maximum value Gl. We can put

  be in service the limitation device 26 by opening a

  3 (0 switch 28 of the starting pulse circuit 18c think

  during a time interval T. In order to determine the starting instant Ts, in the example of embodiment according to FIG. 5, the setpoint 14 is brought to the pulse circuit of

start 18.

  The exemplary embodiment according to FIG. 1 for-

  could be part of a circuit used to regulate the speed of

  rotation of a DC motor by plugging in re-

  sistances. The resistor 16 determines the lowest level of the rotation speed which is activated when the motor 10 is connected. The series resistor 16 limits the intensity Im of the motor in the event of starting. The starting pulse circuit 18a is in parallel with the series resistor 16 and can for example the

  short-circuit by actuating an operating element not

  present. At the instant Ts of starting the motor 10 the inter-

  switch is closed and after the time interval T has expired it opens again. In this way limiting the

  1 current which is produced by the series 16 resistor is con-

  turned in the event of starting and a higher current Im is allowed to pass through the motor, for example the short-circuit current of the motor when starting the motor 10. On

  recognizes the start time Ts when an element of my-

  noeuvre - not shown - is activated to activate the ni-

  calf lowest in rotation speed. This signal controls the starting pulse circuit 18a in a form such that it short-circuits the series resistance 16. After the time interval T has elapsed,

  ) again this short circuit.

  In the second exemplary embodiment according to FIG. 2, the starting pulse circuit 18b bypasses the regulator 22, by predefining for the final stage 20 a

  other variable this setting than regulator 22. To identify

  proud of the start time Ts the fault pulse circuit

  marrage 18b compares setpoint 14 with a value of

  threshold. At rest the setpoint 14 takes the value zero

  ro. If the set value 14 changes and in this case exceeds the threshold value, the starting pulse circuit 3) 18b interprets the exceeding of the threshold value as a wish to start the engine. Starting at

  the instant of starting Ts the starting pulse circuit

  rage 18b produces an adjustment signal for the terminal level which lets an intensity pass through the motor Im, which for example does not exceed the second unwinding of the second maximum value G2b. After the time interval t the starting pulse circuit 18b no longer delivers an adjustment signal to the final stage 20. If the regulator 22 is implemented

  in the form of a digital regulator, the impulse circuit

  then 18b can also be a component of the

control software.

  In a third embodiment example according to

  FIG. 5 the regulator 22 is produced in the form of a

  motor voltage regulator. The limiting device 26 allows a maximum of a first maximum value G1 to pass, as shown in FIG. 4. The output signal of the differential amplifier of the limiting device 26 I) acts via a diode and switch 28

  on the regulating signal of the regulator transistor 22.

  When the switch 28.is closed, the limiting device 26 is active. When starting the engine 10 at the starting instant Ts the starting pulse circuit 18c opens

  the switch 28 during a determined time interval T.

  During the time interval t limitation 26 of the intensity

  Imity of the engine and / or its power is suppressed. Linen-

  motor voltage Im can take values that exceed

  limitation. The start time Ts of the motor 10 is

  detected by a comparison between the set value 14 and

a threshold value.

  Starting from the third embodiment example

  according to figure 5, it is conceivable to have other variations

  tes, and put the limiting device 26 out of service for a time interval T. In normal operation the non-inverting input of the differential amplifier of the limiting device 26 is supplied by a reference voltage Uref. If this reference voltage Uref is increased by a constant voltage, the first maximum value Gi

  shifts upwards, for example, so that it

  then blit the first run of the second maximum value

  male G2a. With the same motor voltage Um we then leave

  arrive at the motor a higher intensity Im. This increase

  tation or this superposition of the reference voltage Uref in turn begins at the instant of starting Ts and ends after the time interval T. Another possibility of putting out of service the first maximum value G1 in favor of the second course of the second maximum value G2b, consists in interrupting the signal taken between the motor and the transistor. It is necessary in this branch, marked by an arrow on the drawing, to add a switch which is open at the instant of starting Ts during the time interval T. Independently of the voltage Um of the motor a determined intensity Im of the engine is not exceeded. To determine the start time Ts it is

  imaginable of using other process variants.

  1 (For this, in addition to the setpoint 14 or the signal from the operating element, the intensity can also be used

  Im from the engine. If the motor intensity Im or its gradient

  pass a determined threshold, we conclude that we are in the presence

  from the start of a start-up and the instant when the threshold is lowered

  past coincides with the start time Ts. There occurs

  also to monitor the actual value of the rotational speed

  or the motor voltage Um as measures of the vi-

  rotation speed of the motor 10 as regards exceeding one

  threshold, to detect a startup process.

  According to another alternative, we use for

  end the start instant Ts the output signal of the differential amplifier of the limiter 26. If during

  starting process the motor intensity Im comes to at-

  switch off the first maximum value G1, there is then a change in signal from the differential amplifier. The fact that the maximum value is reached for the first

  times indicates the start time Ts.

  The time interval X can take a value

  which can be fixed in advance, and which

  on the one hand a safe engine start, on the other hand is so short that the pulse is not audible or detectable

  by the driver when using the engine for

fan control.

  A time interval X depends on magnitudes ca-

  current characteristics of engine 10 such as for example

  the motor current Im, the motor voltage Um or the vi-

  engine rotation size. These quantities are in turn

  compared to a threshold, which differs from the corresponding threshold

  used to determine the start time Ts. The respective thresholds must be dimensioned in such a way

  that the characteristic quantities of the motor which are used

  surely exceed these in the event of a start-

  rage. For this purpose it is necessary to use unwindings

  typical of the characteristic curves of the engine during

  marrage. Limitation device 26 is activated again

  when, the corresponding threshold is reached.

  Another possibility to determine the 1M time X interval is to compare the amount of energy received

  from the moment of starting Ts with a limit value.

  As a measure of the quantity of energy, the area enclosed by the time course of the intensity Im of the motor is used, such that it can for example be detected by means of

  the voltage of a capacitor. You can also use the voltage

  motor um to determine the amount of energy.

  The device according to the invention can be used in the case of blower motors, preferably in the

  case of blower motors of air conditioning systems

  tion, upstream of which is mounted a system for adjusting the speed of rotation. The invention is not however limited

to that.

Claims (8)

R E V E N D I C A T I ON S   1) Device for starting an engine, with a limitation system (26) which limits an intensity (Im) of the motor current and / or its power to a first maximum value (Gi), characterized in that provides a starting pulse circuit (18a, 18b, 18c) which deactivates the limitation system (26) during a time interval (T) from the instant (Ts) of io starting the engine (10).   2) Device according to claim 1, characterized in that the starting pulse circuit (18a, 18b, 18c) limits the intensity (Im) of the motor and / or its power to a second maximum value (G2, G2a, G2b).   3) Device according to one of the preceding claims,   characterized in that the starting pulse circuit (18a, 18b, 18c) delivers from the instant (Ts) of starting during a time interval (Tau) a control signal to a final stage (20) which exerts an influence on the intensity (Im) of the motor and / or on the voltage (Um) of the motor.   4) Device according to one of the preceding claims,   characterized in that a reference value (14) brought to a regulator (22) of the intensity (Im) or of the voltage (Um) of the motor is compared to 3 (a threshold value for determining the instant of starting (Ts).    ) Device according to one of the preceding claims,   characterized in that a signal from an operating element which controls the motor (10) is used to determine the instant of starting (Ts)   6) Device according to one of the preceding claims, It characterized in that   a measurement of the speed of rotation of the motor (10) and / or of the voltage (Um) of the motor is used to determine the instant of starting (Ts) and / or the time interval (T).   7) Device according to one of the preceding claims, characterized in that   the intensity (Im) of the motor is used to determine the starting time (Ts) and / or the time interval (T) .10   8) Device according to one of the preceding claims,   characterized in that an activation of the limiting device (26) is exploited   to determine the start time (Ts).   9) Device according to one of the preceding claims,   characterized in that the interval for time (T). 2 ()    ) Device according to one of the preceding claims,   characterized in that the time interval (t) depends on the amount of energy brought to the motor (10).