EP0807312B1 - Circuitry for an engagement relay - Google Patents

Abstract

The invention relates to circuitry for the engagement relay for a starting device of an internal combustion engine with an auxiliary relay actuating a relay coil of the engagement relay. There is a control and/or regulating circuit (16) affecting and in particular clocking the operating current (I) of the auxiliary relay (18) in order to reduce its power losses.

Description

The invention relates to a circuit arrangement for an engagement relay according to the preamble of the claim 1. (US-A-4873607)

State of the art

It is known to use engagement relays for in motor vehicles to use a starting device of an internal combustion engine. These engagement relays are used to provide a high Electricity with a relatively low control current to switch. The high current (starter current, the for starting an internal combustion engine Starter is required), for example at Cars up to approx. 1000 A. The during the Starting process via the relay coil of the engagement relay In contrast, flowing current is, for example approx. 80 to 100 A. This compared to the starter current relatively small current is still too big, to directly via a start switch (ignition lock) or switched via an electronic control unit will. For this purpose, among others, from DE 37 37 430 C known to assign an auxiliary relay to the engagement relay, that by means of the starter switch of the motor vehicle can be actuated. The disadvantage here is that not just an additional one for the additional auxiliary relay Installation space provided in the motor vehicle must be, but that this is an additional Consumers with a correspondingly high power loss represents.

Advantages of the invention

The circuit arrangement according to the in Features mentioned claim 1 has the advantage that the auxiliary relay optimizes, that is, in particular be reduced in size can, so that the available installation space is also scalable. The fact that one Control current influencing operating current of the auxiliary relay and / or control circuit is provided, it is advantageous possible the operating current of the auxiliary relay to influence depending on selectable criteria that this for each operating state of the auxiliary relay only takes the size that is actually necessary, so that the power loss occurring at the auxiliary relay is reduced as much as possible. That’s it possible to integrate the auxiliary relay into the engagement relay, so that a compact unit is created.

In an advantageous embodiment of the invention, that the control circuit is a clocked Control or current control circuit contains, with about the clock frequency and / or the duty cycle Amount of operating current depending on certain Operating states of the auxiliary relay can be determined is. This advantageously makes it possible to reduce the operating current of the auxiliary relay changing operating conditions, for example an operating temperature and / or an armature position of the auxiliary relay. By means of this optimal adaptation of the operating current to the operating state of the auxiliary relay the power loss of the auxiliary relay is reduced. This results in particular from a lowering of the operating current after the anchor of the Auxiliary relay has picked up or just this its movement along the path of movement started Has. It is also advantageous that by a optimal, controlled clocking of the operating current of the Auxiliary relay setting a constant large Average operating current under different operating conditions, especially different Temperature conditions, is possible. It is too take into account that at different temperatures the characteristic of a return spring for the armature of the auxiliary relay and on the other hand the magnetization behavior of the auxiliary relay as well change the ohmic resistance of the coil with which Consequence that the operating current of the auxiliary relay changes. The coil of the auxiliary relay is in the Usually according to the maximum operating current dimension. Through the control according to the invention of the operating current of the auxiliary relay, however possible, the auxiliary relay with a smaller, constant large clocked average operating current operate so that the different operating conditions by choosing a current setpoint of a clock frequency and / or the clock ratio are taken into account can. As a result, the coil can now handle the maximum current be designed at the highest operating temperature.

Further advantageous embodiments of the invention result from the rest of the subclaims mentioned features.

drawings

Figur 1

schematisch ein Blockschaltbild einer erfindungsgemäßen Schaltungsanordnung;

Figur 2

ein Diagramm des Verlaufs von Soll- und Istwert des Betriebsstromes des Hilfsrelais;

Figur 3 bis Figur 6

einige Signalverläufe für verschiedene Tastverhältnisse des getakteten Betriebsstroms des Hilfsrelais;

Figur 7 und 8

ein zweites Ausführungsbeispiel der Erfindung

The invention is explained in more detail below in exemplary embodiments with reference to the associated drawings. Show it:

Figure 1

schematically shows a block diagram of a circuit arrangement according to the invention;

Figure 2

a diagram of the course of setpoint and actual value of the operating current of the auxiliary relay;

Figure 3 to Figure 6

some waveforms for different duty cycles of the clocked operating current of the auxiliary relay;

Figures 7 and 8

a second embodiment of the invention

Description of the embodiments

FIG. 1 shows an overall designated 10 Circuit arrangement for a starter Internal combustion engine. The circuit arrangement 10 has a switch-on element 12, for example an ignition lock or Start switch on with an electronic control unit 14 is connected. The electronic control unit 14 has a control circuit 16 for one with the Control device 14 connected auxiliary relay 18. Of the Control circuit 16 is also a temperature detection circuit 20 associated with not here shown temperature sensors that are near the Auxiliary relay 18 or are arranged in the engine compartment, connected is. The control circuit 16 includes one trigger stage 19 operating as a Schmitt trigger, the Response values a) and b) are changeable and the Feel the current profile at the output of control unit 14.

The control unit 14 has further ones that are not relevant here Circuit parts necessary for the function of the Motor vehicle are necessary. Not shown here Switch contacts of the auxiliary relay 18 are with connected to the windings of an engagement relay 22, the Switch contacts, also not shown, the Main circuit of a starter 24 on and turn off.

Based on the purely schematic representation the operation of the circuit arrangement 10 briefly explained will. When actuating the switch-on element 12 is the coil of the auxiliary relay 18 via the electronic Control unit 14 energized. The energization of the Coil of the auxiliary relay 18 takes place in a still to be explained Way via the control circuit 16 for the Operating current of the auxiliary relay 18. The switch contacts of the auxiliary relay 18 connect the relay coil of the Engagement relay 22 with an operating voltage so that the armature of the engagement relay 22 the main power contacts the starter 24 closes and this with a Voltage source, usually in the motor vehicle Motor vehicle battery, connects. Via the main power contacts the starter 24 flows here the relatively high starter current, which is approximately 1000 A. can. Via the switching contacts of the auxiliary relay 18, which the relay coil of the engagement relay 22 with the Voltage source connects, a switching current flows in Height of about 80 to 100 A. About the coil of the Auxiliary relay 18 flows from the control circuit 16 of the control device 14 influenced operating current I of up to 40 A.

FIG. 2 shows the setpoint and actual value of the operating current in the exemplary embodiment for controlling the operating current I according to FIG. 1. In this case, the setpoint I _{soll of} the operating current is reduced by the control circuit 16 to a lower value at the time t2. This ensures that the actual value of the operating current I _{ist shown in} simplified form in the left-hand illustration. This takes into account the physical circumstances that a lower magnetic flux density is sufficient to hold the armature of the auxiliary relay 18 than is necessary for the armature to be tightened. By reducing the operating current I by approximately 50%, the power loss can be reduced to approximately 25%, since a lower current is sufficient for the magnetic flux density required for the closed magnetic circuit. This lower operating current I flows through the coil resistance of the coil and thus generates a lower power loss in the form of thermal energy compared to the higher operating current I before time t2.

The specific structure of the control circuit 16, which clocks the operating current I in the control unit 14 on the one hand and the lowering of the operating current I on the other hand, is not to be considered in more detail here. However, it contains in addition to the trigger stage 19 is still a time stage for the time t2, switching the trigger level of the higher response values a1 and b1 off (a1) and switching on (b1) of the operating current I _is on the lower thresholds a2 and b2. In the example, the setpoint of the operating current I is reduced from 25 A to 12 A after t2-30 ms. The use of generally known multivibrators, precision Schmitt triggers or other suitable oscillator circuits, preferably also microprocessors, lends itself to the control circuit 16. The time period t2 until the current is reduced is such that the relay armature surely lifts from its rest position at an earlier time t1. Via the temperature detection circuit 20, it is possible, the limit values of the operating current I _is lower than the variable response values a and b of the trigger stage 19 with increasing temperature. In addition, the time t2 until the operating current is reduced can be shortened with increasing temperature. In this way it is possible to compensate for the temperature-dependent friction of the moving relay armature and, if necessary, a temperature-dependent spring force of the armature return spring.

In Figures 3 to 6 are waveforms for the Clocking the operating current I shown. The waveform is here with exact square-wave signals an exact duty cycle, i.e. the clock frequency, representable. For the provision of the square wave signals can the control circuit 16 for example contain appropriately designed function generators. In Figure 3, for example, at Clock frequency of 2 kHz the waveform with a 30% duty cycle shown, that is, related per unit time (period) is the operating current I switched on in 30% of this time unit, while it is off for the remaining 70%. Correspondingly, a signal curve is shown in FIG a 60% duty cycle, in Figure 5 a waveform with a 90% duty cycle and in figure 6 shows a signal curve with a 100% duty cycle shown. According to the selected duty cycle one of the lines of the operating current results I overlapped area and thus known the energy supplied to the coil. Each the clock rate is smaller, i.e. the duty cycle On / Off, is selected, the smaller the supplied Energy and thus that occurring in the coil Power dissipation.

It is by means of the clocking of the operating current I also possible depending on the duty cycle certain operating parameters of the auxiliary relay 18 change. For example, the duty cycle depending on an operating temperature of the auxiliary relay 18 to maintain the predetermined operating current to be changed. At the same time the lowering of the operating current I through a reduction the duty cycle realized as well be changed depending on the temperature.

So from a trigger stage 19 of the control circuit 16 in just selected sample duty ratios the operating current I for an auxiliary relay 18 at switch-on for approx. 30 msec with a 60% clocking are applied while at Time t2 (Figure 2) the duty cycle to 30% is converted. Thus, by simple generation of the square wave signals of the trigger stage 19 Energy requirement of the coil of the auxiliary relay 18 drastically reduce. By coupling the control circuit 16 with the temperature detection circuit 20 can Clocking the operating current I in a simple manner adapted the respective existing operating conditions will. So it is useful, for example a cold relay at the moment of operation the operating current I with a 60% clock rate and at the time To provide t2 with a 30% clock rate. At one in normal operating temperature Auxiliary relay 18 can the duty cycle at the moment of switching Amount to 90% while it is on at time t2 50% is switched. For example warmed auxiliary relay 18 can the at the moment Clocking with 100% take place at time t2 is switched to a 60% clock rate. Means the control circuit 16 and the temperature detection circuit 20, the time t2 for the switching of the duty cycle can be influenced. For example, for a cold auxiliary relay 18 the time t2 at 30 msec, for a normal heated auxiliary relay 18 at time t2 at 25 msec and for a heated auxiliary relay 18 the time t2 is 15 msec.

It is therefore clear that the duty cycle and the switching time of the duty cycle between the pick-up area and the holding area of the auxiliary relay 18 control of the auxiliary relay 18 possible which enables drastic energy savings.

Overall, operation of the auxiliary relay 18 is thus despite different operating conditions, in particular different operating temperatures, with one constant operating current mean value adjustable. By the clocking of the operating current I is beyond - as mentioned - a reduction in power loss of the auxiliary relay 18 causes.

Due to the constant mean operating current at different Temperature conditions result the possibility of the constructive design of the Auxiliary relay 18 to influence. On the one hand results the possibility of the spring force of the return spring for the armature of the auxiliary relay 18 to increase the auxiliary relay 18 no longer on the least favorable Operating case, namely to the maximum Operating current I designed at the highest temperature are needed. By increasing the spring force for the Anchor of the auxiliary relay 18 can be the bounce reduce the switching contacts, so that hereby a Increasing the life of the contacts is achievable. Another advantage is that this Increasing the spring force and thus reducing the Bouncing tendency an installation of the auxiliary relay 18 in a Housing of the engagement relay 22 is possible. The while of the switching operations of the engagement relay 22 occurring Accelerations or shocks the starting device, which ranges up to 5000 up to 10000 g, can therefore be of the stronger Spring force of the return spring of the auxiliary relay 18 can be better intercepted.

In addition, it is also possible in the event that no major spring forces are to be overcome, to reduce the coil winding of the auxiliary relay 18, because overall a lower energy input to the function necessary is. Through the resulting less installation space is also a better one Integration of the auxiliary relay 18 in the engagement relay 22 possible.

The timing of an auxiliary starter relay is not only possible with the aid of the control circuit explained in FIGS. 1 and 2, but can also be implemented with a control and regulating circuit according to FIGS. 7 and 8. There, the operating current of the control relay is clocked by a controller 17 via a clock stage in the control unit 14 'in such a way that the average current value which is established in the ratio of the clocking _is regulated to a predetermined target value I target. For this purpose, the actual value of the operating current I _ist, which is constantly changing due to the clocking, _is sensed on the auxiliary relay 18. The setpoint can now be lowered as a function of time after the relay is switched on or, with the aid of a further sensor 21, depending on the position of the auxiliary relay armature.

According to the attached diagram (Figure 8) it is provided that before the relay armature starts moving to the target current Isl, with the armature moved to the smaller nominal current Is2 and at fully engaged relay anchor on the even smaller one Set current Is3 is regulated.

The winding is designed so that, for. B. at 0 c and regulation on Is1 a duty cycle of 60% is safe for a relay armature movement sufficient (duty cycles at the same Relay anchor position and Is2 z. B. 40%, at Is3 z. B. 20%). At the maximum winding temperature (e.g. + 100 C) results then due to the relay currents regulated as above of the higher winding resistance a duty cycle of 100% for Is1 (66% for Is2, 33% for Is3).

The relay current is therefore basically independent of disturbance variables (such as temperature, battery voltage, etc.), but depending on the state of the relay armature (e.g. position, speed) and regulated by the magnetic force requirement. The duty cycle is automatically set correctly by the controller.

• thermische Entlastung
• verkleinerte Stöße beim Ankeraufprall, verringertes Prellen
• erhöhte Funktionssicherheit (höhere Ankeranzugskraft)
• vergrößerte Relaislebensdauer

Overall, a relay current control that depends on the relay armature force requirement results in particular with the advantages

• thermal relief
• reduced impacts on anchor impact, reduced bouncing
• increased functional reliability (higher anchor tightening force)
• increased relay life

Claims (13)

1. Circuit arrangement for an engagement relay for a starter device of an internal combustion engine, having an auxiliary relay (1) which activates a relay coil of the engagement relay, characterized in that an open-loop and/or closed-loop control circuit (16, 16') which influences the magnitude of the operating current (I) in the coil of the auxiliary relay (1) as a function of temperature in the switched-on state is provided, such that the operating current can be changed as a function of the operating temperature of the auxiliary relay (18) and/or of the starter device (24).
2. Circuit arrangement according to Claim 1, characterized in that the open-loop and/or closed-loop control circuit (16, 16') contains a clock stage for a clocked power circuit.
3. Circuit arrangement according to one of the preceding claims, characterized in that the open-loop and/or closed-loop control circuit (16, 16') has a trigger stage (19) for clocking the operating current (I) with a specific pulse duty factor which can be influenced.
4. Circuit arrangement according to one of the preceding claims, characterized in that the pulse duty factor of the operating current (I) can be changed over time.
5. Circuit arrangement according to one of the preceding claims, characterized in that the clocked operating current (I) is reduced after a selectable point in time (t2) has been reached.
6. Circuit arrangement according to Claim 5, characterized in that, after the armature of the auxiliary relay (18) starts to move out of the position of rest and/or when the working position is reached, the clocked operating current (I) is reduced.
7. Circuit arrangement according to one of the preceding claims, characterized in that the reduced operating current (I) has a smaller pulse duty factor than the non-reduced operating current (I).
8. Circuit arrangement according to one of the preceding claims, characterized in that the pulse duty factor is changed as a function of the operating temperature of the auxiliary relay (18) and/or of the engine, in such a way that the operating current can be reduced when the temperature is rising.
9. Circuit arrangement according to Claim 5, characterized in that the point in time (t2) for the reduction of the pulse duty factor can be varied as a function of an operating temperature of the auxiliary relay (18) and/or of the engine.
10. Circuit arrangement according to one of the preceding claims, characterized in that the pulse duty factor of the clocked operating current (I) can be varied as a function of the armature position of the auxiliary relay (18).
11. Circuit arrangement according to Claim 3, characterized in that at maximum admissible operating temperature, the auxiliary relay (18) produces the necessary attraction force given a pulse duty factor of the clocked operating current (I) of 100%.
12. Circuit arrangement according to Claim 3, characterized in that, by means of the open-loop and/or closed-loop control circuit (16, 16'), the clocked operating current (I) can be reduced from a first setpoint value (I_soll) to at least one further low setpoint value after a time (t1, t2, t3).
13. Circuit arrangement according to Claim 12, characterized in that the reduction in the clocked operating current (I) takes place in two steps as a function of the switch-on time (t1, t3) or the armature position of the auxiliary relay (18).

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