FR2608524A1 - Digital proportional regulation device for heating and/or air conditioning of a motor vehicle - Google Patents

Abstract

A motor M determines the position of a hot-air and cold-air mixing valve. A microprocessor MP is actuated at a predetermined rate in order to determine, on each run, values desired for the direction of rotation, a number of working periods and a number of off periods of the motor, while counting the number of periods in progress. The control of the motor M is modified when the desired values do not correspond to the actual state of the motor, whilst the counting is returned to a starting value.

Description

Digital proportional control device for heating and / or air conditioning an automobile.

The invention is in the field of heating and / or air conditioning systems for automobiles.

More specifically, we are interested here in forced air heating devices, which involve on the one hand a first air flow, which is either direct, or forced to pass through an evaporator for air conditioning, if the vehicle is equipped, and on the other hand a second air flow passing through a heating exchanger, itself supplied by the coolant of the vehicle engine.

 I1 has already been proposed that the regulating actuator is a motor acting on the position of at least one mixing member, incorporated in a pipe for blowing the heating / air conditioning air. The regulation then consists in making comparisons to control the rotation of the motor, in one direction or the other, when a measured temperature difference deviates in a predetermined manner from a reference value, respectively by higher values. and lower.

Compared to the known variant in which the regulating actuator is a valve for supplying hot fluid to an exchanger, this type of regulation acting on the air mixture is often felt by the user as providing a much better impression. comfort.

However, the difficulty is to carry out in this case a precise and effective regulation. Indeed, the relationship between the position of the mixing device and the air temperature blown into the passenger compartment is subtle. These include the air flow characteristics in the pipe, at the level of the mixer, which will of course vary with its position, and also the fact that, for other reasons, it is interesting that the temperature is not constant, in a cross section of the blowing pipe, because we want to have air at slightly different temperatures depending on whether it is blown towards the windshield to defrost, towards the faces passengers or, on the contrary, towards their feet.

On the technical level, it is moreover desirable that the motor can be as simple as possible, for example a DC motor admitting an operation in locked rotor, when it comes into abutment, which makes all the more delicate the design of the regulatory system. It is also worth remembering that this must in no way be subject to pumping phenomena, which would result in oscillatory variations in the temperature of the heating / air conditioning air.

The object of the present invention is to provide a satisfactory solution to this problem.

It also aims to provide a solution which can be implemented on a simple microprocessor which, itself and all its accessories, easily meets the particular constraints encountered on board a motor vehicle.

The proposed device is of the type defined above, intended to control a motor acting on the position of at least one mixing member, incorporated in a supply line for heating / air conditioning air, and in which comparisons for controlling the rotation of the motor, in one direction or the other, when a measured temperature difference deviates in a predetermined manner from a reference value, respectively by upper and lower values.

We will return later on how to make these comparisons according to the invention.

One of the essential characteristics of the invention resides in that the device comprises a microprocessor, actuated according to a predetermined periodicity, to determine each time desired values for the direction of rotation, a number of running periods and a number of engine stop periods, while maintaining at least one count of numbers of periods in progress, and to modify the engine control when the desired values do not correspond to the actual state of the engine, while then reducing the count to a starting value, which is for example 1.

According to another aspect of the invention, when the engine is stopped, the count is simply incremented if its value is less than the number of stop periods, while otherwise, the engine is actuated in the desired direction if the number of walking periods is greater than a threshold, for example zero, the counting being in any case brought back to the starting value.

According to another aspect of the invention, when the engine is running in the direction opposite to the desired direction, it is stopped, the counting being brought back to the starting value.

According to yet another aspect of the invention, when the engine is running in the desired direction, the counting is simply incremented if its value is less than the number of running periods, while otherwise the engine is stopped if the number of stop periods is greater than a threshold (again zero in practice), the counting being in any case brought back to the starting value.

Finally, according to yet another aspect of the invention, when the engine is running in the desired direction, the number of running periods is reached, and the number of stopping periods is less than or equal to the threshold, the motor movement is maintained, the count being brought back to the starting value.

Advantageously, the microprocessor performs the acquisition of the input quantities between these regulation periods.

The device can in practice be supplemented by a multiplexer and analog-digital converter assembly for acquiring the measured temperatures, which include at least the internal temperature and the temperature of the supply air, advantageously also the external temperature.

For its part, the set temperature is acquired, in digital form, through a separate user interface.

Of course, other information can be acquired through this interface.

Other characteristics and advantages of the invention will appear on examining the detailed description below, and the appended drawings, in which: - Figure 1 is a block diagram of a device according to the invention; - Figure 2 is a schematic drawing of a heating / air conditioning system for implementing the invention; and FIG. 3 is a flow diagram of the operations carried out by the microprocessor, in one embodiment of the invention.

In FIG. 1, a microprocessor MP is connected by different bidirectional digital links on the one hand to a multiplexer and analog-digital converter MC assembly, receiving an internal temperature TI, an external temperature TE and a supply air temperature TA.

The microprocessor is also connected to a user interface IU allowing the acquisition, in direct digital form, of a setpoint temperature TC, for example using a keyboard. Finally, the microprocessor MP controls a motor M through a motor interface IM, which may for example consist of a bridge with power transistors.

The microprocessor can be for example the 4-bit model
COP sold by the Société National Semiconducteurs, which internally has a fixed memory of 1 or 2 kilobytes, and a random access memory of 124 bytes. The multiplexer-converter MC assembly can be, for example, the ADCOt3XX model and the user interface TU can, for example, be the "Driver type S452" device from the same manufacturer.

In FIG. 2, we recognize fresh air lines AN and recycled air AR, connected in adjustable proportion under the effect of a shutter VE to a blower S. This therefore introduces air into a room refrigeration system equipped with an EVP evaporator. The output of the chamber CR can communicate with a heating chamber CC provided with a heat exchanger ECH whose heating fluid is the engine coolant. The common exit from the CR and
CC is located at the location marked STA, which also indicates the position of the supply air temperature sensor. After that, a first distributor flap VR1 makes it possible to direct the air either to aerators AER, or to a second distributor flap VR2 which distributes the air between the defrost outlet ADG and the low ventilation outlet, for the feet , noted AEP.

The essential shutter for regulation is naturally the shutter VM, which can take any position of adjustment between the situation where it completely blocks the passage by the heating chamber CC, and the opposite position where it forces all the air coming from the room CR to pass through the ECH exchanger, through the CC chamber.

The supply air temperature sensor is the STA sensor in FIG. 2, in principle provided with a thermistor, which is advantageously mounted as defined in Patent Application NO 86 16494 filed on November 26, 1986 in the name of the Applicant, under the title "Temperature sensor and its use for air conditioning the passenger compartment of a motor vehicle".

The internal temperature sensor TI can be placed on the dashboard, to be partially subjected to the influence of solar heat, in known manner, and it can also be placed in a housing subjected to a vacuum with respect to the passenger compartment, also in a known manner.

The TE outdoor temperature sensor is for example placed at the air inlet of the device, upstream of the shutter.

Reference is now made to FIG. 3, for the description of the operation of the microprocessor according to the invention.

This microprocessor executes a loop every 33 milliseconds, the operations of which are illustrated in FIG. 3. This can be obtained by providing a high priority interrupt forcing the microprocessor to perform this loop with the chosen periodicity.

The first step 30 consists in the calculation of three quantities: - SRd which is a binary quantity indicating the direction of rotation desired for the motor, - Kon, which is an integer representing the number of periods during which it is desired that the motor is started in the direction of SRd; and - Koff, which is the number of periods during which it is desired that the engine is then kept in the stopped state.

It should be emphasized here that these calculations are carried out at the start of each loop, taking into account the values of the parameters which exist at this time, and which will not have a direct relationship with the real behavior of the engine.

Indeed, one could envisage, after these calculations, to carry out entirely the complete cycle planned for the engine as it has just been calculated, and to carry out only after that a new evaluation of the desired values, which would be in turn fully implemented.

The present invention prefers to use a much simpler method, which involves a new calculation of the desired values at each elementary loop, and thereby allows an optimization of the system response time. This is particularly important, given the difficulties, already noted above, that regulation presents in the context considered here.

After the calculation step 30, a step 31 determines whether the engine is stopped. This is still easy to obtain binary information, since the microprocessor always has access to the state controlled by the engine interface IM.

It should now be specified that each time the loop is run, the microprocessor will update a counter for the number of regulation periods, or more exactly the number of loop passages. The value of this counter, at the start of the loop, is noted KB.

If the engine is stopped, a test 32 consists in determining whether the number KB is greater than or equal to the number Koff calculated in step 30,
If KB is less than Koff, we go directly to step 39 which consists of incrementing KB.

Otherwise, the desired period for stopping the engine is over. Step 33 then determines whether there is a desired period of engine running, i.e. if
Kon may or may not be zero. If Kon is positive, step 34 activates the motor in the direction defined by SRd, then step 49 reduces the KB count to 1.

If, on the contrary, Kon is zero, we go directly to step 49 to reduce the KB count to 1.

We now consider the other term of the alternative at the end of test 31, that is to say the case where the engine is running.

Step 40 determines whether the direction of operation of the motor is that defined by SRd.

If this is not the case, we go directly to step 41 which consists in stopping the engine, then in step 49 which consists in reducing KB to 1.

If, on the contrary, the direction of operation of the motor is that defined by SRd, we go to step 43 which examines whether KB is at least equal to Kon.

If this is not the case, it means that it is desired that the motor continues to rotate in the direction SRd, and step 39 increments the counting KB.

Otherwise, it is not desired that the motor continues to rotate in the direction SRd. Step 45 determines whether a certain number of stop periods is desired.

If Koff is zero, the engine is stopped and step 49 then reduces the KB count to 1.

According to a particular originality of the invention, if an engine stopping time is not desired at the level of test 45, the engine is continued to rotate in the direction defined by SRd, and step 49 returns the counting KB at 1.

 I1 is now reminded that this loop is traversed every 33 milliseconds, each time with a new calculation of the values SRd, Kon and Koff.

Experience has shown that the process defined by the steps described above is particularly effective for temperature regulation on board an automobile, while having recourse to simple and proven technical means.

The calculations of step 30 can be carried out on the basis of a temperature difference quantity, including the sign. defines meaning information, while the integers Kon and
Koff define the desired response law as a function of the amplitude of the temperature difference.

Those skilled in the art will understand that this makes it possible to construct any desired relationship, linear or not, from the temperature difference, which in turn depends on a linear combination of three measured temperatures and the set temperature, with possible intervention of a differential component on the supply air temperature, in particular, if desired.

For example, the supply air temperature difference Eas is defined by the following relation
Eas = ecas - eas - 1,5 Bottom with ecas = Dry - 2,7eint - 1,258suc - 23 in which
Eas = error on supply air temperature.

case = calculated supply air temperature.

 8as = measured supply air temperature.

e'as = supply air temperature / time derivative.

 ec 5 set temperature.

 eint = measured interior temperature.

 6sc = outside temperature measured.

In principle, a weight greater than the indoor air temperature is given, a lower weight at the outdoor temperature, and an intermediate weight for the supply air temperature, an intervention of this in differential mode making it possible to compensate for these possible rapid variations.

A variant of the invention consists in taking into account the evolutionary trend of the temperature of the blown air, for example as described in Patent Application No. 84 15131 of the Applicant, published under NO 2,571,160.

The calculations can be carried out not only from calculation operators incorporated in the microprocessor, but also by tables or laws of correspondence recorded in read-only memory therein, possibly by a combination of the two calculation modes.

Claims (10)

Claims. 1. Electronic device for regulating heating and / or air conditioning for an automobile, intended to control a motor (M) acting on the position of at least one mixing member (VM), incorporated in an air blowing pipe heating / air conditioning, and in which comparisons are made to control the rotation of the motor, in one direction or the other, when a measured temperature difference deviates in a predetermined manner from a reference value, respectively by upper and lower values, characterized in that it comprises a microprocessor (MP), actuated according to a predetermined periodicity to determine each time desired values for the direction of rotation (SRd), a number of running periods (Kon ) and a number of engine stop periods (Koff), while maintaining at least one count of number of periods in progress (KB), and to modify the engine control (M) when the desired values (SRd, Kon , Koff) do not match the actual state of the engine, while reducing the count to a starting value. 2. Device according to claim 1, characterized in that, when the engine is stopped, the count is simply incremented if its value (KB) is less than the number of stop periods (off) while otherwise the motor is activated in the desired direction if the number of running periods (Kon) is greater than a threshold, the counting being brought back to the initial value anyway. 3. Device according to one of claims 1 and 2, characterized in that, when the engine is running in the direction opposite to the desired direction (SRd), it is stopped, the counting being brought back to the starting value. 4. Device according to one of claims 1 to 3, characterized in that, when the engine is running in the desired direction, the count (KB) is simply incremented if its value is less than the number (Kon) of periods of running, while otherwise the engine is stopped if the number of stopping periods (Koff) is greater than a threshold, the counting being brought back to the starting value anyway. 5. Device according to claim 4, characterized in that, when the engine is running in the desired direction, that the number of running periods (Kon) is reached, and that the number of stopping periods (Koff) is less than or equal to the threshold, the movement of the motor is maintained, the counting being brought back to the starting value.  6. Device according to one of the preceding claims, characterized in that the starting value of the count is one, and that the threshold is zero. 7. Device according to one of the preceding claims, characterized in that the microprocessor carries out the acquisition of the input quantities between its regulation periods. 8. Device according to claim 7, characterized in that it comprises a multiplexer and analog-digital converter assembly for the acquisition of the measured temperatures, which comprise at least the internal temperature (TI) and the temperature of the supply air (YOUR). 9. Device according to claim 8, characterized in that the measured temperatures also include the outside temperature (TE). 10. Device according to one of claims 7 to 9, characterized in that the set temperature (TC) is acquired, in digital form, through a separate user interface.