FR2691678A1 - A method of controlling a ventilation system of the passenger compartment of a motor vehicle, according to at least one switching threshold of the concentration of harmful components. - Google Patents

Abstract

a) A method of controlling a ventilation system for the passenger compartment of a motor vehicle, as a function of at least one threshold for switching the concentration of harmful components. b) Method characterized in that the switching threshold is a function of the concentration of harmful components inside the passenger compartment (K (t)), the switching threshold being slaved according to the tendency of the concentration of harmful components inside the passenger compartment ((K (t)).

Description

i "Control method of a passenger compartment ventilation system

  of a motor vehicle, depending on

  at least one switching threshold of the concentration

  The present invention relates to a process for

  control of a ventilation system of a dwelling

  a motor vehicle tackle according to which the concentration of harmful components inside the passenger compartment and the concentration of harmful components at

  outside and we order the installation of ventila-

  This method is known from German Offenlegungsschrift No. 29 41 305, according to which DE-OS 29 41 305 is measured according to at least one switching threshold of the concentration of harmful components.

  the concentration of harmful components of the external air

  and indoor air using sensors These

  two values are compared with a threshold, respectively.

  From this comparison, a signal of

  command which implements the installation of ventilators

tion.

  According to the document DE-OS 33 04 324 it is already known to enslave the threshold of the value of the con-

  concentration in harmful components of the outside air, determined by a sensor signal, during a period of operation according to the trend of the

BAD ORIGINAL to

  This means that the fresh air supply is only dependent on the base load variation of the outside air. This process does not take into account the concentration of harmful components of the indoor air. Moreover, the

  signal service does not take account of the

  However, semiconductor gas sensors are tainted with instability depending on the parameters of air humidity and operating time that can lead to signal drift. , these sensors are

  also sensitive to gases that react

  in the same way on the surface of the sensors as the measured gas (CO, NO,) The object of the present invention is to remedy these drawbacks and for this purpose concerns a method corresponding to the type defined above, characterized in that the switching threshold is a function of the concentration of harmful components inside the passenger compartment, the switching threshold being controlled according to the trend of the concentration of components

  harmful to the interior of the cabin.

  This method offers the advantage of taking into account the variable base load of the concentration in

  harmful components of the indoor air

  thus to the concentration of harmful components of

  indoor air, concentration to which passengers

gers are directly exposed.

  According to a particularly advantageous characteristic, a switching threshold is provided for

  closing and a switching threshold for opening

  the supply of fresh air, these thresholds being

  predetermined according to the concentration in

  harmful posers from indoor air and being enslaved

  according to the evolution of these quantities.

BAD ORIGINAL "

  It is furthermore intended to enslave at least the closing switching threshold of the power supply.

  outside air according to the operating point-

sensor.

  Beside the absolute signal of the sensor, the first derivative as a function of time is used as

  a quantity characterizing the variation of the concentration

  Thus, to the extent of the concentration of harmful components of the outside air, it is possible to adapt

  the use of the sensor signal to the characteristics

  particular characteristics of semi-gas

  driver, so that the instabilities of the ab-

  sensor sol (signal drift) no longer influences operation.

  The present invention will be described in a manner

  1 is a graph of the evolution of the calculated concentration of CC 2 in FIG.

the cabin according to di, time.

  Figure 2 shows a flow chart of the

  assigned according to the invention to control the supply

in fresh air.

  Description of the exemplary embodiment

  A ventilation system regulates the food

  fresh air of the passenger compartment of a motor vehicle For this we compare the concentration in

  harmful components of the air outside the concentra-

  harmful components of the indoor air and, from this comparison, a

  command implementing the installation of ventilators

  tion. Since the concentration of C 02 is a measure

  of air consumption in iron volumes.

  This gas is used as the guiding gas for

BAD ORIGINAL

  air quality in a passenger car interior

  In closed enclosures in which people live, the content of CC 2 is enriched

  because of the respiratory activity of the occupants.

  This concentration can also be exploited as an indirect measure of a deterioration of the air quality by fumes, body fumes, etc. The concentration of C 02 in a passenger compartment is determined by the calculation according to the invention from of the equation representing the balance sheet LM -d K (t) / dt = Szu + SQU Sab (1) in this equation LM represents the amount of air in the passenger compartment of the vehicle, K (t) represents the concentration in C 02 inside the passenger compartment, which we want to determine, Sz U represents the contribution of C 02 from the outside to the inside, S Qu represents the input of C 02 of the occupants, Sab represents the C02 evacuation from inside to outside. We have Szu = Kc O 2 m

  KC 02 represents the C 02 concentration of the outdoor air

laughing.

  m represents the mass flow rate of air in the dwelling

  when the fresh air supply is open.

Sab = K (t) m.

BAD ORIGINAL

  We obtain the following differential equation from equation (1) LM d K (t) / dt = m (Kc 02 K (t)) + S Qu, (2) Equation (2) corresponds to an air supply

fresh, open.

  The following equation is obtained when the fresh air supply is closed: LM d K (t) / dt = S Qu (3) Equation (2) is solved as follows: K (t) = (K K 2 SQU / m) e- (m / Lm) + Kco 02 + S Qu / m (4)

  Ksortie 1 represents the concentration of the volume

  at the moment of the opening of the

fresh air.

  Equation (3) resolves as follows: K () = (SQU / LM) t + Kout 2 (5)

  Ksortie 2 represents the concentration of the volume

  at the moment of closure of the food

fresh air.

  To calculate the C 02 concentration of the

  internal lume K (t) the parameters of equation (4) and those of equation (5) must first be determined. The mass flow rate of air m is a function of the speed of displacement v and the electric power absorbed by the air blowers (fans) To doublets of value v and P we can associate a mass flow rate of air min corresponding This association is BAD ORIGINAL j) characteristic of the vehicle and is written in the read only memory ROM A calculator The calculator then continuously determines the mass flow rate of air. The quantity of air LM contained in the passenger compartment of the motor vehicle is also included in the calculation.

calculator as constant.

  The supply of C 02, SQU is caused by the breathing of the passengers. This contribution of the calculation unit is determined as a function of the number of passengers and by multiplying by a mean value corresponding to the quantity of CO 2 gas exhaled per unit of fuel. time by a person The number of passengers is determined

  for example using contacts on the seats.

  The supply of C 02 by the outside air Sz U is

  also recorded as a constant in the calculation

  from an average experimental concentration of C 02 gas in outdoor air equal to 400 ppm Concentrations in the passenger compartment at

  the moment of the opening and closing of the

  Ksortiel and Ksortie 2 are also

  stored in the calculator.

  In particular, the determination of the mass flow rate of air is critical. The consequence is

  that the C 02 concentration of the passenger compartment K (t) differs

  value of the real value The resulting error increases

  with the time t and that in a more than proportional way because of the exponential form of the equation (4) It is provided for this to correct the value calculated by taking points of support In the present embodiment , the points of support are pairs of values lt, K (t) l which give a

  given instant t a concentration K (t) with a pre-

  The initial values are sufficient to allow the restarting process to be restarted.

BAD ORIGINAL

  calculation of the concentration of C 02 within

the passenger compartment K (t).

  Figure 1 shows the concentration curve

  C 02 of the passenger compartment K (t) calculated when the outside air supply is open and

  when closed, as a function of time

  stant to calculate the C 02 concentration of the

  tackle K (t) starting from a value K ,, - ti ,,,

  with fresh air being opened, using the

  (4) At time t 1, which corresponds to the instant ts in the flowchart of Figure 2, the supply of fresh air is closed and the value of the concentration Ksortie 2 is provisionally recorded. The concentration in C 02 of the cabin K (t) is calculated according to equation (5) At time t 2 we open

  air supply and record

  provisionally the new value of the concentration

  Ksortiei; this value is used in the equation

  (4) for a recalculation of the concentration of CO, K (t) The moment t 2 corresponds to the flow chart

from Figure 2 to instant tô.

  As it appears in the outline of the con-

  calculated C 02 concentration K (t) when the outside air supply is open, the function approaches asymptotically for the important values of t, of the concentration of C 02 outside, either

  KC 02 increased by the portion of C 02 from

  SQU divided by the mass flow of the air m Ain-

  if the parametric error of m is incorporated in this value

  their limit inversely proportional.

  The correction of the reference position, already indicated, is executed when the concentration of C 02 in the passenger compartment has approached the value A of the asymptotic value of the concentration.

  this value at time t 3 according to FIG.

BAD ORIGINAL

  For example, we introduce the benchmark

  when the concentration of internal Co 2 K (t) exceeds

  10% concentration limit KCO 2 + Szu / m, when

  that K (t = t) K (t -> o) 100% '10%, (6) then we put K (t) = K (t -> -) = Kc 02 + SQU / m (7) The condition (6) is satisfied when t> 2.3 LM / m (8)

  in equation (7) assume that m is constant.

  As this does not happen for a trip

  real time, it is planned to record the instant of the opening of the fresh air supply and then determine at regular intervals and using

  the instantaneous speed of movement v and the power

  this electric P absorbed by the blower, for determining

  the mass flow of instantaneous air sweeping the passenger compartment of the vehicle From the values thus obtained successively for m from the instant of

  the opening, one permanently forms the average value.

  Every instant value that happens is compared to

  the average value formed from the previous values

  If this new value m is greater than

  re at this average value, it is only used

  to update the average value When this new

  value is lower, it is used to verify

  at the moment corresponding to the condition

  equation 8 for the correction of the

BAD ORIGINAL

  benchmark When this relationship is satisfied, one makes

  a correction of the benchmark with a value of

  mite, resulting from equation (7), using the mean value for m If, on the other hand, equation (8) is not satisfied, this value m is used only to update the mean value This ensures that the correction the benchmark is only done

  inside the 10% band according to equation (6).

  Since it is uninteresting to compare di-

  concentrations due to different gas types, these different types of

  according to their action on the human organism.

  the range of the concentrations for which the perception of well-being is not attenuated is for CO between 0 and 10 ppm and for C 02 between 0 and 1000 ppm Therefore, the concentration of CO of the coefficient must be affected. Compared to the concentration of C 02. If other types of

  gas in the outside air (eg NOX), it is

  determine correct weighting coefficients.

  respondent for example by taking into account the prescrip-

  German MIK or MAK, that is, the concentration of

  mr-ximal legal issue of emission and concentration

  maximum legal status at the workplace.

  In addition to the calculation described for the concentration

  C 02 of the passenger compartment, it is possible to measure the

  tion of harmful components of indoor air also using particular C 02 sensors. Under the same conditions, other reference gases could also be

  C 02 to determine the concentration of components no.

cifs in the indoor air.

  The concentration of harmful components of the outside air is determined using a sensor

  equipping the vehicle For this, we measure the resistance

BAD ORIGINAL

  sensor R which is a measure of the concentration

  The resistance R of the sensor is used both as an absolute value R (t) in

  function of time and as a variation of the concentration

  harmful components at the time of application.

  harmful gas, according to the equation d R (t) / dt The ampli-

  The study and the algebraic sign of this quantity give a measure of the variation of the concentration It should be noted that the proposed magnitude d R / dt depends on the degree of coverage of the sensor surface by the

  harmful gas For a given increase in the concentration

  the amplitude decreases as the degree of recovery increases; it means that the sensor

  reaches a saturation point and its operating point

  moving as a measure of the degree of

  the resistance R (t) of the sensor

  also fixes the operating point of this cap-

  tor. In the present embodiment,

  then compare the resistance of the sensor R (t) as a function

  time with the C 02 concentration of the

  tackle K (t) For this we define two thresholds SI and 52

  for the values of the C 02 concentration of the

  tackle; the SI threshold corresponds to the closure of

  the outside air supply and the threshold 52 on the

  opening of the outside air supply.

  According to FIG. 2, the method for controlling the supply of fresh air will be described below. The process starts with step 1, the air supply.

  charge being opened The calculator contains in memory

  re, according to step 2, the initial values for the

  switching thresholds SI and 52; these values are

  necessarily kill in the intermediate zone of the C 02 concentration of the passenger compartment The calculator continuously compares, as a function of time, according to

BAD ORIGINAL to

  In step 3, the change in the concentration of harmful components d R / dt and the threshold Si When the condition d R / dt <Si <O is satisfied, the supply of fresh air is closed according to step 4 same time, in step 5, the sensor signal at the instant of the

  R (ts) is recorded in the calculator.

  While the fresh air supply is

  closed, it is continuously checked in step

  If S indicates that the concentration in

  harmful components continue to increase.

  harmful components does not continue to increase.

  ter, the calculator compares in step 7, the value

  absolute of the sensor signal R (t) to the value of the

  sensor signal R (ts) at the moment of closing the fresh air supply If the following pipe is satisfied, R (t) R (ts)> 52 lK (t) l <O

R (ts) -

  the fresh air supply is opened again

  step 8 The sensor signal at the instant of the

  R (t 5) is written in the calculator according to

step 9.

  In the following step 10, account is taken of the instantaneous C 02 concentration in the passenger compartment K (t) as well as the saturation effect of the sensor of harmful components, as described for that purpose.

  the switching threshold Si corresponding to the

  when closing the fresh air supply in

  function of K (t), that is to say that we have Si lK (t) l.

  To take into account the degree of saturation of the sensor,

  it is planned to correct the value of Si by R (t).

  For this, the range of R (t) is subdivided into a few

  In the different zones, a coef-

BAD ORIGINAL

  correction factor FlR (tô) l giving by multiplication

  If the value corrected for Si The calculations mentioned above and the memory functions

are made by the calculator.

  The corrected value of Si is compared with the change in concentration of harmful components d R / dt in step 10 If the following condition is satisfied, d R / dt S FLR (t = t0) l SI lK (t) l, the supply of fresh air is closed during step 11 and the sensor signal R (ts) is stored in memory.

  the moment of closure during Step 12 Pen-

  As soon as the fresh air supply is closed, again, as in the first closing cycle corresponding to step 6, the variation of

  concentration of harmful components d R (t) / dt

  time and the corrected threshold SI according to step 13.

  If the variation in the concentration of

  harmful effects does not continue to increase, control returns to step 7; at this moment the instantaneous signal

  of the sensor R (t F), corresponding to the moment of the last

  If the following condition is satisfied R (t) R (ts), 52 lK (t), the fresh air supply is again opened according to the step 8 and the sensor signal R (ss) is recorded at the moment of opening The comparison cycles

  described above for the two thresholds SI and 52 are

  fart during a period of operation.

  The described variation of switching thresholds

  tion Si and 52 as a function of K (t) and R (t) has the consequence

BAD ORIGINAL

  Variation Influence on Sizes Thresholds of Influencing Effects Switching Down K (t) Increase Attenuation of the

  (W 'supply of Si condition of iron

in fresh air is meture that is

open) say that the

positive closes

for concentration

external

relative-

  Low R (t) Increase Attenuation of the

of If condition of iron-

meture; correction

  operating point increase R (t) Lowering Accentuation of the

of Si Condition of iron-

  meture; setting on the operating point Increase K (t) Lowering Attenuation of the

  (the food of 52 condition of opening

  in fresh air is ture; closed) the device opens for concentrations

external relations

elevated

BAD ORIGINAL J)

Claims (5)

CLAIMS) A method of controlling a ventilation system for the passenger compartment of a motor vehicle according to which the concentration of harmful components inside the passenger compartment and the concentration of harmful components in the passenger compartment are determined. outside and the ventilation system is controlled according to at least one switching threshold of the concentration of harmful components, characterized in that the switching threshold is a function of the concentration of harmful components inside. of the passenger compartment (K (t)), the switching threshold being controlled according to the trend of the concentration of harmful components inside the passenger compartment ((K (t)).   2) The process according to claim 1, wherein   in that it also enslaves the   mutation to the trend of concentration in harmful effects of the outside air.   The method of claim 1, wherein   achieved by having a first switching threshold   (SI) to close the fresh air supply and a se-   switch threshold (52) to open the power supply   fresh air and the switching thresholds are   (Si) and (52) to a sensor signal giving the   concentration of harmful components of the outside air.   The method of claim 3, wherein   characterized in that, the fresh air supply being open, the first derivative of the sensor resistance as a function of time is formed as a sensor signal at the moment of the application of the harmful gas and the result of this operation at the switching threshold (SI) and the supply of fresh air is closed if the following condition is satisfied by R (t) / dt 'Si <0 BAD ORIGINAL    Method according to claim 4, characterized in that the switching threshold (SI) is slaved to the trend of the concentration of harmful components of the passenger compartment and the resistance of the sensor (R (t)).   6. A process according to claim 5, characterized   in that the switching threshold (Si) is increased when the concentration of harmful   the interior of the passenger compartment (K (t)) decreases.   7) A method according to claim 5, characterized   in that the switching threshold (51) is increased when the sensor signal (R (t)) decreases and   when the sensor signal (R (t)) increases the switching threshold (SI).   8. Process according to claim 3, characterized   in that as a sensor signal the   sensor resistance (R (t)) and open the food   fresh air if the following condition is satisfied made R (t) R (ts) 2 O / 52 <0   R (ts) relatico in which R (ts) represents the signal of the   sensor at the moment of the previous closing.   9) A method according to claim 8, characterized   controlled by lowering the switching threshold (52) when the concentration of harmful components to   the interior of the cabin increases.    Method according to one of the claims   previous ones, characterized in that   respective initial values for the comparison thresholds   mutation (51) and (52) by placing them in the   term of concentration of harmful components to the interior of the cabin.   11) Method according to one of the claims   preceding, characterized in that as concentration BAD ORIGINAL   harmful components inside the passenger compartment (K (t)) the concentration is measured and / or calculated. CO, inside the cockpit.   12) Process according to claim 11,   characterized in that we weight the concentration in   harmful components of the outside air according to the   of this concentration in relation to the concentration   C 02 inside the cockpit. BAD ORIGINAL has