JP6478045B2 - Ambient temperature control method for catalytic converter - Google Patents

Description

  The present invention relates to a method for controlling the ambient temperature of a catalytic converter, and more particularly to a method for controlling the ambient temperature of a catalytic converter applied to performance evaluation of a catalytic converter by a bench test.

  As is well known, in the performance evaluation of a catalytic converter by a bench test, it is important to approximate the surrounding environment of the target catalytic converter to the surrounding environment in an actual vehicle. For example, Patent Document 1 discloses a container that surrounds the catalytic converter, a heat exchanger that adjusts the internal temperature of the container, a plurality of temperature sensors that measure the internal temperature of the container, and a target temperature of the internal temperature of the container. The catalytic converter performance evaluation apparatus provided with the control apparatus which recognizes is disclosed. In the performance evaluation device, the control device calculates the internal temperature of the container from the measurement results of each temperature sensor, that is, the average temperature of the ambient temperature of the catalytic converter (hereinafter referred to as “ambient temperature”), and the calculated average temperature The feedforward control and the feedback control of the heat exchanger are performed so as to approximate the target temperature.

Japanese Patent Laying-Open No. 2015-135259

  By the way, as will be described later in detail, the heat transfer equation (heat transfer function) of the ambient temperature in the heat transfer system of the catalytic converter performance evaluation apparatus described above becomes a first-order lag element. Further, when the ambient temperature in the bench test is approximated to the ambient temperature in the actual vehicle, if the feedback gain is increased in order to improve the response of the control system, the stability near the target temperature is lowered. Conversely, if the feedback gain is reduced with emphasis on stability, the time until the target temperature is reached increases, and the response of the control system decreases.

  Therefore, the present invention was made in view of the above circumstances, and in a bench test, it is possible to achieve both responsiveness and stability of the control system that approximates the ambient temperature of the catalytic converter to the ambient temperature of the actual vehicle. An object of the present invention is to provide a method for controlling the ambient temperature of a catalytic converter.

In order to solve the above-described problems, a method for controlling the ambient temperature of a catalytic converter according to the present invention includes a container that houses a catalytic converter, a blower that blows air cooled by a heat exchanger into the container, and the heat exchanger. A method for controlling the ambient temperature of a catalytic converter in a catalytic converter performance evaluation apparatus, comprising: a chiller that cools cooling water used for heat exchange in the apparatus; and a control device that controls the blower and the chiller. A target temperature value determining step for determining a target value of the ambient temperature of the catalytic converter housed in the converter, a deviation calculating step for calculating a deviation between the target value and an actual measured value of the ambient temperature of the catalytic converter, and the catalytic converter feedback gain to determine the feedback gain based on the flow rate of air in the container was measured by a flow meter installed in the vicinity A constant step, characterized in that it comprises a control input value determining step of determining a temperature control input value to the blower and the chiller on the basis of said deviation and the feedback gain.

According to the present invention, the feedback gain is determined based on the flow rate of the air convection in the container, that is, the feedback gain is varied according to the convection state in the container. Therefore, the ambient temperature of the catalytic converter in the bench test can be approximated to the ambient temperature in the actual vehicle.

It is a conceptual diagram of the catalytic converter performance evaluation apparatus to which this embodiment is applied. It is explanatory drawing of this embodiment, Comprising: It is a block diagram containing a control apparatus. It is a conceptual diagram of the feedback control system of ambient temperature to which the control method of this embodiment is applied.

An embodiment of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a schematic diagram of a main part of a catalytic converter performance evaluation apparatus 1 to which the present embodiment is applied. The catalytic converter performance evaluation apparatus 1 is for performing performance evaluation of the catalytic converter 2 by a bench test, and includes a container 3 that houses the catalytic converter 2 and an interior of the container 3 (hereinafter referred to as “inside the container”). A blower 4 for blowing air, a heat exchanger 5 for cooling air blown by the blower 4, cooling water used for heat exchange in the heat exchanger 5, and cooling water between the heat exchanger 5 And a control device 7 (see FIG. 2) for controlling the blower 4 and the chiller 6. The basic structure of the catalytic converter performance evaluation apparatus 1 is the same as that of the existing catalytic converter performance evaluation apparatus.

As shown in FIG. 2, a catalyst temperature sensor 11, a container inlet temperature sensor 12, an ambient temperature sensor 13, and a blower blast amount sensor 14 are connected to the control device 7. The catalyst temperature sensor 11 outputs a detection signal of the temperature of the catalyst stored in the catalytic converter 2 (hereinafter referred to as “catalyst temperature (θ _ex )”) to the control device 7. The container inlet temperature sensor 12 detects a detection signal of the temperature at the container inlet 3A of air blown by the blower 4 (hereinafter referred to as “container inlet temperature (θ _i )”), and further, a detection signal of the temperature of the cooling water in the chiller 6 Output to the control device 7. The ambient temperature sensor 13 outputs a detection signal of the temperature of the air around the catalytic converter 2 (hereinafter referred to as “ambient temperature (θ)”), in other words, a detection signal of the temperature of the air convection in the container. Output to. The blower air volume sensor 14 detects a detection signal of the air volume generated by the blower 4 (hereinafter referred to as “blower air volume (q)”), in other words, a detection signal of the flow rate of the air sent into the container. Output to.

  In addition, the attachment position and quantity of each sensor 11-13 can be selected suitably. In addition, a dedicated or general-purpose microcomputer is applied to the control device 7, and each functional unit 22, 24, 26 configuring the control unit 8 described later is constructed by software.

Ｃ_ｅｘ：触媒の熱容量
ｋ：熱通過率［強制対流＝自然対流×（２〜６０）］
Ａ：触媒コンバータ２の表面積
Ｑ：排気ガス熱量 Next, a control method for approximating the ambient temperature (θ) in the bench test using the catalytic converter performance evaluation apparatus 1 described above to the ambient temperature of the actual vehicle will be described. Here, the heat transfer characteristics in the apparatus 1 will be described.
First, the heat transfer equation of the catalyst temperature (θ _ex ) in the heat transfer system of the apparatus 1 is expressed by (Equation 1).

C _ex : heat capacity of catalyst k: heat passage rate [forced convection = natural convection × (2 to 60)]
A: Surface area of catalytic converter 2 Q: Exhaust gas heat quantity

Ｃ：容器３の熱容量 On the other hand, the heat transfer equation of the ambient temperature (θ) in the heat transfer system of the apparatus 1 is expressed by (Equation 2).

C: Heat capacity of container 3

また、（式３）は（式４）のように変形することができる。

When (Equation 2) is Laplace transformed, (Equation 3) is obtained.

Further, (Equation 3) can be transformed as (Equation 4).

  (Equation 4) shows that the heat transfer equation (heat transfer function) of the ambient temperature (θ) is a first-order lag element. Further, from (Equation 4), when the ambient temperature (θ) is feedback-controlled, when the heat passage rate (k) is large, that is, the convection state in the container (hereinafter referred to as “convection state”) is forced convection. In this case, the value of (Equation 5) corresponding to the time constant (T) of the feedback control system (hereinafter referred to as “time constant (T)”) becomes small, and it can be seen that the responsiveness becomes high. On the other hand, when the heat transfer rate (k) such as natural convection is small, the time constant (T) becomes large and the response of the feedback control system becomes low. Furthermore, from (Equation 4), since the convection state depends on the blower air flow rate (q), the time constant (T) largely fluctuates in combination with the heat passage rate (k) due to the fluctuation of the blower air flow rate (q). I understand that

Further, from (Equation 4), the values of (Equation 6) and (Equation 7) corresponding to the gain of the feedback control system (hereinafter referred to as “feedback gain (K)”) are the heat transfer rate (k) and the blower. It turns out that it fluctuates greatly by the fluctuation | variation of ventilation volume (q). Thus, it can be seen that the heat transfer characteristic of the ambient temperature (θ) varies greatly depending on the blower airflow rate (q) that is the control input of the feedback control system.

  Therefore, in the present embodiment, paying attention to the correlation between the blower air flow rate (q) in the heat transfer system of the device 1 and the convection state in the container, the convection state, and consequently the flow rate of air convection in the container Therefore, a feedback control system for the ambient temperature (θ) was constructed so that the optimum feedback gain was selected. FIG. 3 is a conceptual diagram of an ambient temperature (θ) feedback control system to which the control method of this embodiment is applied. Based on FIG. 3, the flow of control in the feedback control system of the ambient temperature (θ) to which the control method of this embodiment is applied, in other words, the flow of control of the control device 7 (see FIG. 2) will be described.

  The control device 7 reads the target value (A) of the ambient temperature (θ) at the time (t) and the time (t) from the target temperature lookup table 21 provided in the control unit 8 (see FIG. 2) (temperature target value). Decision step). Next, the control device 7 detects the target value (A) of the ambient temperature (θ) and the detection signal output from the ambient temperature sensor 13 (see FIG. 2), that is, the measured value (B) of the ambient temperature (θ). (E) is calculated by the deviation calculation unit 22 included in the control unit 8 (deviation calculation step). The target temperature look-up table 21 includes the time (t) when the vehicle equipped with the catalytic converter 3 to be evaluated is driven in mode on the chassis dynamometer, and the measured value of the ambient temperature (θ). And the control device 7 reads the measured value of the ambient temperature (θ) in the target temperature look-up table 21 as the target value (A) of the ambient temperature (θ) used for feedback control.

As shown in FIG. 3, the control device 7 outputs to the blower 4 two control input values that are control input values of the control system in parallel with the calculation of the deviation (E) by the deviation calculating unit 22. blower blowing amount command value (q) (U _B) and the command value of the chiller set temperature to be output to the chiller 6 to determine the (U _C), and calculates the feedback gain (K) (feedback gain determination step) . In the control system, the container inlet temperature (θ _i ) approximate to the cooling water temperature in the chiller 6 can be appropriately used as an actual measurement value of the cooling water temperature in the chiller 6.

The control device 7 reads the time (t) and the vehicle speed (V) at the time (t) from the target speed lookup table 23 provided in the control unit 8 (see FIG. 2). Further, the control device 7, the ambient flow rate calculation unit 24 by the control unit 8 is provided, by multiplying a gain predetermined for the vehicle speed read _(V) (K V), it flows around the catalytic converter 2 container calculating an air flow rate of the inner (hereinafter referred to as "ambient flow (R)"). Note that the target speed look-up table 23 includes actual values of time (t) and vehicle speed (V) when a vehicle equipped with the catalytic converter 3 to be evaluated is driven in mode on the chassis dynamometer. Is stored. Then, the control device 7 reads an actual measurement value of the vehicle speed (V) from the target speed lookup table 23.

  Next, the control device 7 reads the feedback gain (K) for the calculated ambient flow rate (R) from the feedback gain lookup table 25 provided in the control unit 8 (see FIG. 2). The feedback gain look-up table 25 stores correspondence data between the ambient flow rate (R) and a predetermined optimum feedback gain (K) at the ambient flow rate (R).

Then, the control device 7 calculates the control amount of the ambient temperature (θ) by multiplying the deviation (E) by the feedback gain (K) by the control input calculation unit 26 included in the control unit 8 (see FIG. 2). Furthermore, the control device 7, based on the control amount, the blower air blow amount command value (q) (U _B) and the command value of the chiller set temperature (U _C) and calculated (control input value determining step), Directive The value (U _B ) is output to the blower 4 and the command value (U _C ) is output to the chiller 6.

This embodiment has the following effects.
According to this embodiment, the feedback gain (K) of the control system for the ambient temperature (θ) is based on the ambient flow rate (R), which is the flow rate of the air convection in the vessel, that is, the convection state of the air in the vessel. Since it is determined, the optimum feedback that is predetermined according to the convection state of the air in the container is selected. In other words, it is possible to select an optimum feedback gain (K) that is determined in advance according to fluctuations in heat transfer characteristics in the heat transfer system of the catalytic converter performance evaluation apparatus 1.
This makes it possible to achieve both responsiveness and stability of the control system of the ambient temperature (θ), and by extension, approximate the ambient temperature (θ) in the bench test to the ambient temperature in the actual vehicle. it can. As a result, the accuracy and reliability of the performance evaluation of the catalytic converter 2 by the bench test can be improved.

In addition, this invention is not limited to the above-mentioned embodiment, For example, it can comprise as follows.
In the above-described embodiment, the vehicle speed (V) is read from the target speed lookup table 23, and the ambient flow rate calculation unit 24 multiplies the read vehicle speed (V) by a predetermined gain (K _V ). Although the flow rate (R) is calculated, a flow meter 30 (see FIG. 2) is installed in the vicinity of the catalytic converter 2 inside the container 3 without using the target speed lookup table 23 and the ambient flow rate calculation unit 24. The meter 30 can be configured to directly measure the flow rate of air in the container, that is, the ambient flow rate (R).
In this case, the control device 7 reads the feedback gain (K) for the ambient flow rate (R) measured by the flow meter 30 from the feedback gain look-up table 25 provided in the control unit 8 (see FIG. 2).

1 catalytic converter performance evaluation device, 2 catalytic converter, 3 vessel, 4 blower, 5 heat exchanger, 6 chiller, 7 control device

Claims (1)

A container that houses the catalytic converter, a blower that blows air cooled by a heat exchanger into the container, a chiller that cools cooling water used for heat exchange in the heat exchanger, the blower, and the A control device for controlling a chiller, and a catalytic converter ambient temperature control method in a catalytic converter performance evaluation device,
A temperature target value determining step for determining a target value of the ambient temperature of the catalytic converter housed in the container;
A deviation calculating step for calculating a deviation between the target value and an actual measured value of the ambient temperature of the catalytic converter;
A feedback gain determination step for determining a feedback gain based on the flow rate of air in the container measured by a flow meter installed in the vicinity of the catalytic converter ;
A control input value determining step for determining a control input value to the blower and the chiller based on the deviation and the feedback gain;
A method for controlling the ambient temperature of a catalytic converter, comprising:

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