JP4675284B2 - Internal combustion engine temperature measurement device - Google Patents

Description

  The present invention relates to a temperature measuring device for an internal combustion engine.

  As a temperature measuring device for an internal combustion engine, for example, a technique described in Patent Document 1 below is known. In the technique described in Patent Document 1, the output gas with respect to the temperature change of the exhaust aftertreatment device is added to the exit gas temperature detected by the exhaust temperature sensor installed downstream of the DPF (exhaust aftertreatment device) with oxidation catalyst. A first DPF temperature estimated value is calculated by multiplying the temperature change by a reverse transfer function that defines the first order delay and the waste time L. Further, the previous outlet gas temperature is predicted for the time corresponding to the waste time L from the temperature changes at the two latest outlet gas temperatures, and the second DPF temperature estimated value is calculated by multiplying the predicted value by the reverse transfer function. .

In addition, the first DPF temperature estimated value is used in the calculation of the PM deposition amount that requires accuracy, and the second DPF temperature estimated value is used in the excessive temperature rise prevention control that requires responsiveness. The post-processing device is appropriately controlled.
JP 2004-245109 A

  However, in the above-described prior art, it is necessary to calculate the first and second DPF temperature estimated values, and the configuration is complicated. Further, the second DPF temperature estimated value is calculated using the previous predicted value for a time corresponding to the waste time, but there is a disadvantage that the temperature prediction is difficult and the calculation accuracy is lowered.

  Accordingly, an object of the present invention is to provide an internal combustion engine temperature measuring apparatus that solves the above-described problems and that measures the temperature of the internal combustion engine such as the exhaust temperature with high accuracy while having a simple configuration.

In order to solve the above object, in the temperature measuring device of an internal combustion engine according to claim 1, is installed in an internal combustion engine, the exhaust gas temperature detection means for detecting the exhaust temperature of the exhaust system, which is the detected exhaust Exhaust temperature time fluctuation calculating means for calculating the time fluctuation of temperature, filter processing means for filtering the calculated time fluctuation of the exhaust temperature, and the detected exhaust temperature and the filtered temperature Exhaust temperature calculation means for calculating the exhaust temperature of the exhaust system based on the time fluctuation amount of the exhaust system , and the filter processing means has a high frequency corresponding to the time fluctuation amount as the calculated time fluctuation amount of the exhaust temperature decreases. While the filter output for the component decreases, the filter output for the low frequency component corresponding to the time variation increases as the time variation of the calculated exhaust temperature increases. And as configured to change the filter pass characteristic.

The internal combustion engine temperature measuring apparatus according to claim 2, wherein the filter processing means includes a weight function of a filter output for the low frequency component corresponding to the time variation, and the time variation of the calculated exhaust temperature. The weight function is set such that the value of the weight function decreases as the value decreases, while the value of the weight function increases as the calculated time variation of the exhaust temperature increases .

In the internal combustion engine temperature measuring apparatus according to claim 1, the time variation of the detected exhaust temperature is calculated, the time variation of the calculated exhaust temperature is filtered, and the detected exhaust temperature and calculates the exhaust temperature of the exhaust system on the basis of the time change of the filtered exhaust gas temperature, the more time change of the calculated exhaust gas temperature decreases, while the filter output is decreased with respect to high-frequency components of the time change More specifically, as the time variation of the calculated temperature increases, the filter output for the low frequency component of the time variation increases, more specifically, as the time variation of the calculated temperature decreases, Since the pass frequency (cutoff frequency) is lowered, the filter pass characteristic is changed so that the pass frequency is increased as the time variation of the calculated temperature increases. With a simple configuration, the exhaust temperature of the internal combustion engine, while removing noise, can be accurately measured, further, it is possible to achieve both the improvement in accuracy and responsiveness.

In the temperature measuring device of an internal combustion engine according to claim 2, one value of the weighting function as time change of the calculated exhaust gas temperature becomes smaller you decrease, the greater the time change of the calculated exhaust gas temperature since the value of the weighting function is constructed as you increase, in addition to the effects mentioned above, the improvement in accuracy and responsiveness can be further achieved.

That is, Ruhodo to reduce the time variation of the exhaust temperature, to so that to the filter output is reduced for the high-frequency components, in other words, it decreases time change is reduced to Ruhodo pass frequency of the exhaust temperature (the cutoff frequency) Thus, by changing the filter pass characteristic, noise can be removed, and the calculated exhaust temperature becomes a value close to the detected exhaust temperature, so that the detection accuracy is improved.

On the other hand, since the appearing significant time variations in the high frequency side, Ruhodo to increase time change of the exhaust temperature, to so that to increase the filter output for the low frequency components, in other words, time change of the exhaust temperature by but changing the filter pass characteristic so go up Ruhodo passing frequency to increase, it is possible to greatly reflects the most recent detected temperature to the filter output, it is possible to improve the responsiveness. As described above, both improvement in accuracy and responsiveness can be achieved.

  The best mode for carrying out an internal combustion engine temperature measuring apparatus according to the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a schematic view schematically showing a temperature measuring device for an internal combustion engine according to an embodiment of the present invention. In the embodiment, an exhaust gas processing apparatus for an internal combustion engine will be described as an example of a temperature measuring apparatus for the internal combustion engine.

  In FIG. 1, reference numeral 10 denotes a four-cylinder internal combustion engine (diesel engine; hereinafter referred to as “engine”), and 10a denotes a main body thereof. In the engine 10, the intake air drawn from the air cleaner 12 flows through the intake pipe 14.

  An intake shutter 16 is disposed at an appropriate position of the intake pipe 14. The intake shutter 16 includes a valve 16a and an actuator 16b such as an electric motor connected thereto. When the actuator 16b is driven through a drive circuit (not shown), the valve 16a is driven in the closing direction accordingly. The opening degree of the intake pipe 14 is adjusted in the throttle direction to reduce the amount of intake air passing therethrough.

  The air flowing through the intake pipe 14 passes through the intake manifold 20 downstream thereof and reaches each cylinder. When the intake valve (not shown) is opened and the piston (not shown) is lowered, the combustion chamber (see FIG. (Not shown). The sucked air is compressed and becomes hot when the piston moves up.

  Fuel (light oil) stored in a fuel tank (not shown) is supplied to an injector 22 disposed at a position facing the combustion chamber of each cylinder via a pump and a common rail (both not shown). When driven (opened) via a drive circuit (not shown), it is injected into the combustion chamber, is compressed and becomes hot, and spontaneously ignites and burns. As a result, the piston is driven downward and then rises again. When an exhaust valve (not shown) is opened, exhaust (exhaust gas) is discharged to an exhaust manifold (exhaust system) 24. The exhaust then flows through an exhaust pipe (exhaust system) 26 downstream thereof.

  The exhaust pipe 26 is provided with an EGR pipe 30 connected to the intake pipe 14, and the EGR pipe 30 is provided with an EGR valve 30 a. When the EGR valve 30a is operated via a drive circuit (not shown), the EGR pipe 30 is opened to recirculate part of the exhaust gas to the intake system.

  Further, in the exhaust pipe 26, a turbocharger (not shown) 32 turbine (not shown) is provided downstream of the connection position of the EGR pipe 30 and is rotated by exhaust gas. The connected compressor 32a is driven, and the air sucked from the air cleaner 12 is supercharged.

  In the exhaust pipe 26, an oxidation catalyst device (shown as “CAT” in the figure) 34 made of platinum or the like is arranged downstream of the arrangement position of the turbocharger 32. The oxidation catalyst device 34 oxidizes and removes unburned HC in the exhaust.

  A DPF (Diesel Particulate Filter) 36 is disposed downstream of the oxidation catalyst device 34 to collect particulate matter (Particulate) in the exhaust gas. The DPF 36 is made of a ceramic honeycomb filter, and the inside thereof has an exhaust passage closed at the upstream end and the downstream end opened, and the upstream end opened and the downstream end closed. Exhaust passages are alternately arranged, and a porous wall surface having many pores with a diameter of about 10 μm is formed between adjacent passages, and particulate matter in the exhaust is collected by the pores. .

  After passing through the DPF 36, the exhaust flows through a silencer, a tail pipe, etc. (all not shown) and is discharged to the outside of the engine 10.

  A crank angle sensor 40 including a plurality of sets of electromagnetic pickups is disposed near the crankshaft (not shown) of the engine 10 and outputs a cylinder discrimination signal and outputs a TDC signal at or near each TDC of the four cylinders. In addition, a crank angle signal is output for each predetermined crank angle.

  Further, a water temperature sensor 42 is disposed in the vicinity of a cooling water passage (not shown) of the engine 10 and outputs a signal corresponding to the engine cooling water temperature TW, and an intake air temperature sensor in the vicinity of the air cleaner 12 in the intake pipe 14. 44 is arranged to output a signal corresponding to the temperature of the intake air taken into the engine 10.

  Further, an accelerator opening sensor 50 is arranged near the accelerator pedal 46 arranged on the floor of a driver's seat (not shown) of the vehicle on which the engine 10 is mounted, and outputs a signal corresponding to the accelerator opening θAP. In addition, a wheel speed sensor 52 is disposed at an appropriate position of a wheel (not shown), and outputs a signal for each rotation per predetermined angle of the wheel.

  In the exhaust system of the engine 10, a first exhaust temperature sensor 54 is disposed at an appropriate position downstream of the turbocharger 32 and upstream of the oxidation catalyst device 34, and corresponds to the exhaust temperature upstream of the oxidation catalyst device 34. An output Ts1 is generated, and a second exhaust temperature sensor 56 is disposed immediately downstream of the oxidation catalyst device 34 and immediately before the DPF 36, and generates an output Ts2 corresponding to the exhaust temperature upstream of the DPF 36. Specifically, the first and second exhaust temperature sensors 54 and 56 are composed of a thermistor using electric resistance.

  Further, a differential pressure sensor 60 is disposed in the DPF 36 and generates an output corresponding to the differential pressure PDIF between the exhaust pressure flowing into the DPF 36 and the exhaust pressure flowing out from the DPF 36.

  The output of the sensor group described above is sent to an ECU (Electronic Control Unit) 62.

  The ECU 62 includes a microcomputer including a CPU, ROM, RAM, and an input / output circuit. The ECU 62 counts the crank angle signal output from the crank angle sensor 40 among the outputs of the sensor group with a counter to detect (calculate) the engine speed NE, and counts the output of the wheel speed sensor 52 with the counter. To detect the vehicle speed.

  When it is determined that regeneration of the DPF 36 is necessary, the ECU 62 calculates the basic injection amount of the post injection from the engine speed NE and the normal fuel injection amount Q, and the first and second exhaust temperature sensors 54, 56. The correction amount is calculated from the exhaust temperature detected from the outputs Ts1, Ts2.

  Next, when the engine 10 is at a low and medium load, the ECU 62 post-injects fuel corresponding to the injection amount obtained by correcting the basic injection amount in the vicinity of the transition from the explosion stroke to the exhaust stroke. The injected fuel flows through the exhaust system and reaches the oxidation catalyst device 34 to cause an oxidation reaction (combustion). The exhaust gas heated by the combustion flows to the downstream DPF 36, removes the particulate matter deposited there, and regenerates the DPF 36.

  Based on the above, a temperature measuring apparatus for an internal combustion engine according to this embodiment will be described.

  As shown in FIG. 1, the ECU 62 includes an exhaust temperature estimation calculation block 62a. The exhaust temperature estimation block 62a estimates the estimated exhaust temperature Tex ′ (estimated temperature that approximates the exhaust temperature Tex with high accuracy) from the outputs Ts of the first and second exhaust temperature sensors 54 and 56 that measure the temperature of the exhaust system. (Temperature measurement). Since the temperatures detected by the first and second exhaust temperature sensors 54 and 56 are both exhaust temperatures, their outputs are simply referred to as Ts hereinafter.

  FIG. 2 is a block diagram showing in detail the processing of the exhaust temperature estimation calculation block 62a.

  The output (detected temperature) Ts of the first exhaust temperature sensor 54 (or the second exhaust temperature sensor 56) is input to the time variation calculation block 62a1 every predetermined time Δt, where the time variation according to the equation shown in the figure. (Time fluctuation value) dTs is calculated. In this specification, t and Δt represent discrete sample numbers, t is a current value, that is, a value input or detected this time, (t−Δt) is a value input or detected before Δt, That is, it indicates the previous value. Specifically, Δt is 0.1 sec.

  Since the calculated time variation dTs includes a variation component not related to the exhaust temperature, the calculated time variation dTs is input to the low-pass filter (low-pass filter) 62a2 in order to remove it.

  The pass characteristic parameter C of the low-pass filter 62a2 is set by the parameter setting block 62a3. In the parameter setting block 62a3, the arc tangent of the square of the time variation dTs is obtained based on the illustrated filter characteristic function, and the parameter C is calculated by multiplying it by a constant p.

The filter characteristic function. More specifically, Ruhodo to increase the value of the calculated time change dTs is, you increase the value of the parameter C, conversely, the value of the time change dTs calculated reduction to Ruhodo consists functions with so that properties to decrease the value of the parameter C, arctangent shown is one example. The constant p is assumed to be 0.1.

  In the low-pass filter 62a2, using the calculated (set) parameter C, the output is calculated according to the equation shown in the figure. That is, in the low-pass filter 62a2, the output is calculated by adding the product of the current value of the time variation dTs and C, the previous value of the time variation dTs and the product of (1-C), and more specifically. The output is calculated by calculating the weighted average of the current value and the previous value for the time variation while using the parameter C as a weight.

  The output of the low-pass filter 62a2 is sent to the amplification block 62a4, where it is amplified at an appropriate magnification. However, in this embodiment, the amplification factor is 1.

  The output dTs (filter) of the amplification block 62a4 is input to the addition block 62a5, where it is added to the output Ts of the first exhaust temperature sensor 54 (or the second exhaust temperature sensor 56) as a correction amount, and the sum is estimated exhaust. Output (temperature measurement) as temperature Tex ′.

  FIG. 3 and FIG. 4 are graphs showing simulation results performed by the inventors in order to verify the exhaust gas temperature estimation calculation (temperature measurement) shown in FIG.

  3 and 4 show the exhaust temperature sensor output Ts and the true exhaust temperature Tex. Since the first and second temperature sensors 54 and 56 have heat capacities, a thermal response delay occurs, and when the true exhaust temperature Tex changes suddenly, the exhaust temperature sensor output Ts can follow the fluctuation with good responsiveness. Can not.

  Therefore, the output of the addition block 62a5 when the parameter C is set to a fixed value in the configuration of FIG. 2, that is, regardless of the magnitude of the time variation dTs of the exhaust temperature sensor output Ts, is shown in FIG. This is indicated by Texfh and Texfl. Symbol Texfh indicates a case where the parameter C is set to a high constant value, and Texfl indicates a case where the parameter C is set to a low constant value.

  As is apparent from FIG. 3, Texfl is used with emphasis on accuracy rather than responsiveness in the regions ta and tc where the temperature change is small, while Texfh is used with emphasis on responsiveness rather than accuracy on the region tb where the temperature change is large. Is desirable. However, in the region tc, the true exhaust temperature Tex continues to rise gently, and Texfl that does not place importance on temperature change correction has an error with respect to the true exhaust temperature Tex. Thus, in the region tb where the temperature change is large and the transient regions ta and tc, errors are inevitable unless both accuracy and responsiveness are achieved.

  Therefore, in this embodiment, as described above, the filter characteristic function is set so that the value of the parameter C is large when the time variation dTs of the temperature is large and small when it is small. In FIG. 4, the estimated exhaust gas temperature value obtained thereby is indicated by a symbol Tex ′.

  Since this embodiment is configured as described above, the response of the exhaust temperature estimation in the region tb where the change in the exhaust temperature is large and the region ta where the change in the exhaust temperature is small are not required without determining the amount of time variation of the temperature. , Tc, and the exhaust gas temperature can be estimated more accurately when the change in the region tc is transient.

  That is, the parameter C set in the parameter setting block 62a3 is set so as to increase as the temperature variation dTs increases, and the filter output in the low-pass filter 62a2 is weighted by the parameter C. It is calculated by calculating the weighted average value of the current value and the previous value for the time fluctuation. More specifically, the filter output is calculated by adding the product of the current value and C for the time variation of temperature, the previous value, and the product of (1-C).

Accordingly, the filter output becomes large when the time variation dTs temperature is large, in other words, you increase the filter output for the low frequency components of the time change dTs of Ruhodo temperature to increase time change dTs of temperature In other words, since the correction by the filter output is configured to increase, the responsiveness of the estimated exhaust gas temperature Tex ′ can be improved.

That is, a large time variation from that appearing in the high frequency side, that the time variation of the temperature changes the filter pass characteristic as to Ruhodo pass frequency increases increases, thereby greatly reflects the most recent detected temperature to the filter output Responsiveness can be improved.

On the other hand, when the time change dTs of temperature is small, Ruhodo to decrease time change dTs of the calculated temperature, the so that to reduce the filter output for the high-frequency components of the time change dTs of temperature, in other words Since the filter output is reduced and the correction amount is reduced, the estimated exhaust gas temperature Tex ′ becomes a value close to the sensor output Ts and the accuracy is improved.

That is, by time change of the temperature is arranged to change the filter pass characteristic as to Ruhodo passing frequency (cutoff frequency) decreases reduced, noise can be removed, temperature calculated were detected temperature The detection accuracy is improved with a value close to.

Thus, in the temperature measuring device of an internal combustion engine (engine) 10 according to this embodiment is installed in an inner combustion engine (engine) 10, an exhaust system of the exhaust temperature (the temperature sensor 54 and more specifically, 56 output) exhaust temperature detecting means (first and second exhaust temperature sensors 54, 56) for detecting Ts, and exhaust temperature time fluctuation calculating means for calculating the time fluctuation dTs of the detected exhaust temperature Ts. (exhaust temperature estimation calculation block 62a, time change calculation block 62a1), filtering means (exhaust temperature estimation calculation block 62a for filtering the time change dTs of the calculated exhaust gas temperature, the low-pass filter 62a2, parameter setting the exhaust based block 62a3), and the time change dTs of the the detected exhaust gas temperature Ts the filtered exhaust temperature Exhaust gas temperature calculation means for calculating the exhaust gas temperature (exhaust temperature estimation calculation block 62a, the amplification block 62a4, the addition block 62a5) with and a, the filtering means, time change dTs of the calculated exhaust gas temperature is reduced The filter output for the high frequency component of the time variation dTs decreases as the time variation increases, while the filter output for the low frequency component of the time variation dTs increases as the time variation dTs of the calculated exhaust temperature increases. Specifically, the passing frequency (cutoff frequency) decreases as the calculated temperature variation dTs decreases, while the passing frequency increases as the calculated temperature variation dTs increases. The filter pass characteristic (pass characteristic parameter C) is changed. Thereby, the temperature of the engine 10 such as the exhaust temperature can be measured with high accuracy while removing noise while having a simple configuration. Further, both accuracy and responsiveness can be improved.

  Moreover, since no predicted value is used, an estimation error due to a prediction error does not occur. Further, by using the temperature thus measured, it is possible to always perform optimum control in all the operation modes of the internal combustion engine.

More specifically, the filter processing means includes a filter output weight function (passage characteristic parameter C) for the low frequency component of the time variation dTs, and the calculated exhaust temperature time variation dTs decreases. while the value of the weighting function C decreases enough to, as the value of the weighting function C as time change dTs of the calculated exhaust gas temperature increases is increased, as to set the weighting function C configuration did. Thereby, in addition to the above-described effects, it is possible to further improve both accuracy and responsiveness.

  In the above description, the arc tangent function is used as the filter characteristic function used in the parameter setting block 62a3 in FIG. 2, but the present invention is not limited to this. The filter characteristic function may be any function as long as it has a characteristic that increases as the time variation dTs of temperature increases or decreases as it decreases, that is, a function having a monotonically increasing characteristic.

  Further, the temperature of the installation part is estimated and calculated (measured) from the outputs of the two temperature sensors including the first and second exhaust temperature sensors 54 and 56 installed in the exhaust system of the internal combustion engine. This is also valid when the temperature is estimated and calculated (measured) based on the output of one exhaust temperature sensor. The configuration of the exhaust system is not limited to that shown in FIG.

  Further, the case where the exhaust gas temperature is measured as the temperature of the internal combustion engine is taken as an example, but the present invention is not limited to this, and can also be applied to the case where the temperature of the intake system is measured.

  Furthermore, the case where a diesel engine is used as the internal combustion engine and the temperature thereof is measured is taken as an example. However, the present invention may be a case where the temperature of the gasoline engine is measured, and further includes an internal combustion engine and an electric motor. A hybrid type temperature may be measured.

  In the above description, the present invention has been described with reference to an internal combustion engine for a vehicle. However, the present invention can also be applied to an internal combustion engine for a marine propulsion engine such as an outboard motor having a crankshaft as a vertical direction. Is possible.

1 is a schematic view schematically showing an internal combustion engine temperature measurement device according to an embodiment of the present invention, taking an exhaust treatment device as an example. FIG. It is a block diagram which shows in detail the process of the exhaust gas temperature estimation calculation block of ECU shown in FIG. It is a graph which shows the simulation result which inventors performed in order to verify the exhaust gas temperature estimation calculation shown in FIG. Similarly, it is a graph which shows the simulation result which the inventors performed in order to verify the exhaust gas temperature estimation calculation shown in FIG.

Explanation of symbols

10 diesel engine (internal combustion engine) 54 first exhaust temperature sensor 56 second exhaust temperature sensor 62 ECU (electronic control unit) 62a exhaust temperature estimation calculation block 62a1 time fluctuation calculation block 62a2 low Band pass filter, 62a3 parameter setting block, 62a4 amplification block, 62a5 addition block

Claims (2)

Is installed in an internal combustion engine, the exhaust gas temperature detection means for detecting the exhaust temperature of the exhaust system, the detected exhaust temperature time change calculating means for calculating a time change of the exhaust temperature, the calculated time of the exhaust gas temperature together comprising a filtering means for filtering the variation, and an exhaust temperature calculation means for calculating the exhaust temperature of the exhaust system on the basis of the time change of the detected exhaust gas temperature and the filtered exhaust temperature the filter processing unit, while the time change of the calculated exhaust gas temperature is the filter output decreases for higher frequency components of the time change decreases, the more time time change of the calculated exhaust gas temperature increases A temperature measuring device for an internal combustion engine , wherein the filter pass characteristic is changed so that the filter output for the low frequency component corresponding to the fluctuation increases . The filter processing means includes a filter output weight function for the low frequency component corresponding to the time variation, and the weight function value decreases as the calculated exhaust temperature time variation decreases. 2. The temperature measuring device for an internal combustion engine according to claim 1, wherein the weighting function is set so that the value of the weighting function increases as the exhaust gas temperature variation with time increases.

Images