JP3849349B2 - Atmospheric pressure estimation device for vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an atmospheric pressure estimation device for a vehicle that estimates an actual atmospheric pressure using a physical quantity detected during operation of an in-vehicle engine as a parameter.
[0002]
[Prior art]
In general, in a vehicle engine control system, the atmospheric pressure changes depending on the altitude of the place where the vehicle travels. Therefore, in order to always obtain good engine performance, the actual atmospheric pressure during driving is detected and the atmospheric pressure is detected. It is necessary to correct the contents of the engine control according to the situation.
[0003]
In addition, for vehicles equipped with an automatic engine stop control system (a system that automatically stops the engine when a predetermined stop condition is met while driving to save fuel and reduce exhaust emissions), stop the engine. As a result, the negative pressure of the surge tank, which is the energy source of the brake booster, is an important issue. Therefore, this is the standard for ensuring the negative pressure (relative to the atmospheric pressure) of the brake booster. It is important to know the atmospheric pressure accurately.
[0004]
The atmospheric pressure can be detected directly by providing an atmospheric pressure sensor that detects the absolute pressure at the site where the atmospheric pressure directly acts on the engine. A dedicated sensor is required, resulting in increased costs.
[0005]
Therefore, generally, a method is used in which the atmospheric pressure is indirectly estimated from other parameters during engine operation without providing a dedicated sensor, thereby avoiding an increase in cost due to the installation of the dedicated sensor.
[0006]
For example, Japanese Patent Application Laid-Open No. 8-122191 discloses an intake air amount parameter value representing an intake air mass flow rate during engine operation, and intake air in an operation under standard atmospheric conditions at the same throttle opening and engine speed. A method for calculating the actual atmospheric pressure based on the value of the quantity parameter is disclosed.
[0007]
In this case, the larger the throttle opening, the less affected by the throttle opening detection error (detection variation), so the calculation of atmospheric pressure at a throttle opening smaller than the previous atmospheric pressure calculation is prohibited. By calculating the atmospheric pressure only when the throttle opening is greater than or equal to the throttle opening at the time of calculating the atmospheric pressure, it is possible to improve the estimation accuracy of the atmospheric pressure or to prohibit updating to a calculated value with a low estimation accuracy. I am doing so.
[0008]
[Problems to be solved by the invention]
By the way, when the atmospheric pressure is calculated only when the throttle opening is updated to the large side as in the above-described conventional example, the calculation accuracy of the atmospheric pressure at the time of calculation increases, There is a possibility that the update frequency may decrease, and various controls may be performed with the atmospheric pressure calculation value deviating from the actual value until the next update.
[0009]
In consideration of the above circumstances, the present invention provides an atmospheric pressure estimation device for a vehicle that can increase the frequency of updating an atmospheric pressure calculation value and always prepare an atmospheric pressure calculation value close to the actual atmospheric pressure. Objective.
[0010]
[Means for Solving the Problems]
The invention of claim 1 solves the above problems by adopting the following configuration. That is, the invention of claim 1, the intake pipe pressure of the engine detected with a change in the throttle opening of the engine during operation of the vehicle mounting the engine and the atmospheric pressure estimation parameter, based on the large pressure estimation parameter Large estimating the pressure, at atmospheric pressure estimating apparatus for a vehicle that sets the atmospheric pressure based on the estimation result, means and two different throttle opening is the detection for detecting a throttle opening degree TA1, TA2 of the engine TA1 , Means for determining whether or not the amount of change in TA2 is greater than or equal to a predetermined value, and when it is determined that the amount of change in the throttle openings TA1 and TA2 is greater than or equal to a predetermined value, means for newly obtaining the intake pipe pressure PM1, PM2 of the engine based on each of the two different throttle was detected opening degree TA1, TA2, was detected Two different throttle openings TA1 and TA2 and two intake pipe pressures PM1 and PM2 obtained based on these throttle openings TA1 and TA2 are expressed by the following equations (1) and (2), or equations (3) and (3): with substituted 4), equation (1) and (2) the solved for atmospheric pressure PA, or formula (3) and (4) solving the atmospheric pressure PA, and means for calculating the atmospheric pressure PA It is an atmospheric pressure estimating device characterized by being.
PM1 / PMo1 = (PA / Po) × {1-cos (TA1 + C)} × K2 (1)
PM2 / PMo2 = (PA / Po) × {1-cos (TA2 + C)} × K2 (2)
PM1 = PA × {1-cos (TA1 + c ′)} (3)
PM2 = PA * {1-cos (TA2 + c ')} (4)
However, Po is a standard atmospheric pressure (for example, 1 atm), PMo1 and PMo2 are standard intake pipe pressures in the standard atmospheric pressure state and are obtained from the map, K2 is a coefficient related to the outside air temperature and the standard outside air temperature, and C is a throttle. A variation correction value that is an unknown including an error between the detected value of the opening and the actual throttle opening and an opening error during idling, and c ′ is a correction term that is an unknown in the idle state.
[0011]
In the present invention, the throttle opening is changed, to a predetermined value or more if the amount of change is determined in advance, and the atmospheric pressure estimated parameters in the throttle opening before the change, the atmospheric pressure in the throttle opening degree after being changed two putative parameters (or two pairs), new atmospheric pressure by solving the above continuous simultaneous equations as stipulated a relationship between the atmospheric pressure and the variation correction value and the intake pipe pressure as a variable in their respective throttle opening to de San in. Therefore, regardless of whether the throttle opening changes to the large side or the small side, as long as the change amount is equal to or greater than a predetermined value, the atmospheric pressure is reset and the atmospheric pressure is calculated based on the change amount. As a result, the calculation frequency of the atmospheric pressure increases, and an atmospheric pressure estimated value close to the actual atmospheric pressure can always be prepared.
[0012]
Conventionally, the atmospheric pressure is obtained by comparing the measured parameter value at the same throttle opening and the parameter value in the standard atmospheric state. However, in the present invention, two (or two sets) at different throttle openings are obtained. Atmospheric pressure is calculated using measured parameter values. Therefore, specifically, the difference in throttle opening is calculated, and the influence of variation in the absolute value of the throttle opening can be reduced. In addition, the atmospheric pressure estimation parameter is also calculated, so that the influence of the variation of the parameter itself can be reduced.
[0014]
The intake pipe pressure of the engine in this case may be measured, for example, by providing a pressure sensor directly on the surge tank, or from the intake air amount detected by the air flow sensor, the engine rotation speed, and the outside air temperature (intake air temperature). It may be obtained by estimation.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0016]
FIG. 1 is a schematic diagram illustrating an overall configuration of a vehicle drive system including an atmospheric pressure estimation device according to an embodiment.
[0017]
In FIG. 1, 1 is an engine, 2 is an intake pipe of the engine, and 3 is a surge tank provided in the intake pipe 2 in order to stabilize the air flow. The surge tank 3 communicates with the brake booster 5 via the brake booster valve 4. The brake booster 5 is provided with a brake boost pressure sensor 6.
[0018]
A throttle valve 7 having an opening degree corresponding to the operation amount of the accelerator pedal is provided upstream of the surge tank 3 in the intake pipe 2. A throttle opening sensor 8 detects the opening of the throttle valve 7.
[0019]
A hot wire type air flow meter 9 is provided on the upstream side of the throttle valve 7. The hot-wire air flow meter 9 has a hot wire such as platinum arranged in the intake air flow in the intake pipe 2 and controls the energization current so that the hot wire is energized and heated and the hot-wire temperature is constant. Thus, the intake flow rate in the intake pipe 2 is detected.
[0020]
Further, 11 is an engine speed sensor, 12 is an air cleaner, 13 is an outside air temperature sensor, and 14 is an ISC (idle speed control) valve for stabilizing idle rotation. The ISC valve 14 is provided in a bypass passage 15 that guides air in the intake pipe 2 upstream of the throttle valve 7 to the surge tank by bypassing the throttle valve 7. Reference numeral 16 denotes an ISC valve opening sensor that detects the opening of the ISC valve 14. In addition, a surge tank pressure sensor 18 for detecting the pressure in the surge tank 3 is provided as necessary.
[0021]
FIG. 2 shows the configuration of the control device 20.
[0022]
The control device 20 is mainly composed of a microcomputer, and includes an input / output interface 21, a CPU 22, a ROM 23, a RAM 24, a backup RAM 25, and the like. The control device 20 receives detection signals from the throttle opening sensor 8, the air flow meter 9, the engine speed sensor 11, and the outside air temperature sensor 13. In addition, signals of the brake boost pressure sensor 6, the ISC valve opening sensor 16, and the surge tank pressure sensor 18 are input as necessary.
[0023]
Next, the content of the control performed by the control device 20 will be described with reference to the flowchart of FIG.
[0024]
The routine shown in the flowchart of FIG. 4 is interrupted when the throttle opening changes or when the (previous) atmospheric pressure calculation is completed. When the throttle opening changes, in step 101, the accumulated data before the throttle opening changes is read from the backup RAM. That is, the intake air amount (weight or mass) GA1 detected by the air flow meter 9, the throttle opening TA1 detected by the throttle opening sensor 8, the engine rotation speed NE1 detected by the engine rotation speed sensor 11, the outside air temperature sensor The outside air temperature Ta detected by 13 is read out.
[0025]
In step 102, the current data with the changed throttle opening is read. That is, the intake air amount (weight) GA2 detected by the air flow meter 9, the throttle opening TA2 detected by the throttle opening sensor 8, and the engine rotational speed NE2 detected by the engine rotational speed sensor 11 are read. The outside air temperature Ta is not read in this step, assuming that there is not much change in a short time.
[0026]
Here, the one with “1” at the end of the symbol is the data when the previous atmospheric pressure calculation was performed, and the one with “2” at the end of the symbol is the data that will be used for this calculation. is there.
[0027]
Next, in step 103, it is determined whether or not the amount of change in the throttle opening is equal to or greater than a predetermined value K1, and if the amount of change is less than K1, the process directly returns to the main routine (not shown). When the amount of change exceeds K1, the routine proceeds to step 104 to newly calculate the atmospheric pressure, and at this step 104, intake air amounts GN1 and GN2 per engine revolution at each throttle opening are obtained. The intake air amounts GN1 and GN2 per engine rotation can be calculated as values obtained by dividing the intake air amounts GA1 and GA2 detected by the air flow meter 9 by the engine rotational speeds NE1 and NE2.
[0028]
Next, in step 105, intake pipe pressures (surge tank pressures) PM1 and PM2 are obtained based on the intake air amounts GN1 and GN2 per engine revolution and the outside air temperature Ta. The relationship between GN, Ta, and PM is mapped for each throttle opening, and PM1 and PM2 are obtained from the map.
[0029]
Next, in step 106, the atmospheric pressure PA is obtained from PM1, PM2, and TA1, TA2. As a calculation formula at this time,
PM1 / PMo1 = (PA / Po) × {1-cos (TA1 + C)} × K2
PM2 / PMo2 = (PA / Po) * {1-cos (TA2 + C)} * K2
Is used.
[0030]
Here, what is indicated by {1-cos (TA + C)} is a value indicating the ease of air passage. As shown in FIG. 3, when the area of the throttle valve 7 is S, the substantial passage area at the throttle opening TA can be approximated by S (1-cosTA). On the other hand, since there is an error in the throttle opening measured by the throttle opening sensor 8 and the ISC valve 14 is bypassed when idling, there is a passage area even if the throttle opening is zero. Therefore, the above-described {1-cos (TA + C)} includes the error correction value and includes the variation correction value C.
[0031]
In the above formula, PA is a calculated atmospheric pressure, Po is a standard atmospheric pressure (for example, 1 atm), PMo1 and PMo2 are standard intake pipe pressures in the standard atmospheric pressure state, and are obtained from the map. K2 is a coefficient related to the outside air temperature Ta and the standard outside air temperature To. The map of the standard intake pipe pressure may be obtained as “standard intake pipe pressure for each throttle opening in the standard atmospheric pressure state”, or “standard air pressure for each intake air amount in the standard atmospheric pressure state”. It may be obtained as “intake pipe pressure”. In this case, the variation correction value C and the coefficient K2 are different from each other.
[0032]
Here, Po is a constant, TA1, TA2 are actually measured values, PM1, PM2, PMo1, PMo2, and K2 are values obtained from a map or the like, so the unknowns in the above two formulas are only the atmospheric pressure PA and the variation correction value C. become.
[0033]
Since the intake pipe pressure PM is basically proportional to GN, PM1 = GN1 / KTP (TA, NE) where the charging effect for TA and NE is KTP (TA, NE).
PM2 = GN2 / KTP (TA, NE)
It is also possible to approximate.
[0034]
Further, the above formula is simplified a little more so that PM1 = PA × {1-cos (TA1 + c ′)}
PM2 = PA * {1-cos (TA2 + c ')}
c ′ may be a correction term in the idle state.
[0035]
Therefore, the atmospheric pressure PA and the variation correction value C can be obtained by solving the above two equations as simultaneous equations.
[0036]
When the atmospheric pressure is calculated, the routine proceeds to step 107, where the negative pressure control of the brake booster is performed based on the calculated atmospheric pressure PA, and the process returns to the main routine. When returning to the main routine, the atmospheric pressure update value is written into the backup RAM 25, and the values of each data at the time of atmospheric pressure update are also updated.
[0037]
At this time, each value in the throttle opening TA2 is replaced with TA1 for the next calculation, and the outside air temperature Ta is also read.
[0038]
Thus, when the throttle opening degree TA changes by a predetermined amount or more, the intake pipe pressure PM1 at the throttle opening degree TA1 before the change and the intake pipe pressure PM1 at the throttle opening degree TA2 after the change are large. Since the atmospheric pressure PA is calculated using the atmospheric pressure estimation parameter, the atmospheric pressure can be calculated as long as the amount of change is not less than a predetermined value regardless of whether the throttle opening TA changes to the large side or the small side. Done. Therefore, the calculation frequency of the atmospheric pressure is increased, and an estimated atmospheric pressure value close to the actual atmospheric pressure can always be prepared for various controls. As a result, the accuracy of various controls using atmospheric pressure data is improved. It can contribute to improvement.
[0039]
In addition, since the atmospheric pressure is calculated using parameter values at different throttle openings, the difference in the throttle opening is calculated, and the influence of variations in the absolute value of the throttle opening can be reduced. Similarly, the value actually detected or calculated as the atmospheric pressure estimation parameter also takes a difference in calculation, thereby reducing the influence of variation in the parameter itself.
[0040]
In the above embodiment, the intake pipe pressures PM1 and PM2 are obtained from the map based on the intake air amount GA and the outside air temperature Ta. However, as indicated by a two-dot chain line in FIG. A sensor 18 may be provided for direct measurement. In such a case, steps 104 and 105 in the flowchart of FIG. 4 can be omitted, and the accuracy of the atmospheric pressure calculation can be improved as much as no error occurs in the surge tank pressure calculation stage.
[0041]
Next, another embodiment will be described with reference to the flowchart of FIG.
[0042]
In general, it can be said that the intake pipe pressure during idling has a strong positive correlation with atmospheric pressure. Therefore, the atmospheric pressure is calculated by making use of this characteristic and using a map or the like.
[0043]
First, when the processing of the routine of this flowchart is started, in step 201, the throttle opening degree TA, the engine speed NE, the intake air amount GA, and the outside air temperature Ta are read. Next, it is determined whether or not the idle state continues for a predetermined time K3 (sec). If the idle state continues for a predetermined time K3, in step 203, the intake pipe pressure PM in the surge tank is calculated from the engine speed NE, the intake air amount GA, and the outside air temperature Ta.
[0044]
Next, in step 204, the atmospheric pressure PA is determined by a map or calculation based on the engine speed NE, the ISC valve opening TV, the calculated intake pipe pressure PM, the intake air amount GA, and the like. While the engine is running, the determination in the next step 205 is NO, so the flow of steps 201 → 202 → 203 → 204 → 205 is repeated.
[0045]
When the engine is automatically stopped due to an eco-run or the like, the process proceeds from step 205 to step 206, and the brake booster internal pressure PB is read. Then, the difference between the brake booster internal pressure PB and the calculated atmospheric pressure PA is checked at step 207, and when the difference exceeds a predetermined value K4, it is determined that the boost pressure is insufficient, and the routine proceeds to step 208 to restart the engine, etc. The fail-safe process is performed, and the process of this routine is finished.
[0046]
Although the control flow in FIG. 5 itself is a flow in which the atmospheric pressure can be calculated, various applications are possible. For example, in this flow, various information at the time of idling can be obtained, and this may be used as information on the atmospheric pressure estimation parameter in “one of the two throttle openings”. Further, the atmospheric pressure obtained by this control flow may be used as a correction coefficient or a guard value when obtaining the atmospheric pressure by the control flow of FIG. 4 described above.
[0047]
【The invention's effect】
As described above, according to the present invention, when the amount of change each time the throttle opening is changed is the Tokoro value than, because out newly calculate the atmospheric pressure based on the amount of change, large The calculation frequency of the atmospheric pressure can be increased, and an estimated atmospheric pressure value close to the actual atmospheric pressure can always be prepared.
[Brief description of the drawings]
FIG. 1 is a block diagram of a vehicle drive system including an atmospheric pressure estimation device according to an embodiment of the present invention. FIG. 2 is a block diagram of a control system of the system. FIG. 4 is a control flowchart showing the contents of an embodiment of the present invention. FIG. 5 is a control flowchart of another embodiment.
DESCRIPTION OF SYMBOLS 1 ... Engine 2 ... Intake pipe 3 ... Surge tank 5 ... Brake booster 7 ... Throttle valve 8 ... Throttle opening sensor 9 ... Air flow meter 11 ... Engine rotational speed sensor 13 ... Outside temperature sensor

Claims (1)

The engine intake pipe pressure detected with the change in the throttle opening of the engine during operation of the vehicle-mounted engine is used as an atmospheric pressure estimation parameter, and the atmospheric pressure is estimated based on the atmospheric pressure estimation parameter. Based on the estimation result In the atmospheric pressure estimation device for a vehicle that sets the atmospheric pressure,
Means for detecting a throttle opening degree TA1, TA2 of the engine,
Means for determining whether or not the detected change amounts of the two different throttle openings TA1 and TA2 are equal to or greater than a predetermined value;
The throttle opening TA1, if a change amount of TA2 that is determined is a predetermined or greater than a predetermined value, the intake pipe of the engine based on each of the two different throttle opening TA1, TA2 which was detected and hand-stage newly obtaining the pressure PM1, PM2,
Two different throttle openings TA1 and TA2 detected and two intake pipe pressures PM1 and PM2 obtained based on these throttle openings TA1 and TA2 are expressed by the following formulas (1) and (2) or formula ( 3) Substituting into (4) and solving equations (1) and (2) for atmospheric pressure PA or solving equations (3) and (4) for atmospheric pressure PA to calculate atmospheric pressure PA When
Atmospheric pressure estimating apparatus for a vehicle, characterized in that you are provided with.
PM1 / PMo1 = (PA / Po) × {1-cos (TA1 + C)} × K2 (1)
PM2 / PMo2 = (PA / Po) × {1-cos (TA2 + C)} × K2 (2)
PM1 = PA × {1-cos (TA1 + c ′)} (3)
PM2 = PA * {1-cos (TA2 + c ')} (4)
However, Po is a standard atmospheric pressure (for example, 1 atm), PMo1 and PMo2 are standard intake pipe pressures in a standard atmospheric pressure state and are obtained from a map, K2 is a coefficient related to the outside air temperature and the standard outside air temperature, and C is a throttle. A variation correction value that is an unknown including an error between the detected value of the opening and the actual throttle opening and an opening error during idling, and c ′ is a correction term that is an unknown in the idle state.

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