JP3423851B2 - Vehicle running resistance detection device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle running resistance detection device, and more particularly to a technique for maintaining the accuracy of running resistance estimation based on engine load.

[0002]

2. Description of the Related Art In the shift control of an automatic transmission for a vehicle, it is general to determine the shift stage by referring to a shift map in which the shift stage is set in advance according to the throttle opening and the vehicle speed. However, in the configuration for determining the shift speed as described above, the change in running resistance is not taken into consideration. Therefore, for example, when traveling on an uphill road, unnecessary upshifting or downhill driving is performed by releasing the accelerator pedal when entering a corner. Occasionally, the highest speed stage is selected, so that the engine brake cannot be applied and the load on the foot brake increases.

Therefore, for example, in the device disclosed in Japanese Patent Publication No. 4-4351, the torque generated by the engine is calculated based on the throttle valve opening and the engine speed, and the calculated torque, vehicle acceleration, and vehicle weight. By calculating the running resistance (gradient resistance) of the vehicle based on the above, and comparing the running resistance with a preset value according to the shift speed, a desired acceleration (engine braking) can be obtained at the time of downhill. The configuration is such that the shift speed is determined so as to be obtained.

Further, in Japanese Patent Laid-Open No. 5-71623,
When the engine load changes suddenly, the estimation accuracy of the running resistance (driving force) deteriorates. Therefore, when the engine load changes suddenly, the estimation of the running resistance is stopped and the change of the shift characteristics is stopped accordingly. There is a disclosure of. Specifically, the absolute value of the change amount of the throttle opening is compared with a predetermined value, and when the absolute value of the change amount is equal to or more than a predetermined value, the estimation of the running resistance and the change of the shift characteristic are stopped for a predetermined time. It is configured to do.

[0005]

By the way, in the method disclosed in Japanese Unexamined Patent Publication No. 5-71623, the absolute value of the amount of change in the throttle opening is compared with a constant value to make the engine load suddenly change. Although it is determined whether or not there is the same, the estimation error of the driving force varies depending on the gear ratio at that time even with the same change amount (see FIG. 6). Therefore, as in the above-described conventional case, when the configuration is such that a sudden change in the engine load is determined based on a certain amount of change and the calculation of the running resistance is stopped, the running resistance cannot be estimated although the required estimation accuracy cannot be maintained. However, on the contrary, there is a case where the estimation of the running resistance is stopped and the responsiveness of the control based on the running resistance is deteriorated even though the necessary and sufficient estimation accuracy can be secured.

Further, even when the absolute amount of engine load change is the same, the error in estimating the driving force is generally smaller when the engine load is decreasing and changing than when the engine load is changing (Fig. 7), in the above-mentioned conventional method, since the sudden change of the engine load is determined by the absolute value of the change amount regardless of the change direction of the engine load, the estimation of the running resistance is unnecessarily stopped when the engine load decreases and changes. There were times when it happened.

The present invention has been made in view of the above-mentioned problems, and it is possible to surely avoid inappropriately changing the shift characteristic due to deterioration of the accuracy of estimating the running resistance (driving force) based on the engine load. An object of the present invention is to prevent the estimation control of the running resistance from being stopped more than necessary.

[0008]

Therefore, in the invention according to claim 1, in the vehicle running resistance detecting device for calculating the running resistance equivalent value of the vehicle based on the parameter including at least the engine load, the engine load suddenly changes. Whether or not the engine load is suddenly changed, the calculation of the running resistance equivalent value is stopped, and the determination level of whether or not the engine load is suddenly changed is determined by the transmission of the transmission combined with the engine. It is configured to change according to the ratio.

According to this structure, it is determined whether or not the engine load is suddenly changed based on the determination level that is changed according to the gear ratio at that time, and when the engine load is suddenly changed, the estimation accuracy of the running resistance equivalent value is improved. The estimation is stopped assuming that it will deteriorate. Therefore, even when the amount of change in engine load is the same, the estimation of the running resistance may be stopped or may not be stopped depending on the gear ratio at that time.

In order to stop the estimation calculation of the running resistance equivalent value, the calculation process of the running resistance equivalent value itself is not executed, and the estimated value of the running resistance equivalent value is held at the value immediately before the cancellation or calculated. In the case of a configuration in which the calculated running resistance equivalent value is not used for gear shift control and the calculated running resistance equivalent value is used as a weighted average, the weighting in the weighted average is changed. It also includes reducing the influence of the latest calculated value.

According to the second aspect of the invention, the lower the gear ratio of the transmission is, the more easily the engine load is suddenly changed. According to such a configuration, when the gear ratio is on the low speed side, even if the change in the engine load is relatively small, the calculation of the running resistance equivalent value is stopped because it is a sudden change in the engine load. When the gear ratio is on the high speed side, it is not judged that the engine load has changed suddenly unless the change in the engine load is more rapid, and the running resistance equivalent value is calculated over a wider range.

According to the third aspect of the invention, the calculation of the running resistance equivalent value is stopped only when the sudden change in the engine load is in the increasing direction. According to such a configuration, when the engine load suddenly changes, when the engine load rapidly increases and when the engine load sharply decreases, only when the engine load is increasing and changing, the calculation of the running resistance equivalent value is stopped, When the change in the engine load is gradual or when the engine load is changing in the decreasing direction, the running resistance equivalent value is calculated.
The calculation of the running resistance based on the engine load includes the estimation of the driving force based on the engine load and the calculation of the running resistance equivalent value based on the driving force.

[0013]

According to the invention described in claim 1, when the sudden change of the engine load at which the estimation of the running resistance equivalent value should be stopped is determined based on the determination level corresponding to the gear ratio of the transmission. The estimation of the traveling resistance equivalent value is stopped while avoiding the execution of gear shift control or the like based on the traveling resistance having an error, because it is possible to accurately determine the time when the engine load suddenly changes, which deteriorates the estimation accuracy. The effect is that the control response can be secured by shortening the time.

According to the second aspect of the present invention, it is possible to prevent the estimation calculation from being unnecessarily limited on the high speed side where the estimation accuracy of the running resistance equivalent value can be secured even if the engine load changes relatively. Further, even if the change in the engine load is relatively small, it is ensured that the shift control and the like are performed based on the running resistance equivalent value having a large error on the low speed side where the estimation accuracy of the running resistance equivalent value deteriorates. The effect is that it can be avoided.

According to the third aspect of the invention, the estimation of the running resistance equivalent value is not interrupted when the running resistance equivalent value estimation error is sufficiently small as compared with the increase of the engine load. When the engine load decreases and changes, the control based on the running resistance equivalent value can be executed with good response.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. FIG. 1 shows a system configuration of an internal combustion engine for a vehicle according to an embodiment. In FIG. 1, the engine 1 is connected to an automatic transmission 2 so that the generated torque is transmitted to drive wheels (not shown). The automatic transmission 2 includes a torque converter 3 for inputting a torque generated by the engine 1, a multi-stage speed change gear mechanism 4 for inputting an output of the torque converter 3 and changing and outputting the same, and a hydraulic pressure (not shown) for driving these. And a mechanism.

The hydraulic mechanism of the speed change gear mechanism 4 includes:
Solenoid valves 6A and 6B are incorporated, and by switching the combination of opening and closing of the solenoid valves 6A and 6B, the combination of engagement and disengagement of each clutch included in the speed change gear mechanism 4 is switched, and a desired gear position is achieved. The gear shift to. ON / OFF control of the plurality of solenoid valves is performed by CPU, ROM, R
This is performed based on a control signal from a control unit 50 including an AM, A / D converter and an input / output interface.

Signals from various sensors are input to the control unit 50. As various sensors, there are provided a throttle sensor 7 that outputs an output signal according to the throttle opening TVO, and a vehicle speed sensor 8 that detects the vehicle speed VSP by detecting the rotation speed of the output shaft (output shaft 5) of the automatic transmission 2. Has been. Here, the control unit 50
Is configured to estimate the running resistance of the vehicle and change the standard shift characteristic based on the estimated result. still,
The change of the standard shift characteristic includes correction of a shift speed according to the standard shift characteristic, selection of a shift pattern (shift map) according to running resistance, and the like.

The flowchart of FIG. 2 shows how the running resistance is estimated by the control unit 50. In step 1 (denoted as S1 in the figure, the same applies hereinafter), the vehicle speed VSP and throttle opening are set. Read TVO.
In step 2, the current acceleration resistance (RESI-A) is calculated.
The current acceleration resistance (RESI-A) can be calculated by the following equation.

RESI-A = ALF × kα where ALF is the current acceleration and kα is an acceleration resistance calculation constant set by the vehicle weight or the like. In step 3, the air resistance + rolling resistance is set in advance corresponding to the vehicle speed VSP.
Referring to the table that stores RESI-RL (see Figure 3),
Air resistance + rolling resistance RE corresponding to the current vehicle speed VSP
Calculate SI-RL.

In step 4, the present turbine rotation speed Nt (that is, the output shaft rotation speed of the torque converter 3) is obtained. The turbine rotation speed Nt can be calculated by the following equation. Nt = VSP × kNt (g) Note that g indicates the current shift speed, and kNt (g) is a constant determined from the current shift speed. The current shift speed may be detected by providing the gear position sensor 9 for detecting the shift speed position in the shift gear mechanism 4, but may be determined from the current shift command signal of the control unit 50 or the like. good.

In step 5, the map (see FIG. 4) in which the turbine torque Tt is stored in advance according to the turbine rotation speed Nt and the throttle opening TVO (engine load) is referred to, and the current turbine rotation speed Nt and the throttle opening are opened. Degree TV
A turbine torque Tt corresponding to O and is calculated. In step 6, the current driving force FCE is calculated from the following equation.

FCE = Tt × kTt (g) It should be noted that g indicates the current shift speed, and kTt (g) is a constant determined from the current shift speed. In step 7, running resistance RESI-I (running resistance equivalent value) is obtained from the following equation.

RESI-I = (FCE)-(RESI-RL)-(RESI-A) Since the traveling resistance RESI-I corresponds to the gradient resistance, the gradient is obtained as the traveling resistance equivalent value. The configuration may be adopted, and the calculation method and the type of the running resistance are not limited as long as the running resistance is estimated and calculated based on the engine load. Further, in the present embodiment, the engine load is represented by the throttle opening, but parameters other than the throttle opening may be used.

As described above, the control unit 50 estimates and calculates the running resistance RESI-I based on the driving force FCE calculated based on the throttle opening TVO. However, when the engine load suddenly changes, the error of the driving force FCE is calculated. (The shaded area in FIG. 7 corresponds to the error) becomes large and the estimation accuracy of the running resistance RESI-I deteriorates. Therefore, as shown in the flowchart of FIG. It is designed to prevent the shift characteristic from being inappropriately controlled based on the estimated result.

In addition, in order to stop the estimation calculation of the running resistance, the running resistance RESI-I calculation process itself is not executed, and the estimated value of the running resistance is held at the value immediately before the stop and used for gear shift control or the like. In addition, in the case of a configuration in which the calculated running resistance is not used for gear shift control and the calculated running resistance is used by weighted averaging, the weighting in the weighted average is changed. This also includes reducing the degree of influence of the calculated value. Further, the control using the running resistance is not limited to the shift control.

The routine shown in the flowchart of FIG.
It is executed every predetermined time.First,
In Top 11, the latest detected throttle opening TVO
_NEWRead. In step 12, the previous
The previous value which is the throttle opening TVO read at the time of line
TVO_OLDRead out.

[0028] Then, in step 13, the latest opening TVO
_NEWTo previous value TVO_OLDBy subtracting the change amount ΔTVO
Calculate The change amount ΔTVO is the execution cycle of this routine.
Throttle opening change amount ΔTVO per period (unit time)
Becomes In step 14, the current gear (gear ratio) GR
The next step 15 is to load the current
Based on the speed (gear ratio) GR, the change amount ΔTVO
The determination level TH (> 0) is determined. Where the determination
The level TH will be set to a larger value on the higher speed side.
I have it.

In step 16, the change amount ΔTVO is
As described above, the determination level TH determined according to the shift speed
It is determined whether or not the above. The change amount ΔTVO is
When the throttle opening TVO (engine load) is decreasingly changed, it is calculated as a negative value.
When TVO is equal to or higher than the positive determination level TH, the throttle opening TVO is increasing and changing at a speed equal to or higher than a predetermined speed, in other words, the engine load is rapidly increasing.

Further, the determination level TH to be compared with the change amount ΔTVO is set to a larger value when the gear ratio is on the high speed side, so that a larger change occurs when the gear ratio is on the high speed side. Only when the engine load is rapidly increasing, it is determined that the engine load is rapidly increasing. When the gear ratio is on the low speed side, it is determined that the engine load is rapidly increasing even if the change is relatively small.

When it is determined in step 16 that the change amount ΔTVO is equal to or higher than the determination level TH, the process proceeds to step 17, and the estimation calculation of the running resistance RESI-I is stopped. On the other hand, when the change amount ΔTVO is less than the determination level TH,
That is, when the throttle opening (engine load) is substantially stable, or when the throttle opening (engine load) is in a decreasing change, the running resistance RESI-I is estimated by bypassing step 17. Then, the shift control based on the estimation result is performed.

As shown in FIG. 6, the estimation accuracy of the running resistance RESI-I varies depending on the gear ratio at that time even if the amount of change ΔTVO is the same, and a larger change occurs on the high speed side. Although sufficient estimation accuracy can be ensured even when there is a change, the estimation accuracy is significantly reduced on the low speed side even when the change is relatively small. Therefore, in the present embodiment, the determination level TH is set to a larger value on the higher speed side, and only when there is a relatively large increase change on the high speed side compared to the low speed side, it is determined that the engine load suddenly changes. It is decided.

Thus, the estimation of the running resistance is not unnecessarily stopped when the gear ratio is on the high speed side, and
On the low speed side, it is possible to avoid the calculation of running resistance having an error. Also, the same throttle opening (engine load)
Even when there is a sudden change in
Since it is possible to secure the necessary and sufficient estimation accuracy (see FIG. 7), the estimation calculation is stopped only when the increase is changed, thereby preventing the estimation calculation from being unnecessarily stopped when the engine load decreases. it can.

The amount of change ΔTVO is the judgment level TH.
From the above state, the change amount ΔTVO is equal to the determination level T
Even if the state is switched to less than H, the estimation calculation may be stopped within the predetermined time.
In the above embodiment, when the engine load is suddenly reduced, the running resistance is calculated unconditionally.
When the engine load decreases and changes, the judgment level that makes it more difficult to cancel the running resistance estimation than when it changes increases is set as a fixed value or a value according to the gear ratio, and the running resistance is compared based on the comparison with the judgment level. It is also possible to adopt a configuration in which the estimation calculation of is stopped.

Further, in the above, it is determined whether or not the engine load is suddenly changed based on the throttle opening change amount ΔTVO per execution period (unit time) of the routine shown in the flowchart of FIG. It is also possible to measure the time required to change by a certain degree of opening and compare the measured time with a reference time as a determination level to determine a sudden change in the engine load. Of the change amount ΔTVO within the time frame, and when the change time period of the change amount ΔTVO is different, the change amount ΔTVO is changed.
It is also possible to convert O into a unit time value and compare it with the determination level.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of a vehicle internal combustion engine according to an embodiment.

FIG. 2 is a flowchart showing how the running resistance is estimated in the above embodiment.

FIG. 3 is a diagram showing a table of air resistance + rolling resistance in the embodiment.

FIG. 4 is a diagram showing a turbine torque map in the embodiment.

FIG. 5 is a flowchart showing running resistance estimation stop control in the embodiment.

FIG. 6 is a diagram showing a correlation between a gear ratio and a driving force estimation error.

FIG. 7 is a diagram showing a correlation between an engine load (throttle opening) change and a driving force estimation error.

[Explanation of symbols]

1 organization 2 automatic transmission 3 Torque converter 4 speed change gear mechanism 7 Throttle sensor 8 vehicle speed sensor 50 control unit

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI F16H 59:70 F16H 59:70 (56) References JP-A-5-71624 (JP, A) JP-A-3-74679 (JP , A) JP 59-97352 (JP, A) JP 10-252873 (JP, A) JP 7-127720 (JP, A) JP 4-4351 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) F16H 59/00-61/12 F16H 61/16-61/24 F16H 63/40-63/48 G01L 5/00-5/28 B60K 41/00- 41/28 F02D 13/00-28/00 F02D 29/00-29/06 F02D 41/00-41/40 F02D 43/00-45/00

Claims (3)

(57) [Claims] 1. A running resistance detecting device for a vehicle, which calculates a running resistance equivalent value of a vehicle based on a parameter including at least an engine load, judges whether the engine load is suddenly changed, and when the engine load is suddenly changed. It is configured to stop the calculation of the running resistance equivalent value, and to change the determination level of whether or not the engine load is suddenly changed according to the gear ratio of the transmission combined with the engine. Vehicle running resistance detection device. 2. The lower the gear ratio of the transmission is,
2. The running resistance detection device for a vehicle according to claim 1, wherein a determination level is set that makes it easy to determine that the engine load is suddenly changed. 3. The running resistance detecting device for a vehicle according to claim 1, wherein the calculation of the running resistance equivalent value is stopped only when the sudden change of the engine load is in an increasing direction.