JPS63101549A - Automatic speed change control method for vehicle - Google Patents

Abstract

PURPOSE:To prevent busy shift by finding an acceleration state after upshift according to running resistance calculated from the running state of a car, and keeping a speed change ratio when it is judged that the car is not accelerated to a upshift value from the acceleration state. CONSTITUTION:On reaching an upshift point to a small speed change ratio with engine load more than designated, running resistance is calculated from the running state. The accelerating state of a car after upshift is found from the running resistance and a speed change ratio after upshift. When it is judged that the car is not in the accelerating state after upshift, the present speed change ration is kept. Accordingly, it is possible to prevent shift during full- throttle running.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an automatic gear shift control method for a vehicle, and particularly to a control method when gear shifts are performed when the engine is under high load.

[Conventional technology] Conventionally, in vehicles equipped with automatic transmissions, technology (
For example, Japanese Patent Application Laid-open No. 58-174749 (Japanese Patent Application Laid-open No. 58-174749, "Shift Shock Reduction Device for Automatic Transmission") and automatic transmission shift points are set and changed according to the vehicle's driving conditions to improve fuel efficiency and increase output. Techniques are known that allow for both use and use.

These technologies aim to improve driving performance and provide a good drive feeling by precisely controlling automatic gear shifts, including engine output control.
One of these is to prevent frequent gear changes (busy shifts) when the vehicle is running under high load (full throttle).

A rough shift that occurs in a vehicle when driving under high load is a phenomenon in which the vehicle speed changes due to changes in running resistance such as road surface conditions, slope, wind direction, etc., and upshifts and downshifts are frequently repeated between the shift points. It is. As a method to prevent this frequent repetition of upshifts and downshifts (busy shifts), for example, when driving at full throttle, 4th gear (0/D
> Turn on the kickdown switch to 3rd gear,
Downshift to 3rd gear and use 3rd gear, which has more driving power, and cut fuel before the engine speed reaches overrun speed to prevent the vehicle speed from exceeding the engine overrun speed. A technique to do this has been proposed.

By the way, in the technique of preventing busy shifting using the above kickdown switch, the O/D (
4th speed) cannot be used, therefore, as a technique for using O/D even at full throttle, a technique is used to control the automatic transmission according to the shift line shown in FIG. 7. This technology prevents engine overrun by setting an upshift point at vehicle speed V7u when the throttle opening is 85% or more and performing an upshift when the vehicle speed reaches V7u. By providing a downshift point (kickdown point) at the vehicle speed V7d on the side and downshifting when the vehicle speed decreases to V7d, a busy shift is prevented from occurring even with a slight variation in vehicle speed.

[Problems to be Solved by the Invention] However, in the above conventional technology, in order to prevent busy shifting when running at full throttle and at high speed, it is necessary to reduce the speed difference (hysteresis) between the upshift point and the downshift point. If this was done, there would be a problem in that there would be cases where the vehicle would not be able to perform a kick motion to increase the driving force when going uphill or overtaking.

For example, in a running condition 286 where the throttle opening is θA6 and the vehicle speed is VA8, even if the throttle opening is depressed to a throttle opening of θ^7, which is 85% or more, for the purpose of kickdown, the 4th gear (0/ Since the downshift line from D> to 3rd gear is not reached, kickdown from O/D to 3rd gear cannot be performed.

Therefore, in order to kick down to 3rd gear, you must reduce the vehicle speed, perform kickdown at the downshift point (vehicle speed V7d), and then accelerate again, or manually change the O/D.
It is necessary to perform operations such as releasing the switch and kicking down to 3rd gear.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and achieve both prevention of busy shifts and utilization of maximum driving force during full throttle running.

[Means for solving the problem] As illustrated in FIG. 1, as a method for achieving the object of the present invention, when an upshift point to a smaller gear ratio is reached with an engine load higher than a predetermined value (step A), , calculate the running resistance from the running condition of the vehicle (Step B), and calculate the acceleration state of the vehicle after the upshift based on the running resistance and the vehicle specifications based on the gear ratio after the upshift (Step C).
), and when it is determined that the vehicle is not in an accelerating state after an upshift (step D), the current gear ratio is maintained (step E).

The running resistance of the vehicle is calculated, for example, based on the current engine output and the acceleration state of the vehicle, or by calculating wind resistance, slope resistance, frictional resistance, etc. determined by the vehicle specifications.

The current gear ratio is maintained, for example, by limiting the speed change, controlling the engine output so that the speed change does not occur, or by limiting the speed change and controlling the engine output in combination.

[Operation] According to the automatic shift control method for a vehicle of the present invention, the acceleration state of the vehicle after upshifting is determined based on the running resistance calculated from the running state of the vehicle, and the vehicle accelerates from the acceleration state after upshifting. If it is determined not to do so, control is performed to maintain the current gear ratio. As a result, if the driving force of the vehicle is insufficient after the upshift and the vehicle speed decreases, the upshift will not be performed.

[Example] An example of the present invention will be described based on FIGS. 2 to 6. FIG. 2 shows the configuration of a system to which this embodiment is applied. In the figure, 10 is an engine, and the engine 10 is opened and closed by a first throttle valve 11 and a throttle actuator 12 that are linked to an accelerator pedal. The output can be controlled by the second throttle valve 13. 20 is an automatic transmission, automatic transmission 2
O is two solenoid valves (No, 1. No, 2>218°21
b allows for four-speed shifting. The throttle actuator 12 and the solenoid valve 218.21b are driven by signals from a control circuit 30, and the control circuit 30 receives signals from sensors placed in various parts of the vehicle including the engine 10 and automatic transmission 20. Signals are input to control the present embodiment.

The above-mentioned sensors include a throttle position sensor 14 that detects the opening degree of the first throttle valve 11 disposed in the intake pipe of the engine 10, an engine rotation speed sensor 15 that detects the rotation speed of the engine 10, and an automatic sensor that is proportional to the vehicle speed. This is a vehicle speed sensor 23 that detects the rotation speed of the output shaft 22 of the transmission.

The throttle position sensor 14 generates a gray code signal indicating the opening degree of the first throttle valve 11, the engine rotation speed sensor 15 generates a pulse signal whose frequency is proportional to the rotation speed of the engine 10, and the vehicle speed sensor 23 generates a pulse signal whose frequency is proportional to the vehicle speed. Generates a pulse signal proportional to .

The control circuit 30 is configured using a microcomputer, and the microcomputer includes a CPU 31.
．． ROM32. RAM33. Input port 34. and output ports 35 are connected to each other by a common bus 36. Signals from each of the above-mentioned sensors are input to the input port 34 via pulse input sections 38a, 38b or directly. The output port 35 includes a throttle actuator drive unit 39 that drives the throttle actuator 12, and a solenoid valve 21a.

Electromagnetic valve drive units 40a and 40b that drive 21b are connected.

Next, the control of this embodiment will be explained based on the shift control routine shown in FIG. The speed change control routine includes an input processing routine for the opening degree of the throttle valve 11 (not shown), engine speed, and vehicle speed, and the acceleration of the vehicle per unit time (
This routine is periodically executed together with the routine for calculating the acceleration value Δα).

In this routine, first, the throttle position sensor 14
It is determined whether or not the output code indicates a region (full throttle) of 85% or more of the throttle opening θ of the shift pattern shown in FIG. 4 (step 100). Next, in the case of full throttle, it is determined whether the input/output pulse signal of the vehicle speed sensor 23 has reached the allowable vehicle speed VH of the third gear (see FIG. 4) (step 110). If the judgments in both steps 100 and 110 above are both rYEsJ,
In other words, when the shift point from 3rd gear to O/D or from O/D to 3rd gear is reached at full throttle in the shift pattern shown in FIG. 4, the acceleration value Δα of the vehicle is read (step 1).
20). Next, it is determined whether or not the engine output has already been controlled in step 190 (described later) (step 130), and if the engine output is not being controlled, the value of the acceleration value Δα read in the above step 120 is determined. Based on this, the vehicle accelerates (Δ
If α≧OWL, it is determined whether the vehicle speed VH in driving state B has been reached, or whether the vehicle speed has been decelerated from driving state C (Δα<O) and the vehicle speed VM in driving state B has been reached (Step 1 in Fig. 3).
40). If the acceleration value Δα is positive, it is assumed that an upshift request exists, and the driving force before and after the shift is checked.

First, the current vehicle speed V while driving in 3rd gear and full throttle
) The driving force FM at l is calculated based on the acceleration value Δα of the vehicle speed according to the engine map shown in FIG. 5, the driving force F map shown in FIG. 6, and the efficiency of each transmission gear (vehicle specifications). ).

The method for calculating this driving force F)1 is as follows (1) formula (% formula % FA... Maximum driving force M in the current transmission gear...
Vehicle mass: Inertia of the engine, tires, etc. The maximum driving force FA shown in Figure 6 is calculated based on the engine map shown in Figure 5, the transmission gear ratio, the efficiency of the transmission gear, the vehicle speed, etc. It is determined from the driving force F map. That is, FA is a value corresponding to 100% throttle opening θ of the third speed driving force line.

Next, the maximum driving force FB (see Figure 6) at 4th gear (0/D>) after upshifting is calculated based on the vehicle specifications and vehicle speed (Step 160 in Figure 3). Following the calculation, the maximum driving force FB for 4th gear
is larger than the current driving force F) (step 170>, and if FB>FH, upshift from 3rd to 4th speed (step 180). Since FB>FM , the vehicle can continue to accelerate even after an upshift.

On the other hand, if the maximum driving force after upshifting is smaller than the driving force before shifting (FB≦FH) (step 170),
Without upshifting to 4th gear, the current vehicle speed V)
f is maintained by controlling the engine output (step 19
0). The engine output may be controlled by controlling the opening and closing of the second throttle valve 13 with the throttle actuator 12, by opening and closing the linkless throttle valve, controlling the fuel supply amount, or by controlling the ignition timing. It may be controlled. By controlling the above engine output, 3
The control to maintain the speed is performed until the judgments in steps 100 and 110 are negative, or if the maximum driving force after upshifting is greater than the current driving force (FB > F) in step 170.
This continues until it is determined that t ) and an upshift is performed. As a result, full-throttle driving in third gear continues until full-throttle driving is no longer possible, or until there is sufficient driving force after upshifting, and the driving state uses maximum driving force without causing engine overrun. can be maintained.

Next, the case where the vehicle is decelerated from the running state @C in FIG. 4 to the running state B will be described. The determination that the vehicle has decelerated and entered the running state B is made when the acceleration value Δα is negative in step 140. In this case, the driving force FM required to maintain the vehicle speed VM after downshifting from 4th gear to 3rd gear is calculated based on the current driving state (step 200). Following the calculation of the driving force FM, the vehicle is downshifted to third gear (step 210), and the engine output is changed to the driving force FH by controlling the opening degree of the second throttle valve 13 to maintain the vehicle speed VM (step 210). 190). This state of maintaining vehicle speed V)l is similar to maintaining VH during acceleration as described above, until full throttle driving is no longer performed or until surplus driving force is generated in 4th gear (F
B>F)l) is maintained (steps 100-130
, 150-170.190>. As a result, when the driving state B is changed from the driving state C in FIG. 4 due to deceleration on an uphill road, etc., the vehicle speed V)l of said B can be maintained in third gear with a large margin of driving force, and moreover, If surplus driving force is generated in 4th gear while the vehicle is running, it is possible to upshift to 4th gear again and accelerate again. Therefore, since the occurrence of busy shifts can be prevented, drivability and durability can be improved.

Note that if the vehicle is not running at full throttle (step 100 in Figure 3) or if the vehicle speed is not VH, step 1 is not executed.
10), according to the upshift line (solid line) and downshift line (dotted line) in FIG. 4, shift control of the automatic transmission 20 is performed based on the vehicle speed and throttle opening (step 220 in FIG. 3). ).

In this embodiment, the method of changing gears between 3rd and 4th speeds was shown, but similarly, the method of changing speeds between 3rd and 2nd speeds, and the method of changing speeds between 2nd and 1st speeds.
It may also be used for a method of changing gears between speeds.

As explained above, by using this embodiment, when driving at full throttle, while there is sufficient driving force in 4th gear, driving is performed in 4th gear, and when there is no extra driving force in 4th gear, 3rd gear If the vehicle speed becomes lower than the maximum vehicle speed of 3, the maximum vehicle speed of 3rd gear can be maintained in 3rd gear, which has a larger margin of driving force. This makes it possible to prevent a busy shift in which acceleration in third gear, which has a large margin of driving force, and deceleration in fourth gear, which has no margin of driving force, are repeated. Therefore, drivability and durability are improved.

The embodiment described above is one embodiment of the present invention, and various modifications can be made without changing the gist.

[Effects of the Invention] According to the automatic gear shift control method for a vehicle of the present invention, when an upshift is performed during full throttle driving, if it is determined that the vehicle will not accelerate, control is executed to not perform an upshift. This prevents the vehicle speed from decreasing after an upshift and being downshifted to the gear ratio before the upshift, thereby preventing busy shifts in which upshifts and downshifts are repeated every time the running resistance changes. It can produce excellent effects.

As a result, the drivability and durability of the vehicle under high loads are improved.

[Brief explanation of the drawing]

FIG. 1 is a flowchart illustrating the basic configuration of the automatic transmission control method for a vehicle according to the present invention, FIG. 2 is a configuration diagram of a system to which an embodiment of the present invention is applied, and FIG. 3 is a control diagram of the same embodiment. FIG. 4 is a graph showing the shift line of the same embodiment; FIG. 5 is a graph showing the engine map of the same embodiment; FIG. 6 is a graph showing the driving mechanism of the vehicle of the same embodiment; FIG. 7 is a graph showing a shift line of a conventional example. 10... Engine 20... Automatic transmission 30... Control circuit

Claims (1)

[Claims] When an upshift point to a smaller gear ratio is reached with an engine load above a predetermined level, running resistance is calculated from the running condition of the vehicle, and vehicle specifications are calculated based on the running resistance and the gear ratio after the upshift. An automatic gear shift control method for a vehicle that calculates the acceleration state of the vehicle after an upshift based on the above, and maintains the current gear ratio when it is determined that the vehicle is not in an acceleration state after the upshift.