JP3404918B2 - Transmission control device for transmission - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speed change control device for a transmission, and more particularly, to a speed change characteristic in a combination of a device for performing speed change control using an engine load having a hysteresis characteristic and an engine whose target air-fuel ratio can be switched. For improving technology.

[0002]

2. Description of the Related Art Conventionally, as a shift control of a continuously variable transmission,
There is one disclosed in JP-A-57-161346. This is a continuously variable transmission including a belt and two pulleys, in which a target engine rotation speed (target drive pulley rotation speed) is determined based on a throttle opening corresponding to an engine load and a vehicle speed, This is a shift control method in which a rotation speed (driving pulley rotation speed) is compared with the target rotation speed, and a gear ratio is controlled according to the rotation speed difference so that the two always match.

Here, there are cases where the engine load (throttle opening) used for gear shift control has a hysteresis characteristic as described above. Specifically, the latest throttle opening detection signal is ADCH2 and the hysteresis characteristic value is TVO.
HYS (fixed value), latest hysteresis correction opening signal TVO2, previous hysteresis correction opening signal TVO1
Then, when ADCH2 <TVO1, TVO2 = ADCH2 TVO1 ≦ ADCH2 <TVO1 + TVOHYS TVO2 = TVO1 ADCH2 ≧ TVO1 + TVOHYS TVO2 = ADCH2-TVOHYS, and the latest hysteresis correction opening signal TVO2
The gear shift characteristic is determined based on.

[0004]

On the other hand, in order to meet the recent demand for low fuel consumption, the target air-fuel ratio of the engine is set in the vicinity of the theoretical air-fuel ratio and significantly leaner than the theoretical air-fuel ratio in accordance with the operating conditions. A so-called lean burn engine has been developed which is configured to switch to an air-fuel ratio (for example, an air-fuel ratio of 20 to 23, hereinafter simply referred to as a lean air-fuel ratio).

Here, such a lean burn engine,
The following problems have occurred when combined with a transmission that performs shift control based on the engine load having the hysteresis characteristic. That is, when the air-fuel ratio of the engine is the stoichiometric air-fuel ratio and when it is the lean air-fuel ratio,
Even under the same engine operating conditions (the engine speed and the generated torque are the same), the throttle opening differs, and under the same operating conditions, the throttle opening becomes larger during lean air-fuel ratio combustion.

Therefore, if the hysteresis correction is performed with the same hysteresis characteristic value TVOHYS based on each throttle opening, the lean air-fuel ratio combustion is performed based on the characteristic that the throttle opening is larger during the lean air-fuel ratio combustion. Hysteresis correction range only when (TVO1 ≤ ADC
In the case of H2), as shown in FIG. 8, the throttle opening used for setting the target engine rotation speed (target drive pulley rotation speed) becomes significantly larger during lean air-fuel ratio combustion than during theoretical air-fuel ratio combustion. There was an occasion. As a result, the engine rotation speed is controlled to be higher during lean air-fuel ratio combustion than during stoichiometric air-fuel ratio combustion, and the fuel consumption improvement effect due to lean combustion is reduced by operating at high rotation and low load. There was a problem that it would end up.

On the other hand, even when the lean air-fuel ratio and the stoichiometric air-fuel ratio both fall within the hysteresis correction range, the lean air-fuel ratio has a characteristic that the throttle opening is higher, as shown in FIG. When the lean air-fuel ratio is used, the throttle opening TVO2 used for the shift control becomes higher, and similarly, there is a problem that the fuel consumption improving effect due to lean combustion cannot be sufficiently obtained.

The present invention has been made by paying attention to such a conventional problem. Even when the air-fuel ratio is switched, proper shift control is performed based on the engine load for which hysteresis correction is performed. The purpose is to be exposed.

[0009]

Therefore, a shift control device for a transmission according to the invention of claim 1 is a shift control device for a transmission which is combined with an engine in which a target air-fuel ratio is switched according to operating conditions. It is configured as shown in FIG. In FIG. 1, the shift control means controls the gear ratio of the transmission based on the vehicle speed and the engine load.

The hysteresis control means gives a hysteresis characteristic to the engine load used by the shift control means. Here, hysteresis characteristic switching means, wherein
The hysteresis characteristic by the hysteresis control means,
When using the lean air-fuel ratio as the target air-fuel ratio,
Generates a delay characteristic that is larger than when the target air-fuel ratio is near
Switch to live.

[0011] In the shift control device for a transmission according to the invention of claim 2, wherein said hysteresis characteristic switching means, wherein
Switching the hysteresis characteristic according to the target air-fuel ratio
At the same time, the hysteresis characteristic is changed according to the vehicle speed.

[0012]

According to the transmission shift control device of the present invention, the shift control is performed based on the engine load having a hysteresis characteristic. However, when the target air-fuel ratio of the engine is switched, the engine load of the engine load is changed. The hysteresis characteristic is changed, and the hysteresis correction of the engine load is performed with the characteristic that is different for each target air-fuel ratio.

That is, when the lean air-fuel ratio under which the engine load becomes relatively large under the same engine operating conditions, the hysteresis characteristic of the engine load is delayed by a greater amount than when the target air-fuel ratio is near the stoichiometric air-fuel ratio. The engine load used for gear shift control is controlled to be relatively low when the air-fuel ratio is lean.

According to the shift control device for a transmission according to the second aspect of the present invention, the hysteresis characteristic is changed along with the switching of the target air-fuel ratio, and the hysteresis characteristic is also changed depending on the vehicle speed, so that the engine load used for the gear ratio control is changed. Change the characteristics of.

[0015]

EXAMPLES Examples of the present invention will be described below. Figure 2
1 is a system configuration diagram showing an embodiment of a shift control device for a transmission according to the present invention. In FIG. 2, a continuously variable transmission 1 for a vehicle combined with an engine (not shown) is composed of a belt and two pulleys. That is, in the continuously variable transmission 1, the primary pulley 2 to which the driving force from the engine side is transmitted via an electromagnetic clutch (not shown), the secondary pulley 3 for transmitting the driving force to the axle, and the pulleys 2 and 3 are provided. Belt 4 wrapped between
The gear ratio can be changed steplessly by changing the pulley ratio by adjusting the primary hydraulic pressure and the secondary hydraulic pressure by the hydraulic control valve 5.

Detection signals from various sensors such as a vehicle speed sensor 7, a throttle sensor 8 and an engine rotation sensor 9 are input to a shift control unit 6 which controls the hydraulic control valve 5. The vehicle speed sensor 7 detects a vehicle speed VSP by taking out a rotation signal corresponding to the vehicle speed VSP from the secondary pulley 3, for example, and the throttle sensor 8 opens the throttle valve TVO for adjusting the intake air amount of the engine. Further, the engine rotation sensor 9 extracts the rotation signal of the engine from the camshaft or crankshaft of the engine to detect the engine rotation speed.

The speed change control unit 6 includes a throttle opening TVO corresponding to an engine load and a vehicle speed V.
A target engine rotation speed is determined based on SP, the actual engine rotation speed detected by the engine rotation sensor 9 is compared with the target rotation speed, and the hydraulic pressure is adjusted according to the rotation speed difference so that the two always match. The control valve 5 is adjusted to control the gear ratio. The function of the shift control unit 6 described above corresponds to the shift control means in this embodiment.

Here, a hysteresis characteristic is given to the throttle opening TVO used for controlling the gear ratio to stabilize the gear shift control, and such hysteresis correction (hysteresis control means) is performed according to the flowchart of FIG. explain. In addition, in the flowchart of FIG.
The latest throttle opening detection signal is ADCH2, the hysteresis characteristic value is TVOHYS, the latest hysteresis correction opening signal (throttle opening with hysteresis characteristics) is TVO2, and the previous hysteresis correction opening signal is T
VO1 and the latest hysteresis correction opening signal TVO2 is used in the shift control. Further, the opening degree signal indicates a larger opening degree as the value thereof increases.

First, in step 1, the latest throttle opening detection signal ADCH2, the previous hysteresis correction opening signal TVO1 and the hysteresis characteristic value TVOHYS are read. In step 2, the latest throttle opening detection signal ADCH2 is changed to the previous hysteresis correction opening signal TVO.
It is determined whether it is smaller than 1.

If ADCH2 <TVO1, then the routine proceeds to step 3, where the latest throttle opening detection signal ADCH2 is set to the latest hysteresis correction opening signal TV.
It is set to O2 so that shift control is performed based on the actual throttle opening. On the other hand, in step 2, ADC
When it is determined that H2 ≧ TVO1, it proceeds to step 4, and the latest throttle opening detection signal ADCH2
Is smaller than the value obtained by adding the hysteresis characteristic value TVOHYS to the previous hysteresis correction opening signal TVO1.

Here, ADCH2 <TVO1 + TVOH
If it is determined to be YS, proceed to step 5,
The previous hysteresis correction opening signal TVO1 is set to the latest hysteresis correction opening signal TVO2, and TVO1
When ≤ ADCH2 <TVO1 + TVOHYS, the throttle opening TVO2 used for shift control is not changed.

In step 4, ADCH2 ≧ TVO1
When it is determined that it is + TVOHYS, the routine proceeds to step 6, where ADCH2-TVOHYS is set to the latest hysteresis correction opening signal TVO2, and the shift control is performed based on the opening lower than the actual opening by the hysteresis characteristic value TVOHYS. To be done. By the way, in this embodiment, an engine control unit 10 is provided separately from the shift control unit 6 in order to control the air-fuel ratio of the intake air-fuel mixture of the engine (not shown) by adjusting the fuel injection amount.

The engine control unit 10 includes
The detection signals from various sensors such as the throttle sensor 8 and the engine speed sensor 9 are input, and the fuel injection amount is calculated based on the detected value of the intake air amount to form the air-fuel mixture having the target air-fuel ratio, and the fuel injection is performed. The fuel injection valve is controlled to open based on the amount. Further, in the present embodiment, the target air-fuel ratio is
Depending on the engine operating conditions, an air-fuel ratio near the stoichiometric air-fuel ratio and significantly leaner than the stoichiometric air-fuel ratio (e.g.
And, hereinafter, simply referred to as lean air-fuel ratio).

The switching of the target air-fuel ratio is performed as shown in the flowchart of FIG. In the flowchart of FIG. 4, in step 11 ( denoted as S11 in the drawing; the same applies hereinafter), the activity of the air-fuel ratio sensor used for air-fuel ratio feedback control is determined based on the sensor output level and the like. This is for determining whether or not the air-fuel ratio feedback control for feedback controlling the fuel injection amount can be executed so that the actual air-fuel ratio detected by the air-fuel ratio sensor approaches the target air-fuel ratio.

When it is determined that the air-fuel ratio sensor is activated, next, at step 12, it is determined whether or not the warm-up operation is completed based on the cooling water temperature or the like. If the warm-up operation has ended, it is determined in step 13 whether or not the engine load is within the preset lean air-fuel ratio region, and if it is within the lean air-fuel ratio region, further in step 14. It is determined whether the engine speed is within a preset lean air-fuel ratio region.

When both the engine load and the engine speed are in the lean air-fuel ratio range, the vehicle speed V is determined in step 15.
It is determined whether SP is within a preset speed range, and if the vehicle speed VSP is within a predetermined speed range, step 16
Then, the target air-fuel ratio is set to the lean air-fuel ratio. On the other hand, if any one of the steps 11 to 15 is not satisfied, the routine proceeds to step 17, where the target air-fuel ratio is set near the stoichiometric air-fuel ratio.

Here, the engine control unit 10
The result of the target air-fuel ratio switching control (air-fuel ratio switching signal) is output to the shift control unit 6, and in the shift control unit 6,
The target air-fuel ratio switching information is used for the hysteresis correction control of the throttle opening. Specifically, as shown in the flowchart of FIG. 5, the hysteresis characteristic value TVOHYS is calculated based on the target air-fuel ratio switching information.
Is set to change the hysteresis characteristic of the throttle opening (engine load). In this embodiment, the function of the shift control unit 6 shown in the flowchart of FIG. 5 corresponds to the hysteresis characteristic switching means.

Steps in the flowchart of FIG.
In 21, the hysteresis characteristic value TVOHYS set in advance corresponding to the case where the target air-fuel ratio near the theoretical air-fuel ratio is set.
And the vehicle speed VSP. In the next step 22, it is determined whether or not the current target air-fuel ratio is set to the lean air-fuel ratio based on the target air-fuel ratio switching information.

When the lean air-fuel ratio is not set, that is, when the target air-fuel ratio is set to an air-fuel ratio near the theoretical air-fuel ratio, the hysteresis characteristic value TVOHYS is not changed in advance to the vicinity of the theoretical air-fuel ratio. Hysteresis characteristic value T set corresponding to the case where
VOHYS (read data in step 21) is used as it is to give a hysteresis characteristic to the throttle opening TVO.

On the other hand, when the lean air-fuel ratio is set, the routine proceeds to step 23, where the current vehicle speed is referred to by referring to the map in which the lean air-fuel ratio time hysteresis characteristic value TVOHYSL is stored according to the vehicle speed VSP. The corresponding hysteresis characteristic value TVOHYSL is retrieved. In the search for the hysteresis characteristic value TVOHYSL, it is preferable to obtain the hysteresis characteristic value TVOHYSL between the vehicle speed lattices by interpolation calculation.

Then, in step 24, the hysteresis characteristic value TVOHYSL for lean air-fuel ratio is used as a value for giving the hysteresis characteristic to the throttle opening.
Set to VOHYS. The hysteresis characteristic value TV
OHYSL is set to a value larger than the hysteresis characteristic value TVOHYS used when the target air-fuel ratio is set near the stoichiometric air-fuel ratio, and therefore, when the lean air-fuel ratio is set to the target air-fuel ratio, a larger delay characteristic is set. Generate.

Generally, under the same running condition, the throttle opening becomes larger when the target air-fuel ratio is lean air-fuel ratio than when the target air-fuel ratio is near the theoretical air-fuel ratio. The target engine rotation speed also becomes higher when the lean air-fuel ratio is set to the target air-fuel ratio, and as a result, high-speed low-load operation is performed during lean air-fuel ratio combustion.

Therefore, when the lean air-fuel ratio is used as the target air-fuel ratio, a larger hysteresis characteristic value TVOHYS is used.
By giving a hysteresis characteristic with L, the throttle opening TVO2 used for gear shift control can be made smaller in the hysteresis correction range (TVO1 ≦ ADCH2) so that the throttle opening can be made closer to the throttle opening when the target air-fuel ratio is near the theoretical air-fuel ratio. To do.

For example, as shown in FIG. 6, a hysteresis characteristic value T used when the target air-fuel ratio is set near the stoichiometric air-fuel ratio.
In VOHYS, only the throttle opening at the stoichiometric air-fuel ratio satisfies the condition of TVO1 ≦ ADCH2 <TVO1 + TVOHYS, and even when the throttle opening at the lean air-fuel ratio is ADCH2 ≧ TVO1 + TVOHYS, the lean air-fuel ratio becomes If a large hysteresis characteristic value TVOHYSL is given, T
It is possible to satisfy the condition of VO1 ≦ ADCH2 <TVO1 + TVOHYS, and thus it is possible to set an equivalent value as the throttle opening TVO2 used for the shift control.

Further, as shown in FIG. 7, even under the condition that only the throttle opening at the lean air-fuel ratio is within the hysteresis range, if a large hysteresis characteristic value TVOHYSL is given at the lean air-fuel ratio. The hysteresis corrected opening TVO2 can be further lowered to be sufficiently close to the throttle opening at the stoichiometric air-fuel ratio.

Therefore, even when the fuel control is performed with the lean air-fuel ratio as the target air-fuel ratio and the throttle opening is operated relatively high, the throttle opening used for the shift control is kept low and the target engine is operated. It is possible to reduce the rotation speed and avoid operating at a high rotation and low load during lean air-fuel ratio combustion, and thus it is possible to sufficiently exert the fuel consumption improving effect by the lean air-fuel ratio.

The hysteresis characteristic value TV when the lean air-fuel ratio is targeted according to the vehicle speed VSP as described above.
With the configuration in which OHYSL is set, it is possible to prevent the throttle opening TVO2 used for shift control from becoming too low due to an unreasonably large hysteresis characteristic value TVOHYSL at high vehicle speeds. However, it is not limited to the configuration in which the hysteresis characteristic value TVOHYSL is changed according to the vehicle speed VSP, and the hysteresis characteristic value TVOHYS used when the target air-fuel ratio near the theoretical air-fuel ratio is multiplied by the fixed value A (> 1.0). This value may be used as the lean air-fuel ratio hysteresis characteristic value.

[0038]

As described above, according to the shift control device for a transmission according to the first aspect of the present invention, the engine load is proportional.
The target air-fuel ratio is the lean air-fuel ratio that tends to become relatively large.
The engine load used for gear shift control at
It can be approached near the air-fuel ratio, and
Avoid running at high speed and low load at low air / fuel ratio
The effect is that you can do it.

[0039]

[0040] According to the shift control device for a transmission according to the invention of claim 2, the hysteresis characteristic of the engine load, the eye
By switching according to the air-fuel ratio and changing according to the vehicle speed, it is possible to avoid improperly giving an excessive hysteresis characteristic according to the vehicle speed.

[Brief description of drawings]

FIG. 1 is a block diagram showing the basic configuration of the present invention.

FIG. 2 is a system configuration diagram of an embodiment.

FIG. 3 is a flowchart showing hysteresis correction control according to the embodiment.

FIG. 4 is a flowchart showing switching of the target air-fuel ratio of the embodiment.

FIG. 5 is a flowchart showing switching of hysteresis characteristics according to the embodiment.

FIG. 6 is a time chart showing a hysteresis characteristic in the example.

FIG. 7 is a time chart showing a hysteresis characteristic in the example.

FIG. 8 is a time chart showing a conventional hysteresis characteristic.

FIG. 9 is a time chart showing a conventional hysteresis characteristic.

[Explanation of symbols]

1 continuously variable transmission 2 primary pulley 3 Secondary pulley 4 belts 5 Hydraulic control valve 6 Shift control unit 7 vehicle speed sensor 8 Throttle sensor 9 Engine rotation sensor 10 Engine control unit

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Claims (2)

(57) [Claims] 1. A shift control device for a transmission, which is combined with an engine in which a target air-fuel ratio is switched according to an operating condition, wherein the shift control means controls the shift ratio of the transmission based on a vehicle speed and an engine load. When the hysteresis control means for providing a hysteresis characteristic to the engine load to be used in speed change control means, the hysteresis characteristic by the hysteresis control means
When using the lean air-fuel ratio as the target air-fuel ratio,
Larger delay characteristics than when the target air-fuel ratio is near the fuel ratio
A shift control device for a transmission, comprising: a hysteresis characteristic switching means for switching so as to generate . Wherein said hysteresis characteristic changeover means, before
Switch the hysteresis characteristics according to the target air-fuel ratio
Rutotomoni, the shift control device for a transmission according to claim 1, wherein the changing the hysteresis characteristic according to the vehicle speed.