JPH0450547A - Maximum speed limiting method in continuously variable transmission mounted-vehicle - Google Patents

Abstract

PURPOSE:To realize a limit of maximum speed without entailing any fuel cutting by calculating a desired transmission gear ratio in multiplying the current gear ratio of a continuously variable transmission by a gear ratio operation factor, and controlling the CVT gear ratio into the said desired transmission gear ratio. CONSTITUTION:A CVT computer 41 judges whether output shaft speed, namely, the current car speed has exceeded the limiting speed or not, and when exceeding it, setsthe desired gear ratio of a continuously variable transmission 6. This desired gear ratio finds a gear ratio operation factor after dividing a limiting speed equivalent revolution by the output shaft speed, and this factor is multiplied to the current CVT gear ratio, thus it is found. The gear ratio operation factor is smaller than 1 when car speed exceeds the limiting speed, therefore the desired gear ratio becomes smaller than the current gear ratio. The said CVT gear ratio is controlled into the desired gear ratio found. When the gear ratio of the transmission 6 becomes smaller, rotational frequency of an engine 1 (engine speed) drops, driving torque also drops, thus the car speed goes down as well. With this constitution, a limit of maximum speed is thus realizable with no fuel-cut.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for limiting the maximum speed of a vehicle equipped with a CVT system.

(Prior art and problems to be solved) Conventionally, in vehicles equipped with automatic transmissions, when the vehicle speed exceeds a predetermined speed, for example, 180 km/h, the maximum speed is reduced by cutting the fuel supplied to the engine. I'm trying to limit the speed.

However, such speed restrictions due to fuel cuts can cause the engine to suddenly lose torque while driving at high speeds, causing the car to jerk and surprise the passengers, and also to reduce the risk of the car being in a rich atmosphere until the fuel cut is made. Since air is injected due to the fuel cut, they mix and burn in the catalyst, raising the bed temperature of the catalyst and causing problems such as lowering the durability of the catalyst.

The present invention has been made in view of the above-mentioned points, and is a CVT (Content) that can steplessly control the gear ratio as an automatic transmission.
inuosly Variable Transmises
To provide a method for limiting the maximum speed of a vehicle equipped with a CVT system, which limits the maximum speed by steplessly controlling the gear ratio using a CVT without cutting fuel. With the goal.

(Means for Solving the Problems) In order to achieve the above object, according to the present invention, a CvT system capable of steplessly controlling the gear ratio is installed as an automatic transmission, and the rotational speed of the input shaft of the CVT system is is detected to determine the rotation speed equivalent to the limit speed, the rotation speed of the final stage output shaft of the drive system is detected to determine the output shaft rotation speed, and when the output shaft rotation speed exceeds the rotation speed equivalent to the limit speed, The speed ratio operation coefficient is calculated by dividing the rotation speed equivalent to the limit speed by the output shaft rotation speed, the target speed ratio is calculated by multiplying the current speed ratio of the CVT by the speed ratio operation coefficient, and the target speed ratio is adjusted to the target speed ratio. Said C
The gear ratio of the VT is controlled.

(Operation) The CVT computer that controls the CVT system determines whether the pressure shaft rotation speed of the vehicle exceeds the rotation speed equivalent to the speed limit, that is, whether the current vehicle speed exceeds the speed limit. , and set the target gear ratio of the CVT. This target gear ratio is determined by dividing the rotation speed corresponding to the limit speed by the output shaft rotation speed to obtain a gear ratio operation coefficient, and then multiplying the current gear ratio of the CVT by this gear ratio operation coefficient. The gear ratio operation coefficient is smaller than l when the output shaft rotational speed is larger than the rotational speed equivalent to the limit speed, that is, when the vehicle speed exceeds the speed limit, and therefore the target gear ratio is smaller than the current gear ratio. . The CVT computer controls the gear ratio of the CVT to the determined target gear ratio. When the gear ratio of the VCVT decreases, the engine speed decreases, driving torque decreases, and the vehicle speed decreases accordingly. This makes it possible to limit the maximum speed without cutting fuel.

(Example) An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows an engine and a power transmission system of a vehicle equipped with a CVT system according to the present invention. The output shaft of the torque converter 4 is connected to a drive pulley 7 of a V-belt drive continuously variable transmission (rCVTJ) 6 via a planetary gear 5, and the drive pulley 7 is connected to a drive pulley 7 via a V-belt 9. Driven pulley 8 is connected to pulley 8.
The output shaft lO of is connected to left and right axles 13, 14 via a gear system 11 and a differential mechanism 12.

The drive pulley 7 and the driven pulley 8 are connected to the hydraulic chamber 1, respectively.
5.16, and these hydraulic chambers 15.16 are:
It is connected to a hydraulic control valve system 17. The hydraulic control valve system 17 includes C.
Based on the control signal from the VT computer 41, the hydraulic pressure in the hydraulic chamber 15, 16 is controlled to continuously vary the pulley diameters of the drive pulley 7 and driven pulley 8.

The intake manifold 20 of the engine 1 includes a surge tank 2
1 to an air cleaner 22.

Spark plug 2 installed in the cylinder head of engine 1
3 is connected to an ignition coil 24, an injector 25 is provided downstream of the intake manifold 20, and a throttle valve 26 is provided between the surge tank 21 and the air cleaner 22.

These ignition coils 24 and injectors 25 are connected to an engine control computer 4o.

Hydraulic pressure sensors 3o and 31 are disposed in the hydraulic chambers 15 and 16 of the drive pulley 7 and driven pulley 8 of the CVT 6, and an air flow sensor 32 for detecting the intake air amount of the engine 1 is disposed in the air cleaner 22. Further, an input shaft rotation sensor 34 is disposed on the output shaft of the torque converter 4 of the automatic transmission 3, and an output shaft rotation sensor 35 is disposed on the axle 13, that is, the final output shaft of the drive system. The rotation speed of the output shaft of the torque converter 4 is slightly lower than the rotation speed of the input shaft. Therefore, by detecting the rotation speed of the output shaft of the torque converter 4, the actual rotation speed of the input shaft of the automatic transmission 3 is detected.

And oil pressure sensor 30,31 and air flow sensor 3
2 is connected to an engine control computer 4o, and an input shaft rotation sensor 34 and a force shaft rotation sensor 35 are connected to a CVT computer 41 that controls the CVT system. Further, the engine control computer 40 receives an engine rotation speed signal from an engine rotation sensor (not shown), and the CVT computer 41 receives an accelerator opening signal from an accelerator opening sensor (not shown). An engine rotation speed signal is input from the select lever position sensor (not shown), and a select lever position (parking, neutral, drive, reverse, etc.) signal is input from the select lever position sensor (not shown). Further, the hydraulic control valve system 17 is connected to a CVT computer 41.

The operation will be explained below with reference to the flowchart shown in FIG.

The engine control computer 40 detects the operating state of the engine 1 based on the engine rotation speed signal and each signal input from the sensors 30 to 32, and determines the optimal fuel injection amount, injection timing, ignition timing, etc. according to the operating state. is determined, the injector 25 is driven to inject fuel, and the spark plug 23 is ignited, while the CVT computer 41
Measures the actual rotation speed of the input shaft of the automatic transmission 3 based on the signal from the input shaft rotation sensor 34 (step l) L, and measures the rotation speed of the axle 13, that is, the pressure shaft, based on the signal from the output shaft rotation sensor 35. (Step 2) and set the target gear ratio of the CVT 6 (Step 3). Input shaft rotation sensor 3
The number of revolutions corresponding to the speed limit (hereinafter referred to as "the number of revolutions corresponding to the speed limit") can be obtained by the signal No. 4. The target gear ratio is determined as follows.

The CVT computer 41 calculates the output shaft rotation speed (axle 1
3) is equal to or higher than the rotation speed equivalent to the limit speed (for example, 180 km/h) (output shaft rotation speed ≧ rotation speed equivalent to the limit speed) (step 4), and if the determination answer is affirmative ( YES), that is, when the vehicle speed exceeds the speed limit, divide the number of rotations equivalent to the limit speed by the number of rotations of the output shaft, and calculate the gear ratio operation coefficient (-number of rotations equivalent to the limit speed/output shaft rotation number). ) is calculated (step 5). This gear ratio operation coefficient takes a value smaller than 1 when the output shaft rotational speed is larger than the rotational speed equivalent to the speed limit, that is, when the vehicle speed exceeds the speed limit.

Next, the CVT computer 41 multiplies the current speed ratio of the CVT 6 by the calculated speed ratio operation coefficient to calculate the target speed ratio at the limit speed (=current speed ratio x speed ratio operation coefficient). Therefore, the target gear ratio becomes a value smaller than the current gear ratio when the vehicle speed exceeds the speed limit.

When the determination answer in step 4 is negative (NO), that is, when the vehicle speed is below the speed limit, the CVT computer 41
Based on the accelerator opening signal, the gear ratio of the CVT 6 is set to a normal target gear ratio using the accelerator opening as a parameter. For example, as shown in the characteristic diagram in Figure 3, this normal target gear ratio is the maximum gear ratio when the accelerator opening is 100% (fully open), and the maximum gear ratio when the accelerator opening is 0% (fully closed). This is set to be the minimum gear ratio, and the gear ratio in between is set according to the accelerator opening. This target gear ratio is written in a map of the CVT computer 41 using the accelerator opening as a parameter.

After setting the target gear ratio at the limited speed as described above (step 3), the CVT computer 41 executes gear ratio control (step 8).

That is, the CVT computer 41 determines that the vehicle speed is within the speed limit (1
80 km/h), outputs a hydraulic control signal and adds it to the hydraulic control valve system 17.
The hydraulic pressure in the hydraulic chambers 15 and 16 of the drive pulley 7 and driven pulley 8 of the VT6 is controlled to increase the diameter of the drive pulley 7 and decrease the diameter of the driven pulley 8 (by controlling the
The gear ratio of VT6 is made smaller than the current gear ratio. As a result, the rotational speed of the engine 1 decreases and the driving torque decreases, and the vehicle speed decreases accordingly and is controlled so as not to exceed the above 180 km/h, and fuel is not cut to the engine 1. . The CVT 6 is a continuously variable transmission, so the transition from the current gear ratio to the target gear ratio is performed smoothly. Moreover, even when the vehicle travels in the maximum speed range, the engine 1 is operated in a lower speed zone with better fuel efficiency, resulting in improved fuel efficiency.

(Effects of the Invention) As explained above, according to the present invention, the automatic transmission is equipped with a CVT system that can control the gear ratio steplessly,
The rotation speed of the input shaft of the CVT system is detected to determine the rotation speed equivalent to the limit speed, the rotation speed of the final stage output shaft of the drive system is detected to determine the output shaft rotation speed, and the output shaft rotation speed is set to the limit speed. When the rotation speed equivalent to the speed is exceeded, the rotation speed corresponding to the limit speed is divided by the output shaft rotation speed to obtain a gear ratio operation coefficient, and the current gear ratio of the CVT is multiplied by the gear ratio operation coefficient to determine the target gear ratio. By calculating the gear ratio of the CVT and controlling the gear ratio of the CVT to the target gear ratio, the fuel is not cut even if the vehicle speed exceeds the speed limit, so there is no shock to the vehicle body (
This eliminates the driver's discomfort and prevents the bed temperature of the catalyst from rising, improving durability. Furthermore, even when the vehicle is running at the maximum speed, the engine is operated in a low speed zone with good fuel efficiency, resulting in excellent effects such as improved fuel efficiency.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a CVT system-equipped vehicle to which the maximum speed limiting method for a CVT system-equipped vehicle according to the present invention is applied, FIG. 2 is a flowchart showing the procedure for implementing the control method of the present invention, and FIG. 3 is a characteristic diagram showing the relationship between the throttle opening and the normal target gear ratio of the CVT. 1...Engine, 3...Automatic transmission, 6...CV
T, 15.16...Hydraulic chamber, 17...Hydraulic pressure control no. (lube system, 30.31...Hydraulic pressure sensor,
32... Air flow sensor, 34... Input shaft rotation sensor, 35... Output shaft rotation sensor, 40... Engine control computer, 4... CvT computer. Applicant Mitsubishi Motors Corporation Agent Patent Attorney Kanji Nagado

Claims (1)

[Claims] Equipped with a CVT system that can control the gear ratio steplessly as an automatic transmission, the rotation speed of the input shaft of the CVT system is detected to determine the rotation speed equivalent to the limit speed, and the rotation speed of the final stage output shaft of the drive system is determined. detecting the output shaft rotation speed, and when the output shaft rotation speed exceeds the limit speed equivalent rotation speed, divide the limit speed equivalent rotation speed by the output shaft rotation speed to calculate a gear ratio operation coefficient, A target gear ratio is calculated by multiplying the current gear ratio of the CVT by the gear ratio operation coefficient, and the gear ratio of the CVT is controlled to the target gear ratio.
How to limit the maximum speed of vehicles equipped with the VT system.