JP7210106B2 - vehicle controller - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device used in a vehicle equipped with an electronically controlled coupling that distributes torque for running to main drive wheels and auxiliary drive wheels.

2. Description of the Related Art Conventionally, an active torque split 4WD system is widely known as a 4WD (four-wheel-drive) system for vehicles such as four-wheeled vehicles. In one example of an active torque split 4WD system, torque for driving the vehicle is normally transmitted to the main drive wheels (for example, the left and right front wheels), and depending on the driving conditions of the vehicle, the torque is transmitted by an electronically controlled coupling. It is actively distributed to the main and auxiliary drive wheels.

The electronically controlled coupling has a main clutch consisting of a multi-plate friction clutch, and torque distribution to the auxiliary drive wheels is changed by controlling the torque capacity of the main clutch. Therefore, in the electronically controlled coupling, heat is generated due to friction of the main clutch when torque is distributed to the auxiliary drive wheels. If the amount of heat generated increases, the main clutch may be damaged due to overheating.

FIG. 3 is a diagram showing changes over time in the ON/OFF state of an ignition switch of a vehicle and the amount of heat (actual amount of heat, calculated amount of heat) of an electronically controlled coupling.

In order to prevent the main clutch of the electronically controlled coupling from being damaged due to overheating, when the vehicle's ignition switch is on, the amount of heat generated by the electronically controlled coupling is calculated based on the torque transmitted by the main clutch, etc. is exceeded, the electronically controlled coupling is prohibited from transmitting torque to the auxiliary drive wheels.

Japanese Patent No. 4840566

However, conventionally, when the ignition switch is turned from on to off, the heat quantity calculated so far is reset to 0, so when the ignition switch is turned on from off, the calculated heat quantity and the actual There is a discrepancy between the heat quantity (actual heat quantity) of Depending on the amount of deviation, even though the actual heat quantity exceeds the hardware protection heat quantity threshold, the calculated heat quantity does not exceed the hard protection heat quantity threshold, so torque transmission to the auxiliary drive wheels by the electronically controlled coupling is not prohibited, and there is a concern that the main clutch may be damaged due to overheating.

SUMMARY OF THE INVENTION An object of the present invention is to provide a vehicle control device capable of protecting an electronically controlled coupling from overheating even when an ignition switch is once switched from ON to OFF and then switched to ON again. be.

In order to achieve the above object, a vehicle control device according to the present invention is equipped with an electronically controlled coupling with a built-in friction clutch so that torque for running is applied to main driving wheels and sub-driving wheels by the electronically controlled coupling. and a control device for use in a vehicle capable of distributing to and, while the ignition switch of the vehicle is on, a heat amount calculation means for calculating the heat amount of the friction clutch, and the heat amount calculated by the heat amount calculation means exceeded a threshold value. coupling protection means for prohibiting the operation of the electronically controlled coupling when the ignition switch is switched from ON to OFF; Considering the time measured by the time measuring means for measuring the off time and the time measured by the time measuring means in response to the switching of the ignition switch from off to on, heat absorption in the electronically controlled coupling and heat dissipation to the outside air , a heat radiation amount calculating means for calculating the heat radiation amount of the friction clutch, the heat amount calculating means calculating the heat amount calculated by the heat radiation amount calculating means from the heat amount stored in the storage means after the ignition switch is switched from off to on. Calculation of the heat amount of the friction clutch is restarted with the value obtained by subtracting the heat release amount as the initial value.

According to this configuration, while the ignition switch of the vehicle is on, the amount of heat of the friction clutch of the electronically controlled coupling is calculated, and when the calculated amount of heat exceeds the threshold value, the operation of the electronically controlled coupling is prohibited. be. This protects the electronically controlled coupling from overheating.

When the ignition switch is switched from on to off, the heat quantity calculated at that time is stored in the storage means. After that, when the ignition switch is switched from off to on, the heat dissipation amount of the friction clutch is calculated in consideration of heat absorption in the electronically controlled coupling and heat dissipation to the outside air during the time the ignition switch was off. Then, the calculation of the heat amount of the friction clutch is restarted using a value obtained by subtracting the heat amount stored in the storage means from the heat amount thus calculated as an initial value. Therefore, even after the ignition switch is switched from off to on, the deviation of the calculated heat amount (calculated heat amount) from the actual heat amount (actual heat amount) can be kept small. Therefore, the electronically controlled coupling can be well protected from overheating even when the ignition switch is once switched from ON to OFF and then switched to ON again.

According to the present invention, it is possible to protect the electronically controlled coupling from overheating even when the ignition switch is once switched from ON to OFF and then switched to ON again.

1 is a plan view of a vehicle equipped with a vehicle control device according to an embodiment of the present invention; FIG. FIG. 3 is a diagram showing the on/off state of an ignition switch of a vehicle, actual heat quantity and calculated heat quantity of a main clutch of an electronically controlled coupling, and changes over time in time measured by an IG off timer. FIG. 5 is a diagram showing temporal changes in actual heat quantity and calculated heat quantity of a conventional electronically controlled coupling;

BEST MODE FOR CARRYING OUT THE INVENTION Below, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

<Vehicle configuration>
FIG. 1 is a plan view of a vehicle 1 equipped with a vehicle control device according to an embodiment of the invention.

The vehicle 1 employs an active torque split 4WD system. Vehicle 1 includes engine 2 , transmission 3 , front differential gear 4 , transfer 5 , propeller shaft 6 and rear differential gear 7 .

The engine 2 is laterally mounted (mounted) on the front portion of the vehicle 1 so that the crankshaft is oriented laterally with respect to the longitudinal direction of the vehicle 1, that is, so that the crankshaft extends in the vehicle width direction.

The transmission 3 may be, for example, a stepped automatic transmission (AT) equipped with a Ravigneau-type planetary gear mechanism, or a belt-type continuously variable transmission (CVT). may

A ring gear 12 is fixed to a differential case 11 of the front differential gear 4 . The rotation of the engine 2 is changed by the transmission 3 and input to the ring gear 12 . The rotation input to the ring gear 12 causes the differential case 11 to rotate integrally with the ring gear 12 . The rotation of the differential case 11 is converted into rotation of the side gears 14 via the pinion gear 13, and the left and right front drive shafts 15L and 15R rotate together with the side gears. It is transmitted to the front wheels 16L and 16R, which are drive wheels.

The transfer 5 includes, for example, a first bevel gear 17 that rotates integrally with the differential case 11 of the front differential gear 4 and a second bevel gear 18 that meshes with the first bevel gear 17 . A front end of a propeller shaft 6 extending in the longitudinal direction of the vehicle 1 is connected to the center of the second bevel gear 18 .

The propeller shaft 6 is divided into a front side portion 6F and a rear side portion 6R, and an electronically controlled coupling 21 is interposed between the front side portion 6F and the rear side portion 6R. . The electronically controlled coupling 21 includes a main clutch MC consisting of a multi-plate friction clutch that transmits torque, and an electromagnet that controls the torque capacity of the main clutch MC. A configuration is adopted in which the torque capacity of the main clutch MC increases in proportion to the ring current value.

A rear end of the propeller shaft 6 is connected to a drive pinion shaft of a rear differential gear 7 . Torque transmitted from the propeller shaft 6 to the rear differential gear 7 rotates the rear drive shafts 22L, 22R, and the rotation of the rear drive shafts 22L, 22R is transmitted to the rear wheels 23L, 23R, which are auxiliary drive wheels, respectively.

The vehicle 1 also includes an ECU (Electronic Control Unit) 31 including a microcomputer (microcontroller unit).

A tire rotation sensor 32 is provided for each of the front wheels 16L, 16R and the rear wheels 23L, 23R for outputting a pulse signal synchronized with the rotation of each tire as a detection signal. Each tire rotation sensor 32 is connected to the ECU 31 . The ECU 31 also receives an engine rotation sensor 33 that outputs a pulse signal synchronized with the rotation of the engine 2 (rotation of the crankshaft) as a detection signal, and a detection signal corresponding to the operation amount of the accelerator pedal provided in the vehicle 1. An accelerator sensor 34 for output is connected.

Various sensors required for control are also connected to the ECU 31 . Various sensors include, for example, an outside air temperature sensor 35 that outputs a detection signal corresponding to the outside air temperature.

The ECU 31 obtains the tire rotation speeds of the front wheels 16L, 16R and the rear wheels 23L, 23R from the detection signals of the tire rotation sensors 32, respectively. The ECU 31 obtains the engine rotation speed, which is the rotation speed of the engine 2 , from the detection signal of the engine rotation sensor 33 , and obtains the accelerator opening from the detection signal of the accelerator sensor 34 . The accelerator opening is the amount of operation of the accelerator pedal, and is a percentage of 100%, for example, when the accelerator pedal is fully depressed. The ECU 31 controls the electronically controlled coupling 21 based on numerical values obtained from detection signals input from various sensors.

Although only one ECU 31 is shown in FIG. 1, the vehicle 1 is equipped with a plurality of ECUs having the same configuration as the ECU 31 in order to control each part. A plurality of ECUs including the ECU 31 are connected so as to be capable of two-way communication by CAN (Controller Area Network) communication protocol. Moreover, only a part of various sensors required for control by the ECU 31 are shown in FIG.

<Hardware protection processing>
FIG. 2 is a diagram showing the ON/OFF state of the ignition switch of the vehicle, the amount of heat (actual amount of heat, calculated amount of heat) of the main clutch MC of the electronically controlled coupling 21, and the change over time of the time (count value) measured by the IG off timer. .

In order to prevent damage to the main clutch MC of the electronically controlled coupling 21 due to overheating, the ECU 31 performs hardware protection processing described below.

In the hardware protection process, when the ignition switch of the vehicle 1 is on, the amount of heat generated by the main clutch MC is calculated by a known technique based on the transmission torque of the main clutch MC. In addition, based on the heat capacity of other parts other than the main clutch MC built in the electronically controlled coupling 21, the heat capacity of the oil, and the outside air temperature detected by the outside air temperature sensor 35, the amount of heat released from the main clutch MC to the other parts and the oil is determined. The amount of heat and the amount of heat released from the electronically controlled coupling 21 to the outside air are estimated. Then, the amount of heat radiation is subtracted from the amount of heat generated by the main clutch MC, and the subtracted value is integrated to calculate the amount of heat of the main clutch MC (calculated by calculation).

When the heat amount of the main clutch MC exceeds a predetermined hardware protection heat amount threshold, the operation of the electronically controlled coupling 21 is prohibited, and torque transmission to the rear wheels 23L and 23R by the electronically controlled coupling 21 is prohibited.

When the ignition switch is switched from ON to OFF, the latest heat quantity calculated up to that time is stored in the non-volatile memory incorporated in the ECU 31 . In addition, an IG off timer that measures the time during which the ignition switch is off (IG off time) is activated in response to the ignition switch being switched from on to off. The IG off timer is provided in a volatile memory built in the ECU 31, and counts up (increments the count value) at regular intervals.

After that, when the ignition switch is switched from off to on, the IG off timer is stopped, and the heat release amount of the main clutch MC during the period when the ignition switch was off is obtained from the IG off time measured by the IG off timer.

Immediately after the ignition switch is switched from ON to OFF, the heat of the main clutch MC is taken away by other members and oil in the electronically controlled coupling 21, so the amount of heat of the main clutch MC drops sharply. After the temperature distribution in the electronically controlled coupling 21 becomes substantially uniform, the decrease in the amount of heat in the main clutch MC is mainly caused by the temperature difference between the temperature of the main clutch MC and the outside air temperature. The decrease in the amount of heat is slowed down. Taking these factors into consideration, the heat dissipation amount of the main clutch MC is determined.

Specifically, based on the heat capacity of oil and other parts other than the main clutch MC in the electronically controlled coupling 21, the amount of heat radiated from the main clutch MC to other parts and oil is estimated and detected by the outside air temperature sensor 35. The amount of heat radiation from the electronically controlled coupling 21 to the outside air may be estimated based on the ambient temperature, etc., and the estimated heat radiation amount may be added to calculate the heat radiation amount of the main clutch MC. .

Then, the heat release amount of the main clutch MC while the ignition switch is off is subtracted from the heat amount stored in the non-volatile memory of the ECU 31, and the calculation of the heat amount of the main clutch MC is restarted using the subtracted value as the initial value. be done.

<Effect>
As described above, while the ignition switch of the vehicle 1 is on, the heat amount of the main clutch MC of the electronically controlled coupling 21 is calculated. 21 is prohibited. Thereby, the electronically controlled coupling 21 can be protected from overheating.

When the ignition switch is switched from ON to OFF, the heat quantity calculated at that time is stored in the non-volatile memory of the ECU 31 . After that, when the ignition switch is switched from off to on, the heat dissipation amount of the main clutch MC is calculated in consideration of the heat absorption in the electronically controlled coupling 21 and the heat dissipation to the outside air during the time the ignition switch was off. . Then, the calculation of the amount of heat of the main clutch MC is restarted with a value obtained by subtracting the calculated heat amount from the amount of heat stored in the nonvolatile memory as an initial value. Therefore, even after the ignition switch is switched from off to on, the deviation of the calculated heat amount (calculated heat amount) from the actual heat amount (actual heat amount) can be kept small. Therefore, the electronically controlled coupling 21 can be well protected from overheating even when the ignition switch is once switched from ON to OFF and then switched to ON again.

<Modification>
Although one embodiment of the present invention has been described above, the present invention can also be implemented in other forms.

For example, in the above-described embodiment, when calculating the amount of heat released from the main clutch MC, the heat capacity of components other than the main clutch MC incorporated in the electronically controlled coupling 21, the heat capacity of the oil, and the external temperature detected by the outside air temperature sensor 35 Based on the air temperature, the amount of heat radiation from the main clutch MC to other parts and oil and the amount of heat radiation from the electronically controlled coupling 21 to the outside air are estimated. These heat dissipation amounts may be estimated by computation, or may be estimated according to a heat dissipation amount map prepared in advance.

In particular, in estimating the heat release amount after the ignition switch is switched from on to off, the heat release amount that rapidly increases due to the heat of the main clutch MC being taken away by other members and oil in the electronically controlled coupling 21 is A map corresponding to the heat quantity of the main clutch MC at the time when the ignition switch is turned off is selected from among a plurality of heat dissipation quantity maps created for each predetermined heat quantity range, and the ignition switch is selected from the selected map. The amount of heat dissipation corresponding to the time during which the is off is acquired, and the amount of heat dissipation that slowly increases due to the temperature difference between the temperature of the main clutch MC and the outside air temperature is obtained by obtaining a plurality of heat dissipation amounts created for each predetermined outside air temperature range. A map corresponding to the outside air temperature at the time the ignition switch was turned off is selected from the heat quantity maps, and the amount of heat dissipation corresponding to the time when the ignition switch was turned off is obtained from the selected map. good too.

Although the configuration in which the front wheels 16L and 16R are the main driving wheels to which power is transmitted when power is not distributed, the vehicle control device according to the present invention is such that the main driving wheels to which power is transmitted when power is not distributed are: It can also be used for a vehicle having rear wheels 23L and 23R.

The transmission 3 may be a power split type continuously variable transmission. A power split type continuously variable transmission, for example, is equipped with a belt-type continuously variable transmission mechanism that changes the power steplessly by changing the gear ratio, and divides the power into two paths between the input shaft and the output shaft. It is a transmission that can be transmitted by

In addition, various design changes can be made to the above configuration within the scope of the matters described in the claims.

1: Vehicle 16L, 16R: Front wheels (main driving wheels)
21: Electronically controlled coupling 23L, 23R: Rear wheels (auxiliary driving wheels)
31: ECU (control device, heat amount calculation means, coupling protection means, storage means, timekeeping means, heat dissipation amount calculation means)
MC: Main clutch (friction clutch)

Claims (1)

A control device for use in a vehicle equipped with an electronically controlled coupling with a built-in friction clutch and capable of distributing torque for running between the main drive wheels and the auxiliary drive wheels by the electronically controlled coupling,
heat quantity calculation means for calculating the heat quantity of the friction clutch while the ignition switch of the vehicle is on;
coupling protection means for prohibiting operation of the electronically controlled coupling when the heat amount calculated by the heat amount calculation means exceeds a threshold;
storage means for storing the amount of heat calculated by the heat amount calculation means in response to switching of the ignition switch from on to off;
a timer for measuring the time during which the ignition switch is off;
a heat dissipation amount calculation means for calculating the heat dissipation amount of the friction clutch while the ignition switch was off from the time measured by the time measuring means in response to the switching of the ignition switch from off to on. including
The heat radiation amount calculating means estimates the amount of heat radiation from the friction clutch to oil and other members other than the friction clutch in the electronically controlled coupling, estimates the amount of heat radiation from the friction clutch to the outside air, and Calculate the heat dissipation amount of the friction clutch by adding the heat dissipation amount of
After the ignition switch is switched from off to on, the heat amount calculation means uses a value obtained by subtracting the heat dissipation amount calculated by the heat dissipation amount calculation means from the heat amount stored in the storage means as an initial value. A vehicle control device that restarts the calculation of the heat quantity of the friction clutch.

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