JP2002081471A - Clutch control device for hybrid vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a clutch control device in a power transmission path for a hybrid vehicle power-assisted by an electric motor for controlling the decrease of the maximum transmission torque (stall torque) at creep with the decrease of the motor assistance due to the reduction of the remaining capacity of a battery. SOLUTION: The changing characteristic of a torque transmission capacity of a clutch at creep is varied from the characteristic of an a1-line during full assistance to the characteristic of an a2-line during non-assistance with the reduction of the motor assistance. If the changing characteristic of the torque transmission capacity of the clutch is not varied from the a1-line, the stall torque during the non-assistance is at a B-point but it is at C-point with the variation to the a2-line, where the stall torque is greater than that in no variation of the changing characteristic of the torque transmission capacity of the clutch.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a clutch disposed on a power transmission path of a hybrid vehicle having an engine and an auxiliary power source such as an electric motor for applying torque to the engine.

[0002]

2. Description of the Related Art In this type of hybrid vehicle, a clutch is provided in a power transmission path in place of a fluid torque converter used in a general automatic transmission in order to increase the efficiency of deceleration regeneration by an electric motor as an auxiliary power source. It is desirable.

[0003] Although not a hybrid vehicle, a clutch called a so-called starting clutch, which is conventionally provided in place of the fluid torque converter, is designed so that a smooth power transmission function equivalent to that of the fluid torque converter can be obtained when the vehicle starts. It is known that the clutch is controlled in a half-clutch state so that the torque transmission capacity T becomes a value obtained by the following equation, T = τ × Ne ² when the vehicle starts moving (Japanese Patent Laid-Open No. 9-7235).
No. 3). Here, Ne is the engine speed, and τ is the torque coefficient, which is set to change as shown in FIG. 3 according to the clutch speed ratio e.

[0004]

When the clutch is controlled as described above, the vehicle is stopped and the speed ratio e of the clutch is increased.
The change characteristic of the torque transmission capacity T of the clutch at the time of the start of the stall at which is zero is as shown by the line a1 in FIG. In the hybrid vehicle, the intersection of the line representing the total torque of the engine torque and the assist torque provided by the auxiliary power source and the line a1 is the stall operating point which is the maximum point of the transmission torque at the start of the stall. Here, when the auxiliary power source is an electric motor, the torque adding capacity of the electric motor changes according to the remaining capacity of the motor battery, and the total torque is calculated from the b1 line when the torque adding capacity is the maximum. The b2 line and the b3 line change as the pressure decreases, and finally the b4 line includes only the engine torque. The stall operating point greatly changes from point A when the torque adding capability is maximum to point B when the torque cannot be applied, and the transmission torque (stall torque) at the stall operating point is also greatly reduced. Therefore, it is necessary to set the transmission ratio of the transmission as a whole to a low speed side so that a required uphill performance (maximum driving force) can be obtained only by the engine torque, which adversely affects fuel efficiency.

In view of the above, it is an object of the present invention to provide a clutch control device capable of suppressing a decrease in stall torque due to a decrease in a torque adding ability of an auxiliary power source.

[0006]

Means for Solving the Problems In order to solve the above problems,
The present invention relates to a clutch control device interposed in a power transmission path of a hybrid vehicle having an engine and an auxiliary power source for applying torque to an engine, wherein a torque transmission capacity of the clutch changes with predetermined characteristics when the vehicle starts. A control means for controlling the clutch in such a manner that the change characteristic of the torque transmission capacity of the clutch is changed according to the torque applied state of the auxiliary power source.

The change of the change characteristic is controlled so that the torque transmission capacity of the clutch becomes a value calculated from the above-mentioned equation using the torque coefficient according to the clutch speed ratio and the engine speed as parameters. In this case, the correction can be performed by correcting the torque coefficient. For example, when the torque adding ability of the auxiliary power source is reduced, the torque coefficient is corrected to decrease, and the change characteristic of the torque transmission capacity of the clutch when the torque cannot be added is changed to the characteristic indicated by the line a2 in FIG. To be done. According to this, when the stall operating point when torque cannot be applied does not correct the torque coefficient,
The point shifts from the point to the point C, and the stall torque increases as compared with the case where the torque coefficient is not corrected. Therefore, the required climbing performance can be ensured even if the transmission gear ratio is not set too low, and the fuel efficiency can be improved.

When the auxiliary power source is an electric motor,
Since the torque addition state changes according to the remaining capacity of the battery for the electric motor, the torque coefficient may be corrected according to the remaining capacity of the battery. The steps S3, S4, and S5 in FIG. 2 correspond to the above-described correction means in an embodiment described later.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, reference numeral 1 denotes an engine. An electric motor 2 is provided as an auxiliary power source comprising a rotor 2a on a crankshaft 1a of an engine 1 and a stator 2b around the rotor. The motor 2 can apply torque to the engine 1. The power from the engine 1 and the electric motor 2 is input to a continuously variable or stepped automatic transmission 4 via a clutch 3 called a start clutch provided in place of the fluid torque converter, and the automatic transmission 4
Is transmitted to the driving wheels 5 and 5 of the vehicle. The electric motor 2 is connected to a motor battery 6 via a motor driver 7, and the motor driver 7 is controlled by a controller 8 composed of a vehicle-mounted computer to provide power assist by the electric motor 2 at the time of starting or a high load. And energy regeneration during deceleration. The clutch 3 is constituted by a hydraulic clutch, and a solenoid 8 in a hydraulic control circuit (not shown) of the clutch 3 and the automatic transmission 4 is controlled by a controller 8 to control the clutch 3 and shift the automatic transmission 4. Control.

The clutch 3 is controlled in a start mode in a half-clutch state when the vehicle starts, and then in a direct drive mode. In the start mode, as described in the section of the related art, the torque transmission capacity Tsc of the clutch 3 has a torque coefficient τ corresponding to the speed ratio e of the clutch 3 and an engine rotation speed Ne as parameters. The clutch 3 is set to have a value of T calculated from the equation of τ × Ne ^2.
Control.

The details of the control of the clutch 3 are as shown in FIG. 2. First, in step S1, the speed ratio e (= Nout / Nout /) of the clutch 3 is determined from the input rotation speed Nin and the output rotation speed Nout of the clutch 3. Nin) is calculated. Next, proceeding to step S2, a table shown in FIG. 3 that defines the relationship between the speed ratio e and the torque coefficient τ in a manner similar to the characteristics of the fluid torque converter is searched, and the speed ratio e calculated in step S1 is obtained. The corresponding value of τ is the reference value τ of the torque coefficient.
It is determined as base. Next, in step S3, the remaining capacity S of the battery 6 is determined based on the integrated value of charging and discharging of the battery 6.
Calculate OC. Next, the process proceeds to step S4 to search a table shown in FIG. 4 that defines the relationship between the remaining capacity SOC and the correction coefficient kτ of the torque coefficient, and to determine the correction coefficient kτ corresponding to the remaining capacity SOC calculated in step S3. Find the value of
Next, in step S5, the reference value τbase of the torque coefficient
Is multiplied by a correction coefficient kτ to calculate a torque coefficient τ. Then, in step S6, the clutch 3 in the start mode is set.
Is calculated by multiplying the square value of the engine rotation speed Ne by the torque coefficient τ.

Next, in step S7, the engine torque T
After e is estimated from the intake negative pressure of the engine 1 and the rotation speed, the total torque Tem is calculated by adding the motor torque Tm to the engine torque Te in step S8, and then, in S9.
In step (d), the torque transmission capacity Tdr of the clutch 3 in the direct drive mode is calculated by multiplying the total torque Tem by a predetermined safety factor Sf in consideration of the variation in the friction coefficient of the clutch 3. Then, in step S10, Tst and Tdr
If Tst ≦ Tdr, the actual torque transmission capacity Tsc of the clutch 3 becomes Tst in step S11.
If Tst> Tdr, the clutch 3 is controlled so that Tsc becomes Tdr in step S12.

Thus, at the time of starting, the torque transmission capacity Tsc of the clutch 3 increases with a change characteristic of Tst = τ × Ne ^{2 as} the engine speed Ne increases until Tst reaches Tdr. Then, the battery 6 is fully charged (SO
C = 100%), and when the torque adding capability of the electric motor 2 is maximized, when the speed ratio e of the clutch 3 is zero, that is, when the stall starts, the change characteristic of Tst is shown in FIG.
The intersection A between the b1 line and the a1 line indicating the total torque Tem when the torque adding capability is at the maximum is the stall operation point. Here, when the remaining capacity SOC of the battery 6 decreases, the total torque Tem decreases to the b2 line and the b3 line, and finally, the motor torque Tm becomes zero and becomes the b4 line including only the engine torque Te. When the change characteristic of Tst is not changed from the a1 line, when the motor torque Tm becomes zero, the stall operation point becomes the point B, and the transmission torque (stall torque) at the stall operation point is greatly reduced.
Therefore, in order to obtain the required climbing performance (maximum driving force) even when the motor torque Tm becomes zero, the speed ratio of the transmission 4 must be set to a lower speed as a whole.

Until Tst reaches Tdr, the clutch is in a half-clutch state and generates heat. Therefore, it is necessary to provide the clutch 3 with a heat absorbing ability to absorb the generated heat. Then, the calorific value is proportional to the product of the transmission torque and the engine rotation speed, and the calorific value becomes maximum at the point A which is the stall operation point when the torque adding capability of the electric motor 2 is the maximum.
The heat absorption capacity is set so as to absorb the calorific value at point A. In this case, the limit of the heat absorption capacity is as shown by the line c in FIG. Therefore, at point B, the heat absorption capacity of the clutch 3 is not fully used.

Therefore, in the present embodiment, the correction coefficient kτ is set so that the stall operating point is on the c-line, which is the heat absorption capacity limit, regardless of the torque addition capacity of the electric motor 2, that is, the magnitude of the remaining capacity SOC of the battery 6. A table (FIG. 4) is set. For example, when the remaining capacity of the battery 6 is 0%, the change characteristic of Tst when the speed ratio e of the clutch 3 is zero is a line a2 passing through a point C which is an intersection of the line b4 and the line c. Is set to the correction coefficient kτ. Therefore, B
The point C where the rotation is higher than the point is the stall operation point when the electric motor 2 cannot apply the torque. Where engine 1
Has a characteristic that a peak torque is generated in a rotation range higher than the stall rotation range including the point C, and the torque increases with an increase in the rotation speed until the peak torque is reached.
The stall torque is larger by ΔT at point C than at point B. Thus, the required climbing performance can be obtained without setting the speed ratio of the transmission 4 to a very low speed side.

[0016]

As is apparent from the above description, according to the present invention, it is possible to suppress a decrease in the stall torque due to a decrease in the torque adding ability of the auxiliary power source, and therefore, the climbing performance when the torque adding ability decreases. Can be ensured without setting the transmission gear ratio of the transmission too low, thereby improving fuel efficiency.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a drive system of a hybrid vehicle to which the present invention is applied.

FIG. 2 is a flowchart showing a clutch control program.

FIG. 3 is a graph showing a torque coefficient setting table used in the control of FIG. 2;

4 is a graph showing a correction coefficient setting table used in the control of FIG. 2;

FIG. 5 is a graph showing a change characteristic of the torque transmission capacity of the clutch when the total torque of the engine and the motor and the speed ratio of the clutch are zero.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Engine 2 Electric motor (auxiliary power source) 3 Clutch 6 Battery 8 Controller

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroyuki Okajima 1-4-1 Chuo, Wako-shi, Saitama F-term in Honda R & D Co., Ltd. (Reference) 3J057 AA06 BB03 GA21 GB02 GB13 GB19 GE13 HH01 JJ01 3J552 MA01 MA13 NA01 NB01 NB07 NB10 PA35 RB04 UA03 VA42W VB10W VC01Z 5H115 PA12 PC06 PG04 PI16 PI29 PO02 PO06 PO17 PU01 PU22 PU25 QE01 QE03 QE04 QE08 QE10 QI04 QN03 RB08 SE06 SE08 TE02 TE05 TE06 TI02 TI10

Claims (2)

[Claims] 1. A control device for a clutch provided in a power transmission path of a hybrid vehicle having an engine and an auxiliary power source for applying torque to an engine, wherein the clutch has a predetermined torque transmission capacity with a predetermined characteristic when the vehicle starts. A clutch control device for a hybrid vehicle, comprising: a control unit that controls a clutch so as to change, the correction unit changing a change characteristic of a torque transmission capacity of the clutch according to a torque addition state of an auxiliary power source. 2. The apparatus according to claim 1, wherein the auxiliary power source is configured by an electric motor, and the correction unit is configured to change the change characteristic according to a remaining capacity of a battery for the electric motor. 2. The clutch control device for a hybrid vehicle according to claim 1.