JP2000310324A - Gear ratio control device for continuously variable transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sufficient engine brake at traveling downhill without making control complicated and increasing a program capacity. SOLUTION: In this gear ratio control device for a continuously variable transmission 60 for controlling a gear ratio in the continuously variable transmission connected to an engine, setting means 51-55 set a target rotating speed of an input part 21 of the continuous variable transmission based on a target output of the engine at traveling downhill. A control means 56 controls the gear ratio of the continuously variable transmission such that an actual rotating speed of the input part 21 becomes the target rotating speed of the input part 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speed ratio control device for a continuously variable transmission used in a vehicle.

[0002]

2. Description of the Related Art A belt-type continuously variable transmission is a typical example of a continuously variable transmission. The belt-type continuously variable transmission includes a primary pulley (input unit), a secondary pulley (output unit), With a belt. Then, feedback control is performed so that the actual primary rotation speed of the primary pulley matches the target primary rotation speed.

In this case, the target primary rotational speed is set according to the vehicle speed and the throttle opening based on a control characteristic as shown in FIG. For example, when the throttle opening is fully closed (0%), the target primary rotational speed is such that the speed ratio of the continuously variable transmission becomes overdrive (OD) according to the vehicle speed as shown in FIG. Is set to

[0004]

However, when traveling downhill, the throttle is fully closed, and as shown in FIG.
If the target primary rotational speed is set such that the speed ratio of the continuously variable transmission is overdrive (OD), sufficient engine braking may not be obtained. Therefore, it is conceivable to perform the speed ratio control of the continuously variable transmission so that the actual acceleration of the vehicle becomes the target acceleration set based on the engine output characteristics so that sufficient engine braking can be obtained during downhill traveling. (For example, Japanese Patent No. 284023
No. 3).

However, during normal traveling such as traveling on a flat road, the speed ratio control of the continuously variable transmission is controlled so that the actual primary rotational speed of the primary pulley provided in the continuously variable transmission becomes the target primary rotational speed. Therefore, as in the conventional example described above, separately adding the speed ratio control of the continuously variable transmission, which is performed so that the actual acceleration of the vehicle becomes the target acceleration for downhill running, complicates the control. This leads to an increase in program capacity. In addition, the gear ratio may suddenly change at the time of control switching, causing a feeling of strangeness, which leads to deterioration of drivability.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has been made to provide a sufficient engine brake during downhill driving without complicating the control and increasing the program capacity. It is an object of the present invention to provide a transmission ratio control device for a continuously variable transmission.

[0007]

According to the present invention, a continuously variable transmission for controlling a speed ratio of a continuously variable transmission connected to an engine is provided. Wherein the setting means sets the target rotation speed of the input section of the continuously variable transmission based on the target output of the engine during traveling on a downhill, and the control means sets the actual rotation speed of the input section to the input section. The speed ratio of the continuously variable transmission is controlled so as to achieve the target rotation speed.

Preferably, a target acceleration is set based on a road gradient and a vehicle speed, a target driving force is set based on the target acceleration, a target output is set based on the target driving force, and the target output is set based on the target output. Set the input section target rotation speed.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. A gear ratio control device for a continuously variable transmission according to an embodiment of the present invention will be described with reference to FIGS. In the present embodiment, a belt-type continuously variable transmission is used as the continuously variable transmission (CVT).

First, the power transmission mechanism according to the present embodiment will be described. As shown in FIG. 2A, in this power transmission mechanism, the driving force output from the engine 1 is controlled by a torque converter (torque converter) 2, Belt-type continuously variable transmission 20
, And transmitted to the tire 30 via the differential 31. A forward / reverse switching mechanism 4 is disposed between the output shaft 7 of the torque converter 2 and the input shaft 24 of the belt-type continuously variable transmission 20.
Is input to the continuously variable transmission mechanism 20 via the forward / reverse switching mechanism 4.

As shown in FIG. 2B, the continuously variable transmission mechanism 20 comprises a primary pulley (input pulley) 21, a secondary pulley (output pulley) 22, and a belt 23. The rotation input from the mechanism 4 to the primary shaft 24 is input from the primary pulley 21 coaxial with the primary shaft 24 to the secondary pulley 22 coaxial with the secondary shaft 25 via the belt 23.

The primary pulley 21 and the secondary pulley 22 are respectively two sheaves 21a, 21 which rotate integrally.
1b, 22a and 22b. One of the sheaves 21a, 22a is a fixed sheave fixed in the axial direction, and the other sheave 21b, 22b is a movable sheave movable in the axial direction by hydraulic actuators (eg, hydraulic pistons) 21c, 22c.

The oil pump 62 pressurizes and discharges the oil in the oil tank 61, and the discharge pressure is regulated to a predetermined pressure (predetermined line pressure) by a pressure regulating valve 63. The line pressure PL regulated by the pressure regulating valve 63 is applied to the hydraulic actuator 22 c of the secondary pulley 22, and the flow rate is regulated by the flow regulating valve 64 disposed downstream of the pressure regulating valve 63 to the hydraulic piston 21 c of the primary pulley 21. Adjusted hydraulic oil is supplied, and this hydraulic oil acts as a gear ratio adjustment hydraulic pressure.

The line pressure PL should be as low as possible within a range where power transmission can be ensured while avoiding slippage of the belt 23, so as to reduce the energy loss due to the oil pump 62 and the durability of the transmission itself. The belt tension control pressure (pressure corresponding to the line pressure PL) Pout based on the CVT input torque TIN, the CVT input rotation speed (primary rotation speed) NP, and the speed ratio RAT.
Is set, and based on the belt tension control pressure Pout, the line pressure control is performed by controlling the pressure regulating valve 63 to regulate the discharge pressure of the oil pump 62.

The pressure regulating valve 63 and the flow regulating valve 64
Is the controller (Electronic control unit = E
CU) 50. The ECU 50 includes an engine speed sensor (crank angle sensor or cam angle sensor) 41, an air flow sensor 4
2, a primary rotation speed sensor (first rotation speed sensor) 43 for detecting the rotation speed of the primary pulley 21, a secondary rotation speed sensor (second rotation speed sensor) 44 for detecting the rotation speed of the secondary pulley 22, and a line pressure PL.
The ECU 50 controls the pressure regulating valve 63 and the flow regulating valve 64 based on these detection signals.

In this embodiment, the speed ratio control of the continuously variable transmission is performed so that sufficient engine braking can be obtained when traveling on a downhill road. For this reason, the ECU 50 is provided with a gear ratio control device 60 as shown in the functional block diagram of FIG. 1, and the actual gear longitudinal acceleration (actual longitudinal G) during traveling on a downhill road is provided by the gear ratio control device 60. The continuously variable transmission 2 is set by setting a target primary rotation speed so as to be a target acceleration and performing feedback control so that an actual primary rotation speed (actual primary rotation speed) matches the target primary rotation speed.
0 gear ratio control is performed.

In this case, the speed ratio control is performed during traveling on a downhill road. However, when the vehicle is traveling on a downhill road, the throttle opening is not more than a predetermined value when the throttle is fully closed (including when the throttle is almost fully closed). It is desirable to apply the present invention to the speed ratio control. As shown in FIG. 1, the transmission ratio control device 60 includes a descending slope determination unit 51, a target acceleration setting unit 52, a target driving force setting unit 53, a target output setting unit 54, and a target primary rotational speed setting unit. 55, and primary pulley control means 56 for controlling the primary pulley 21 (oil pressure to the hydraulic actuator 21c) based on the target primary rotational speed set by the target primary rotational speed setting means 55. You.

The downhill determination means 51 determines whether or not the vehicle is traveling on a downhill on the basis of the road gradient information. Is output to the target acceleration setting means 52 in order to perform the speed ratio control according to. The target acceleration setting means 52 calculates the vehicle speed V and the road gradient SL (= weight /
The target acceleration GXT is set based on the gradient resistance RS / vehicle weight [GXT (V, SL)], and a signal corresponding to the set target acceleration GXT is output to the target driving force setting means 53 described later. Has become. In addition, weight
The gradient resistance RS is a value obtained by subtracting the acceleration resistance, the air resistance, and the rolling resistance from the engine driving force.

Specifically, the target acceleration setting means 52
So as to calculate the target acceleration GXT by adding a target acceleration learned value GXT _L set based on the driver's driving operation to the target acceleration base value GXT _B which is set based on the vehicle speed V and the road gradient SL And is represented by the following equation (1). GXT = GXT _B + GX _L (1) where the target acceleration GXT is the target acceleration upper limit GXT _CLU
In the case of (GXT ≧ GXT _CLU ), the target acceleration GXT is set to the target acceleration upper limit GXT _CLU (GXT =
GXT _CLU ). On the other hand, when the target acceleration GXT is equal to or smaller than the target acceleration lower limit GXT _CLL (GXT ≦ GXT _CLL )
Sets the target acceleration GXT to the target acceleration lower limit GXT _CLL (GXT = GXT _CLL ). Thus, the target acceleration G
By providing upper and lower limits for XT, control is simplified and stabilized.

Here, the target acceleration base value GXT _B is
The vehicle speed V and the road gradient SL are set as shown by shading in the three-dimensional coordinates in FIG. That is, the vehicle speed V
Specific values V ₁ , V ₂ and the specific values SL ₁ , SL _{2 of the} road gradient SL
Accelerations GXB ₁₁ , GX set based on
B ₁₂ , GXB ₂₁ , and GXB ₂₂ have velocity coefficients K _V ,
It is obtained by multiplying the road gradient coefficient K _SL and is represented by the following equation (2).

[0021] Here, when calculating the target acceleration base value GXT _B is the vehicle speed coefficient K _V is the vehicle speed V, the first predetermined vehicle speed V
_1, the second predetermined vehicle speed _{V 2 (V 2> V 1} ) is calculated based on _{[K V = (V-V 1} ) / (V 2 -V 1) ]. Also,
The road slope coefficient K _SL is the road slope SL and the first predetermined road slope S
L ₁ , which is calculated based on the second predetermined road gradient SL ₂ (SL ₂ > SL ₁ ) [K _SL = (SL−SL ₁ ) / (SL ₂
-SL ₁ )].

GXT_B= (1-K_V) ・ (1-K_SL) ・ GXB₁₁ + K_V・ (1-K_SL) ・ GXB₁₂ + (1-K_V) ・ K_SL・ GXB_{twenty one} + K_V・ K_SL・ GXB_{twenty two} ... (2) The vehicle speed coefficient K_VIs smaller than 0 (K_V<0)
Is the vehicle speed coefficient K_VIs 0 (K_V= 0) and the vehicle speed coefficient K_VBut
If greater than 1 (K_V> 1) is the vehicle speed coefficient K _VIs 1
(K_V= 1). Also, the road gradient coefficient K_SLIs greater than 0
Is also small (K _SL<0) is the road gradient coefficient K_SLIs 0 (K
_SL= 0) and the road gradient coefficient K_SLIs greater than 1
(K_SL> 1) is the road gradient coefficient K_SLIs 1 (K_SL= 1)
You.

Specifically, the target acceleration setting means 52 is
Configured as comprising a three-dimensional map for the target acceleration setting the target acceleration GXT _B was related with respect to the vehicle speed V and the road gradient SL, as shown in FIG. 3, the target acceleration GXT based on a map for the target acceleration setting _It is preferable to set _B. The target driving force setting means 53 sets a target driving force FET of the vehicle for realizing the target acceleration GXT set by the target acceleration setting means 52, and outputs a signal corresponding to the target driving force FET. Output is made to a target output setting means 54 described later.

Specifically, the target driving force setting means 53
Vehicle weight W and differential shaft inertia equivalent weight W
_IDIFAnd the primary shaft inertia equivalent weight W_IPRIGear ratio R
Add the value obtained by multiplying the square of the AT and add the target acceleration
Multiplied by the target acceleration GXT set by the degree setting means 52.
By calculating the target acceleration resistance RA [= (W + W_IDIF+ W
_IPRI・ RAT^Two) · GXT], and calculate the weight / gradient
Add the distribution resistance RS, air resistance RL, and rolling resistance RR
By calculating the target driving force FET
And is expressed by the following equation (3).

FET = (W + W _IDIF + W _IPRI · RAT ² ) · GXT + RS + RL + RR (3) The target output setting means 54 is the target driving force setting means 5 described above.
The target output WET of the engine 1 is set so that the target driving force FET set by the control unit 3 is obtained, and the target output WET is output to target primary rotational speed setting means 55 described later.

[0026] Specifically, the target output setting means 54, the target driving force FET of the vehicle set by the target driving force setting means 53, obtained by dividing the tire radial r a final reduction ratio i _F and the secondary rotational speed By multiplying by NS, a net target output [FET ／ (r / i _F ) ・ NS] corresponding to the target driving force is calculated, and this net target output is set to the primary rotation speed NP by the input rotation dependent transmission loss torque TLR. Primary loss output (TLR · NP) calculated by multiplication
And the crankshaft inertia torque TIC and the oil pump drive loss torque TLP are added to the engine speed N
E to calculate the engine loss output [(TIC +
TLP) .NE] and the target output WE
T is calculated, and is represented by the following equation (4).

WET = FET ・ (r / i _F ) ・ NS + TLR ・ NP + (TIC + TLP) ・ NE (4) When the load of the compressor for the air conditioner is considered, the compressor load torque TLC is described in the third term. Is multiplied by the engine speed NE. The target primary rotational speed setting means 55 includes a target output WET of the engine 1 set by the above-described target output setting means 54,
The reference rotation speed NE _EB of the engine 1 and the learning reference torque T
A target primary rotational speed setting unit 55A that sets a target primary rotational speed NPT based on E _EB and a learning reference torque updating unit 55B that updates the learning reference torque TE _EB when predetermined learning conditions are satisfied. The primary rotation speed NPT is output to the primary pulley control means 56.

The target primary rotation speed setting unit 55A calculates a rotation speed (WET / TE _EB ) corresponding to the target output calculated by dividing the target output WET from the reference rotation speed NE _EB by the learning reference torque TE _EB. The target primary rotational speed NPT is calculated by subtraction, and is expressed by the following equation (5). NPT = NE _EB − (WET / TE _EB ) (5) Here, FIG. 4 is an approximation of the output characteristic when the throttle is fully closed with respect to the engine speed by a straight line. Here, the case where the engine rotation speed is low and medium rotation speed is shown.

The reference rotational speed NE _EB is such that the engine output is zero.
In this case, the engine speed is the idle speed of the engine, and corresponds to the coordinates of the intersection of the output characteristic of FIG. 4 with the axis indicating the engine speed in the output characteristic when the throttle is fully closed. Further, the learning reference torque TE _EB is a slope of the output characteristic when the throttle is fully closed in FIG. Specifically, the target primary rotational speed setting unit 55A is configured to include a map of engine output characteristics as shown in FIG. 4, and sets the target primary rotational speed NPT according to the target output WET using this map. You should do it.

The target primary rotational speed NPT is
Primary rotation speed N for overdrive (OD)
The secondary rotation speed N is set so as not to be smaller than P.
S is the overdrive (OD) gear ratio i_ODAlso divided by
(NPT <NS / i_OD), Target plastic
Imari rotation speed NPT is higher than secondary rotation speed NS.
Gear ratio i during ball drive (OD)_ODDivided by
(NPT = NS / i _OD).

When the throttle opening voltage VHT is higher than the target throttle opening voltage VHT _NPT calculated based on the target primary rotational speed NPT (VHT>
VHT _NPT ), the target primary rotational speed NPT is the previous target primary rotational speed NPT. Here, the target primary rotational speed NPT set by the above equation (5) is calculated by two low-pass filters having filtering cutoff frequencies f _NPT arranged in series with each other.
Filtering is performed in stages to remove minute fluctuation components.

The learning reference torque updating unit 55B is adapted to operate even when the throttle is fully closed while traveling on a downhill road so as not to be affected by variations in engine output characteristics when the throttle is fully closed. The engine output characteristic when the throttle is fully closed is updated based on the actual primary rotation speed (actual primary rotation speed) during steady running and the engine driving force.

Specifically, the learning reference torque updating unit 55B
Means that all of the learning conditions (1) to (10) described later
Predetermined time t_TEEBJudge whether or not only
Determination means for determining that a learning condition is satisfied by the determination means.
If it is determined, it is used until the current learning condition is satisfied.
Learning reference torque TE_{EB (OLD)}(That is, the previous learning standard
Torque) and the reference torque calculated when the current learning condition is satisfied.
Luc TE_EB0And the filtering constant K_TEEB
Learning reference torque TE _EB(Tsuma
The current learning reference torque TE_EBLike to set
And is expressed by the following equation (7).

[0034] TE_EB= K_TEEB・ TE_EB0+ (1-K_TEEB) ・ TE_{EB (OLD)}... (7) And the update provided in the learning reference torque update unit 55B
The means is the previous learning reference torque TE_{EB (OLD)}This study
Learning reference torque TE_EBUpdate to Also, the learning reference torque
The deciding means provided in the updating unit 55 </ b> B
Reference torque TE _EBEngine output characteristics based on
You. The engine output characteristics determined in this way
Is the target primary rotational speed until the next learning condition is satisfied.
It is used for setting the degree NPT.

Here, when the predetermined learning conditions (1) to (10) described later are _satisfied , the reference torque TE _EB0 is the engine driving force F detected or estimated when the learning conditions are satisfied.
E _L , engine speed NE _L , primary speed N
It is calculated as follows based on P _L and the secondary rotation speed NS _L. That is, first, the engine driving force FE
_L is multiplied with and secondary rotational speed NS _L as divided by the final reduction ratio i _F tire diameter r to calculate the net engine power corresponding engine driving force _{[FE L · (r / i F} ) ·
NS _L ]. Then, taking into account the loss of the engine output, the net engine power, the primary power loss which is calculated by multiplying the primary rotation speed NP _L to the input rotation dependent transmission loss torque TLR (TLR · NP _L)
And the crankshaft inertia torque TIC and the oil pump drive loss torque TLP are added to the engine speed N
E _L multiplied by the engine loss output [(TIC
+ TLP) · calculates the actual engine output (actual engine output) by NE _L] and adding. Then, the reference torque T as the engine torque of the actual engine output corresponding by dividing the actual engine output is obtained by subtracting the primary rotation speed NP _L from the reference rotational speed NE _EB
E _EB0 is calculated, and is represented by the following equation (6).

TE _EB0 = [FE _L · (r / i _F ) · NS _L + TLR · NP _L + (TIC + TLP) · NE _L ] / (NE _EB −NP _L ) (6) Then, the learning reference torque TE
_The following learning conditions (1) to (10) are set in order to determine whether the vehicle is in a steady state when traveling downhill so that _EB can be set. It should be noted that such a learning condition is provided in order that the learning is for improving the engine braking performance, so that the learning can be accurately performed in a running state which does not affect the learning condition. .

(1) The throttle is fully or almost fully closed, that is, the throttle opening voltage VTH is smaller than the learning throttle opening voltage VTH _TEEB (VTH <VT).
H _{TE EB} ). (2) The brake is off, that is, the brake switch BS is off (BS = 0).

(3) The vehicle speed V is within a predetermined range, that is, the vehicle speed V is equal to the learning vehicle speed lower limit value V _{TE EBA} (for example, about 10
km / h) and the learning vehicle speed upper limit V
_Less than _TEEBB (eg, about 100 km / h) (V _TEEBA <V <V _TEEBB ). (4) The road gradient SL is within a predetermined range, that is, the road gradient SL is larger than the learning road gradient lower limit SL _TEEBA (for example, about 5%) and the learning road gradient upper limit SL.
_Less than _TEEBB (for example, about 10 to 15%) (S
L _TEEBA <SL <SL _TEEBB ).

(5) The primary rotation speed NP is within a predetermined range, that is, the primary rotation speed NP is equal to the learning primary rotation speed lower limit NP _TEEBA (for example, about 100
0 rpm) and smaller than the upper limit value NP _TEEBB for learning (for example, about 2000 rpm) (NP _TEEBA <NP <NP _TEEBB ). (6) The engine driving force FE is the learning engine driving force FE.
_Less than _TEEB (FE <FE _TEEB ). The reason for this is that it is considered that engine braking is not required when the engine driving force FE is large.

(7) The gear ratio RAT (primary rotational speed NP / secondary rotational speed NS) is equal to the learning gear ratio RAT.
_Less than _TEEB (RAT <RAT _TEEB ). The reason for this is that if the gear ratio is too large, the primary rotational speed NP and further the engine rotational speed NE become too large. (8) The absolute value of the difference between the longitudinal acceleration GX and the target acceleration GXT is larger than the learning acceleration deviation GXT _TEEB (|
GXT-GX |> GXT _TEEB ).

(9) There is no ON / OFF change of the cooler compressor switch. (10) No direct on / off change. If all of the learning conditions (1) to (10) continue to be satisfied, the reference torque TE _EB0 is calculated by the above equation (6) for each predetermined learning determination time t _TEEB , and this reference torque TE _Based on _EB0 , the learning reference torque TE _EB is set by the above equation (7).

However, at the time of initial setting, the learning reference torque TE
_EB is a learning reference torque initial value (first learning torque value) TE
_Let it be _EB1 (TE _EB = TE _EB1 ). Further, when the next learning reference torque TE _EB is larger than the learning reference torque upper limit value (second learning torque value) TE _EBU (TE _EB > TE _EBU )
Is that the next learning reference torque TE _EB is the learning reference torque upper limit TE _EBU (TE _EB = TE _EBU ), and the next learning reference torque TE _EB is smaller than the learning reference torque lower limit (third learning torque value) TE _EBL. When small (TE _EB <TE _{EB L} )
Sets the next learning reference torque TE _EB to the learning reference torque lower limit TE _EBL (TE _EB = TE _EBL ). It should be noted that the data of the learning reference torque TE _EB set in this manner is retained even after the ignition key is turned off.

Since the target primary rotational speed setting means 55 is configured as described above, the learning reference torque updating unit 55B uses the learning used in setting the target primary rotational speed NPT as follows. The reference torque TE _EB is updated. That is, as shown in the flowchart of FIG. 5, first, in step A10, the learning conditions (1) to (1) are set by the learning reference torque updating unit 55B.
It is determined whether all of the learning conditions (1) to (10) are satisfied. As a result of this determination, it is determined that all of the learning conditions (1) to (10) are satisfied. It is determined whether or not the predetermined time t _TEEB for learning determination has elapsed in a state where all of the conditions (1) to (10) are satisfied.

As a result of this determination, the learning determination predetermined time t
If it is determined that _TEEB has elapsed, the process proceeds to step A30, in which the reference torque TE _EB0 is calculated.
At 0, the previous learning reference torque TE _{EB (OLD)} is read, and the routine proceeds to step A50. In step A50, each of the previous learning reference torque TE _{EB (OLD)} and the reference torque TE _EB0 calculated when the learning condition is satisfied is filtered by a filtering constant K _TEEB to set the current learning reference torque TE _EB , Update the previous learning reference torque TE _EB to the current learning reference torque TE _EB and return.

When the learning reference torque TE _EB is updated in this way, the engine output characteristic is determined based on the updated learning reference torque TE _EB, and the determined engine output characteristic is determined when the next learning condition is satisfied. This is used for setting the target primary rotational speed NPT. Note that, as described above, the target primary rotational speed NP is calculated from the target driving force FET.
The coefficient when setting T is the actual longitudinal acceleration (longitudinal G)
And the target acceleration GXT are sequentially corrected.

The speed ratio control by the speed ratio control device for the continuously variable transmission according to the embodiment of the present invention is performed as shown in the flowchart of FIG. That is, as shown in FIG. 6, in step S10, the downhill road determination means 51 determines whether the vehicle is traveling on a downhill road, and as a result of this determination, when it is determined that the vehicle is traveling on a downhill road, Step S2
Go to 0.

In step S20, the target acceleration setting means 52 reads the vehicle speed V, proceeds to step S30, reads the road gradient SL, and proceeds to step S40. In step S40, the target acceleration setting means 52
A target acceleration GXT is set based on the vehicle speed V and the road gradient SL (= weight / gradient resistance RS / vehicle weight W) [GXT (V,
SL)], and proceed to step S50.

In step S50, the target driving force setting means 53 sets a target driving force FET for realizing the target acceleration GXT set in step S40.
Specifically, the target driving force setting means 53 determines that the vehicle weight W
And the differential shaft portion inertia equivalent weight W _IDIF and the primary shaft portion inertia equivalent weight W _IPRI multiplied by the square of the gear ratio RAT are added, and the target acceleration GXT set by the target acceleration setting means 52 is added to this. By multiplying, the target acceleration resistance RA [= (W + W _IDIF + W _IPRI · RAT
² ) · GXT] is calculated, and the weight / gradient resistance RS,
The target driving force FET is calculated by adding the air resistance RL and the rolling resistance RR.

Next, at step S60, the target output setting means 54 sets the target output WET so as to attain the target driving force FET set at step S50. Specifically, the target output setting means 54 sets the target driving force FET set by the target driving force setting means 53 to the tire diameter r.
Is divided by the final reduction ratio i _F and the secondary rotation speed NS to obtain a net target output [FET
. (R / i _F ) · NS], and the net target output is added to the input rotation dependent transmission loss torque TLR.
Is multiplied by a primary rotational speed NP, a primary loss output (TLR · NP), a crankshaft inertia torque TIC, and an oil pump drive loss torque TLP are multiplied by an engine rotational speed NE. The target output WET is calculated by adding the engine loss output [(TIC + TLP) .NE].

Next, the routine proceeds to step S70, where the target primary rotational speed setting means 55 executes the above-mentioned step S60.
The target primary rotational speed NPT is set so as to achieve the target output WET set in the above. Specifically, the target primary rotation speed setting means 55 subtracts a rotation speed (WET / TE _EB ) corresponding to the target output calculated by dividing the target output WET by the reference torque TE _EB from the reference rotation speed NE _EB. Thus, the target primary rotational speed NPT is calculated. Specifically, target primary rotational speed setting unit 55A
Is a target primary rotational speed NP according to a target output WET using a map of engine output characteristics as shown in FIG.
Set T.

Then, the process proceeds to step S80, in which the primary pulley control means 56 controls the actual primary rotation speed NP to the target primary rotation speed NPT set in step S70 so as to control the speed ratio of the primary pulley 21. A feedback control signal corresponding to the control amount of the primary pulley 21 is set in the
4 to output a control signal. As a result, when traveling downhill, the primary rotational speed NP is feedback-controlled according to the target output, and a desired engine brake can be applied.

If it is determined in step S10 that the vehicle is not traveling on a downhill road, the process returns without performing the gear ratio control. Therefore, according to the speed ratio control device for the continuously variable transmission, the actual primary rotation speed NP is controlled so as to become the target primary rotation speed NPT set based on the target output WET during downhill traveling, and the CVT 20 Since the gear ratio is reduced (shift down), there is an advantage that an appropriate engine brake can be applied to the vehicle when traveling on a downhill road, particularly when the throttle is fully closed.

Since the speed ratio control of the CVT 20 is performed so that the actual primary rotation speed NP becomes the target primary rotation speed NPT corresponding to the target output WET,
The target primary rotational speed is determined from the vehicle speed and throttle opening, and feedback control is performed so that the actual primary rotational speed matches the target primary rotational speed. In addition, there is an advantage that the program capacity can be reduced, and control complexity can be prevented. Furthermore, since there is no switching in the control system, there is an advantage that the gear ratio does not change suddenly and it is possible to prevent a sense of incongruity from occurring. Thereby, deterioration of drivability can be prevented.

In the above-described embodiment, the target primary rotational speed setting means 55 sets the target acceleration GXT based on the road gradient SL and the vehicle speed V, and sets the target acceleration GXT.
The target driving force FET is set based on the target driving force FE.
The target output WET is set based on T and the target output WET is set.
Is set based on the target primary rotation speed NPT, but the method of setting the target output WET at this time is not limited to this. For example, the target acceleration GXT
May be set based on the target output.

In the above-described embodiment, the target primary rotational speed setting means 55 sets the target primary rotational speed N
The reference torque TE _EB is used for setting the PT. The reference torque TE _EB is set each time a predetermined learning condition is satisfied. However, the reference torque TE _EB may be a fixed value. In the above embodiment, the present invention has been described as being applied to the belt type CVT.
It is also conceivable to apply the present invention to other CVTs such as a toroidal CVT.

[0056]

As described above in detail, according to the speed ratio control apparatus for a continuously variable transmission according to the first aspect of the present invention, the target primary rotational speed set based on the target output during traveling on a downhill road is obtained. In order to reduce the speed ratio of the continuously variable transmission (shift down) by controlling the actual primary rotational speed so as to make it possible to apply an appropriate engine brake to the vehicle when traveling on a downhill road, particularly when the throttle is fully closed. There is an advantage that you can. Further, since the speed ratio control of the continuously variable transmission is performed so that the actual primary rotation speed becomes the target primary rotation speed corresponding to the target output, the target primary rotation speed is determined from the vehicle speed and the throttle opening, and the actual primary rotation speed is determined. Feedback control to make the primary rotational speed match the target primary rotational speed can effectively utilize the common part with feedback control when traveling on a flat road, and can reduce the program capacity and complicate control. There is also an advantage that can be prevented.

[Brief description of the drawings]

FIG. 1 is a functional block diagram of a gear ratio control device for a continuously variable transmission according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a speed ratio control device for a continuously variable transmission according to an embodiment of the present invention, where (a) is a schematic diagram illustrating an entire configuration of a drive system having the continuously variable transmission; (B) is a schematic diagram showing a configuration of the continuously variable transmission.

FIG. 3 is a diagram for explaining setting of a target acceleration of the speed ratio control device for the continuously variable transmission according to the embodiment of the present invention;

FIG. 4 is a diagram showing output characteristics when the throttle is fully closed with respect to the engine rotation speed of the transmission ratio control device for the continuously variable transmission according to the embodiment of the present invention.

FIG. 5 is a flowchart illustrating a learning reference torque update control in the transmission ratio control device for the continuously variable transmission according to the embodiment of the present invention.

FIG. 6 is a flowchart illustrating a speed ratio control by a speed ratio control device for a continuously variable transmission according to an embodiment of the present invention.

FIG. 7 is a diagram for explaining a speed ratio control during downhill running by a conventional speed ratio control device for a continuously variable transmission.

[Explanation of symbols]

 Reference Signs List 20 continuously variable transmission (CVT) 21 primary pulley 50 controller (ECU) 51 descending slope determination means 52 target acceleration setting means 53 target driving force setting means 54 target output setting means 55 target primary rotation speed setting means 55A target primary rotation speed setting Unit 55B learning reference torque updating unit 56 primary pulley control means 60 gear ratio control device

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) F16H 63:06

Claims (1)

[Claims] 1. A continuously variable transmission speed ratio control device for controlling a speed ratio of a continuously variable transmission connected to an engine, wherein the continuously variable transmission is controlled based on a target output of the engine during traveling on a downhill road. Setting means for setting a target rotation speed of the input unit; and control means for controlling a speed ratio of the continuously variable transmission so that the actual rotation speed of the input unit becomes the target rotation speed of the input unit. A transmission ratio control device for a continuously variable transmission, characterized by: