JP2006258195A - Speed change ratio control device for continuously variable transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a speed change control device for a continuously variable transmission capable of improving fuel economy. <P>SOLUTION: This speed change control device for a continuously variable transmission is provided with target speed change ratio operation means 20 and 20e to operate a target speed change ratio of the continuously variable transmission based on a driving state of a vehicle, a target speed change speed operation means 20d to operate a target speed change speed based on the driving state of the vehicle and the target speed change ratio, an actual speed change ratio detecting means 20a to detect an actual speed change ratio based on input side rotation speed and output side rotation speed of the continuously variable transmission, and a speed change control means 20 to control the speed change ratio of the continuously variable transmission based on the target speed change speed in such a way that the actual speed change coincides with the target speed change ratio. The target speed change speed operation means is provided with an input torque detecting means to detect input torque from a motor, an upper limit operation means to operate an upper limit value of the target speed change speed based on the input torque, and input side inertia moment and output side rotation speed of the continuously variable transmission, and a target speed change speed setting means to set the target speed change speed based on the driving speed not to exceed the upper limit value. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an improvement in a CVT gear ratio control apparatus.

As a conventional CVT gear ratio control device, there is one that calculates a gear ratio Basei in a steady state and performs gear shift control using the gear ratio Basei, the detected output shaft rotational speed No and the current gear ratio i. (See Patent Document 1). This conventional control device for a vehicle with a continuously variable transmission calculates a stationary gear ratio Basei from the vehicle speed and the throttle opening, and from the difference or ratio between the stationary gear ratio Basei and the current gear ratio i. A coefficient TTINR is calculated, and a shift speed SV = TTINR / (engine inertia moment × i × No) is calculated from the detected current speed ratio i, output shaft rotational speed No, and coefficient TTINR. The shift control is performed in accordance with the shift speed SV so that the current shift ratio i becomes the steady-state shift ratio Basei, and the object is to realize good drivability by the control considering the inertia torque at the shift. It is said.
JP-A-7-239002

  However, such a conventional CVT gear ratio control device focuses only on the inertia torque, and does not focus on the change in the torque increasing action accompanying the change in the gear ratio, leaving room for improvement in drivability. It was.

  The present invention has been made paying attention to such conventional problems, and aims to improve drivability by taking into account the change in the torque increasing action accompanying the change in the gear ratio.

  The present invention provides a target transmission ratio calculation means for calculating a target transmission ratio of a continuously variable transmission based on a driving state of a vehicle, and a target transmission speed for calculating a target transmission speed based on the driving state of the vehicle and the target transmission ratio. An arithmetic means, an actual speed ratio detecting means for detecting an actual speed ratio from the input side rotational speed and the output side rotational speed of the continuously variable transmission, and the actual speed ratio so as to coincide with the target speed ratio. Shift control means for controlling a gear ratio of the continuously variable transmission according to a target shift speed, wherein the target shift speed calculating means is an input torque for detecting an input torque from the prime mover. Detecting means; upper limit value calculating means for calculating an upper limit value of the target shift speed based on the input torque, the actual gear ratio, the input side moment of inertia of the continuously variable transmission, and the output side rotational speed; and exceeding the upper limit value Not to said And a target shift speed setting means for setting a target shift speed based on the rolling conditions.

  The change in the torque increasing effect due to the change in the gear ratio can be kept larger than that in the inertia torque, and the output torque of the CVT accompanying the increase in the gear ratio (in the operating region where the engine torque is saturated with respect to the accelerator operation amount) Good driving performance can be realized by increasing the driving force.

  Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a schematic configuration diagram of a V-belt continuously variable transmission, and FIG. 2 is a conceptual diagram of a hydraulic control unit and a CVT control unit.

  In FIG. 1, a continuously variable transmission (CVT) 5 is connected to an engine 1 via a torque converter 2 having a lock-up clutch and a forward / reverse switching mechanism 4, and a primary pulley 10 on the input shaft side as a pair of variable pulleys. A secondary pulley 11 connected to the output shaft 13 is provided, and the pair of variable pulleys 10 and 11 are connected by a V-belt 12. The output shaft 13 is connected to the differential 6 via an idler gear 14 and an idler shaft.

  The transmission ratio of the continuously variable transmission 5 and the contact friction force of the V belt are controlled by a hydraulic control unit 100 that responds to a command from the CVT control unit 20. The CVT control unit 20 determines a gear ratio and a contact friction force based on input torque information from an engine control unit 21 that controls the engine 1 and an output from a sensor or the like described later, and controls the hydraulic control unit 100.

  The primary pulley 10 of the continuously variable transmission 5 has a fixed conical plate 10b that rotates integrally with an input shaft that transmits the power of the engine 1, and a V-shaped pulley groove that is disposed opposite the fixed conical plate 10b. The movable conical plate 10a can be displaced in the axial direction by the hydraulic pressure (primary pulley pressure) acting on the primary pulley cylinder chamber 10c.

  The secondary pulley 11 is a fixed conical plate 11b that rotates integrally with the output shaft 13, and is disposed opposite to the fixed conical plate 11b to form a V-shaped pulley groove, and the hydraulic pressure acting on the secondary pulley cylinder chamber 11c. The movable conical plate 11a can be displaced in the axial direction according to (secondary pulley pressure).

  The drive torque input from the engine 1 is input to the continuously variable transmission 5 via the torque converter 2 and the forward / reverse switching mechanism 4 and transmitted from the primary pulley 10 to the secondary pulley 11 via the V belt 12. By changing the pitch radius with the V belt 12 by displacing the movable conical plate 10a of the primary pulley 10 and the movable conical plate 11a of the secondary pulley 11 in the axial direction, the gear ratio between the primary pulley 10 and the secondary pulley 11 is changed. It can be changed continuously. The transmission ratio of the continuously variable transmission 5 and the contact friction force of the V belt 12 are controlled by the hydraulic control unit 100.

  As shown in FIG. 2, the hydraulic control unit 100 includes a regulator valve 60 that controls the line pressure, a pressure reducing valve 30 that controls the hydraulic pressure in the primary pulley cylinder chamber 10c (hereinafter referred to as primary pulley pressure), and a secondary pulley cylinder chamber 11c. The pressure reducing valve 61 that controls the supply pressure (hereinafter referred to as secondary pulley pressure) is mainly configured.

  The line pressure control system is composed of a regulator valve 60 having a solenoid for regulating the pressure oil from the hydraulic pump 80, and is predetermined according to the operation state in accordance with a command (for example, a duty signal) from the CVT control unit 20. The line pressure PL is adjusted.

  The line pressure PL is supplied to a pressure reducing valve 30 having a solenoid 31 for controlling the primary pressure and a pressure reducing valve 61 having a solenoid 62 for controlling the secondary pressure.

  The pulley ratio between the primary pulley 10 and the secondary pulley 11 is controlled by the pressure reducing valves 30 and 61 driven in accordance with a shift command signal from the CVT control unit 20, and the line pressure PL supplied to the pressure reducing valves 30 and 61 is adjusted. Then, the primary pressure is supplied to the primary pulley 10 and the secondary pressure is supplied to the secondary pulley 11, and the groove width is variably controlled and set to a predetermined pulley ratio. The actual pulley ratio is calculated by the ratio between the rotation speed of the primary pulley 10 and the rotation speed of the secondary pulley. On the other hand, the actual transmission ratio is a value that takes into account the gear ratio of the idler gear 14 to this actual pulley ratio.

  Here, the CVT control unit 20 in FIG. 1 has a primary pulley speed sensor 26 that detects the rotational speed of the primary pulley 10 of the continuously variable transmission 5 and a secondary pulley speed that detects the rotational speed (or vehicle speed) of the secondary pulley 11. The signal from the sensor 27, the shift position from the inhibitor switch 23, and the stroke amount from the operation amount sensor 24 corresponding to the operation amount of the accelerator pedal operated by the driver (or the throttle valve according to the stroke amount of the accelerator pedal). Opening degree), the oil temperature of the continuously variable transmission 5 is read from the oil temperature sensor 25, and the gear ratio and the contact friction force of the V belt 12 are variably controlled.

  The CVT control unit 20 includes target gear ratio calculation means 20a for calculating a target gear ratio and a target gear ratio change speed from the stroke amount of the accelerator pedal, the vehicle speed, the engine torque, the secondary pulley rotational speed and the actual gear ratio, and an actual gear shift. The gear ratio control means 20b controls the hydraulic control unit 100 so that the ratio becomes the target gear ratio.

  The speed ratio control means 20b drives the solenoids 31 and 62 of the pressure reducing valves 30 and 61 according to the target speed ratio and the target speed ratio changing speed from the target speed ratio calculating means 20a, and the speed of change (or speed ratio) is changed. Control is performed so that the target gear ratio changing speed (or target gear ratio) is obtained.

  Next, a method for calculating the target speed ratio of the target speed ratio calculating means 20a will be described.

  In the above-described conventional technology, there is room for improvement in realizing good drivability because attention is paid only to the inertia torque at the time of gear shift, and not attention is paid to the change in torque increasing action accompanying the change in gear ratio. .

  That is, at an acceleration of a medium load or higher where the engine torque is saturated with respect to the accelerator operation amount, the engine torque does not increase even if the accelerator operation amount is increased, but the driving force can be increased by increasing the speed ratio. Therefore, when the gear ratio is increased, the inertia torque causes pulling to decrease the output torque. However, the gear ratio or the gear ratio changes so that the increase in torque increase due to the gear ratio increase is kept larger than the inertia torque. By controlling the speed, it is possible to obtain a good feeling of acceleration by eliminating the influence of a decrease in output torque (driving force) due to inertia torque.

  The influence ΔTo1 on the output torque To of the continuously variable transmission 5 due to the change in torque increasing action accompanying the shift can be expressed by the following equation.

ΔTo1 = Te × ΔR (1)
Here, Te is the engine torque, and ΔR is the change in the actual gear ratio.

  On the other hand, the influence ΔTo2 of the inertia torque on the output torque To of the continuously variable transmission 5 accompanying the shift can be expressed by the following equation.

ΔTo2 = Ii × ωo × R × (ΔR / Δt) (2)
Here, Ii: input side moment of inertia, ωo: output side rotational speed, R: actual gear ratio, Δt: time required to change the actual gear ratio by a predetermined amount (predetermined gear ratio change amount).

As described above, the change ΔTo (= ΔTo1-ΔTo2) of the output torque To of the continuously variable transmission 5 needs to be positive for a good acceleration feeling of the vehicle.
△ To1> △ To2
It becomes the relationship. That means
Δt> Ii × ωo × R / Te (3)
Therefore, the time Δt for changing the actual speed ratio by a predetermined amount needs to be longer than the quotient obtained by dividing the product of the input side inertia moment Ii, the output side rotational speed ωo, and the actual speed ratio R by the engine torque Te. . In other words, an upper limit value is set for the amount of change in the gear ratio R per unit time, that is, the change speed, and the change speed is equal to or lower than the upper limit value, thereby eliminating the influence of a decrease in the output torque of the inertia torque. Drivability can be ensured.

  FIG. 3 is a block diagram showing a configuration of the CVT control unit 20.

  The target gear ratio calculation means 20a includes a first target gear ratio calculation unit 20c, a target gear ratio change speed calculation unit 20d, and a second target gear ratio calculation unit 20e.

  The accelerator operation amount APS and the vehicle speed VSP are input to the first target speed ratio calculating unit 20c, and the first target speed ratio tR1 is calculated. FIG. 4 is an example of the first target speed ratio tR1 set according to the accelerator operation amount APS and the vehicle speed VSP. Even in the operation region where the engine torque is saturated, the driving force is set to change according to the accelerator operation amount APS by changing the speed ratio.

The target speed ratio changing speed calculation unit 20d receives the first target speed ratio tR1, the actual speed ratio R, the engine torque Te, and the output side rotational speed ωo, and is stored in advance on the input side of the continuously variable transmission 5. Using the moment of inertia Ii, the aforementioned ΔTo = ΔTo1-ΔTo2
Thus, a change ΔTo in the output torque To is obtained.

  Then, the target gear ratio change speed calculation unit 20d calculates the target gear ratio change speed so that the change ΔTo of the output torque To becomes positive.

  The second target speed ratio calculating unit 20e calculates the second target speed ratio so as to follow the first target speed ratio tR1 based on the first target speed ratio tR1 and the target speed ratio changing speed. This calculation can be obtained by, for example, a first-order lag filter using a predetermined time constant.

  A second target speed ratio tR2 and an actual speed ratio R are input to the speed ratio control means 20b, and feedback control is performed so that the actual speed ratio R matches the second target speed ratio tR2. That is, the second target speed ratio is given as a target speed ratio for each control cycle (predetermined time).

  FIG. 5 is a flowchart showing the control contents of the CVT control unit 20. This flowchart is executed every predetermined time (for example, 10 msec).

  In step S1, the first target speed ratio tR1 is calculated based on the map of FIG. 4 from the accelerator operation amount APS and the vehicle speed VSP.

  In step S2, the basic value dtRB of the target speed ratio change amount is calculated using a predetermined function from the deviation between the first target speed ratio tR1 and the previous value of the second target speed ratio tR2. The basic value dtRB of the target speed ratio change amount is a large value when the deviation between the first target speed ratio tR1 and the second target speed ratio tR2 is large, and is small so that a stable speed change can be realized quickly. Is set to a small value.

  In step S3, it is determined whether or not the engine torque is saturated. If it is saturated, the process proceeds to step S4, and if it is not saturated, the process proceeds to step S6. Whether the engine torque Te is in a saturated state is determined using the relationship between the accelerator operation amount APS and the engine torque Te shown in FIG. FIG. 6 is a diagram showing the relationship between the accelerator operation amount APS and the engine torque Te, and the engine torque Te is saturated at a smaller accelerator operation amount APS as the engine speed is lower.

In step S4, a change time Δt for changing the speed ratio (second target speed ratio) by a predetermined amount is calculated from the engine torque Te, the speed ratio R, the input side inertia moment Ii, and the output side rotational speed ωo by the following equation.
Δt = Ii × ωo × R / Te (4)
Then, a shift speed at which the speed ratio is changed by a predetermined amount within the change time Δt is obtained as an upper limit value dtRUL of the target speed ratio change speed.

  In step S5, the basic value dtRB of the target speed ratio change amount and the upper limit value dtRUL of the target speed ratio change amount are compared. If dtRB <dtRUL, the process proceeds to step S6, and if dtRB ≧ dtRUL, the process proceeds to step S7.

  In step S6, the basic value dtRB of the target speed ratio change amount is selected as the target speed ratio change amount dtR. On the other hand, in step S7, the upper limit value dtRUL of the target gear ratio change amount is selected as the target gear ratio change amount dtR.

  In the subsequent step S8, the first target speed ratio tR1 and the second target speed ratio tR2 are compared. If tR1 = tR2, the process proceeds to step S11. If tR1 <tR2, the process proceeds to step S9. Proceed to S10.

  In step S9, the target speed ratio change amount dtR is added to the second target speed ratio tR2, and in step S10, the target speed ratio change amount dtR is subtracted from the second target speed ratio tR2. Since these calculations are executed at predetermined time intervals, the target gear ratio change speed is the target gear ratio change amount dtR / predetermined time.

  In step S11, feedback control of the speed ratio R is executed so that the speed ratio R becomes equal to the second target speed ratio tR2.

  When the first target speed ratio tR1 is obtained based on the driving state by the above processing, the basic value dtRB (target speed ratio change speed) of the target speed ratio changing speed is calculated from the previous value of the second target speed ratio tR2 and the first target speed ratio tR1. Basic speed) is determined.

  On the other hand, an upper limit value dtRUL (target shift speed upper limit value) of the target gear ratio change speed is obtained from the change time Δt obtained from the engine torque Te, the actual speed ratio R, the input side inertia moment Ii, and the output side rotational speed ωo. It is done.

  Next, the magnitude relationship between the basic value dtRB of the target shift speed and the upper limit value dtRUL is compared. If the basic value dtRB is equal to or higher than the upper limit value dtRUL, the target speed ratio changing speed is restricted to the upper limit value dtRUL.

  As a result, as shown in the above equation (3), the change time Δt for which the actual speed ratio R changes by a predetermined speed ratio change amount is the input side moment of inertia Ii, the output side rotational speed ωo, and the actual speed ratio R. Is larger than the value obtained by dividing the product by the engine torque Te, so that it is possible to compensate for a decrease in output torque due to inertia torque at the time of shifting.

  In the present invention, control is performed so that the target speed ratio change amount does not exceed the upper limit value dtRUL in order to make the increase amount of the output torque accompanying the change of the speed ratio larger than the decrease amount of the output torque due to the inertia torque. In other words, the amount of change in the gear ratio is selected so that the change ΔTo in the output torque To of the continuously variable transmission 5 during shifting is positive. Therefore, it is possible to keep the change in the torque increasing effect due to the change in the gear ratio larger than the change in the torque increasing effect due to the inertia torque, and even in the operating region where the engine torque is saturated with respect to the accelerator operation amount Can be realized.

  In the above embodiment, an example in which an engine is connected to a continuously variable transmission as a prime mover has been shown. However, a combination of an engine and an electric motor may be used as the prime mover.

It is a schematic block diagram of the V belt type continuously variable transmission which shows one Embodiment of this invention. It is a schematic block diagram similarly of a CVT control unit and a hydraulic control unit. It is a block diagram which shows the structure of a CVT control unit. It is an example of 1st target gear ratio tR1 set according to accelerator operation amount APS and vehicle speed VSP. It is a flowchart of the control which a CVT control unit performs. It is a map which judges the saturation state of an engine torque.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 5 Continuously variable transmission 10 Primary pulley 11 Secondary pulley 12 V belt 20 CVT control unit 20a Target speed ratio calculating means 20b Speed ratio control means 20c First target speed ratio calculating part 20d Target speed ratio changing speed calculating part 20e Second Target gear ratio calculation unit 100 Hydraulic control unit

Claims (3)

Target gear ratio calculating means for calculating a target gear ratio of the continuously variable transmission based on the driving state of the vehicle;
Target shift speed calculating means for calculating a target shift speed based on the driving state of the vehicle and a target gear ratio;
An actual gear ratio detecting means for detecting an actual gear ratio from an input side rotational speed and an output side rotational speed of the continuously variable transmission;
Shift control means for controlling the gear ratio of the continuously variable transmission by the target shift speed so that the actual gear ratio matches the target gear ratio;
In a continuously variable transmission shift control device comprising:
The target shift speed calculation means includes input torque detection means for detecting input torque from the prime mover,
Upper limit value calculating means for calculating an upper limit value of the target shift speed based on the input torque, the actual gear ratio, the input side moment of inertia of the continuously variable transmission, and the output side rotational speed;
Target shift speed setting means for setting a target shift speed based on the driving state so as not to exceed the upper limit value;
A transmission control device for a continuously variable transmission.   The upper limit calculating means has a change time calculating means for calculating a value obtained by dividing the product of the actual gear ratio, the input side inertia moment of the continuously variable transmission and the output side rotational speed by the engine torque, as a change time, The shift control device for a continuously variable transmission according to claim 1, wherein a shift speed for shifting by a predetermined speed ratio change amount within the change time is calculated as the upper limit value. The target gear ratio calculating means includes
First target gear ratio calculating means for calculating a first target gear ratio from the accelerator operation amount and the vehicle speed as the driving state;
Second target speed ratio calculating means for calculating a second target speed ratio that follows the first target speed ratio based on the target speed change;
Have
The target shift speed calculation means includes basic value calculation means for calculating a basic value of the target shift speed based on a deviation between the first target speed ratio and the second target speed ratio, and the basic value and the upper limit value Set the smaller one as the target shift speed,
3. The continuously variable transmission according to claim 2, wherein the transmission control unit controls a transmission ratio of the continuously variable transmission based on the target transmission speed so that the actual transmission ratio matches the second target transmission ratio. A transmission control device for a transmission.

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