JP2741029B2 - Transmission control device for continuously variable transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

The present invention relates to a shift control device that performs shift control according to a speed ratio, an engine speed, and the like in a belt-type continuously variable transmission for a vehicle, and more particularly, to a downshift of a continuously variable transmission that occurs with an increase in engine output torque. The correction control.

[Prior art]

Conventionally, in a continuously variable transmission of this type, a shift control system based on detection values such as rotation speeds of a primary pulley and a secondary pulley, a throttle opening, etc., and an engine rotation speed in order to perform a shift control during vehicle running as desired. In the course of obtaining respective duty ratios in a line pressure control system based on detected values such as a throttle opening and a throttle opening, various controls have been proposed in which various corrections are made according to operating conditions. For example, as disclosed in Japanese Unexamined Patent Publication No. 59-231250, a rapid shift detecting means for calculating a change speed of a signal from an engine load sensor, and a correction value corresponding to a degree of the rapid shift calculated by this means are provided. There has been proposed a control device which has a target gear shift correcting means for calculating a target gear shift signal at the time of a sudden gear shift, and corrects the target gear ratio signal read out from the storage device based on the degree of acceleration. I have.

[Problems to be solved by the invention]

By the way, in the above proposed control device, when the engine output torque is increased by increasing the throttle opening during traveling, the primary cylinder pressure Pp and the secondary cylinder pressure for maintaining a constant speed ratio are shown in the characteristic diagram of FIG. Pressure
The ratio Pp / Ps to Ps increases by Δ (Pp / Ps) corresponding to the increase ΔT of the engine output torque. For this reason, as shown in FIG. 6, there has been a problem that the diameter of the primary pulley is reduced, the belt is bent, and a downshift occurs. SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems. Even if there is an increase in torque to the continuously variable transmission during traveling, the primary pressure is corrected so that a downshift phenomenon does not occur. It is an object of the present invention to provide a shift control device for a step transmission.

[Means for solving the problems]

In order to achieve the above object, the present invention has a detection unit that detects an actual gear ratio, an engine torque, and a secondary pressure that are detected according to an operation state, and detects a detection that is detected by the detection unit when the engine torque increases. Correction value searching means for inputting a value to search for a correction value of the primai pressure according to the increase in engine torque; and inputting the primary pressure correction value obtained from the secondary pressure detection value and the correction value searching means to input the primary pressure correction value. Correction means for correcting pressure.

[Action]

Based on the above configuration, when the engine output torque is increased while the vehicle is running, the output of the simple correction means increases the primary cylinder pressure by an amount corresponding to the increased engine output torque, so that the ratio between the primary cylinder pressure and the secondary cylinder pressure is predetermined. Since the unbalance between the two pressures due to the value not reaching the value does not occur, a downshift caused by an increase in the engine output torque is prevented in real time.

【Example】

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In FIG. 1, the overall configuration of a drive system in which a belt-type continuously variable transmission is combined with an electromagnetic clutch will be described. The engine 1 is connected to a continuously variable transmission 4 via an electromagnetic clutch 2 such as an electromagnetic powder type and a forward / reverse switching device 3, and is connected to the continuously variable transmission 4 from the continuously variable transmission 4.
The transmission gears are configured to be transmitted to drive wheels 9 via a set of reduction gears 5, output shafts 6, differential gears 7, and axles 8. The electromagnetic powder type clutch 2 has a drive member 2a on an engine crankshaft 10 and a driven member 2b having a clutch coil 2c on an input shaft 11. And clutch coil 2c
The electromagnetic powder is coupled and accumulated in the gap between the two members 2a and 2b in a chain by the clutch current flowing through the clutch, and the clutch engagement / disengagement and clutch torque are variably controlled by the coupling force. The forward / reverse switching device 3 is synchronously meshed with a gear, a hub, and a sleeve between the input shaft 11 and the transmission main shaft 12, and includes a forward position at which the input shaft 11 is directly connected to the main shaft 12, and an input shaft. And a retracted position for transmitting the rotation of the rotation 11 to the main shaft 12 in the reverse direction. The continuously variable transmission 4 includes a main shaft 12 and a sub shaft arranged in parallel with the main shaft 12.
The primary shaft 12 is provided with a primary pulley 14 having a hydraulic cylinder 14a having a hydraulic cylinder 14a and the secondary shaft 13 is similarly provided with a secondary pulley 15 having a hydraulic cylinder 15a. A drive belt 16 is wound around both pulleys 14 and 15, and both cylinders 14a and 15a are configured as a hydraulic control circuit 17. Then, a line pressure according to the transmission torque is supplied to both cylinders 14a and 15a to apply a pulley pressing force, and the primary pressure changes the ratio of the winding diameter of the drive belt 16 to the pulleys 14 and 15 to continuously change the speed. It is configured to control. Next, an electronic control system of the electromagnetic powder type clutch 2 and the continuously variable transmission 4 will be described. Engine speed sensor 19 for engine 1 and primary pulley speed sensor 2 for continuously variable transmission 4
1, a secondary pulley rotation speed sensor 22, and sensors 23 and 24 for detecting the operation status of the air conditioner and the choke. Also,
The shift lever 25 of the operation system is mechanically coupled to the forward / reverse switching device 3 and has a shift position sensor 26 for detecting each range of reverse (R), drive (D), and sporty drive (Ds). Further, the accelerator pedal 27 has an accelerator switch 28 for detecting an accelerator depression state,
A throttle opening sensor 29 is provided on the throttle valve side. The various signals of the switches and the sensors are input to the electronic control unit 20 and processed by software using a microcomputer or the like. The clutch control signals in the start, drag, and direct connection modes output from the electronic control unit 20 are input to the electromagnetic clutch 2, and the shift control signal and the line pressure control signal are input to the hydraulic control circuit 17 of the continuously variable transmission 4. The operation is performed. 2, the electromagnetic clutch control system and the continuously variable transmission control system of the control unit 20 will be described. First, the electromagnetic clutch control system includes a reverse excitation mode determination unit 32 to which signals of the engine speed Ne and the neutral (N) and parking (P) ranges other than R, D, and Ds of the shift position sensor 26 are input. For example, in the case of Ne <300 rpm or in the case of the P and N ranges, the reverse excitation mode is determined, and the output determining unit 33 allows a small current in a direction opposite to the normal direction to flow. Then, the electromagnetic clutch 2 is completely released except for the residual magnetism. Further, there is provided an energization mode determination unit 34 to which a determination output signal of the reverse excitation mode determination unit 32, a depression signal of the accelerator switch 28, and a rotation (hereinafter referred to as vehicle speed V) signal of the secondary pulley rotation speed sensor 22 are input. And the like, and the discrimination signal is input to the start mode current setting unit 35, the drag mode current setting unit 36, and the direct connection mode current setting unit 37. The start mode current setting unit 35 sets the start characteristics individually in relation to the engine speed Ne and the like in the case of normal start or start using the air conditioner and choke. Then, the starting characteristics are corrected based on the travel ranges of the throttle opening θ and the vehicle speeds V, R, D, and Ds, and the clutch current is set. The drag mode current setting unit 36 determines a small drag current when the accelerator is released at a low vehicle speed in each range of R, D, and Ds,
A drag torque is generated in the electromagnetic clutch 2 to reduce the play of the belt and the drive system, thereby smoothly starting the vehicle. In this mode, the current is determined to be zero current until just before the vehicle stops after the clutch in the D range is released, thereby ensuring the coasting. The direct-coupling mode current setting unit 37 determines the direct-coupling current based on the relationship between the vehicle speed V and the throttle opening θ in each of the ranges of R, D, and Ds, fully engages the electromagnetic clutch 2, and saves power in the engaged state. . The output signals of these current setting units 35, 36, and 37 are input to the output determination unit 33, and the clutch current is determined according to the instruction. Next, regarding the shift speed control system of the continuously variable shift control, the primary pulley speed Np and the secondary pulley speed Ns of the primary pulley speed sensor 21 and the secondary pulley speed sensor 22 are input to the actual speed ratio calculating unit 40. , The actual speed ratio i is calculated from the actual speed ratio i = Np / Ns. The actual gear ratio i and the throttle opening θ of the throttle opening sensor 29
Is input to the target primary rotation speed search unit 41, and the target primary rotation speed NPD is searched using the i-θ map based on the shift pattern for each of the R, D, and Ds ranges. The target primary speed NPD and the secondary speed Ns are calculated by the target gear ratio calculation unit.
The target speed ratio is is calculated by is = NPD / Ns. Then, the target speed ratio is input to the target speed ratio change speed calculating section 43, and the target speed ratio change speed dis / dt is calculated based on the amount of change of the target speed ratio is for a certain period of time. The actual gear ratio i, the target gear ratio is, and the target gear ratio change speed dis / dt
And the coefficients K ₁ and K ₂ of the coefficient setting unit 44 are input to the shift speed calculating unit 45, and the shift speed di / dt is calculated as follows. di / dt = K ₁ (is−i) + K ₂ · dis / dt In the above equation, is−i is a control amount of the target and actual speed ratio deviation, and dis / dt is a delay correction element of the control system. The gear speed di / dt and the actual gear ratio i are the duty ratio search units.
Enter 46. Here, the duty ratio D of the manipulated variable is D
= F (di / dt, i), the duty ratio D becomes di / dt in upshift and downshift.
-Searched using the map of i. Then, the value of the duty ratio D of the manipulated variable is input to a duty ratio correction unit 49, where a duty ratio correction described later is performed, and a shift of the hydraulic control circuit 17 is performed via the drive unit 47 by the output correction duty ratio Dc. Output to the speed control solenoid valve 48. Subsequently, a line pressure control system of the continuously variable transmission control will be described. Engine speed sensor 19, throttle opening sensor 29
And an engine torque search unit 50 to which the engine speed Ne and the throttle opening θ are inputted, and obtains the engine torque T from the torque characteristic map of θ-Ne. This engine torque T
And the signal of the actual speed ratio i of the actual speed ratio calculation unit 40 is input to the target line pressure setting unit 51, and the target run-in pressure PLd is determined by the product of the required line pressure according to the engine torque and the actual speed ratio i.
On the other hand, since the maximum value of the line pressure fluctuates as the pump discharge pressure changes depending on the engine speed, the maximum line pressure search unit 52 for inputting the engine speed Ne and the actual speed ratio i to detect this fluctuation state. And the maximum line pressure PLmax is obtained from the Ne-i map. The target line pressure PLd and the maximum line pressure PLmax are input to the pressure reduction value calculation unit 53, and the line pressure PLR is calculated by the ratio of the target line pressure PLd to the maximum line pressure PLmax.
To determine the duty ratio D according to the line pressure PLR. The duty signal is output to the line pressure control solenoid valve 56 via the drive unit 55. Further, the output engine torque T from the engine torque search unit 50 in the line pressure control system, the target line pressure setting unit
The output target run-in pressure PLd from 51 and the actual gear ratio i from the actual gear ratio calculator 40 of the gear speed control system are used as a correction value search unit.
57, and in the correction value search unit 57, the sixth
A search is made for a correction signal for correcting a downshift caused by the reduction phenomenon of the primary pulley diameter shown in the figure. That is, the correlation between the ratio Pp / Ps of the target line pressure PLd (hereinafter referred to as the secondary pressure Ps) to the primary pressure Pp, and the engine torque T and the actual gear ratio i is the characteristic shown in FIG. Based on the primary pressure correction signal Δ (Pp
/ Ps) and retrieve this primary pressure correction signal Δ (Pp / Ps)
And the secondary pressure Ps is input to the duty ratio correction unit 49, and the duty ratio D is corrected to correct the duty ratio Dc.
Is output, and the solenoid valve 48 is operated via the drive section 47. Next, the operation of the thus configured shift control device for a continuously variable transmission will be described. First, the power corresponding to the depression of the accelerator from the engine 1 is input to the primary pulley 14 of the continuously variable transmission 4 via the electromagnetic clutch 2 and the forward / reverse switching device 3, and the drive belt 16,
The power is shifted by the secondary pulley 15 and is transmitted to the drive wheels 9 to travel. During the traveling, the target line pressure is set to be larger as the engine torque T is larger in the low speed stage where the value of the actual speed ratio i is larger, and a duty signal corresponding to this is input to the solenoid valve 56 to regulate the control pressure. by Gosuru line pressure in the averaged pressure, to increase the line pressure P _L. Then, as the speed ratio i decreases and the engine torque T decreases as the speed shifts to the higher gear, the line pressure P _L is controlled to decrease by acting in the same manner. A pulley pressing force corresponding to the transmission torque acts. The line pressure P _L is always supplied to the secondary cylinder 15a, and the shift speed is controlled by supplying and discharging oil to and from the primary cylinder 14a by a shift speed control valve (not shown) by the control pressure of the solenoid valve 48. This will be described below. First, the signals Np, Ns, and θ from the primary pulley rotation speed sensor 21, the secondary pulley rotation speed sensor 22, and the throttle opening sensor 29 are read, and the actual gear ratio calculation unit 40 of the control unit 20 obtains the actual gear ratio i. . Further, the target primary rotation speed search unit 41 outputs R, D, Ds from the shift position sensor 26.
The target primary rotational speed NPD is once retrieved from a map based on the actual gear ratio i and the throttle opening θ on the basis of the gear shift pattern for each range, and the target gear ratio calculating section 42 sets the target corresponding to the target primary rotational speed NPD. The gear ratio is is calculated. Therefore, in the region where the primary speed is constant, the target speed ratio is becomes the same fixed value as calculated by the Ns-θ method, but in the region where the primary speed is variable, the target speed ratio is
is is set to be offset toward the lower gear, as compared with that calculated by the Ns-θ method, and the target speed ratio is is a value that changes by itself. Using the actual gear ratio i, the target gear ratio is, the dis / dt of the target gear ratio change speed calculator 43, and the coefficients K ₁ and K ₂ of the coefficient setting unit 44, the gear speed calculator 45 uses the gear speed di / dt. Ask for. Then, the duty ratio search unit 46 searches the duty ratio D based on the shift speed di / dt and the actual speed ratio i. Here, the engine torque T is changed to increase from T ₀ to T _1, the actual transmission ratio i based on the relationship characteristic diagram of Figure 3
Is a constant value ic, Pp / Ps is changed from Pp ₀ / Ps ₀ corresponding to the intersection A of the ic line and the characteristic curve of T ₀ to Pp ₁ / Ps corresponding to the intersection B of the characteristic curve of T _1. Must be changed to a value of ₁ . For this reason, the correction value search unit 57 outputs the correction signal Δ
(Pp / Ps) = Pp ₁ / Ps ₁ −Pp ₀ / Ps ₀ is searched, and the duty ratio correction unit 49 corrects the duty ratio D based on this correction signal. The execution procedure control of the above operation will be described with reference to the flowchart of FIG. 4 and the characteristic diagram of FIG. First, it seeks engine torque T ₀ in step S101, the current gear ratio ic in step S102, searches the Pp ₀ / Ps ₀ in the engine torque T ₀ when the control amount setting (A point). Then, the current engine torque T ₁ which increased in step S103, searches the Pp ₁ / Ps ₁ corresponding to the current speed ratio ics (B point). Then, the flow shifts to step S104, where the correction signal Δ
(Pp / Ps) = calculates the _{Pp 1 / Ps 1 -Pp 0 /} Ps 0, step S105
Then, the duty ratio D is corrected based on the correction signal, and a corrected duty ratio Dc is output. The duty output signal is input to a solenoid valve 48 to generate a pulse-like control pressure, thereby controlling the shift speed control valve (not shown) repeatedly at two positions of oil supply and oil discharge. Here, when the duty ratio decreases, the operation time of the shift speed control valve at the refueling position increases due to the off-time, and the shift speed control valve refuels the primary cylinder 14a, thereby performing an upshift. On the other hand, when the duty ratio increases,
Conversely, the operating time at the oil discharge position is prolonged due to the on-time, so that the primary cylinder 14a is oil-discharged, thereby downshifting. Here, when the engine torque is increased, the ratio Δ (Pp / Ps) between the primary pressure and the secondary pressure corresponding to the increase ΔT of the engine torque is generated in response to ΔT, so that the primary cylinder 14a and the secondary cylinder Cylinder 15a
There is no imbalance between the control pressures acting on each of the two.

【The invention's effect】

As described above, according to the present invention, when the engine torque increases while the vehicle is running, the duty ratio for operating the primary cylinder is corrected without delay according to the increase in the engine torque. In addition, the downshift phenomenon at the time of a sudden increase in engine torque can be prevented.

[Brief description of the drawings]

FIG. 1 is a block diagram schematically showing a shift control device according to one embodiment of the present invention, FIG. 2 is a block diagram of an electric control system, FIG. 3 is a characteristic diagram of engine torque and actual gear ratio, and FIG. FIG. 5 is a flowchart of the operation of the present invention, FIG. 5 is a characteristic diagram of the engine torque and the actual gear ratio, and FIG. 6 is a schematic diagram showing the behavior of the primary pulley, the secondary pulley and the belt when the engine torque increases. 4 ... continuously variable transmission, 15a ... secondary cylinder, 17 ...
... Hydraulic control circuit, 20 ... Electronic control unit, 40 ... Actual gear ratio calculator, 42 ... Target gear ratio calculator, 45 ... Shift speed calculator, 46 ... Duty ratio search unit, 48 ... Shift Control solenoid valve, 49: Duty ratio correction unit, 57: Correction value search unit.

Claims (1)

(57) [Claims] An engine having a detection unit for detecting an actual gear ratio, an engine torque, and a secondary pressure detected according to an operation state, and inputting a detection value detected by the detection unit when the engine torque increases. Correction value searching means for searching for a primary pressure correction value corresponding to an increase in torque; correcting means for correcting the primary pressure by inputting the secondary pressure detection value and the primary pressure correction value obtained from the correction value searching means And a shift control device for a continuously variable transmission.