JP2599291B2 - Transmission control device for continuously variable transmission - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shift control device that electronically controls a shift in a belt-type continuously variable transmission for a vehicle, and more particularly, to a D-jetronic fuel injection system. And an upshift delay control immediately after the accelerator is released when combined with an engine that performs fuel cut control.

[Conventional technology]

Shift control of this type of continuously variable transmission is based on upshifting or downshifting based on the relationship between the accelerator opening and the engine speed, and the target is to improve the shift response and convergence. A method of electronically performing follow-up control by determining a gear ratio has also been proposed. Therefore, when the accelerator is released from the accelerator depression state as shown by the solid line in FIG. 4, the engine is upshifted to the overdrive side as shown in FIG. 4B, and the engine speed is reduced as shown in FIG. Improves and decelerates with moderate engine braking.

By the way, when the accelerator is released, an increase in the engine negative suction pressure is suppressed due to a rapid decrease in the engine speed due to the upshift, and the negative pressure changes in a shallow state as shown in (d). Therefore, in the case of the D-jetronic system in which the engine calculates the fuel injection amount based on the suction negative pressure and the engine speed, the fuel immediately after the accelerator is opened becomes large due to the shallow suction negative pressure as shown in (e). On the other hand, when the fuel is cut after the accelerator is released, a large change in fuel increases the shock and jerky feeling.

Therefore, in a drive system in which an engine that performs fuel injection control by the D-Jetronic method and a continuously variable transmission are combined, measures are required at the time of an upshift when the accelerator is released. As a countermeasure in this case, it is conceivable that the fuel injection amount is reduced and corrected in accordance with the upshift state on the engine side, but this is not preferable because control becomes complicated. On the other hand, there is no problem even if the upshift is delayed when the accelerator is released in the continuously variable transmission, and the delay of the upshift may cause the engine speed to be temporarily kept high and increase the suction negative pressure. Therefore, it is considered effective to correct the shift control on the continuously variable transmission side to take measures.

Conventionally, as a countermeasure for upshifting of the continuously variable transmission, there is a prior art disclosed in, for example, Japanese Patent Application Laid-Open No. 58-94663.
Here, it is shown that surplus oil of the pressure regulating valve is supplied to the hydraulic servo of the primer pulley to perform a pre-feeling operation, thereby reducing a shift response delay.

[Problems to be solved by the invention]

Incidentally, the prior art described above is to fill the hydraulic servo of the primary pulley with oil in advance at the time of starting a shift, and does not deal with an upshift when the accelerator is released during the shift process.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a continuously variable transmission combined with an engine that performs fuel injection control in a D-Jetronic system so that engine-side fuel injection can be properly performed when an accelerator is released. SUMMARY OF THE INVENTION It is an object of the present invention to provide a shift control device for a continuously variable transmission capable of correcting an upshift to reduce fuel consumption, fuel cut shock, and the like.

[Means for solving the problem]

In order to achieve the above object, the present invention provides an accelerator opening,
A gearshift control device that performs fuel injection control together with gearshift control by combining a continuously variable transmission that performs gearshift control with factors such as vehicle speed and engine speed, and an engine that performs fuel injection control in a D-jetronic system. Sometimes, an upshift is delayed to reduce the fuel injection amount by the D-Jetronic method, and after the delay of the upshift is completed, if the engine speed is equal to or higher than a set value, a control means for performing a fuel cut together with the upshift is provided. It is characterized by the following.

[Action]

Based on the above configuration, in the continuously variable transmission, when the accelerator is released, the shift control is performed so as to delay the upshift. At this time, the engine is driven by the wheels to cause an increase in the suction negative pressure, and the D jetronic fuel The injection quantity is effectively reduced and corrected. After the delay of the upshift, when the engine speed is equal to or higher than the set speed, fuel economy control for performing fuel cut together with the upshift is performed. Is performed, the shock at the time of fuel cut is reduced, and smooth control becomes possible.

〔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 configured in a synchronous meshing manner between an input shaft 11 and a transmission main shaft 12 by a gear, a hub and a sleeve, and includes a forward position for connecting at least the input shaft 11 to the main shaft 12; 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 constitute 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. It has a secondary pulley rotation speed sensor 22. The shift lever 25 of the operation system is mechanically coupled to the forward / reverse switching device 3, and includes a shift position sensor 26 for detecting each range of reverse (R), drive (D), and sporty drive (Ds). Have. Further, 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 signal output from the electronic control unit 20 is 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 to perform each control operation. I have.

Referring to FIG. 2, the stepless speed change control system of the control unit 20 will be described. To calculate the actual speed ratio i from the actual speed ratio i = Np / Ns. The actual gear ratio i and the throttle opening θ of the throttle opening sensor 29 are input to the target primary pulley rotation speed search unit 41, and i− based on the speed change pattern for each of the R, D, and Ds ranges.
The target primary pulley rotation speed NPD is searched using the map of θ. The target primary pulley rotation speed NPD and the secondary pulley rotation speed Ns are input to a target gear ratio calculator 42, and a target response gear ratio is is calculated by is = NPD / Ns. The target speed ratio is input to the target speed ratio change speed calculation unit 43 via the correction unit 35 described later, and is input to the target speed ratio is
The target speed ratio change speed dis / dt is calculated from the change amount of the target speed ratio. The actual gear ratio i, the target gear ratio is, 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 gear speed calculator 45, and the gear speed di / dt is calculated. It 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. The value of the duty ratio D of the manipulated variable is supplied to the hydraulic control circuit
Output to the 17 speed change 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 rotation speed Ne and the throttle opening θ are inputted, and obtains the engine torque T from the torque characteristic map of θ-Ne. The signal of the engine torque T and the actual transmission ratio i of the actual transmission ratio calculation unit 40 is input to a target line pressure setting unit 51, and the target line pressure PLd is calculated by multiplying the required line pressure according to the engine torque by the actual transmission ratio i. Is determined. 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 P is calculated as a ratio of the target line pressure PLd to the maximum line pressure PLmax.
LR is calculated, and this is input to the duty ratio search unit 54 to determine the duty ratio D according to the line pressure LR.
The duty signal is output to the line pressure control solenoid valve 56 via the drive unit 55.

Next, the fuel injection control system of the D-Jetronic system of the engine 1 will be described. First, the D JETRONIC system utilizes the fact that the absolute pressure of the intake manifold is substantially proportional to the amount of intake air, and has a pressure sensor 23 for detecting this intake negative pressure. Then, the suction negative pressure P and the engine speed Ne are input to the basic injection amount calculation unit 24, and the basic injection amount Tp is calculated based on the relationship between the two. The basic injection amount Tp is input to the fuel injection amount calculation unit 25, and the fuel injection amount Ti is calculated by using a feedback coefficient α, various correction coefficients K, and a fuel cut coefficient KF in addition to the basic injection amount Tp, and Ti = Tp · α • Calculate from (1 + K) · KF. Then, an injection pulse corresponding to the fuel injection amount Ti is output to the injector 27 via the drive unit 26.

Further, the fuel cut control system has a deceleration determining unit 30 to which the vehicle speed V from the secondary pulley rotation speed sensor 22 corresponding to the throttle opening θ and the vehicle speed is input, and determines the deceleration when the accelerator is released at a speed higher than the set vehicle speed. . The deceleration signal and the engine speed Ne are input to the fuel cut determination unit 31.
Since the continuously variable transmission 4 is upshifted when the accelerator is released and the engine speed decreases, the fuel cut signal is sent to the fuel injection amount calculation unit 25 when the engine speed after a predetermined time by the timer 32 is equal to or greater than a set value. Output, and the fuel cut coefficient KF is determined from 1 to 0.

Therefore, the control system has an upshift delay unit 33 to which a deceleration signal is input as a measure for correcting the fuel injection amount when the accelerator is released. The upshift delay unit 33 has a timer 34, and the output side correction unit 35 of the target gear ratio calculation unit 42 holds the target gear ratio is for a predetermined time before the accelerator is released, thereby delaying the start of the upshift. ing.

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 that is shifted by the secondary pulley 15 is output, and the power is transmitted to the drive wheels 9 so that the vehicle travels.

During the traveling, the target line pressure is set to be larger as the engine torque T is larger in a low speed stage where the value of the actual speed ratio i is larger, and a corresponding duty signal is input to the solenoid valve 56 to generate a control pressure. The line pressure PL is increased by controlling the line pressure with the averaged pressure. Then, as the gear ratio i becomes smaller and the engine torque T becomes smaller as the gear shifts to the higher gear, the line pressure PL is controlled so as to decrease in the same manner, so that the transmission by the drive belt 16 is always performed. A pulley pressing force corresponding to the torque acts.

The line pressure PL is always supplied to the secondary cylinder 15a, and the transmission speed is controlled by supplying and discharging oil to and from the primary cylinder 14a by a transmission speed control valve (not shown) by the control pressure of the solenoid valve 48. 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. . The target primary pulley rotation speed search unit 41 once searches the map for the target primary pulley rotation speed NPD based on the actual gear ratio i and the throttle opening θ, and the target gear ratio calculation unit 42 corresponds to the target primary pulley rotation speed NPD. The calculated target gear ratio is is calculated. Therefore, in the region where the primary pulley rotation speed is constant, the target speed ratio is has the same fixed value as calculated by the Ns-θ method, but in the region where the primary pulley rotation speed is variable, the target speed ratio is Ns−. As compared with the value calculated by the θ method, it is set to be offset toward the lower gear, and the target speed ratio 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 changes the gear speed di. Find / dt. 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.

The duty signal is input to a solenoid valve 48 to generate a pulse-like control pressure, whereby the shift speed control valve is repeatedly operated at two positions of oil supply and oil discharge. Here, when the duty ratio becomes small, the operation time at the refueling position becomes longer due to the off time, and the primary cylinder
Refueling at 14a, thus upshifting. On the other hand, when the duty ratio increases, the operating time at the oil discharge position becomes longer due to the on-time, and the primary cylinder 14a is drained, thereby causing a downshift.
Since the shift speed di / dt in this case corresponds to a change in the duty ratio, when the deviation between the target speed ratio is and the actual speed ratio i is small, the change in the duty ratio is small and the flow rate change of the primary cylinder 14a is small. The gear speed is slowed down due to the small number of gears. On the other hand, as the deviation between the target speed ratio is and the actual speed ratio i increases, the change in the duty ratio causes the flow rate change of the primary cylinder 14a to increase, and the speed change speed increases.

In this way, in the entire shift range of the low-speed gear and the high-speed gear, the upshift or downshift is performed while changing the shift speed, and the gear is continuously changed.

On the other hand, in the engine 1, the suction negative pressure P
And the engine speed Ne, the basic injection amount Tp is calculated,
Since the fuel cut coefficient KF is 1 except for the fuel cut, the fuel injection amount calculation unit 25 uses the basic injection amount Tp, the feedback coefficient α, various correction coefficients K, and the like to determine the fuel injection amount Ti according to each engine operating condition. Is calculated. Then, an injection pulse is output to the injector 27 in accordance with the fuel injection amount Ti and fuel is injected.

Here, when the accelerator pedal is depressed, the continuously variable transmission 4 downshifts to a relatively low speed side, and the engine speed is high and the fuel injection amount is large. When the accelerator is released from this state as shown in FIG. 4 (a), the deceleration judging section 30 judges that the vehicle is decelerating, and its signal is input to the upshift delay section 33, and the correcting section 35 sets the target gear ratio is to the predetermined time t. _The upshift is started with a delay of ₁ as shown by the broken line in FIG. 4 (b). Then, at this time, the engine output is reduced by opening the accelerator, while the speed ratio of the continuously variable transmission 4 is large, so that the engine 1 is driven from the wheel side and the engine 1 is driven as shown by the broken line in FIG. While keeping the rotation speed high, the suction negative pressure changes deeply as shown by the broken line in FIG. 4 (d).

Therefore, the fuel injection amount Ti together with the basic injection amount Tp in the basic injection amount calculation section 24 of the engine 1 decreases as shown by the broken line in FIG. Further, since the deceleration signal when the accelerator is opened also input to the fuel cut determining section 31, to 0 the fuel cut coefficient KF outputs the fuel cut signal at the end of a substantially upshift after a predetermined time t _2,
The fuel injection amount Ti also becomes 0 and the fuel is cut. At this time, the fuel injection amount Ti is reduced as described above, so that the process smoothly shifts to the fuel cut.

According to another embodiment of the present invention shown in FIG. 3, a correction unit 35 is provided on the output side of the shift speed calculation unit 45, and the shift speed di / dt is reduced by a predetermined time by a signal of the upshift delay unit 33. Correction as follows. In this case, the coefficient K ₁ or the shift speed di
What is necessary is just to correct the decrease of the value of / dt itself. Therefore, in this embodiment, after the accelerator is released, the upshift is gradually performed as indicated by the one-dot chain line in FIG. 4 (b), and the fuel injection amount is reduced in the same manner as described above.

 The present invention is not limited only to the above embodiment.

〔The invention's effect〕

As described above, according to the present invention, in the upshift when the accelerator of the continuously variable transmission is opened, the upshift is delayed and corrected, so that the suction negative pressure on the engine side increases and the D The fuel injection amount is effectively reduced. In addition, the shock at the time of fuel cut is reduced accordingly.

Further, since the delay is corrected at the time of the upshift, there is no responsiveness problem unlike the case of the downshift.

[Brief description of the drawings]

1 is a block diagram showing a drive system of a continuously variable transmission to which the present invention is applied, FIG. 2 is a block diagram showing an embodiment of a shift control device, FIG. 3 is a block diagram showing another embodiment, FIG. 4 is a time chart showing a fuel cut state. DESCRIPTION OF SYMBOLS 1 ... Engine, 4 ... Continuously variable transmission, 20 ... Control unit, 25 ... Fuel injection amount calculation part, 30 ... Deceleration determination part, 31 ...
... Fuel cut determination unit, 33 ... Upshift delay unit, 34 ...
... Timer, 35 ... Correction unit

Claims (2)

(57) [Claims] 1. A gear shift control system that performs fuel injection control together with gear shift control by combining a continuously variable transmission that controls gear shift based on factors such as accelerator opening, vehicle speed, and engine speed, with an engine that controls fuel injection by a D-Jetronics method. In the control device, when the accelerator pedal is released from the accelerator depressed state, the upshift is delayed and the fuel injection amount by the D-jetronic method is corrected to be reduced. After the delay of the upshift, if the engine speed is equal to or higher than the set value, the upshift is performed. And a control means for performing a fuel cut. 2. The stepless control device according to claim 1, wherein the control means for delaying the upshift delays the start of the upshift for a predetermined time or reduces the speed of the upshift. Transmission control device for transmission.