JPS63154435A - Method of controlling continuously variable transmission for vehicle - Google Patents

Abstract

PURPOSE:To prevent a shock caused when a speed is changed, by reducing an engine output in accordance with a car speed when the car speed is in a low car speed region where an auxiliary transmission provided with a continuously variable transmission is shifted from a gear position of a large speed change ratio to a gear position of a small speed change ratio. CONSTITUTION:A continuously variable transmission 14 comprising a variable speed pulleys 22, 28 with a transmission belt 22 stretched therebetween has an input shaft 16 coupled with an engine 10 and an output shaft 24 coupled with an auxiliary transmission 30 having two or more forward gear positions and capble of switching a forward and rearward rotations. The rotation of the output shaft (carrier) 44 of the auxiliary transmission 30 is transmitted to a drive wheels 52 via intermediate gears 46, 48 and a final reducer 50. In the case, when an automobile speed is a region of a low speed where the auxiliary transmission 30 is shifted from a gear position of a large speed change ratio to a gear position of a small speed change ratio, a controller 54 controls a throttle actuator 63 to cause an output of an engine 10 to be reduced in accordance with a car speed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of controlling a continuously variable transmission for a vehicle equipped with an auxiliary transmission, and particularly to a method of controlling the auxiliary transmission during gear changes.

[Prior Art] Conventionally, a CVT (belt-type continuously variable transmission) and an auxiliary transmission of a vehicle continuously variable transmission having one auxiliary transmission that can be switched to two or more forward gears have been operated depending on the driving state of the vehicle. Various technologies have been proposed to improve the driving performance of a vehicle by comprehensively controlling the speed change according to the
No. 67, Japanese Patent Application No. 60-278533, etc.).

[Problems to be Solved by the Invention] However, in such conventional continuously variable transmissions, there is a problem in that when the N1 transmission is shifted, the acceleration force of the vehicle increases and the shift feeling deteriorates. there were.

This is because, as shown in Fig. 8, when the vehicle speed VS is upshifted, the engine speed Ne suddenly decreases from Ne to Neh, and as shown by the solid line in Fig. 9, the driving force F changes from Fl to Fh during the upshift. This is because it decreases in a stepwise manner.

In addition, in order to improve the occurrence of the above problem, by shifting the auxiliary transmission at a higher vehicle speed yt, small differences in engine speed Ne (
Nel-Net) Te, moreover, the small difference in driving force F (
It is also possible to switch the sub-transmission from a low-speed gear to a high-speed gear in the state of F lt-Fht), but in this case, the planetary gear in the sub-transmission is directly connected up to the vehicle speed Vt. Otherwise, new problems such as reduced durability and reduced fuel consumption may occur.

In a stepped automatic transmission using a torque converter, this problem occurs because the torque converter has a stepless torque ratio decreasing characteristic. This does not occur due to a smooth transition. Therefore, there has been a strong desire to improve this problem, which is unique to continuously variable transmissions.

An object of the present invention is to solve the above problems and improve the feeling of shifting and the feeling of acceleration.

[Means for Solving the Problems] As a means for achieving the object of the present invention, as illustrated in FIG. A sub-transmission provided in the transmission and capable of switching to two or more forward gears is switched based on the driving state of the vehicle, including at least the vehicle speed (steps SCa, SCb), and the gear ratio of the continuously variable transmission is controlled. (Step SD) In the method, when the vehicle speed or the auxiliary transmission is in a low speed region of the vehicle speed where the sub-transmission is shifted from a gear with a high gear ratio to a gear with a small gear ratio (Step SA), the output of the engine (step SB).

Control to reduce the output of the engine is performed, for example, by reducing the intake depth, retarding the ignition timing, controlling the air-fuel ratio to the lean side, or changing the exhaust gas recirculation direction.

Reducing the engine output according to the vehicle speed means, for example, when the vehicle speed increases and reaches a low speed region between the upshift vehicle speed and the vehicle speed ψ predetermined vehicle speed lower than the upshift vehicle speed, the engine output is reduced. , and then increase the reduction ω of the engine output as the vehicle speed increases.

[Operation] The control method for a continuously variable transmission for a vehicle according to the present invention reduces the output of the engine in accordance with the vehicle speed in the low speed region of the vehicle where the sub-transmission is upshifted.

Thereby, there is a smooth transition from the driving force of the vehicle before the sub-transmission is upshifted to the driving force of the vehicle after the sub-transmission is up-shifted.

[Example 1] Hereinafter, an example of the present invention will be described in detail based on the drawings.

In FIG. 2, a vehicle engine 10 is connected to an input shaft 16 of a continuously variable transmission 14 via a fluid coupling 12 with a lock-up clutch. The input shaft 16 is provided with a variable pulley 22 whose V-groove width, ie, the diameter of the transmission belt 20, is changed by the hydraulic cylinder 18. The output shaft 24 is provided with a variable pulley 28 whose V-groove width is changed by a hydraulic cylinder 26 . Therefore, the rotational force transmitted to the input shaft 16 is transferred to the variable pulley 2.
The transmission is transmitted to the output shaft 24 via the transmission belt 20 that is wound around
transmitted to. The sub-transmission 3° is the first sun gear 32. 2nd Sangir 34. It is equipped with a Ravignaux-type compound planetary gear device consisting of a ring gear 36, etc., and a high-speed clutch 38.
Low speed brake 40. By selectively operating the reverse brake 42 by a hydraulic actuator (not shown), the auxiliary gear is switched to a gear ratio R of 30, or the forward rotation and reverse rotation are switched, as shown in Table 1 below. It has become.

Table 1 Here, in Table 1, ρ1 is Zsl/zr, and ρ2 is Z
s2/Zr. However, ZSI is the 1st Sangia 3
2, ZS2 is the number of teeth of the second sun gear 34, and Zr is the number of teeth of the ring gear 36. Belt type continuously variable speed 1114
The output shaft 24 of the auxiliary transmission 130 constitutes an input shaft of the auxiliary transmission 130, and the carrier 44 that supports the planetary gear in the auxiliary transmission 130 constitutes an output shaft.
The value is obtained by dividing the rotation speed of the output shaft 24 by the rotation speed of 4. The rotational force transmitted to the carrier 44 is transmitted to the intermediate gear 46.
48 and a final reduction gear 50, the signals are transmitted to a pair of drive wheels 52 of the vehicle.

In the vicinity of the variable pulleys 22 and 28, an input shaft rotation speed sensor 58 and an output shaft rotation speed sensor 60 are provided for outputting pulse signals SP1 and SP2 of frequencies corresponding to the rotation speeds of the variable pulleys 22 and 28 to the controller 54. is provided. A vehicle speed sensor 61 is provided near the intermediate gear 48 for outputting a pulse signal SV of a frequency corresponding to the rotation speed of the intermediate gear 48 to the controller 54. A throttle valve 62 installed in the intake pipe of the engine 10 is provided with a throttle actuator 63 and a throttle sensor 64 that open and close the throttle valve 62 according to commands from a controller 54. degree θ
A throttle signal Sθ representing Sθ is supplied to the controller 54. The throttle valve 62 is normally operated when the accelerator is depressed.
The opening degree is controlled based on the accelerator depression maximum signal Sτ representing the accelerator depression amount τ from the sensor 65.

In this embodiment, a shift lever is used as a shift switching device.
66 is used, and the operation position sensor 68 detects the operation position of the shift lever 66.
A signal SP representing the shift operation position @Psh of 66 is supplied to the controller 54.

This shift lever 66 is mechanically associated with a manual valve in the hydraulic circuit 70, and when operated to the neutral range, the high speed clutch 38. Low speed brake 40. Hydraulic pressure is prevented from being supplied to any of the hydraulic actuators for operating the reverse brakes 42, but when the reverse range is operated, hydraulic oil is supplied only to the hydraulic actuators that operate the reverse brakes 42. let Further, when the shift lever 66 is operated to the normal driving range (D=nidry range) of the forward range, it allows hydraulic oil to be supplied only to the hydraulic actuator that operates the high speed clutch 38, The high speed gear stage is maintained.Also, the shift lever 66 is set in the automatic shift range (S range) of the forward range or the engine brake range (
L range), high-speed clutch 3
Hydraulic oil is allowed to be supplied to either of the respective hydraulic actuators that actuate the brake 8 and the low speed brake 40. Hydraulic pressure is alternatively supplied to these hydraulic actuators from a shift valve that operates in response to the operation of a shift electromagnetic valve 72 provided in the hydraulic circuit 70.

The hydraulic circuit 70 supplies line hydraulic pressure regulated in accordance with the actual gear ratio of the continuously variable transmission 14 and the output torque of the engine 10 to the hydraulic cylinder 26 provided on the output shaft 24, and control the tension as necessary and sufficient. Further, the hydraulic circuit 70 supplies or discharges hydraulic oil to the hydraulic cylinder 18 provided on the input shaft 16 in response to the operation of the shift direction switching valve 74, and also responds to the operation of the shift speed switching valve 76. In response, hydraulic cylinder 18
The hydraulic oil inflow speed to the hydraulic cylinder 18 or the hydraulic oil discharge speed from the hydraulic cylinder 18 is changed. The hydraulic pump 78 is driven by the engine 10 or the like to force-feed the hydraulic oil in the oil tank 80 to the hydraulic circuit 70, and functions as a hydraulic source for the hydraulic circuit 70.

The controller 54 has an input/output interface 82
．． Central processing unit 84. and a storage section 86, etc., and processes various input signals inputted through the input/output interface 82 according to programs and data stored in advance in the storage section 86, and based on the processing results, shifts the solenoid valve for shift. By controlling the operation of 72, the sub-transmission 3
By automatically shifting the gear position of Q and controlling the operations of the shift direction switching valve 74 and the shift speed switching valve 76, the gear ratio of the continuously variable transmission 14 is changed to an optimal value.

Next, the engine output control routine of this embodiment, which is executed at predetermined time intervals according to the flowchart of FIG. 3, will be explained. and is executed at a predetermined time angle.

The sub-transmission switching routine (not shown) is based on the pulse signal SV from the vehicle speed sensor 61 and the accelerator depression area signal Sτ from the accelerator depression amount sensor 65 in accordance with the data map corresponding to the shift pattern shown in FIG. , determines the gear stage of the sub-transmission 30, and outputs a drive signal to the shift solenoid valve 72 so that the gear stage is realized.

In FIG. 4, U12 is prepared in consideration of the driving performance of the vehicle, and is used to determine upshift from a low gear (first gear) to a high gear (second gear). D21 in the figure is the upshift line used, and is prepared in order to form an appropriate hysteresis and in consideration of the acceleration performance due to kickdown. This is a downshift line used to determine downshift. The control routine (not shown) for the continuously variable transmission is such that when the auxiliary transmission 30 is switched to a low speed gear, the auxiliary transmission 30 When the gear is switched to high speed, the vehicle speed sensor 61 is activated according to the data map corresponding to the target rotation speed Nin pattern shown in FIG.
Pulse signal SV from and accelerator depression Q sensor 65
Based on the accelerator depression maximum signal Sτ from
continuously variable transmission 14 so that the target rotational speed Nin* and the actual rotational speed Nin of the input 0I116 match.
The gear ratio is changed by controlling the line oil pressure and hydraulic oil to the hydraulic cylinder 26.18.

In Figures 5 and 6, τO2τi and τ100 are prepared to reflect the load on the vehicle, and τO is the target rotation speed line used when the accelerator depression amount τ is O (%). Yes, τi is τ1 when τ=i (%)
00 is the target rotation speed line used when τ=100 (%). In addition, γmax in the figure indicates the maximum gear ratio γ, and γm
in indicates the minimum gear ratio γ.

When the engine output control routine of this embodiment shown in FIG. 3 is started, which is executed at predetermined time intervals together with the auxiliary transmission switching routine (not shown) and the continuously variable transmission control routine (not shown). , First, the above sub-transmission switching routine (
monitors the gear position command state of the sub-transmission 30 (not shown), determines whether or not the sub-transmission 30 is in the low gear (LOW) (step 100), and then performs the next step based on the determination result. Shift to processing. When it is determined that the auxiliary transmission 30 is Low, the accelerator speed is calculated based on the vehicle speed V calculated based on the pulse signal SV from the vehicle speed sensor 61 and the accelerator depression signal Sτ from the accelerator depression amount sensor 65. According to the amount of depression τ, the current vehicle speed V(τ) is a predetermined vehicle speed lower than the upshift vehicle speed, based on the shift pattern shown in FIG. 4.
(τ) is exceeded (low speed side chain region) or not (V(τ))
VO(τ)) (step 110), and the process moves to the next step. The current vehicle speed ■(τ) is in the low speed region (V(τ)
)>VO(τ)), the throttle valve 6
2 to the throttle actuator 63 (step 12).
0). The throttle opening θ output to the throttle actuator 63 is normally a value corresponding to the accelerator depression τ (here, τi (%)=θi (%)), but in step 120, the current accelerator depression amount τ1 The value obtained by subtracting the product of the function K(τ) of the accelerator depression amount τ and the vehicle speed V(τ) from the throttle opening θ1 corresponding to (θ1−K(
τ)・V(τ)), for example, the driving force F characteristic (F12 to Fh2) shown by the solid line in FIG.
In other words, the characteristic value may be similar to a change in drive torque due to a change in torque ratio of a torque converter of an automatic transmission.

The throttle opening degree θ is decreased in step 120 until it is determined in the next step 130 that the sub-shift is started at 30 to start switching from LOW to the high speed gear (high). Detection of the start of switching from LOW to 1-(i gh in step 130) is performed by monitoring the switching routine of the sub-transmission (not shown).

When it is determined in step 130 to start to 1-OW) Value corresponding to accelerator depression Dτ (here, θi (%) = τi (%
)) is output to the throttle actuator 63 (step 140). The throttle opening degree θ output to the throttle actuator 63 is determined in step 1 above.
The value obtained by adding the product of the function K'' (τ) of accelerator depression mτ and the time t (τ) set corresponding to the amount of accelerator depression to the value θ'1 closed by 20 (θ'1 + Klτ)・t (
τ)) is output until θj (%)=τi (%), and the optimum value may be determined in advance by experiment.

On the other hand, in step 100, the current sub-shift t2130 is set to L.
When it is determined that it is not oW, or when it is determined in step 110 that it is not in the low speed region, step 120
~140 without executing engine torque control,
This engine output control routine ends immediately.

LOW-, which was the basis for the judgment in step 130 above.
) After switching to High, the engine speed will be 8th.
However, by controlling the target rotation speed Nin'' of the continuously variable transmission by the control routine of the continuously variable transmission (not shown), the engine rotation speed Ne is controlled to the target rotation speed Nin in the high gear stage. Ru.

The control method of the continuously variable transmission for a vehicle according to the present embodiment, which has been explained above using the engine output control routine shown in FIG. This allows the large driving force before upshifting to smoothly transition to small driving force after upshifting.

As a result, by the control method of the continuously variable transmission for vehicles of this embodiment, the change in the vehicle drive before and after the upshift becomes smooth as shown in FIG. 7, and the shock during gear shifting is reduced.
Moreover, in this example, the driving force before and after the upshift is smoothly transferred by highly responsive engine output control, without relying on the speed increase control of the continuously variable transmission 14, which has low responsiveness. The feeling of a drop in acceleration force due to a drop in engine speed Ne is reduced, and the sub-shift 1
This has the effect of making the shift feel and acceleration feel extremely good when upshifting.

Note that the present invention is not limited to the above-described embodiments, and various embodiments can be implemented without changing the gist of the present invention.

For example, in the above-described embodiment, the sub-transmission 30 is of a type that can be selectively switched to two forward gears, but it may also have three or more forward gears. .

Further, in the continuously variable transmission 14, the transmission belt 20 is connected to the variable pulley 2.
Although the belt-type continuously variable transmission is of a type in which the belts are wound around the belts 2 and 28, other types of continuously variable transmissions, such as those using balls such as bearings, may be used.

[Effects of the Invention] According to the control method for a continuously variable transmission for a vehicle of the present invention, when the vehicle speed is in the low speed region of the upshift vehicle speed of the auxiliary transmission, the output of the engine is reduced according to the vehicle speed, and the upshift is performed. To smoothly transfer driving force between front and rear. As a result, the driving force is smoothly transferred before and after the upshift of the auxiliary transmission, so there is no drop in the acceleration force of the vehicle or shock during gear shifting, and the feeling of shifting and acceleration of the continuously variable transmission is extremely high. It has an excellent effect of improving

[Brief explanation of the drawing]

FIG. 1 is a flowchart illustrating the basic configuration of a control method for a continuously variable transmission for vehicles according to the present invention, FIG. 2 is a configuration diagram of a system to which an embodiment of the present invention is applied, and FIG. 3 is an embodiment of the present invention. Flowchart t--1'' of the engine output control routine, the fourth
The figure is a graph showing the shift line of the auxiliary transmission of the example, Figure 5 is a graph showing the control characteristics of the continuously variable transmission when the auxiliary transmission of the example is in the low speed gear stage, and Figure 6 is the graph of the example. Figure 7 is a graph showing the control characteristics of the continuously variable transmission when the iWJ speed is the high speed gear.
The figure is a graph showing engine speed characteristics of a conventional example, and FIG. 9 is a graph showing driving force characteristics of a conventional example. 10... Engine 14... Continuously variable transmission 30... Sub-transmission 54... Controller 63... Throttle actuator 65... Accelerator depression amount sensor 70... Hydraulic circuit

Claims (1)

[Scope of Claims] A continuously variable transmission that is provided in a continuously variable transmission connected to an engine and that switches between two or more forward gears based on the driving state of the vehicle, including at least the vehicle speed. In the method for controlling the gear ratio of the engine, when the vehicle speed is in a low speed range where the sub-transmission is shifted from a gear with a large gear ratio to a gear with a small gear ratio, the output of the engine is controlled. A control method for a continuously variable transmission for a vehicle, characterized in that the transmission is reduced in accordance with vehicle speed.