JPS63203439A - Control for continuously variable transmission for vehicle - Google Patents

Abstract

PURPOSE:To permit the stable fuel cut control by controlling the speed change ratio on the basis of the engagement state of a direct coupled clutch in the fuel cut control, in the constitution in which a fluid power transmission means and a direct coupled clutch are interposed between an engine and a continuously variable transmission. CONSTITUTION:The power of an engine 10 is transmitted to the input shaft 16 of a belt type continuously variable transmission 14 through a fluid coupling 12 equipped with a direct coupled clutch 11. When it is judged that the condition for carrying out the fuel cut control of each engine 10 is established, in a controller 54 into which the output signals of a variety of detecting means for detecting the operation state are input, in the above-described device, the engagement state of the direct coupled clutch 11 is judged. When it is judged that the lock-up ON (OFF) state is judged, an aimed input side revolution speed as the revolution speed for carrying out fuel cut of an engine according to the lock-up ON (OFF) is determined, and the speed change ratio is controlled on the basis of the aimed input side revolution speed.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a continuously variable transmission for a vehicle connected to an engine via a fluid power transmission means with a direct coupling clutch, such as a fluid coupling or a torque converter. (Hereinafter referred to as CVT
related to transmission ratio control technology.

[Prior Art] Conventionally, when a vehicle decelerates, a target input-side rotation speed of the Cv king is set, and the gear ratio is controlled so that the target input-side rotation speed matches the actual input shaft rotation speed. A technique has been disclosed that aims to improve fuel consumption efficiency and engine brake function through fuel cut by maintaining the engine rotation speed at or above the engine fuel cut rotation speed (Japanese Unexamined Patent Application Publication No. 1983-1989-1).
18648).

[Problems to be Solved by the Invention] However, when the above conventional technology is applied to a vehicle in which a fluid coupling with a direct coupling clutch or a torque converter with a direct coupling clutch is installed between the engine and the CVT, the following problems occur. The following problems may occur.

In other words, when the lock-up of the above-mentioned direct clutch is "on", the CVT input shaft rotation speed and the engine revolution speed match, but when the lock-up is "off", the fluid coupling etc. slip and the rotation of the CVH input shaft is affected. As the number becomes larger than the engine speed, the lock-up "
When the engine is turned off, there may be cases where the engine fuel cut is not executed. This is due to slipping of the fluid coupling during deceleration, even though the CVT input shaft rotation speed is maintained above the fuel cut rotation speed of the engine. This is because they do not rise to the level of numbers.

Furthermore, in the conventional technology, it is possible to set the target input side rotation speed high in consideration of slippage when the lock-up is "off", but in this case, the A new problem arises in which engine braking increases and the driving feeling of the vehicle deteriorates.

An object of the present invention is to perform stable fuel cut control using a CVT while effectively maintaining the driving feeling of a vehicle by solving the above-mentioned problems.

[Means for Solving the Problems] As a means for achieving the above object, a method for controlling a continuously variable transmission for a vehicle according to the present invention, as illustrated in FIG. When the condition for performing fuel cut control is met, the gear ratio of the continuously variable transmission for vehicles is adjusted so that the engine speed becomes the speed at which fuel cut is performed. In the method for controlling the above, a fluid power transmission means for transmitting power via fluid and a direct coupling clutch are interposed between the engine and the continuously variable transmission for a vehicle, step SA), When conditions for performing fuel cut control are met (step SB), a target input rotation speed of the vehicle continuously variable transmission is determined based on the engagement state of the direct coupling clutch (step SC), and the gear ratio is controlled. (Step SD)

The fluid power transmission means includes, for example, a fluid coupling such as a fluid coupling, or a torque converter.

The direct coupling clutch is, for example, a clutch that directly couples the input side and output side of the fluid power transmission means.

The target input side rotation speed of the continuously variable transmission for a vehicle is the rotation speed that is a control target for the actual rotation speed on the input side of the CVH,
For example, it is the input side or output side rotation speed of the fluid power transmission means, or the rotation speed that is the control target of the rotation speed of the input pulley of the CVT.

[Operation] According to the control method for a continuously variable transmission for a vehicle of the present invention, when a fluid power transmission means and a direct coupling clutch are interposed between the engine and the CVT (step SA), the engine by the CVT When it is determined that the conditions for performing the fuel cut control are satisfied (step SB), the engagement state (lockup state) of the direct coupling clutch is first determined (step SC).
1"), when the lockup is "on", determine the target input side rotation speed at which the engine rotation speed is the rotation speed at which fuel cut is performed when the lockup is "on".
C2) The gear ratio is controlled so that the target input side rotation speed and the actual CvT input shaft rotation speed match (step SD). On the other hand, when the lockup is ``off'', the target input side rotational speed is set so that the engine rotational speed becomes the rotational speed at which fuel cut is performed when the lockup is ``off'', that is, the target input side rotational speed is higher than when the lockup is ``on''. Finally, in step 5C3), the gear ratio of the CVT is controlled (step SD).

Note that when the conditions for performing fuel cut control of the engine by the CVT are not satisfied, gear ratio control based on the normal running state of the vehicle is executed.

Such CVT gear ratio control may be performed so that the target input side rotation speed and the actual input side rotation speed match,
Alternatively, for example, a target speed ratio may be determined instead of the target input side rotation speed, and the target speed ratio may be matched with the actual speed ratio of the CVT.

[Example] 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 direct coupling clutch 11. The input shaft 16 has
The V-groove width, ie the transmission belt 2, is controlled by the hydraulic cylinder 18.
A variable pulley 22 is provided whose diameter of 0 is changed. The output shaft 24 is provided with a variable pulley 28 whose 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 22.
It is transmitted to the output shaft 24 via the transmission belt 20 wound around the transmission belts 28 and 28, and is also transmitted to the sub-transmission 30 at the subsequent stage. The sub-transmission 30 includes a first sun gear 32. Second
Sungear 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. By selectively operating the low gear brake 40, 41 and advance brake 42 by a hydraulic actuator (not shown), the gear ratio Rf of the auxiliary transmission 30 is switched, or the forward rotation , reverse rotation can be switched.

Table 1 Here, in Table 1, ρ1 is ZS1/Zr, and ρ2 is Z
s2/Zr. However, ZSl is the 1st Sungear 3
2, ZSl is the number of teeth of the second sun gear 34, and Zr is the number of teeth of the ring gear 36. The output shaft 24 of the belt-type continuously variable transmission 14 constitutes the input shaft of the auxiliary transmission 30, and the carrier 44 that supports the planetary gear in the auxiliary transmission 30 constitutes the output shaft. Gear ratio is carrier 44
The value is obtained by dividing the rotation speed of the output shaft 24 by the rotation speed. The rotational force transmitted to the carrier 44 is transmitted to the intermediate gear 46.4.
8 and a final reduction gear 50 to a pair of drive wheels 52 of the vehicle.
It is designed to be transmitted to each of the following.

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 SPI and SP2 of frequencies corresponding to the rotation speeds of the variable pulleys 22 and 28 to the controller 54. A vehicle speed sensor 61 for outputting a pulse signal Sv of a frequency corresponding to the number of rotations of the intermediate gear 48 to the controller 54 is provided near the six intermediate gears 48 in which the intermediate gear 48 is provided. A throttle valve 62 provided in the intake pipe of the engine 10 is opened and closed by operating an accelerator pedal 63, and a throttle sensor 6 is attached to the throttle valve 62.
4a and an idle switch 64b are provided,
The throttle valve opening θ is detected from the throttle sensor 64a.
The throttle signal Sθ representing the idle switch 64b
The idle switch status is LLr on” and “off”.
An idle signal SLL representing the value is supplied to the controller 54. The ignition circuit of the engine 10 is provided with an engine rotation speed sensor 65a, and the engine rotation speed sensor 65a sends a rotation speed signal @i representing the engine rotation speed Ne.
S N E is provided to controller 54 . The water jacket of the engine 10 has a water temperature sensor 65b.
A water temperature signal STW representing engine water CTW is supplied from the water temperature sensor 65b to the controller 54.

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 operates the shift speed switching valve 76. In response to this, the hydraulic oil inflow speed into the hydraulic cylinder 18 or the hydraulic oil discharge speed from the hydraulic cylinder 18 is changed, and in response to the operation of the lock-up switching valve 77, the direction of the hydraulic oil to the direct coupling clutch 11 is switched. Note that the hydraulic pump 78 is connected to the engine 10.
The oil tank 80 is driven by
The hydraulic fluid inside the pump is fed under pressure to the hydraulic circuit 70, and functions as a hydraulic pressure 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 0 gear stage and controlling the operation 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 the optimum value, and the operation of the lock-up switching valve 77 is controlled. By controlling the lock-up of the direct coupling clutch 11, the lock-up is turned on or the lock-up is turned off.

Next, the gear ratio control routine of this embodiment, which is executed at predetermined time intervals (here, Bmsec), will be explained with reference to the flowchart of FIG.

FIG. 3 shows a control routine for controlling the gear ratio of the entire transmission of the vehicle. First, step 100 is executed to control the vehicle speed V, the throttle opening θ, and the rotational speed Nin of the input shaft 16. , rotation speed Noot of output shaft 24, engine rotation speed NO, shift lever 66
operating position Psh, idle switch 64b state LL
, engine water temperature TW is signal SV, So, , SP1. SP
2. Loaded based on SNE, SP, SLL and STW. Next, in step 110, the shift lever
It is determined whether the actual operating position of 66 is in the normal driving range or in the automatic shift range.

If it is determined that it is the normal driving range, step 120 is executed and the fourth range stored in advance in the storage unit 86 is
The gear ratio control routine in the normal running range shown in the figure is executed, and the gear ratio γ of the continuously variable transmission 14 is optimally controlled.

Meanwhile, in step 110, the shift lever 66
If it is determined that the automatic shift range has been controlled, step 130 is executed, and 30 shift controls are executed for the sub-shift. That is, the storage unit 86
The gear position of the auxiliary transmission 830 is determined based on the vehicle speed V and the throttle opening θ from a shift pattern stored in advance in do. The shift pattern is shown in FIG. 5, for example, and is stored in the form of a data map or the like. In the figure, U12 is prepared in consideration of the driving performance of the vehicle, and is used to determine an upshift from a low gear (first gear) to a high gear (second gear). It is a shift line, and in the figure [)21
is a downshift line that is prepared to create an appropriate hysteresis and take into consideration the acceleration performance due to kickdown, and is used to judge the downshift from a high speed gear to a low speed gear. be.

Next, in step 140, it is determined whether the actual gear stage of the sub-shift l130 is a high speed gear stage or a low speed gear stage. If it is determined that the gear is on the high speed side, step 150 is executed and, for example, instead of the speed ratio control routine (step 120) in the normal driving range shown in FIG. The gear ratio control routine is started, and the continuously variable transmission 1
4 speed ratio 1 control is executed.

If it is determined in step 140 that the gear position of the auxiliary transmission 30 is a low speed gear position, step 16
0 is executed, for example, the gear ratio control routine in the normal running range (step 120), the details of which are shown in FIG.
Instead, a gear ratio control routine for a low gear stage, the details of which are not shown, is started, and the gear ratio control of the continuously variable transmission 14 is executed.

Next, the gear ratio control routine in the normal running range shown in FIG. 4 will be explained. In the control routine of FIG. 4, first, in step 200, it is determined whether a fuel cut condition is satisfied. The judgment that this fuel cut condition is satisfied is that the engine coolant temperature TW is 70 [°C] or more and the vehicle speed V is 35 [K1].
This is performed when all the conditions of 11713 and above and that the idle switch 64b is "on" are satisfied. In addition,
Appropriate hysteresis is provided for the vehicle speed V in order to prevent hunting from occurring when determining whether the fuel cut condition is met and to allow the fuel cut to continue for a long time until the vehicle speed becomes low once the fuel cut condition is satisfied.

When the vehicle is in a normal running state, that is, when it is determined that the fuel cut condition is not satisfied, step 2 is performed.
10, the data map for the normal driving range shown in FIG. 6 stored in advance in the storage unit 86, that is, the throttle opening θ and the vehicle speed Vi (i = O to max), determines the optimum range when the shift lever 66 is in the normal driving range. The data map that gives the target rotational speed Nin is selected.

Next, in step 220, the target rotational speed Nin is determined by map interpolation based on the selected data map and the throttle opening θ and the vehicle speed ■.

Following the determination of the target rotational speed Nin, step 230
As a result, control is executed to make the actual input shaft rotational speed Nin match the target rotational speed Nin''. That is, first, it is determined whether the target rotational speed Nin'' is greater than or equal to the rotational speed Nin of the input shaft 16. Next, if Nin''≧Nin, it is determined that the rotational speed Nin of the input shaft 16 is to be increased, and the shift direction switching valve 14 and the shift speed switching valve 76 are
Control (downshift control) for increasing the gear ratio γ of the continuously variable transmission 14 is executed by controlling the . on the other hand,
When the target rotational speed Nin'' is smaller than the rotational speed Nin of the input shaft 16, control to reduce the transmission ratio γ of the continuously variable transmission 14 (upshift control) is executed.

By executing steps 200 to 230, control is performed to optimize the gear ratio of the continuously variable transmission 14 when the shift lever 16 is in the normal travel range.

Determine the target rotation speed Nrn based on the data map of the target rotation speed Nin'' and control the gear ratio γ (steps 210 to 230) In the driving state, the fuel cut condition is satisfied by releasing the accelerator pedal. (Step 2)
00), then in step 240, direct coupling clutch 1
1 is actually engaged (lockup “on”)
It is determined whether the lockup is "off" or not. This lock-up “on” judgment is based on fluid coupling 1
2, the engine rotation speed Ne is the input side rotation speed, and the rotation speed N of the input shaft 16 of the continuously variable transmission 14 is the output side rotation speed.
rYEsJ when the engine rotational speed Ne and the input shaft rotational speed Nin are the same, that is, whether the direct coupling clutch 11 is actually engaged or not.

If it is determined that the lock-up of the direct coupling clutch 11 is "on", the target rotation speed Nin'' is determined in the next step 250.
The target rotational speed Nin” at the time of “ON” is the current fuel cut rotational speed NCut (here, 1.20Or
pm) and a predetermined value α (Ninne←N cut+α). The value of this predetermined value α is selected to be the necessary and minimum value in order to perform the fuel cut, and the value of the predetermined value
The optimal value is determined in advance through experiments, taking into consideration the degree of descent of the engine, the delay in hydraulic system operation when downshifting the continuously variable transmission 14, and the like. Note that the predetermined value α is set to a large value in order to increase the effect of the engine brake, for example, when the shift range is the engine brake range.

Following the determination of the target rotation speed Nin'', step 23
0, the shift control is executed to make the actual input shaft rotational speed Nin match the target rotational speed Nin'', similarly to when the fuel cut condition described above is not satisfied.

For example, when the vehicle speed decreases and the lock-up shifts from the lock-up "on" state to the lock-up "off" state,
When the determination is made in step 240, the process moves to the next step 260.

Step 26 executed when this lockup is “off”
0, the target rotational speed Nin* is determined when there is slippage in the fluid coupling 12, that is, when the engine rotational speed Ne is lower than the actual input shaft rotational speed Nin (here, usually 150 rpm lower). This target rotation speed Ni
n” is the current fuel cut rotation speed Ncu
It is determined by adding a predetermined value β to t (Nin*←NCut+β). The value of this predetermined value β is
Similar to the predetermined value α described above, in order to perform a fuel cut, the necessary and minimum value is selected,
A value obtained by adding 150 rpm, which is approximately equal to the number of slip rotations of the fluid coupling 12, to the predetermined value α is used.

After the target rotational speed Nin* is determined, the shift control is executed to match the actual input shaft rotational speed Nin with the target rotational speed Nin'', similarly to when the lockup is turned on (step 230).

As described in detail above, as shown in the diagram showing the operating state of FIG. 7, in the vehicle to which this embodiment is applied, the lock-up "on
/CI ON)), the optimum target rotation speed Nin (NCUt + α or Ncut + β) is determined.
is determined, and the gear ratio is controlled based on the target rotational speed Nin.

As a result, when the fluid coupling is not slipping (when the lock-up is "on"), that is, when the engine speed Ne and the actual input shaft speed Nin are the same, the engine uses fuel at the target speed Nin. Minimum value necessary for cutting (N cut + α)
By setting it to
The engine rotation speed Ne can be made equal to or higher than the rotation speed Ncut at which the fuel cut is activated. therefore,
Vehicle fuel consumption efficiency and driving sensation can be improved.

On the other hand, when the fluid coupling 12 is slipping (
(when the lock-up is "off"), that is, when the engine speed Ne is lower than the actual input shaft speed 1"4", the target rotation speed Nin'' is set to a higher value, which is preselected in consideration of the above-mentioned slippage. By setting the value (Ncut + β), the engine speed can be made equal to or higher than the speed NCIJt at which the fuel cut is activated at time T2. Therefore, the fuel consumption efficiency of the vehicle can be improved in the same way as when the lockup is "on" when the direct coupling clutch is engaged.

As a result, fluid coupling 12 and direct coupling clutch 1
1 is interposed between the engine 10 and the continuously variable transmission for a vehicle, the excellent effect of achieving both fuel consumption efficiency and driving sensation of the vehicle is achieved.

Furthermore, after the engine fuel is cut off at the above time point T2, for example, if the vehicle speed V drops extremely and the fuel cut condition is no longer satisfied (time point T3), the target rotational speed Nin changes to the normal value shown in FIG. The value is returned according to the data map shown.

Furthermore, when the vehicle speed V decreases to an extremely low speed or stops (time T4), the target rotational speed Nin'' is reduced to the minimum value Nl.
0W, the engine speed Ne becomes the idle speed N1
Become a clle.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and the present invention is not limited to the above embodiment. It may be controlled so that the γ* matches the actual CVT γ, or the engine rotation speed due to fuel cut control when lock-up is “off” and the engine rotation speed due to fuel cut control when lock-up is “on”. Control may also be used to correct the target rotational speed Nin when the lockup is "off" so that the numbers are the same.

[Effects of the Invention] According to the control method for a continuously variable transmission for a vehicle of the present invention, the optimal target input rotation speed for performing fuel cut is determined regardless of the engagement state of the direct coupling clutch, and the engine rotation speed is The number is controlled.

As a result, the engine speeds when the direct coupling clutch is engaged and when the direct coupling clutch is not engaged are made to be approximately the same value.

In other words, regardless of the engagement state of the direct coupling clutch, the engine speed is reliably shifted to a speed at which fuel cut can be carried out and at which there is less shock, etc. caused by engine braking during fuel cut. be able to.

Therefore, it is extremely advantageous in that it can improve both the fuel consumption efficiency and the driving sensation of the vehicle.

It has a great effect.

[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. FIG. 4 is a flowchart of the speed ratio control routine in the normal running range of the embodiment, FIG. 5 is a graph showing the speed change characteristics of the auxiliary transmission of the embodiment, and FIG. A graph showing the speed change characteristics of the continuously variable transmission, and FIG. 7 is a graph showing the operating state of the embodiment. 10...Engine 11...Direct clutch 12...Fluid coupling 14...Continuously variable transmission 54...Controller 64b...Idle switch 65a...Engine speed sensor 65b... Water temperature sensor 70...hydraulic circuit

Claims (1)

[Claims] Determine whether or not a condition is met to perform fuel cut control of an engine connected to a continuously variable transmission for a vehicle, and when the condition to perform fuel cut control is established, the rotational speed of the engine is adjusted such that the fuel cut is performed. In the method of controlling the gear ratio of the continuously variable transmission for a vehicle so as to achieve the rotational speed, the engine and the continuously variable transmission for a vehicle are directly connected to a fluid power transmission means for transmitting power via fluid. When the condition for performing the fuel cut control is established, the target input rotation speed of the continuously variable vehicle transmission is determined based on the engagement state of the direct coupling clutch, and the speed change is performed. A control method for a continuously variable transmission for a vehicle, characterized by controlling a ratio.