JPS63195037A - Method for controlling continuously variable transmission for vehicle - Google Patents

Abstract

PURPOSE:To improve specific consumption by selecting, based on the operative condition of a direct-coupled clutch, the relationship between the traveling condition of a vehicle and the aimed input side rotational frequency, which achieves an optimum fuel consumption every operative condition of the direct-coupled clutch, and controlling a speed change ratio according to the selected relationship. CONSTITUTION:A continuously variable transmission for a vehicle is coupled with an engine through a hydraulic power transmitting means and a direct-coupled clutch. In the transmission, the speed change ratio is controlled so that the aimed input side rotational frequency coincides with an actual input side one (step SC). On this case, the relationship between the traveling condition of a vehicle and the aimed input side rotational frequency, which achieves an optimum fuel consumption every operative condition of the direct-coupled clutch, is selected based on the operative condition of the direct-coupled clutch (step SA). According to the selected relationship, the aimed input side rotational frequency based on the traveling condition of the vehicle is calculated (step SB). Thus, the specific fuel consumption of the vehicle is optimized irrespective of the operative condition of the direct-coupled clutch.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a continuously variable transmission Ia 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. (Hereafter CV
This invention relates to a transmission ratio control technology (denoted as T).

[Prior art] Conventionally, for example, ffG is disclosed in Japanese Patent Application Laid-open No. 144850/1983.
IThe gear ratio control is performed by the method shownC.
Vehicles equipped with a VT are equipped with a fluid coupling with a direct clutch or a torque converter with a direct clutch in order to smooth the start and reduce power loss during driving.

[Problems to be Solved by the Invention] However, in a vehicle in which a fluid coupling with a direct clutch is interposed between the conventional engine and CVT, simply applying the conventional gear ratio fri control will cause problems.
There was a problem that good fuel efficiency characteristics may not be obtained.

This problem occurs because the vehicle's fuel efficiency (mileage per unit amount of fuel) characteristics differ greatly between when the lock-up of the direct clutch is "on" and when it is "off," as shown in Figure 8. by. That is, when the above-mentioned direct coupling clutch is in the lock-up "ON" state, the CV
The combined efficiency of the T and fluid coupling exhibits the highest efficiency when the CVT gear ratio is 1, and gradually decreases as the gear ratio increases or decreases. As a result, the fuel efficiency of the vehicle when the lock-up is "on" is greatly affected by changes in engine efficiency (fuel consumption rate). Shows good values in the engine speed range.

On the other hand, when the lockup is "off" compared to when the lockup is "on", as shown in the speed ratio-efficiency characteristic diagram of the fluid coupling in Figure 10, the efficiency of the fluid coupling decreases as the speed ratio becomes smaller. Therefore, the efficiency decreases approximately proportionally. As a result, the overall efficiency of the vehicle is as shown in the efficiency characteristic line when lock-up is "off" in Figure 8. ,
The slippage of the fluid coupling increases and deteriorates.

An object of the present invention is to improve the fuel efficiency of a vehicle (to run the vehicle at an optimal fuel consumption rate) by solving the above-mentioned problems.

[Means for Solving the Problems] As a means for achieving the above object, a control method for a continuously variable transmission for a vehicle according to the present invention, as illustrated in FIG. A target input side rotation speed of a vehicle continuously variable transmission coupled to an engine via a power transmission means and a direct coupling clutch of the fluid power transmission means is calculated based on the running state of the vehicle, and the target input side rotation speed is calculated based on the running state of the vehicle. In the method (step SC) of controlling the gear ratio of the continuously variable transmission for a vehicle so that the number of revolutions matches the actual input side rotation speed of the continuously variable transmission for a vehicle, The relationship between vehicle running conditions and target input speed to achieve the optimal fuel consumption rate is
The gist of the present invention is to select the relationship based on the operating state of the direct coupling clutch (step SA>) and to calculate the target input side rotation speed based on the running state of the vehicle in accordance with the selected relationship (step SB).

The optimal fuel consumption rate is one that achieves both drivability and fuel efficiency, that is, the minimum fuel consumption rate that takes into account improvement in drivability.

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 CVT,
For example, the rotational speed is a control target of the engine rotational speed, the input side or output side rotational speed of the fluid power transmission means, or the rotational speed of the input boolean of the CVT.

[Function] According to the method for controlling a continuously variable transmission for a vehicle of the present invention, first, based on the operating state of the direct coupling clutch, a relationship is established to achieve the optimum fuel consumption rate from the running state of the vehicle in the operating state. Then, according to the relationship, calculate the target input side rotation speed based on the running condition of the vehicle, and then set C so that the target input side rotation speed and the actual input side rotation speed match.
Controls the gear ratio of VT. As a result, the fuel consumption rate of the vehicle becomes optimal regardless of the operating state of the direct coupling clutch.

Such CVT gear ratio 11 control may be performed so that the target input side rotational speed matches the actual entrance rotational speed, or, for example, by determining the target gear ratio instead of the target input side rotational speed, It is also possible to make the target gear ratio match the actual CVT gear ratio.

[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 coupled 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 is provided with a variable pulley 22 whose groove width, that is, the diameter of the transmission belt 20 is changed by the hydraulic cylinder 18 . The output shaft 24 is provided with a variable boob 928 whose groove width is changed by the 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 wrapped around the transmission belts 2 and 28.
is transmitted to. The sub-transmission 30 includes a first sun gear 32. 2nd Sangir 34. It is equipped with a Ravignaux-type condensing 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 gear ratio R' of the auxiliary transmission v330 is switched, or forward rotation and reverse rotation are switched, as shown in Table 1 below. It has become.

Table 1 Here, in Table 1, ρ1 is ZS1/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. The output 1111124 of the belt type continuously variable transmission 14 constitutes the input shaft of the sub-transmission 30,
Also, the carrier 4 that supports the planetary gear in the auxiliary transmission Vs30
4 constitutes an output shaft, the gear ratio of the sub-transmission 130 is the value obtained by dividing the rotation speed of the output shaft 24 by the rotation speed of the carrier 44. The rotational force transmitted to the carrier 44 is transmitted to a pair of drive wheels 52 of the vehicle via intermediate gears 46 and 48 and a final reduction gear 50, respectively.

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. is provided. A vehicle speed sensor 61 for outputting a pulse signal @Sv of a frequency corresponding to the rotation speed of the intermediate gear 48 to the controller 1-roller 54 is installed near the intermediate gear 48 . A throttle valve 62 provided in the intake pipe of the engine 10 is opened and closed by operating an accelerator pedal 63. A throttle sensor 64 is provided on the throttle valve 62, and the throttle valve opening θ is detected from the throttle sensor 64. A throttle signal Sθ representing Sθ is supplied to the controller 54. The ignition circuit of the engine 10 is provided with an engine speed sensor 65, and the engine speed sensor 65 outputs the engine speed Ne.
A rotational speed signal SNE representing the rotation speed is supplied 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.

These shift levers 1 to 66 are mechanically associated with manual valves 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 Also, the shift lever 66 is in the forward range for normal driving (D Nidrive).
When the range is operated, hydraulic oil is allowed to be supplied only to the hydraulic actuator that operates the high-speed clutch 38, so that the high-speed gear is maintained. Also, the shift lever 66 is in the automatic shift range (S range) of the forward range or in 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. The flow rate of the hydraulic oil into the hydraulic cylinder 18 or the hydraulic oil discharge rate from the hydraulic cylinder 18 is changed, and the direction of the hydraulic oil to the direct coupling clutch 11 is switched in response to the operation of the lock-up switching valve 77. 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-shift! a
30 gears are automatically shifted, and the shift direction switching valve 74
By controlling the operation of the shift speed switching valve 76, the gear ratio of the continuously variable transmission 14 is changed to an optimum value, and by controlling the operation of the lock-up switching valve 77, the direct coupling clutch 11 is turned into lock-up "on" or Turn lock-up ``off''.

Next, the gear ratio control routine of this embodiment, which is executed at predetermined time intervals (here, 8 m5ec) according to flowchart 1 in FIG. 3, will be explained.

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 Nout of output shaft 24, engine rotation speed Ne, shift lever 66
The operation position ps+1 corresponds to the signal SV, Sθ, , SP1. SP
2. Loaded based on SNE, , B and SP.

Next, in step 110, it is determined whether the actual operating position of the shift lever 66 is the normal driving range or the automatic shift range. If it is determined that the driving range is the normal driving range, step 120 is executed to execute the gear ratio control routine in the normal driving range shown in FIG. The gear ratio γ 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 the 01 shift! Control is executed to shift 1 of a30. Zunawara 1. From the shift pattern stored in advance in the storage unit 86, the vehicle speed V
The gear stage of the 0I transmission 30 is determined based on the OJ: and throttle opening θ, and a drive signal is output to the shift solenoid valve 72 so that the determined gear stage is realized. 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
This is an upshift line used to determine an upshift from a low speed gear (first speed) to a high speed gear (second speed),
In the figure, [ ) 21 is prepared in order to form an appropriate hysteresis and in consideration of acceleration performance due to kickdown, and is used to judge downshift 1 from high speed gear to low speed gear. This is the downshift 1~ line used for.

Next, in step 14Q, it is determined whether the actual gear stage of the auxiliary transmission 30 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 14
The gear ratio control is executed.

If it is determined in step 140 that the gear stage of the auxiliary transmission 130 is a low speed gear stage, step 16
0 is executed, for example, the gear ratio control routine in the normal driving range (step 120) shown in FIG.
), a gear ratio control routine for a low gear stage whose details 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 shown in FIG. 4, first, in step 200, it is determined whether or not the direct coupling clutch 11 is in the lock-up "on" state, that is, the vehicle speed and the throttles 1 to 1 are determined by the control routine of the direct coupling clutch (not shown). When it is determined that the lock-up "on" condition is satisfied based on the opening degree θ, the lock-up switching valve 77
It is determined whether or not the lock-up E is controlled to the "lock-up E on" side. When it is determined that the direct coupling clutch 11 is in the lockup "off" state, in step 210, the elapsed time Toff after the lockup "off" is integrated, and
The process moves to the next step 220, in which the T off is determined.

The step 220 actually turns the lockup "off".
When it is determined that the elapsed time Tof
f is greater than or equal to a predetermined value β (To
When it is determined that ff≧predetermined value β), the process moves to step 230. In step 230, it is determined that the direct coupling clutch 11 is "off" based on the target rotational speed data map at the time of lockup "off" for the normal driving range shown in FIG. , and a data map that provides the optimal target rotation speed N10 when shift 1 to lever 66 are in the normal driving range (here, a data map that achieves both acceleration at start and minimum fuel consumption rate during steady driving) A data map in which the target rotational speed Nin'' during steady running is multiplied by, for example, 1.3 to 1.9 times that when the lockup is “on” is selected.

Next, in step 240, based on the selected data map, ten target rotational speeds N1 are calculated by map interpolation according to the vehicle speed V and the throttle opening θ. Following the calculation of the target rotational speed Nin'', in step 250, the Nin* is calculated as the rotational speed N of the input 01116.
It is determined whether or not it is greater than or equal to in. Nin＊≧NiO
If so, it is determined that the rotational speed Nin of the input @l 116 is to be increased, and step 260 is executed to control the shift direction switching valve 14 and the shift speed switching valve 76 to increase the continuously variable transmission 14. Control (grand shift control) to increase the gear ratio γ is executed. On the other hand, if the target rotational speed Ni0 is smaller than the rotational speed Nin of the input shaft 16, control to reduce the gear ratio γ of the continuously variable transmission 14 (upshift control) is executed in step 270.

As described above, by executing steps 200 to 270, the continuously variable transmission 1 when the direct coupling clutch 11 is "off" and the shift lever 16 is in the normal driving range
Control is performed to optimize the gear ratio of 4.

On the other hand, when the controller 54 outputs the lock-up "on" command, the determination at step 200 is rYEsJ.
That is, it is determined that the direct coupling clutch 11 is in the lock-up "on" state, and in the subsequent step 290, the elapsed time 1'-on after the lock-up "on" is integrated,
The process moves to the next step 300, where the Ton is judged. In step 300, the elapsed time Ton is less than the predetermined value α (T
on<predetermined value α), that is, when it is determined that the lockup is not actually turned on due to a delay in the hydraulic system required for operation even though the lockup is instructed to be turned on. The process moves to step 230. After that, the lock-up of the direct coupling clutch 11 is turned off.
As before, steps 230 to 270 are performed;
Calculation of the optimum target rotational speed Nin'' at the time of lock-up "off" and control of the gear ratio γ are performed.

Elapsed time T for lockup “on” of direct coupling clutch 11
When it is determined that on has become equal to or greater than the predetermined value α (step 300), that is, when it is determined that the engagement of the direct coupling clutch 11 has been completed, the process moves to step 310. In step 310, it is determined that the direct coupling clutch is "on" based on the target rotational speed data map when the lockup is "on" for the normal driving range shown in FIG. and a data map (
Here, a data map is selected that achieves both acceleration when starting and minimum fuel consumption during steady driving.

Next, steps 240 to 270 are executed in the same way as when the lockup is turned off, and the target rotational speed N is set.
calculation of "in" and control of the gear ratio γ are performed.

When it is determined in step 200 that the command has been changed from the lockup "on" state to the lockup "off" state, the process moves to step 210, where the elapsed time Toff of the lockup "off" is integrated, and the next The process moves on to determining the elapsed time Tart. Direct clutch 11
When it is determined that the elapsed time Toff of the lock-up "off" is less than the predetermined value β (step 220>, that is, the lock-up is actually "off" due to the delay in the operation of the hydraulic system).
When it is determined that the cleaning has not been performed, the process moves to step 310. Hereinafter, the direct coupling clutch 11
Similarly, when the lockup is "on", step 310,
240 to 270 are executed and lockup is turned on.
Calculation of the optimum target rotational speed Ni0 at the time, control of the gear ratio γ, etc. are performed.

When it is determined in step 220 that the lockup "off" elapsed time Toff is greater than or equal to the predetermined value β, the lockup "off" in steps 230 to 270 described above is
Shift control is performed during the "off" state.

As explained above using the gear ratio control routine in the normal driving range shown in FIG. By selecting the data map and controlling the gear ratio γ, when the lock-up F is on, the vehicle runs in an area where the engine's pumping loss is small, while when the lock-up is off.
In short, by running the vehicle in a state where the fluid coupling] 2 is highly efficient, that is, the speed ratio of the fluid coupling 12 is close to the value 1, the vehicle can be driven at the minimum fuel consumption rate that takes into account drivability. It can be run.

Furthermore, according to this embodiment, the slippage of the fluid coupling does not increase unnecessarily, so the heat generation of the hydraulic oil is reduced, which improves the durability of the fluid and the fluid coupling.In addition, the capacity of the oil cooler etc. can be made smaller.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and without changing the gist, for example, a target engine speed Ne'' is calculated instead of the target engine speed Nin*, and Ne* and the actual engine speed are calculated. The gear ratio of the CVT may be controlled i, I+ so that the number Ne matches, and the gear ratio is corrected so that the speed ratio of the fluid coupling is equal to or higher than a predetermined value.Ll
control, that is, when the fluid coupling speed ratio falls below a predetermined value, it may be used in conjunction with control to increase the CVT gear ratio, or alternatively, seven target gear ratios are calculated in place of the target rotation speed Nin*. However, control may be performed so that the one line and the actual CVH γ match.

[Effects of the Invention] According to the control method for a continuously variable transmission for a vehicle of the present invention, a relationship that achieves the optimal fuel consumption rate determined in advance for each operating state of the direct-coupled clutch is determined based on the operating state of the direct-coupled clutch. By selecting the relationship and controlling the gear ratio of the CVT according to the selected relationship, the vehicle can be operated at an optimal fuel consumption rate regardless of the operating state of the direct coupling clutch, which is an extremely excellent effect.

Furthermore, when the lock-up of the direct coupling clutch is "off", the speed ratio of the fluid power transmission means is used in a high efficiency range close to 1, so it is possible to reduce the size of the 8-port oil cooler, etc. Moreover, the durability of the hydraulic oil, the fluid power transmission means, etc. can be improved.

[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 FIGS. FIG. 7 is a graph showing the speed change characteristics of the continuously variable transmission of the embodiment, FIG. 8 is a graph showing the fuel efficiency characteristics of the conventional example, and FIG. 9 is a graph showing the efficiency characteristics of the conventional continuously variable transmission with respect to the gear ratio. The graph shown in FIG. 10 is a graph showing efficiency characteristics of a conventional fluid coupling with respect to speed ratio. 10... Engine 11... Direct coupling clutch 12... Fluid coupling 14... Continuously variable transmission 54... Controller 1 to roller 65... Engine rotation speed sensor 70... Hydraulic circuit

Claims (1)

[Scope of Claims] A target input side rotation speed of a continuously variable transmission for a vehicle coupled to an engine via a fluid power transmission means that transmits power via fluid and a direct coupling clutch of the fluid power transmission means, Controlling the gear ratio of the continuously variable transmission for a vehicle so that the target input rotation speed matches the actual input rotation speed of the continuously variable transmission for a vehicle, calculated based on the running state of the vehicle. In the method of
A control method for a continuously variable transmission for a vehicle, characterized in that the selection is made based on the operating state of the direct coupling clutch, and the calculation of the target input side rotation speed based on the running state of the vehicle is performed in accordance with the selected relationship.