JPH0272268A - Automatic clutch controller for vehicle equipped with continuously variable transmission - Google Patents

Abstract

PURPOSE:To release an automatic clutch at the optimum time on the stop of a vehicle by detecting the vehicle deceleration speed on the brake application for the vehicle and release-controlling the automatic clutch at the earlier time as the vehicle deceleration speed becomes larger. CONSTITUTION:A controller 46 receives the signals of a variety of sensors, and when a vehicle is applied with brake by a brake signal SB, the automatic clutch (lock-up clutch) of a continuously variable transmission 14 is released by operating a hydraulic circuit 60 before the stop of the vehicle. In this case, the vehicle deceleration speed in the brake application for the vehicle is detected from a car speed signal SV, and as the vehicle deceleration speed increases more, the automatic clutch is released earlier. Thus, the overdelay of the release on the stop of the vehicle, discomfortable feeling due to the engine brake action due to the change of the speed change ratio of the continuously variable transmission to the deceleration side or the engine stop on the sharp brake application can be prevented, and the automatic clutch can be released at a relatively low speed, and the idle traveling feeling after the release can be reduced to the exceedingly small value.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a control device for controlling the release of an automatic clutch of a vehicle equipped with a continuously variable transmission.

BACKGROUND ART Vehicles equipped with continuously variable transmissions that continuously change the speed of the engine and transmit the rotation to the drive wheels are known.The power transmission path of such vehicles includes a mechanism for controlling power transmission. Automatic clutches such as lock-up clutches and magnetic particle electromagnetic clutches are installed in series with the continuously variable transmission. For example, JP-A-57-129955 and JP-A-60-16122.
The vehicle described in Publication No. 1 is such a vehicle.Normally, in such a vehicle, before the vehicle stops, the gear ratio of the continuously variable transmission is changed to the deceleration side in preparation for restarting, and the engine is To prevent the vehicle from stopping, the automatic clutch is released when the vehicle speed falls below a predetermined certain speed.

Problems to be Solved by the Invention However, in vehicles equipped with continuously variable transmissions equipped with automatic clutches such as lock-up clutches and magnetic clutches as described above, the release of the automatic clutch is too slow when the vehicle is stopped. When the speed ratio of the continuously variable transmission is changed to the deceleration side, a large engine braking effect may be felt, or the engine may stop during sudden braking. On the other hand, if the automatic clutch is released early when the vehicle is stopped, the engine braking action is suddenly canceled, resulting in a feeling of dry running after the automatic clutch is released. That is, when the vehicle speed is still high, the continuous feeling of deceleration suddenly disappears, which may give the driver a sense of abnormality.

The present invention has been made against the background of the above circumstances,
An object of the present invention is to provide a clutch control device for a vehicle equipped with a continuously variable transmission, which allows an automatic clutch to be released at an optimal time when the vehicle is stopped.

Means for Solving the Problems The gist of the present invention for achieving the above object is to provide a vehicle equipped with a continuously variable transmission in which the gear ratio is continuously variable. A control device for releasing an inserted automatic clutch prior to stopping the vehicle, the control device comprising: (a) deceleration detection means for detecting vehicle deceleration during braking of the vehicle; and (b) vehicle deceleration The invention further includes a control means for releasing the automatic flanch earlier as the size increases.

Operation and Effect of the Invention In this way, the larger the vehicle deceleration detected by the deceleration detection means during braking of the vehicle, the more
Since the automatic clutch is released early by the control means, the automatic clutch is released at an optimal time. For this reason, if the automatic clutch is released too slowly when the vehicle is stopped, a large engine braking effect may be felt due to changing the gear ratio of the continuously variable transmission to the deceleration side.
Alternatively, the occurrence of engine stop during sudden braking is eliminated. Further, as a result of the automatic clutch being released at an optimal time in relation to vehicle deceleration, the automatic clutch is released at a relatively low vehicle speed, and the feeling of free running after the automatic clutch is released becomes so small that it does not pose a problem.

EXAMPLE Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 1 shows a power transmission system for a vehicle.

In the figure, power from an engine 10 is transmitted to drive wheels 20 via a fluid coupling with a lock-up clutch 12, a belt-type continuously variable transmission 14, a forward/reverse switching device 15, an intermediate gear device 16, and a differential gear device 18. It is meant to be transmitted.

The fluid coupling 12 includes a pump impeller 24 fixed to the crankshaft (input shaft of the fluid coupling 12) 22 of the engine 10, and an input shaft (output shaft of the fluid coupling 12) 26 of the continuously variable transmission 14. It is equipped with a turbine impeller 28 connected to the pump impeller 24 and a lock-up clutch 29 that directly connects the pump impeller 24 and the human power shaft 26, so that torque is smoothly transmitted from the engine to the continuously variable transmission 14 when the vehicle is started. , or when the vehicle is stopped, the engine 10
During normal running, the pump impeller 24 and input shaft 26 are connected by a lock-up clutch 29 to prevent rotation loss. In this embodiment, this lock-up clutch 29 functions as an automatic clutch.

Further, in this embodiment, between the input shaft 26 and the turbine impeller 28, there is a gap between the input shaft 26 and the turbine impeller 28.
A one-way clutch 27 is provided that allows power to be transmitted in the direction toward the vehicle, but prevents the transmission of power by idling when power is to be transmitted in the opposite direction.

The input shaft 26 of the continuously variable transmission 14 is provided with a primary variable pulley 34 whose groove width, that is, the diameter of the transmission belt 32, is changed by a downstream hydraulic cylinder 30. is provided with a secondary variable boob 1J40 whose V-groove width is changed by the secondary hydraulic cylinder 38. Therefore, when the thrust by the downstream hydraulic cylinder 30 is made larger than the thrust by the secondary hydraulic cylinder 38, the effective diameter of the downstream variable pulley 34 is increased and at the same time the secondary variable pulley 40 is moved. The diameter is decreased, and the gear ratio T (=input shaft rotational speed N, 7/output shaft rotational speed N) of the continuously variable transmission 14 is changed in the direction of decreasing, that is, toward the speed increasing side. On the other hand, when the thrust by the downstream hydraulic cylinder 30 is made smaller than the thrust by the secondary hydraulic cylinder 38, the effective diameter of the downstream variable pulley 34 is reduced and at the same time the effective diameter of the secondary variable pulley 40 is reduced. The diameter is increased, and the gear ratio γ of the continuously variable transmission 14 is changed to a larger direction, that is, to the deceleration side.

The forward/reverse switching device 15 is a double planetary planetary gear mechanism connected to the output shaft 36 of the continuously variable transmission 14,
An output shaft 44 equipped with a gear 42, a forward clutch 43 that sets the output shaft 36 and the output shaft 44 in a forward power transmission state to rotate in the same direction, and a forward clutch 43 that rotates the output shaft 36 and the output shaft 44 in the opposite direction. A reverse brake 45 is provided to set the vehicle in a reverse power transmission state.

The gear 42 provided on the output shaft 44 of the forward/reverse switching device 15 is meshed with the intermediate gear device 16, and the intermediate gear device 16 is meshed with the differential gear device 18. Continuously variable transmission 14 with a constant reduction ratio determined by the structure of gear device 18
output torque is transmitted to the drive wheels 20.

FIG. 2 is a block diagram showing an electronic control device that controls the above-mentioned power transmission mechanism. In the figure, the input shaft rotation sensor 48 and the output shaft rotation sensor 50, which are respectively provided in the vicinity of the -next-side variable pulley 34 and the secondary-side variable pulley 40, output frequencies corresponding to the rotational speeds of the variable pulleys 34 and 40. pulse signals SPI and SF3
is output to the controller 46. Also, engine 10
A pulse signal SE having a frequency corresponding to the rotation speed of the engine 10 is output from the engine rotation sensor 51 provided to the controller 46 . In addition, differential gear device 1B
From the vehicle speed sensor 52 provided near the vehicle speed, a pulse signal S■ having a frequency corresponding to the vehicle speed is outputted to the controller 46. Further, a throttle signal Sθ representing the throttle valve opening degree θ is supplied to the controller 46 from a throttle sensor 54 provided on a throttle valve that is opened and closed by an accelerator pedal (not shown). In addition, from the brake switch 55 that detects the brake operation state,
A brake signal SB indicating that the brake has been depressed is output to the controller 46.

Further, a shift lever 56 is used as a shift switching device, and an operation position sensor 58 that detects the operation position of the shift lever 56 sends a signal SP representing the shift operation position iP of the shift lever 56 to the controller 46. Supplied. This shift lever 56 is mechanically connected to a manual valve in the hydraulic circuit 60, and when operated to the neutral range, the forward/reverse switching device 15
Hydraulic pressure is prevented from being supplied to both the forward clutch 43 and the reverse brake 45, but when the forward range is operated, hydraulic oil is supplied only to the forward clutch 43. Further, when the shift lever 56 is operated to the reverse range, hydraulic oil is allowed to be supplied only to the reverse brake 45.

The hydraulic circuit 60 transfers the line hydraulic pressure regulated by the line hydraulic pressure regulating valve 62 in accordance with the actual gear ratio of the continuously variable transmission 14 and the output torque of the engine 10 to the secondary hydraulic pressure provided on the output shaft 36. It is constantly supplied to the cylinder 38 and the tension of the transmission belt 32 is controlled as necessary and sufficiently. The hydraulic circuit 60 supplies or discharges hydraulic oil to the primary hydraulic cylinder 30 provided on the human power shaft 26 in response to the operation of the shift direction switching valve 64, and also controls the shift speed switching valve 66. In response to actuation, the primary hydraulic cylinder 30
The speed at which hydraulic oil flows into the cylinder or the speed at which hydraulic oil is discharged from the primary hydraulic cylinder 30 is changed. Thereby, the gear ratio γ of the continuously variable transmission 14 is continuously changed at a predetermined rate of change. The hydraulic pump 68 is rotatably driven by the pump impeller 24 to forcefully feed hydraulic oil in an oil tank (not shown) to the hydraulic circuit 60, and functions as a hydraulic source for the hydraulic circuit 60.

Further, the hydraulic circuit 60 includes a lock-up control valve 72.
According to the operating state of said fluid coupling 1
By switching the flow direction of the hydraulic oil supplied to fill the lock-up clutch 29, the lock-up clutch 29 is switched to one of a released state and a engaged state.

The controller 46 is a so-called microcomputer including a CPU, ROM, and RAM. CPU is RAM
The input signal is processed according to a program stored in advance in the ROM while utilizing the storage function of the ROM, and the shift direction is changed in order to realize a gear ratio that operates the engine 10 along an optimal curve that takes into account fuel efficiency and drivability, for example. valve 64
and the operation of the shift speed switching valve 66, while controlling the actual gear ratio γ so that the tension of the transmission belt 32 is optimized.
And the line oil pressure regulating valve 62 is controlled based on the output torque of the engine 10. Further, when the vehicle speed V exceeds a predetermined constant value, the CPU controls the lock-up control valve 7.
2 brings the lock-up clutch 29 into the engaged state. That is, in the lock-up clutch control routine, when the vehicle speed V exceeds a predetermined constant judgment value, for example, 40+n/h, the lock-up clutch 29 is activated in accordance with the switching operation of the lock-up control valve 72. By being in the locked state, rotation loss of the fluid coupling 12 is eliminated.

Furthermore, when the brake is operated, the lock-up clutch 29 is disengaged at an optimal time related to vehicle deceleration prior to the vehicle stopping.

Hereinafter, the main part of the control of the lock-up clutch 29 will be explained according to the flowchart shown in FIG.

First, in step S1, based on the signals SP1 and SP2, SE, SV, Sθ, SB, SP,
The actual rotational speed ni of the input shaft 26, , the rotational speed n of the output shaft. . 5. Engine rotational speed n0, vehicle speed V, throttle valve opening θ, operating position P of shift lever 56, etc. are read, and the change rate of vehicle speed V, which is the rate of change between the previous vehicle speed V and the current vehicle speed V, is read. dv/dL is calculated. In this embodiment, this step S1 corresponds to means for detecting the deceleration of the vehicle.

In step S2, it is determined whether the operating position P of the shift lever 56 is in the travel range, that is, whether it is in the forward travel (D) range or the reverse travel (R) range. If it is determined that the operation position P of the shift lever 56 is not in the driving range, the flag F is reset to "0" in step S15, and the flag F is reset to "0" in step S1.
In step S6, the lock-up clutch 29 is released, and in step S17, quantity reduction ratio control is executed.

In this quantity reduction ratio control, in preparation for starting the vehicle, the speed ratio T of the belt type continuously variable transmission 14 is changed to the maximum value side, in other words, to the maximum deceleration side. Note that the flag F is normally reset to "0" when the ignition switch is turned on.

While the above steps are repeatedly executed, when the shift lever 56 is operated to start the vehicle, step S
The determination in step S3 is affirmative, and it is determined in step S3 whether the content of flag F is "2". Since the initial content of flag F is not "2", the following step S
4, the vehicle speed V is a predetermined constant judgment reference value V.
, is larger than . This judgment standard value■
1 is for determining whether the vehicle speed is in a range where the lock-up clutch 29 can be engaged; for example, 40
A value of about 1 an/h is adopted. Initially, since the vehicle speed V is low, the determination in step S4 is negative, and in step S9 it is determined whether the content of the flag F is "1". Initially, the content of flag F is not set to "1", so the determination in step S9 is also denied, and step S1
At step 4, it is determined whether the accelerator pedal is in a non-operated state. Immediately after the shift lever 56 is operated, the accelerator pedal has not been operated yet, so steps S15 to 317 are executed, but when the accelerator pedal is operated, the accelerator pedal is not in the non-operated state in step S14. In other words, since it is determined that the accelerator pedal is in the operating state, the content of the flag F is reset to "0" in step 318, the lock-up clutch 29 is released in step S19, and the target is not reached in step S20. Rotation speed control is performed. This target rotational speed control
For example, the target input shaft rotational speed or target gear ratio is determined based on the actual throttle valve opening θ and vehicle speed V from a predetermined relationship in order to operate 0 along an optimal curve that takes into account fuel efficiency and drivability. Then, the gear ratio T of the continuously variable transmission 14 is adjusted so that the actual input shaft rotational speed ni or the gear ratio T matches the target input shaft rotational speed or the target gear ratio. The above relationship is the relationship between the target rotational speed and the actual throttle valve opening θ and vehicle speed V, or the relationship between the target gear ratio and the actual throttle valve opening θ and vehicle speed V. The above-mentioned former relationship when is 20+n/h is illustrated.

As mentioned above, when the shift lever 56 is operated to the driving range and the accelerator pedal is operated, if the vehicle speed v'fJ< increases and exceeds the judgment reference value V, the judgment in step S4 is affirmed. , step S5
At this point, the contents of flag F are set to "1". As a result, the determination in step S9 is affirmed,
In step S10 following step S9, the difference (n
.

It is determined whether or not -n;a) is larger than a predetermined constant judgment reference value δ. This judgment reference value δ determines whether the difference in rotational speed between the pump impeller 24 and the turbine impeller 28 is small enough to allow the shock that occurs when the lock-up clutch 29 is engaged. This is a value for judgment, and a value of about 50 rpm is adopted, for example.

In step SIO, if it is determined that the difference between the engine rotational speed n and the input shaft rotational speed nin (n9 n1n) is not larger than the judgment reference value δ, the lock-up clutch 29 is in a state where it can be engaged. Therefore, in step Stt, the contents of the character variable α are set to r200J, and the contents of the character variable β are sent to r□.

Then, in step S13, the manual shaft rotation speed n
i is the criterion value (900+α+β), that is, 111
It is determined whether or not the speed has reached 00rp or more. In this case, the judgment standard (l! (900+α+β) indicates the manual shaft rotation speed for engaging the lock-up clutch 29.The input shaft rotation speed n, 7 is the judgment standard value (900+α
+β), the above-mentioned step S14
, S18.319.320 are executed, but when the input shaft rotational speed nln reaches the judgment reference value (900+α+β), the content of the flag F is set to "2" in step S21, and the lock-up clutch is activated in step S22. 29 is engaged, and step S23
In step S20, target rotational speed control similar to that in step S20 is executed.

When the content of flag F is set to "2" as described above, steps S6 and subsequent steps are executed following step S3. That is, in step S6, it is determined whether or not the brake is being operated. During continuous running or coasting, the determination in step S6 is negative, so the character variable β is set to "0" in step S8, and the character variable α is set to "0" in step S12.
'', it is determined in step S13 whether the input shaft rotational speed nin is equal to or higher than the determination reference value (900 rρm). If the vehicle is running continuously, the determination in step S13 is affirmative. When the input shaft rotational speed n1. .

is initially maintained at 11000 rpm, but the continuously variable transmission 14
After the gear ratio reaches the maximum speed reduction side, the input shaft rotational speed n
in begins to decrease further, and the determination in step S13 becomes negative. As a result, the determination in step 314 is affirmed, and in step 316 following step 315, the lock-up clutch 29 is released, thereby preventing the engine from stopping, and the quantity reduction ratio control is executed in step S17. This amount reduction ratio control is performed in step s14 when the vehicle is started the most.
When it is determined that the accelerator pedal has been operated, or when the accelerator pedal is not operated such as when driving downhill, the vehicle speed V has reached the determination reference value v.

It will be terminated when the limit is exceeded.

While the vehicle is running, if a braking operation is actively performed to stop the vehicle and the determination in step S6 is affirmative, in step S7 the character variable β is determined from a pre-stored map shown in FIG. 5, for example. Actual deceleration of the vehicle l
Determined based on dv/dtl. As a result, the character variable β decreases as the vehicle speed V decreases, and the deceleration ldv
Since /dt is determined to be a larger value as it becomes larger, the determination reference value in step 313 is similarly determined to be a larger value as vehicle speed ■ becomes smaller and deceleration ldv/dt becomes larger. Therefore, the deceleration ldv/dt
The larger l is, the earlier the determination in step S13 is denied, and the earlier the lock-up clutch 29 is released in step S16. In this embodiment, the above step S7,
Step S13, step S16, etc. correspond to a control means for releasing the lock-up clutch 29 at an optimal time when the vehicle is stopped.

As described above, according to this embodiment, when the vehicle is stopped by braking, the larger the deceleration 1dv/dL1 of the vehicle, the larger β is determined in step S7, and the larger the determination reference value in step S13. The lock-up clutch 29 is released at the optimum time. For this reason,
When the lock-up clutch 29 is released too slowly when the vehicle is stopped, a large engine braking effect may be felt due to changing the gear ratio of the continuously variable transmission 14 to the deceleration side, or during sudden braking. This eliminates the problem of engine stoppage. Also, vehicle deceleration 1 dv
As a result of the lock-up clutch 29 being released at an optimal time in relation to /dtl, the lock-up clutch 29 is released at a relatively low vehicle speed, and the dry running window after the lock-up clutch 29 is released is so small that it does not pose a problem. Become.

Although one embodiment of the present invention has been described above based on the drawings,
The invention also applies in other aspects.

For example, in the embodiment described above, the lock-up clutch 29
However, in a vehicle equipped with another automatic clutch such as an electromagnetic clutch instead of the fluid coupling 12, the present invention can also be applied to the release control of those automatic clutches. be.

Further, in step S7 of the above-described embodiment, β was determined based on the vehicle deceleration ldv/dtl and the vehicle speed V, but if only the vehicle deceleration ldv/dL1 or the vehicle deceleration 1dv/dtl and other It may be determined based on parameters.

In addition, in the above embodiment, the deceleration was determined from the differential value of the vehicle speed V, but as another deceleration detection means, an acceleration sensor is provided and the deceleration of the vehicle is detected from the output signal of the acceleration sensor. Alternatively, in a vehicle equipped with a hydraulic brake, the magnitude of the brake oil pressure may be detected, and the deceleration of the vehicle may be estimated from the brake pedal depression force related to the magnitude of the brake oil pressure.

Further, although the one-way clutch 27 was provided in the above embodiment, it does not necessarily have to be provided.

The above-mentioned embodiment is merely one embodiment of the present invention, and various modifications may be made to the present invention without departing from the spirit thereof.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a vehicle power transmission device to which an embodiment of the present invention is applied. FIG. 2 is a block diagram showing an electronic control circuit used in the embodiment of FIG. 1. FIG. 3 is a flowchart illustrating the operation of the embodiment of FIGS. 1 and 2. FIG. 4 and 5 are diagrams showing the relationships used in the explanation of FIG. 3, respectively. FIG. 4 is a diagram showing the relationship for determining the target rotation speed, and FIG. FIG. 3 is a diagram showing a relationship for determining the value of a character variable based on speed and vehicle speed. 14: Continuously variable transmission

Claims (1)

[Claims] In a vehicle equipped with a continuously variable transmission in which the gear ratio can be changed steplessly, a method for releasing an automatic clutch inserted in a power transmission path of the vehicle prior to stopping the vehicle. The control device is a stepless control device, comprising: a deceleration detection means for detecting vehicle deceleration during braking of the vehicle; and a control means for releasing the automatic clutch earlier as the vehicle deceleration increases. Automatic clutch control device for vehicles equipped with a transmission.