JPS61109956A - Speed change ratio control device for stepless speed change gear for vehicle - Google Patents

Abstract

PURPOSE:To permit to eliminate the deterioration of operability by a method wherein the speed ratio of the stepless speed change gear is reduced as the running speed of the vehicle is increased, to restrict shift shock accompanied by the connection of a gear step. CONSTITUTION:The speed change ratio of the stepless speed change gear 14 is controlled so as to reduce it as the vehicle speed V is increased, even in case the shift lever of the vehicle is switched to the neutral range and is switched again from the neutral range to driving range. Accordingly, the shift shock, accompanied by the connection in the predetermined gear step of the sub speed change gear 30 may be eliminated remarkably and the deterioration of the operability of the vehicle, which is due to the shift shock, may be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an improvement in a gear ratio control device for a continuously variable transmission for a vehicle.

Conventional technology Controls the gear ratio of the continuously variable transmission in a vehicle in which a continuously variable transmission is inserted in the power transmission path from the engine to the driving wheels together with a stepped transmission having multiple switching states including neutral. A gear ratio control device is being considered. For example, there is a device described in Japanese Patent Application No. 195613/1983.

According to a vehicle equipped with such a gear ratio control device, since the continuously variable transmission is inserted in the power transmission path together with the stepped transmission, the gear ratio change range of the continuously variable transmission is reduced. , the continuously variable transmission is characterized by a small size.

Problems to be Solved by the Invention However, when the stepped transmission is switched to the neutral state in a vehicle that declines, control is performed to maximize the gear ratio of the continuously variable transmission, similar to when the vehicle is stopped, for example. Therefore, when the vehicle is running at high speed, the neutral state of the stepped transmission is selected by operating the shift lever, and then the stepped transmission is connected at a predetermined gear by switching to the forward range, for example, the drive range. When this happens, a relatively large engine brake suddenly acts on the drive wheels, resulting in shift shock, which sometimes impairs drivability.

Means for Solving the Problems The present invention has been made against the background of the above-mentioned circumstances, and its gist is as shown in the claim correspondence diagram in FIG. (2) neutral state detection means for detecting a neutral state of the stepped transmission; (3) a vehicle speed detecting means for detecting a traveling speed; (3) a vehicle speed detecting means for detecting a neutral state of the stepped transmission; Accordingly, it is desirable to include a gear ratio adjusting means for reducing the gear ratio of the continuously variable transmission.

Operation and Effects of the Invention With this arrangement, when the stepped transmission is in the neutral state, the speed ratio of the continuously variable transmission is reduced as the vehicle travel speed is high (as the speed ratio of the continuously variable transmission becomes smaller), the shift lever cannot be pressed while the vehicle is running. Even if the stepped transmission is engaged at a predetermined gear by switching from the neutral range to the forward (drive) range by operating -, the shift shock associated with it is greatly suppressed, and the operation caused by it is greatly suppressed. The decline in sexuality is erased.

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 rotating shaft 16 of a continuously variable transmission 14 via a lock-up fluid coupling 12.

The input side rotating shaft 16 is provided with a variable pulley 22 whose groove width, that is, the hanging diameter of the transmission belt 20 is changed by the hydraulic cylinder 18. A variable pulley 28 is provided, the variable pulley 28 being variable. Therefore, the rotational force transmitted to the input end rotating shaft 16 is transmitted to the variable pulleys 22 and 2.
The power is transmitted to the output side rotating shaft 24 via the transmission belt 20 wrapped around the transmission belt 8, and is also transmitted to the auxiliary transmission 30, which is a subsequent stepped transmission. The sub-transmission 30 is a first
It includes a Ravigneaux-type compound planetary gear system consisting of a sun gear 32, a second sun gear 34, a ring gear 36, etc., and a high speed clutch 38, a low speed brake 40, and a reverse brake 42 are selectively operated by a hydraulic actuator (not shown). As a result, the gear ratio R changes as shown in FIG.
f can be switched, or forward rotation and reverse rotation can be switched.''Here, in Fig. 3, ρ1 is Z
, , /Z,, ρ2 is Z , , /Z *. However, Z I+ is the number of teeth of the first sun gear 32 , Zs□ 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 side rotating wheel 24 of the belt type continuously variable transmission 14 is
Since the carrier 44 that constitutes the input shaft of the sub-transmission 30 and supports the planetary gears in the sub-transmission 30 constitutes the output shaft, the gear ratio of the sub-transmission 30 is the rotation speed of the carrier 44 on the output side. This is the value divided by the rotation speed of the shaft 24. The rotational force transmitted to the carrier 44 is transmitted to the drive wheels 52 of the pair of vehicles via the intermediate gears 46, 48 and the final reduction gear 50, respectively.

In the vicinity of the variable pulleys 22 and 28, there is an input shaft rotation sensor 58 and an output shaft rotation sensor that outputs pulse signals SPI and SP2 of frequencies corresponding to the rotational speeds of the variable pulleys 22 and 28 to the input cover couch 56 in the controller 54. A sensor 60 is provided. Also, intermediate gear 4
8, a vehicle speed sensor 62 is provided as a vehicle speed detection means for outputting a pulsed vehicle speed signal SV having a frequency corresponding to the rotational speed of the intermediate gear to the input cover sofa 56.

This vehicle speed sensor 62 is provided exclusively to display the vehicle speed on a speedometer provided in front of the driver's seat. Further, a throttle sensor 64 is provided in a throttle valve (not shown) provided in the intake pipe of the engine 10, and a throttle signal Sθ representing the throttle valve opening degree θ is sent from the throttle sensor 64 to the manual vanofer 56.
supplied to Further, a neutral signal SN indicating that the shift lever has been operated to the neutral position is supplied to the human cover sofa 56 from a neutral sensor 66 as neutral state detection means provided on a shift lever (not shown). This shift lever is configured to be operated to each range shown in FIG. 3, and when it is operated to the neutral range, the high speed clutch 38, the low speed brake 40,
Hydraulic pressure is prevented from being supplied to any of the hydraulic actuators that operate the reverse brakes 42, but when the reverse range is operated, the reverse brakes 42 are
Hydraulic oil is supplied only to the hydraulic actuator that operates the system. Furthermore, when the forward range is operated, hydraulic oil is allowed to be supplied to either of the hydraulic actuators that actuate the high speed clutch 38 and the low speed brake 40.

A microcomputer 68 is provided within the controller 54. The microcomputer 68 is a CPU, R
OM, RAM, etc., and processes input signals supplied via the input cover sofa 56 while utilizing the temporary storage function of the RAM according to a program stored in advance in the ROM.
Sub-shift [30, high/low speed switching valve 72, shift direction switching valve 7
4, and drive signals SHL, SDI, and SD2 are outputted to the shift speed switching valve 76 via the output cover sofa 78, respectively.

The high/low speed switching valve 72 is a hydraulic actuator that operates the high speed clutch 38 or the low speed brake 40 when the shift lever is operated in the drive range or the low range of the forward range. This is for selectively supplying hydraulic oil to the pump, and is switched according to the drive signal SHL. When the shift lever is in the drive range, the microcomputer 68 follows a predetermined shift pattern, and when the vehicle speed ■ reaches a predetermined value, switches the sub-transmission 30 from a low gear to a high gear, and vice versa. It is configured to switch from the high speed gear to the low gear when the speed falls below a predetermined value.

FIG. 4 shows an example of the shift pattern, with the solid line as the boundary for upshifting and the broken line as the boundary for downshifting, with the left side being the low gear range and the right side being the high gear range.

Further, the shift direction switching valve 74 is connected to the hydraulic cylinder 18.
The shift direction (speed ratio changing direction) of the continuously variable transmission 14 is switched between a state in which hydraulic oil is supplied to the hydraulic cylinder 18 and a state in which the hydraulic oil is discharged from the hydraulic cylinder 18. For example, when hydraulic oil is supplied into the hydraulic cylinder 18, the gear ratio (input end rotational shaft rotational speed Nin/output side rotational shaft rotational speed Nout) is changed in the direction of decreasing, and conversely, When discharge of the hydraulic oil is allowed, the gear ratio is changed in the direction of increasing it.

Further, the shift speed switching valve 76 is connected to the shift direction switching valve 74.
It is provided in series with the hydraulic cylinder 18 and can be selectively switched between a state of permitting and a state of suppressing the flow of hydraulic oil supplied into the hydraulic cylinder 18 or hydraulic oil discharged from the hydraulic cylinder 18. As a result, continuously variable speed m14
The change speed of the gear ratio is increased or maintained at a desired gear ratio. In addition, the shift speed switching valve 7
6 can continuously control the speed ratio change speed according to duty control. The control device for such duty control, the shift direction switching valve 74 and the shift speed switching valve 76 are constructed in the same manner as described in Japanese Patent Application No. 58-251677, for example.

The operation of the control device configured as above will be explained.

In FIG. 5, when step S1 is executed, output signals Sθ from the throttle sensor 64, human power shaft rotation sensor 58, output shaft rotation sensor 60, vehicle speed sensor 62,
, SP2. According to the SV, the throttle valve opening θ, the rotation speed Nin of the input side rotation shaft 16 (engine 1O), the rotation speed Nout of the output side rotation shaft 24, the vehicle speed ■, etc. are read. Next, steps S2 to S4 are executed, and it is determined whether the operating position of the shift lever is in the neutral range or in the reverse range. shift lever
If the position is in the neutral range, the target rotational speeds N and TI in neutral are determined in step S5. That is, the computer 68 stores the vehicle speed ■ shown in the upper part of FIG. 6, the target rotational speed N in neutral,
The relationship with IT is stored in advance, and based on that relationship, the target rotation speed N in neutral is determined based on the actual vehicle speed.
'' is determined. In the relationship shown in the upper row of FIG. 6, straight line A corresponds to the low speed gear of the sub-transmission 30, and straight line B corresponds to the high speed gear. The shift pattern shown in FIG. As shown in FIG. 6, the position at which the gear changes from the low gear to the high gear is different from the position at which the gear changes from the high gear to the low gear. Therefore, hysteresis is provided correspondingly in the relationship shown in FIG.

On the other hand, if it is determined that the shift lever is in the drive range, the target rotational speed determination routine of step S6 is executed. That is, as shown in FIG. 7, it is determined in step SMI whether the auxiliary transmission 30 is in the high speed gear. If it is a high speed gear, step SM2 is executed and the target rotational speed N0 of the input side rotating wheel 16 is equal to the throttle opening θ and the rotational speed Nout of the output side rotating shaft 24.
Determined based on. This target rotational speed N is determined so that the engine 10 operates approximately along the minimum fuel consumption rate curve.
It is determined from a predetermined relationship (data map) between N and θ with out as a parameter. Note that the target rotational speed No. may be determined based on only the throttle opening θ or it and the vehicle speed V, or may be determined based on the throttle opening θ alone or based on it and the vehicle speed V.
Instead, the amount of load required for the engine 10, such as the operation amount of the accelerator pedal or the negative pressure in the intake pipe of the engine 10, may be used. However, if it is determined in step SMI that it is not a high speed gear, then the throttle opening θ and the output side rotating shaft 2 are determined based on other predetermined relationships.
40 target rotational speed N, based on rotational speed Nout. is determined. This target rotational speed NDD is always larger than the target rotational speed N8.

On the other hand, when it is determined that the shift lever is in the reverse range, the reverse range control in step S7 is executed, and when it is determined that the shift lever is not in the reverse range, the reverse range control is executed in step S.
8 low range control is executed. Reverse range control S7
In the low range control S8 and the low range control S8, a target rotational speed suitable for reversing the vehicle or running the vehicle in a low gear is determined based on at least the throttle opening θ based on predetermined relationships. The target rotational speed determined in this low range control is the same as the target rotational speed NDD. Then, in step S9, which will be described later, so that the target rotation speed and the actual rotation speed Nin of the input side rotation shaft 16 match.
Steps similar to the following are performed.

Returning to FIG. 5, in step S9, the deviation E between the target rotational speed NI, (or Noo, No'') and the actual rotational speed Nin is determined, followed by step 810.
In the following, the gear ratio is controlled so that the deviation E becomes smaller. That is, in step s10, it is determined whether the deviation E is positive or negative. If the deviation E is determined to be negative, it means that the actual rotation speed N of the input side rotating shaft 16 is too high, and it is necessary to shift up, so step Sll is executed. The shift direction switching valve 74 is switched to the shift amplifier state.

That is, hydraulic oil is supplied into the hydraulic cylinder 18, and the effective diameter of the variable pulley 1B is expanded. On the other hand, step 3
If the deviation E is determined to be positive in 10,
This means that the actual rotational speed 1iNin of the input side rotating shaft I6 is too low, and it is necessary to downshift, so step SL2 is executed and the shift direction switching valve 74 is brought into the downshift state. Therefore, the hydraulic oil in the hydraulic cylinder 18 is allowed to be discharged, and the effective diameter of the variable pulley 18 is reduced.

After the shift amplifier state is entered by executing step Sll, steps S13 and SL5 are executed,
It is determined whether the deviation IEI is larger than a predetermined constant value A or smaller than A4. Deviation I
If EI is larger than A or smaller than A4, step S14 or 316 is executed and the shift speed switching valve 76 is set to the maximum shift speed state or the minimum shift speed state. That is, hydraulic cylinder 1
The supply flow rate to 8 is set to the maximum or minimum state. However, the deviation IEI is A.

If it is between , step 521 is executed and the duty ratio D (%) is determined according to the following equation (1).

D= C(1/B) l E l +c) ・1/
100...(1) However, B and C are constants, for example, B=100, C=
It is set to about 0.3.

After the duty ratio is determined in step S21, the shift speed switching valve 76 is reciprocated according to the duty ratio in step S23, and the speed ratio change speed (shift speed) is continuously adjusted according to the magnitude of the deviation. .

Even after the downshift state is set in step S12, steps 517 and S19 are similarly executed to determine whether the absolute value IEI of the deviation is larger than a predetermined constant value A2 or smaller than A3,
If it is larger than A2 or smaller than A3, steps S18 and S20 are executed to set the shift speed to the maximum state and the minimum state. However, the deviation IEI
is between A2 and A3, the duty ratio is determined in step S22. The duty ratio D (%) in this case is determined in (2) 2. Here, D= (1-((1/B)l B +1 +C]・1/
1.00...(2) Similar to the control device described in Japanese Patent Application No. 5.9-14010, the constant values are At>A, a, Az>
A3, A: + > Aa, and the state of the shift speed switching valve 76 allowing the flow and the state of suppressing the flow are reversed as the shift direction switching valve 74 is switched to the shift amplifier state and the shift down state. It is now possible to

Diagnosis in step S24 is then executed to diagnose an abnormality in the input shaft rotation sensor 58, output shaft rotation sensor 60, etc. or an abnormality in the continuously variable transmission [14].

During normal vehicle running, the shift lever is operated in the drive range, so steps 86 and subsequent steps are repeatedly executed. In such a state, the target rotational speed N. is determined so that the vehicle runs continuously at high speed, resulting in favorable fuel economy. For example, when the operating lever is operated to the neutral range while the vehicle is running, the sub-shift n30 is switched to the neutral state as shown in FIG. 3, and the engine 10 is placed in an unloaded state. In such a state, the gear ratio is controlled by executing the steps from step S5 onwards. That is, in step S5, the target rotational speed N in neutral, IT
As a result, the gear ratio of the continuously variable transmission 14 is controlled in a decreasing direction according to the vehicle speed, as shown in the lower part of FIG. 6. Therefore, even if the shift lever is operated from the neutral range to the drive range while the vehicle is traveling, the shift shock associated with the engagement of the sub-transmission 30 at a predetermined gear stage is greatly alleviated, and drivability is maintained suitably. The relationship shown in FIG. 6 is determined in this way. Therefore, according to this embodiment, step S5. And steps S9 to S23 constitute a gear ratio adjusting means in neutral.

As described above, according to the present embodiment, even when the shift lever of the vehicle is switched to the neutral range and then switched from the neutral range to the drive range again, the gear ratio of the continuously variable transmission 14 does not change as the vehicle speed V increases. Since the shift shock caused by the engagement of the auxiliary transmission 30 at a predetermined gear stage is largely eliminated.

Although the embodiment of the present invention has been described above based on the drawings, the present invention can also be applied to other embodiments.

For example, in the embodiment described above, the gear ratio of the continuously variable transmission 14 is the target rotational speed N. Or N, D.

N,") is controlled so that it matches the actual rotational speed Nin, but the control target is throttle opening θ and vehicle speed V.
It may be the target speed ratio determined by - or the target driving force. In short, when the auxiliary transmission is switched to the neutral range regardless of the control target, the gear ratio of the continuously variable transmission is controlled to decrease with the vehicle speed, and when the auxiliary transmission 30 is returned to the drive range, It is sufficient to prevent shift shock from occurring.

Further, although the sub-transmission 30 in the above embodiment is a stepped transmission with two forward speeds as shown in FIG. 3, it may also be a transmission with three or more speeds or a transmission with only one forward speed. good. In the case of a transmission with only one forward gear, the target rotational speed N and PA in neutral are controlled as shown in the upper part of Figure 8, and the gear ratio at this time is as shown in the lower part of Figure 8. As a result, it will be controlled.

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 corresponding to claims of the present invention. FIG. 2 is an explanatory diagram showing the configuration of an embodiment of the present invention. FIG. 3 is a diagram showing switching states in the sub-transmission of FIG. 2. FIG. 4 is a diagram showing an example of a shift pattern diagram used in the embodiment of FIG. 2. Figures 5 and 7 are
3 is a flowchart illustrating the operation of the illustrated embodiment. FIG. 6 shows the relationship used to determine the target rotational speed in neutral in the embodiment shown in FIG. 2, and the gear ratio that is controlled as a result when the target rotational speed is controlled. FIG. FIG. 8 is a diagram corresponding to FIG. 6 in another embodiment of the present invention. 10: Engine 14: Continuously variable transmission 30: Sub-transmission (stepped transmission) 62: Vehicle speed sensor (vehicle speed detection means) 66: Neutral sensor (neutral state detection means) Step S5. Steps S9 to S23: Gear ratio adjustment means Applicant Toyota Motor Corporation Figure 1 Figure 30 Figure 4 Vehicle speed ■ Figure 6 Vehicle speed ■ Figure 8 Vehicle speed ■

Claims (2)

[Claims] (1) In a vehicle in which a continuously variable transmission is inserted in the power transmission path from the engine to the drive wheels together with a stepped transmission that has multiple switching states including neutral, control the gear ratio of the continuously variable transmission. A gear ratio control device comprising: vehicle speed detection means for detecting a running speed of the vehicle; neutral state detection means for detecting a neutral state of the stepped transmission; A gear ratio control device for a continuously variable transmission for a vehicle, comprising a gear ratio adjusting means for decreasing the gear ratio of the continuously variable transmission as the traveling speed of the vehicle increases. (2) In the neutral state of the stepped transmission, the speed ratio adjusting means determines a speed ratio corresponding to a gear position to which the current vehicle running state belongs in a speed change pattern diagram showing a speed change range of the vehicle; The gear ratio control device for a continuously variable transmission for a vehicle according to claim 1, wherein the gear ratio is continuously decreased as the vehicle speed increases.