JP2818812B2 - Control device for continuously variable transmission - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for performing a speed change control by a secondary pressure control and a primary pressure in a belt type continuously variable transmission for a vehicle. Related to switching shock reduction measures.

[Conventional technology]

Generally, a drive system of this type of continuously variable transmission is provided with a forward / reverse switching device, and is provided with a drive (D) or a reverse (R).
The power is transmitted in the forward or reverse direction by shifting the range. Here, with the use of the torque converter on the input side of the continuously variable transmission, the forward / reverse switching device tends to be constituted by a planetary gear, a hydraulic multi-plate clutch and a brake.

Thus, a hydraulic forward / reverse switching device attached to the above-mentioned continuously variable transmission has been filed, for example, in Japanese Patent Application No. 1-264644. Here, the forward / reverse switching device is constituted by a double pinion type planetary gear, the sun gear and the carrier are connected via a forward clutch, and a reverse brake is provided between the ring gear and the case side. In addition, when the reverse rotation of the R range is performed, a torque reaction force approximately twice as large as that at the time of forward movement acts on the reverse brake for fixing the ring gear. It is shown.

[Problems to be solved by the invention]

By the way, in the above-mentioned prior art, the lubricating pressure and the secondary pressure are directly supplied to the clutch and the brake for switching between forward and reverse, but in consideration of reduction of the switching shock, the accumulator is supplied to the supply oil passage. It is conceivable to use. Here, when a constant low lubrication pressure is supplied as in a forward clutch, the same accumulator effect is always obtained, and the accumulator is also downsized. on the other hand,
In the case of a reverse brake, the accumulator becomes large in order to supply a high secondary pressure. In addition, since the secondary pressure changes according to the engine torque and the like, even if the set pressure is determined by a spring or the like, the timing of the accumulator operation range and the timing of the brake meet point may be shifted, and a large shock may occur.

Therefore, as a countermeasure against switching shock when a high secondary pressure is supplied to the reverse brake, it is most effective to smoothly control and supply the secondary pressure itself.

SUMMARY OF THE INVENTION The present invention has been made in view of the foregoing, and an object thereof is to provide a continuously variable transmission capable of effectively reducing a switching shock of a forward / reverse switching device attached to a continuously variable transmission. To provide a control device.

[Means for solving the problem]

In order to achieve the above object, the control device for a continuously variable transmission according to the present invention is configured such that a forward / reverse switching device disposed on an input side of the continuously variable transmission engages a forward clutch with a low lubricating pressure to move to a forward position. In a drive system configured to shift and engage the reverse brake with a high secondary pressure to shift to the reverse position, the secondary pressure is raised stepwise as a function of time when shifting to the reverse position. Are controlled so as to smoothly engage with each other.

[Action]

Based on the above configuration, the drive system of the continuously variable transmission uses the forward / reverse switching device to shift the forward clutch to the forward position by lubricating pressure when shifting in the D range, and to increase the reverse brake when shifting in the R range. The secondary pressure increases the torque capacity and firmly engages to the reverse position.
When the R range is shifted, the secondary pressure is controlled in a stepwise manner and supplied to the reverse brake, so that the reverse brake smoothly engages in a variable range in the middle of the secondary pressure to reduce the switching shock. After the reverse brake is engaged, the reverse position is reliably held at a high secondary pressure.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In FIG. 2, an outline of the drive system of the continuously variable transmission with a lock-up torque converter will be described. Reference numeral 1 denotes an engine, and a crankshaft 2 is configured to be sequentially transmitted to a torque converter device 3, a forward / reverse switching device 4, a continuously variable transmission 5, and a differential device 6.

In the torque converter device 3, the crankshaft 2 is connected to the converter cover 11 and the pump impeller 12 a of the torque converter 12 via the drive plate 10. A turbine liner 12b of the torque converter 12 is connected to a turbine shaft 13, and a stator 12c is guided by a one-way clutch 14. A lock-up clutch 15 integrated with the turbine liner 12b is provided so as to be engaged with or released from the drive plate 10, and transmits engine power via the torque converter 12 or the lock-up clutch 15.

The forward / reverse switching device 4 includes a double pinion type planetary gear 16. The turbine shaft 13 is input to the sun gear 16 a and output from the carrier 16 b to the primary shaft 20. A forward clutch 17 is provided between the sun gear 16a and the carrier 16b.
The reverse brake 1 between the ring gear 16c and the case.
8, the planetary gear 16 is integrated with the forward clutch 17 to directly connect the turbine shaft 13 and the primary shaft 20. In addition, the reverse power is output to the primary shaft 20 by the connection of the reverse brake 18, and the planetary gear 16 is set free by releasing the forward clutch 17 and the reverse brake 18.

The continuously variable transmission 5 includes a primary pulley 22 having a hydraulic cylinder 21 on a primary shaft 20 and a variable pulley interval, and a secondary pulley 25 also having a hydraulic cylinder 24 on a secondary shaft 23. A drive belt 26 is wound around the pulley 25. Here, the pressure receiving area of the primary cylinder 21 is set larger, and the ratio of the winding diameter of the drive belt 26 to the primary pulley 22 and the secondary pulley 25 is changed by the primary pressure to perform stepless transmission.

In the differential device 6, an output shaft 28 is connected to the secondary shaft 23 via a pair of reduction gears 27, and a drive gear 29 of the output shaft 28 meshes with the final gear 30. A differential gear 31 of the final gear 30 is connected to left and right wheels 33 via an axle 32.

On the other hand, an oil pump 34 is provided adjacent to the torque converter 12 in order to obtain a hydraulic source for controlling the continuously variable transmission, and the oil pump 34 is connected to the converter cover 11 by a pump drive shaft 35 so that the engine power Drives the pump to generate hydraulic pressure. Here, in the continuously variable transmission 4, since the hydraulic pressure is controlled in a wide range of high and low, the oil pump 34 is, for example, of a roller vane type, and has
It has a plurality of discharge ports and is configured as a variable displacement type.

 In FIG. 1, the hydraulic control system will be described.

First, regarding the hydraulic control system of the continuously variable transmission, an oil passage 51 from an oil pump 34 communicating with an oil pan 40 communicates with a secondary pressure control valve 52 to generate a predetermined secondary pressure Ps. The pressure Ps is always supplied to the secondary cylinder 24 through the oil passage 53. The secondary pressure Ps is guided to the primary pressure control valve 56 via the oil passage 55, and is supplied to and discharged from the primary cylinder 21 through the oil passage 57, and the primary pressure Pp
Is configured to occur.

The secondary pressure control valve 52 is a proportional solenoid relief valve, and the control unit 90 supplies a solenoid current Is to the proportional solenoid 52a. Then, the electromagnetic force due to the solenoid current Is, the hydraulic reaction force of the secondary pressure Ps, and the spring force act on the spool so as to balance them. That is, the set pressure is made variable by the solenoid current Is, and the secondary pressure Ps is controlled in a one-to-one proportional relationship with the solenoid current Is.

The primary pressure control valve 56 is a proportional electromagnetic relief valve, and like the secondary pressure control valve 52, the proportional solenoid 56
The control unit 90 supplies a solenoid current Ip to a. Then, the electromagnetic force by the solenoid current Ip, the hydraulic reaction force of the primary pressure Pp, and the spring force act on the spool, and the set pressure is made variable by the solenoid current Ip, and the solenoid current Ip is proportional to the one-to-one ratio. The primary pressure Pp is controlled by the relationship.

Here, the hydraulic pressure of the drain-side oil passage 58 of the secondary pressure control valve 52 is relatively high, and can be used not only for lubrication but also for a torque converter, an operating pressure for switching between forward and backward, and a control pressure. Therefore, the lubricating oil passage 58 communicates with the hydraulic relief valve 59 to generate a predetermined lubricating pressure Pl.
60 communicates with a nozzle 62 through a check valve 61 to form a belt 26
Is to be refueled.

Next, a hydraulic control system such as a torque converter will be described.

The lubrication pressure oil passage 58 communicates with the two inlet sides and one control side of the lock-up control valve 63, and the oil passage 65 of the control pressure Pc of the lock-up control solenoid valve 64 that uses the lubrication pressure as the source pressure is The lock-up control valve 63 communicates with the other control side. The oil passage 66 on one outlet side of the primary pressure control valve 63 communicates with the release chamber 15a of the lock-up clutch 15, and the oil passage 67 on the other outlet side has a relief valve 68, Apply room 15b for lock-up clutch 15
Communicate with Also, when the torque converter 12 operates, the oil passage
A drain-side oil passage 69 communicating with 67 is in communication with an oil cooler 70, and an oil passage 65 of a lock-up control solenoid valve 64 is further in communication with a hydraulic relief valve 59 so that the control pressure during lock-up is controlled.
When Pc occurs, the set pressure of the hydraulic relief valve 59 is set to a lower value.

On the other hand, the secondary pressure oil passage 51 and the lubrication pressure oil passage 58 communicate with the forward clutch 17 and the reverse brake 18 via the safety lock valve 71, the oil passages 72 and 73, the manual valve 74, and the oil passages 75 and 76. . On the control side of the safety lock valve 71, the control pressure Pc of the solenoid valve 77 using the lubricating pressure as the original pressure is guided through the oil passage 78, and is forced to drain the oil passage 72 or 73. . The manual valve 74 switches the oil passage in response to each shift operation. In the parking (P) and neutral (N) ranges, the manual valve 74 drains both oil passages 75 and 76, and D
In the range, the forward clutch 17
To the lubrication pressure Pl. On the other hand, in the R range, oil passages 73 and 76
By supplying high secondary pressure Ps to the reverse brake 18 in communication with the reverse brake 18, the torque capacity is increased, and it is possible to engage and fix against both the input and output torque reaction forces acting on the ring gear side.

Therefore, as a switching shock reduction measure, an accumulator 83 communicates with the forward clutch 17 in the middle of the oil passage 75 to the forward clutch 17 through an oil passage 82 in which an orifice 80 and a check valve 81 are arranged in parallel. The accumulator acts so as to gradually engage during refueling. Further, only the oil passage 76 directly communicates with the reverse brake 18, and engagement is facilitated by hydraulic control of the secondary pressure Ps.

Further, the drain side of the hydraulic relief valve 59 has an orifice 86
The oil passage 87 communicates with the suction side of the oil pump 34 via an oil passage 87, and communicates with the oil cooler 70 via an oil passage 89 having an oil cooler valve 88. And torque converter 12
When the lock-up is inoperative, a large amount of oil drained from the hydraulic relief valve 59 can be guided to the oil cooler 70 to be cooled.

Note that a lock-up signal based on the ratio of the input and output rotational speeds of the torque converter 12 and the like is input from the control unit 90 to the solenoid valve 64. A power transmission cutoff signal at the time of an incorrect shift operation is input to the solenoid valve 77.

In FIG. 3, an electronic control system of the control unit 90 will be described.

First, a primary pulley rotation speed sensor 92, a secondary pulley rotation speed sensor 92, an engine rotation speed sensor 93, and a throttle opening sensor 94 are provided as input signal sensors.

Describing the secondary pressure control system, the throttle opening θ of the throttle opening sensor 94, the engine speed sensor
Engine torque calculator that inputs 93 engine speed Ne
96, and the engine torque Te
Is estimated. Further, the engine speed Ne and the primary pulley speed Np on the input and output sides of the torque converter are input to a torque gain calculating unit 97, and a torque gain t according to the speed ratio n (Np / Ne) is determined. Further, the engine speed Ne and the primary pulley speed Np are determined by the primary system inertia torque calculating unit 98.
To calculate the inertia torque gi from the mass and acceleration of the engine 1 and the primary pulley 22. The engine torque Te, the torque amplification factor t, and the inertia torque gi are input to the input torque calculator 99, and the input torque Ti is calculated as follows.

Ti = Te · t-gi On the other hand, the necessary secondary pressure setting section to which the actual gear ratio i is input
Has 100. Here, the secondary pressure Psu of the slip limit required for unit torque transmission is set for each actual speed ratio i, and the required secondary pressure Psu corresponding to the actual speed ratio i is determined from this map. The input torque Ti and the required secondary pressure Psu are input to the target secondary pressure calculation unit 101,
Based on the input torque Ti, the required secondary pressure Psu, and the secondary pulley rotation speed Ns, the target secondary pressure Pss is calculated as follows in consideration of the centrifugal hydraulic pressure gs of the secondary cylinder 24.

Pss = Ti · Psu−gs Further, the target secondary pressure calculation unit 101 receives signals of each range of the inhibitor switch 95, and in the case of the R range, the target secondary pressure Pss is increased several times as compared with the N range. To determine.

The target secondary pressure Pss is further adjusted by the solenoid current setting unit 102.
To determine the solenoid current Is according to the target secondary pressure Pss. In this case, since the secondary pressure control valve 52 has the characteristic of controlling the secondary pressure in a proportional relationship with the solenoid current Is as described above, the solenoid current Is with respect to the target secondary pressure Pss is proportionally controlled by a map according to this. Ask for. Then, this solenoid current Is is supplied to the proportional solenoid 52a of the secondary pressure control valve 52 via the drive unit 103, and thus the secondary pressure Ps is directly controlled to follow the target secondary pressure Pss by the solenoid current Is. It has become.

In the secondary pressure control, the switching shock reduction measure in the case of the R range will be described. An operation amount control unit 104 is provided on the output side of the target secondary pressure calculation unit 101.
It also has a meet point calculation unit 105 to which an engine torque Te and an oil temperature signal from a transmission oil temperature sensor (not shown) are input, and estimates the time and oil pressure at the meet point m based on the relationship between the engine torque Te and the transmission oil temperature. I do. Then, each range signal, meet point signal, engine speed Ne, and throttle opening θ of the inhibitor switch 95 are input to the operation amount control unit 104, and when the R range signal is input, the target secondary pressure Pss is set as shown by the solid line in FIG. First, the voltage gradually rises from the level of the N range, and then gradually rises to reach a predetermined value immediately after reaching the meet point m. Here, the dPss / dt of the smooth variable range is estimated by estimating the vehicle state based on the engine speed Ne, the throttle opening θ, etc., and correcting it with a certain function. It is possible to meet.

Next, the operation of the control device for a continuously variable transmission having such a configuration will be described.

First, the oil pump 34 through the converter cover 11 of the torque converter 12 and the drive shaft 35 by the engine operation.
Is driven to rotate. And the pump discharge oil pressure of the oil pump 34 is guided to the secondary pressure control valve 52 to regulate the pressure,
A predetermined high secondary pressure Ps occurs. The hydraulic pressure in the oil passage 58 on the drain side of the secondary pressure control valve 52 is adjusted by a hydraulic relief valve.
Guided to 59, a constant lubrication pressure Pl is generated, and this lubrication pressure Pl is supplied to each of the solenoid valves 64, 77, so that a control pressure Pc can be generated. Further, the secondary pressure Ps is always supplied to the secondary cylinder 54 to apply a minimum necessary pulley pressing force according to the transmission torque.
Ps is guided to the primary pressure control valve 56 and the manual valve 74. The lubrication pressure Pl is used for lubricating the belt 26, and the control side and the lubrication side of the lock-up control valve 63, and the manual valve 74
Is led to.

Therefore, at the time of stopping and starting, the secondary pressure Ps is reduced most by the primary pressure control valve 56, and the primary pressure Pp of the primary cylinder 21 is controlled to the lowest level.
The belt 26 is the most secondary pulley in the continuously variable transmission 5.
It becomes the low speed stage with the maximum gear ratio shifted to 25. At this time, since the lock-up / off signal is input to the solenoid valve 64 and the control pressure Pc is controlled so as not to be generated, the lock-up control valve 63 operates to one side by the lubrication pressure Pl, as shown in the figure. The lubrication pressure Pl is led to the oil passage 66. Therefore, the lubricating pressure Pl enters the release chamber 15a of the lock-up clutch 15 via the oil passage 66 to turn off the lock-up clutch 15,
Circulation returns to the oil pan 50 via the torque converter 12, the oil passages 67 and 69, and the oil cooler 70, whereby the torque converter 12 is in an operating state.

The safety lock valve 71 guides the lubricating pressure Pl and the secondary pressure Ps to the oil passages 72 and 73 in a normal state.

Here, in the ranges P and N, the forward clutch 17 and the reverse brake 18 of the forward / reverse switching device 4 are both drained and released by the manual valve 74. As a result, the planetary gear 16 becomes free, and power transmission from the engine 1 to the continuously variable transmission 5 is cut off.

Then, when shifting to the D range, the lubricating pressure Pl of the oil passage 72 is supplied to the forward clutch 17 via the oil passage 75, and at this time, the accumulator 83 increases in volume and the hydraulic pressure rises as shown by the thin dotted line in FIG. , And the forward clutch 17 smoothly engages the sun gear 16a and the carrier 16b to reach the forward position. As a result, the engine power is input to the primary shaft 20 via the torque converter 12 and the turbine shaft 13, and the primary pulley 22,
The fluctuating power is output to the secondary shaft 23 by the secondary pulley 25 and the belt 26, and this is output to the differential device 6.
The vehicle travels by transmitting to the wheels 33 via the.

When the primary pressure control valve 56 increases the primary pressure Pp due to various driving and running conditions after the start, the belt
26 shifts to the primary pulley 22 to perform an upshift, and conversely, a downshift is performed by reducing the primary pressure Pp. Thus, the shift control is performed. The secondary pressure control valve 52 variably controls the secondary pressure Ps based on the gear ratio, the engine torque, the torque ratio of the torque converter 12, and the like.

When the torque converter 12 enters the coupling region after the start of the shift, a lock-up / on signal is input to the solenoid valve 64 to generate a control pressure Pc, and the lock-up control valve 63
Is switched to guide the lubricating pressure Pl to the oil passage 67. Therefore, the lubricating pressure Pl acts on the apply chamber 15b of the lock-up clutch 15 via the torque converter 12, and the lock-up clutch 15 is engaged to enter the lock-up state. Therefore, in this case, the engine power is
, Which will be transmitted efficiently. On the other hand, the control pressure Pc is guided to the hydraulic relief valve 59, and by reducing the set pressure, a large amount of oil flows from the hydraulic relief valve 59 to the oil cooler 70 via the oil cooler valve 88 and is cooled.

Next, when shifting to the R range, the secondary pressure Ps is changed by the manual valve 74 to the reverse brake 1 by the oil passages 73 and 76.
Supplied to 8. Then, at this time, the target secondary pressure Pss is increased by the target secondary pressure calculation unit 101 in the secondary pressure control system of the control unit 90 as compared with the N range.
The target secondary pressure Pss changes stepwise and is output by the manipulated variable control unit 104, whereby the secondary pressure Ps by the secondary pressure control valve 52 and the reverse brake 18
Also changes and rises similarly. Therefore, in the vicinity of the meet point m corresponding to the engine torque Te, the reverse brake
The oil pressure of 18 gradually rises to smoothly engage so as not to cause a shock. And reverse brake 18
After the meeting, the ring gear 16c of the planetary gear 16 of the forward / reverse switching device 4 is firmly fixed to the case side with a large torque capacity by the high secondary pressure Ps. For this reason, the reverse power is output to the primary shaft 20 via the carrier 16b to be in the reverse position, and the continuously variable changer 5 and thereafter reversely travel and travel backward.

Here, if the shift to the R range is performed with the accelerator depressed, the meet point m of the reverse brake 18 shifts to the high rotation side. However, the smooth variable range is expanded and corrected by the operation amount control unit 104. The brake 18 engages smoothly. After the engagement, the torque capacity of the reverse brake 18 is further increased by the secondary pressure Ps according to the engine torque Te, and the reaction force of the input / output torque is received without slipping, and with the power corresponding to the accelerator pedal depression. The vehicle will run backward.

The embodiment of the present invention has been described above, but the present invention is not limited to this.

〔The invention's effect〕

As described above, according to the present invention, the forward / reverse switching device provided in the drive system of the continuously variable transmission has the R
In the range where the secondary pressure is supplied to the reverse brake to increase the torque capacity in the range, the secondary pressure itself is smoothly controlled during the shift operation of the R range, so that the switching shock is reliably reduced. I can do it.

Further, since the reverse brake meet point and the variable range of the secondary pressure are detected and corrected by the engine torque or the like, the switching shock can always be appropriately reduced.

Further, since the switching shock is reduced by the secondary pressure control, a large accumulator is not required, and the hydraulic control system becomes compact.

Furthermore, the forward clutch that engages the D range of the forward / reverse switching device with a low lubricating pressure can reliably reduce the switching shock by adding an accumulator.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a hydraulic control system of an embodiment of a control device for a continuously variable transmission according to the present invention, FIG. 2 is a skeleton diagram showing a drive system of the continuously variable transmission, and FIG. FIG. 4 is a block diagram showing the hydraulic pressure rise characteristics at the time of shifting between the D and R ranges. 4 forward marching switching device, 5 continuously variable transmission, 12 torque converter, 17 forward clutch, 18 reverse brake, 75 lubricating oil passage, 76 secondary oil passage, 90: control unit, 95: inhibitor switch, 101: target secondary pressure calculation unit, 104: operation amount control unit

Claims (3)

(57) [Claims] A forward / reverse switching device disposed on an input side of a continuously variable transmission engages a forward clutch at a low lubricating pressure to shift to a forward position, and engages a reverse brake at a high secondary pressure. In the drive system configured to shift to the reverse position, the secondary pressure is raised stepwise as a function of time when shifting to the reverse position, and the reverse brake is controlled so as to be smoothly engaged. Continuously variable transmission control device. 2. The control device for a continuously variable transmission according to claim 1, wherein the variable range of the meet point of the secondary pressure is made variable by a function of an engine speed and a throttle opening. 3. An accumulator is connected to the lubricating pressure supply circuit of the forward clutch via an orifice and a check valve arranged in parallel.
The control device for a continuously variable transmission according to any one of the preceding claims.