JP2631372B2 - Hydraulic control method for continuously variable transmission - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a hydraulic control method for a continuously variable transmission,
In particular, by switching the drive frequency of the pressure control valve means to change the oil pressure according to the oil temperature state of the hydraulic circuit, to ensure the proper oil pressure even at low temperatures when the viscosity of the oil is large,
The present invention relates to a hydraulic control method for a continuously variable transmission that can improve drivability by appropriately maintaining clutch pressure and the like.

[Related Art] In a vehicle, a transmission is interposed between an internal combustion engine and drive wheels. In this transmission, the driving force of the drive wheels and the traveling speed are changed in accordance with the traveling conditions of the vehicle that vary over a wide range, so that the performance of the internal combustion engine is sufficiently exhibited.

In the transmission, for example, a pulley having a fixed pulley part fixed to the rotating shaft and a movable pulley part attached to the rotating shaft so as to be able to approach and separate from the fixed pulley part is formed between the two pulley parts. There is a continuously variable transmission that changes the groove width by hydraulic pressure, reduces the radius of rotation of a belt wound around a pulley, transmits driving force, and changes the gear ratio (belt ratio).

Such a continuously variable transmission is disclosed in, for example,
57-186656, JP-A-59-43249, JP-A-59-43249
-77159 and JP-A-61-233256.

[Problems to be Solved by the Invention] By the way, in the control of a continuously variable transmission that changes the gear ratio by using a hydraulic pressure, a primary pressure control valve, a constant pressure control valve, a line pressure control valve, a clutch A pressure control valve means including various shift control valves such as a pressure control valve and various solenoid valves for operating the various shift control valves is provided, and a movable pulley section is used to change the line pressure (line) of the hydraulic circuit and the actual gear ratio. The primary pressure (ratio) acting on one side and the clutch pressure (clutch) acting on the hydraulic clutch are set to neutral mode, hold mode,
Normal start mode, special start mode,
The drive mode is divided into various control modes, and the duty ratio (%) set according to the various control modes is set.
In addition, various solenoid valves of the pressure control valve means are driven and controlled by an open loop or a closed loop. Also,
Just like controlling the hydraulic pressure of the hydraulic circuit, the various solenoid valves of the various shift control valves use a relatively high speed of 100 Hz to control the hydraulic clutch's control characteristics and reduce vibration when the hydraulic clutch is slid and connected. Driven at the drive frequency.

However, in a low temperature state (for example, −10 ° C. or lower), the viscosity of the oil in the hydraulic circuit becomes larger than that in the high temperature state.
In the case of 0 Hz, it is not possible to obtain output pressure (duty output pressure) from various solenoid valves sufficient to control the operation of various shift control valves of the pressure control valve means.
Even when the vehicle is started, the clutch pressure or the like is not set to an appropriate state, so that the connection of the hydraulic clutch becomes defective, and the vehicle cannot be started smoothly.

[Object of the Invention] Accordingly, an object of the present invention is to switch the drive frequency of the pressure control valve means stepwise to correspond to each temperature range as the oil temperature decreases in order to eliminate the above-mentioned disadvantages. In addition, by increasing the opening / closing time per cycle without changing the duty ratio, appropriate oil pressure is ensured even at low temperatures when the viscosity of oil is large, and the drivability is maintained by maintaining the clutch pressure etc. in an appropriate state. An object of the present invention is to realize a hydraulic control method for a continuously variable transmission that can be improved.

[Means for Solving the Problems] In order to achieve this object, the present invention relates to a method for fixing a pulley between a fixed pulley and a movable pulley detachably attached to the fixed pulley. Pressure control valve means for controlling the hydraulic pressure of the hydraulic circuit in a continuously variable transmission for reducing the groove width by hydraulic pressure to reduce the radius of rotation of the belt wound around the two pulleys and controlling the shift so as to change the gear ratio Provided, an oil temperature sensor that detects an oil temperature state in the hydraulic circuit, a control unit that operates and controls the pressure control valve means with a duty ratio and a drive frequency set according to various control modes, In this control unit, a plurality of temperature ranges for the oil temperature are set, and a drive frequency is set for each of these temperature ranges. The drive frequency of the pressure control valve means is changed to each of the temperature ranges in accordance with a decrease in the oil temperature. To Correspondingly, the switching time is gradually lowered and the opening / closing time per cycle is extended without changing the duty ratio.

According to the method of the present invention, when the oil temperature is low at a low temperature, the viscosity of the oil is larger than at a high temperature, but the pressure control valve means reliably operates, for example, the hydraulic clutch even at a low temperature. In order to obtain sufficient hydraulic pressure, it is operated at a different predetermined drive frequency corresponding to a predetermined temperature range without changing the duty ratio, thereby avoiding slippage or the like occurring in the hydraulic clutch and easily starting the vehicle. The operability can be improved. Further, the viscosity of the oil decreases as the oil temperature increases, but the pressure control valve means is operated at a predetermined drive frequency without changing the duty ratio to obtain an appropriate oil pressure according to the oil temperature state. The function of the clutch can be performed well.

Embodiment An embodiment of the present invention will be described below in detail and specifically with reference to the drawings.

1 to 6 show an embodiment of the present invention.
In FIG. 4, 2 is a continuously variable transmission, 4 is a belt, 6
Is a drive-side pulley, 8 is a drive-side fixed pulley part, 10 is a drive-side movable pulley part, 12 is a driven-side pulley, 14 is a driven-side fixed pulley part, and 16 is a driven-side movable pulley part. is there.

As shown in FIG. 4, the drive-side pulley 6 is fixed to a drive-side shaft 18 which is a rotating shaft, and is driven to be movable in the axial direction of the drive-side shaft 18 and non-rotatably. Side axis
And a drive-side movable pulley piece 10 mounted on the drive pulley 18.

The driven pulley 12 has a configuration similar to that of the driven pulley 6 and is movable in the axial direction of the driven-side fixed pulley portion piece 14 fixed to the driven-side shaft 19 and the driven-side shaft 19. A driven-side movable pulley section piece 16 that is non-rotatably mounted on a driven-side shaft 19;

Driving-side movable pulley piece 10 and driven-side movable pulley piece 16
The first housing 20 and the second housing 22 are respectively mounted on the first and second housings, thereby forming a first hydraulic chamber 24 and a second hydraulic chamber 26, respectively. In the second hydraulic chamber 26 on the driven side, there is provided a pressing spring 28 for urging the driven-side movable pulley portion 16 to approach the driven-side fixed pulley portion 14.

An oil pump 30 is provided at an end of the drive side shaft 18. The oil pump 30 transfers the oil in an oil pan 32 through an oil filter 34 to first and second hydraulic chambers 2 by first and second oil passages 38 and 40 constituting a hydraulic circuit 36.
4 and 26.

In the middle of the first oil passage 38, a primary pressure control valve 44, which is one of shift control valves constituting the pressure control valve means 42, for controlling a primary pressure (ratio) as an input shaft sheave pressure is provided. The pressure control valve means 42 controls the hydraulic pressure of the hydraulic circuit 36.

Further, a line pressure (generally 5 to 25 kg / cm ² ) is applied to the first oil passage 38 closer to the oil pump 30 than the primary pressure control valve 44 by a third oil passage 46 to a constant pressure (1.5 to 2.0 kg / c).
A constant pressure control valve 48, which is one of the speed change control valves constituting the pressure control valve means 42, is connected in series to control the pressure to m ² ).

A primary three-way solenoid valve 52 for primary pressure control is connected to the primary pressure control valve 44 via a fourth oil passage 50. The first three-way solenoid valve 52 for primary pressure control is driven and controlled at a duty ratio (%) by a control unit 90 described later, and operates the primary pressure control valve 44 by an output pressure (duty output pressure: oil pressure). .

In the middle of the second oil passage 40, a line pressure control valve which is one of the speed change control valves constituting a pressure control valve means 42 having a relief valve function of controlling a line pressure (line) as a pump pressure.
54 are connected via a fifth oil passage 56. A second three-way solenoid valve 60 for line pressure control is connected to the line pressure control valve 54 via a sixth oil passage 58. The second three-way solenoid valve 60 for line pressure control is driven and controlled at a duty ratio (%) by a control unit 90 described later, and operates the line pressure control valve 54 by an output pressure (duty output pressure: oil pressure). .

The second hydraulic chamber 26 is located at a position higher than the portion where the line pressure control valve 54 communicates.
In the middle of the second oil passage 40, a clutch pressure control valve 62, which is one of shift control valves constituting the pressure control valve means 42 for controlling clutch pressure (clutch), is provided with a seventh oil passage 64.
It is provided continuously through. This clutch pressure control valve 62 has a third oil pressure control third
A three-way solenoid valve 68 is provided in series. The clutch pressure control third three-way solenoid valve 68 is driven and controlled at a duty ratio (%) by a control unit 90 described later, and operates the clutch pressure control valve 62 by an output pressure (duty output pressure: hydraulic pressure). .

Primary pressure control valve 44, primary pressure control first solenoid valve 52, constant pressure control valve 48, line pressure control valve 54, line pressure control second three-way solenoid valve 60, clutch pressure control valve 62, and clutch pressure control second The three-way solenoid valve 68 is connected to the ninth oil passage 70
Are in communication with each other.

The clutch pressure control valve 62 communicates with a hydraulic clutch 74 via a tenth oil passage 72. In the middle of the tenth oil passage 70, a pressure sensor 78 is connected via an eleventh oil passage 76.

This pressure sensor 78 is used to control the clutch pressure in various control modes such as the hold mode and the start mode.
It is possible to detect the oil pressure directly, and it has a function to instruct this detected oil pressure to be the target clutch pressure. In the drive mode, the clutch pressure is almost equal to the line pressure, contributing to the line pressure control. Is what you do.

The hydraulic clutch 74 includes a piston 80, an annular spring 8
2. It is composed of components such as a first pressure plate 84, a friction plate 86, and a second pressure plate 88.

Further, various conditions such as a throttle opening degree and an engine speed of a carburetor (not shown) of the vehicle are input, and a first three-way solenoid valve 52 for primary pressure control, a second three-way solenoid valve 60 for line pressure control, and a clutch are provided. A control section 90 is provided for controlling the operation of the third three-way solenoid valve 68 for pressure control with a duty ratio (%) and a drive frequency set according to various control modes.

The control unit 90 opens and closes the first three-way solenoid valve 52 for primary pressure control, the second three-way solenoid valve 60 for line pressure control, and the third three-way solenoid valve 68 for clutch pressure control. It works.

The various signals input to the control unit 90 and the functions of the input signals will be described in detail. The following signals are required for each range by the range signals such as P, R, N, D, and L. Control of line pressure (line), primary pressure (ratio), clutch pressure (clutch), carburetor throttle opening detection signal …… Detects engine torque from memory previously input into the program, and sets the target ratio or target engine rotation Determination of number, detection signal of carburetor idle position …… Improvement of accuracy in correction and control of carburetor throttle opening sensor, accelerator pedal signal …… Driver's will is detected based on the depression state of the accelerator pedal, and when driving or starting Brake direction …… Detects whether the brake pedal is depressed or not, and Determining a disconnection or the like control the direction of the switch 74, power mode option signal ...... performance sports of the vehicle (or economy property)
Used as an option for the hydraulic pressure signal... There is a signal corresponding to the oil temperature state of the hydraulic circuit 36, and the like.

The oil pressure signal is output from the oil pan 32 in the oil pressure circuit 36, for example.
This is a signal corrected by an oil temperature signal output from an oil temperature sensor 92 which is installed in the inside and detects an oil temperature state in the hydraulic circuit 36.

Further, the control unit 90 drives the first, second, and third three-way solenoid valves 52, 60, and 68 of the pressure control valve means 42 according to the starting state of the vehicle and the oil temperature state in the hydraulic circuit 36. It has a function of switching the frequency without changing the duty ratio (%) (see Table 1) set according to various control modes.
Here, the duty ratio (%) refers to a ratio of a time (open time) in which a current flows in one cycle in which the first, second, and third three-way solenoid valves 52, 60, and 68 are turned on and off. The drive frequency refers to the number of times that the same waveform is repeated in one second by alternating current to the first, second, and third three-way solenoid valves 52, 60, and 68.

That is, the control unit 90 controls the line pressure (line) of the hydraulic circuit 36 and the drive-side movable pulley part
Primary pressure (ratio) and hydraulic clutch acting on 10
The clutch pressure (clutch) acting on the 74 is divided into various control modes of a neutral mode, a hold mode, a normal start mode, a special start mode, and a drive mode, as shown in Table 1, and is set according to these various control modes. The operation of the first, second and third three-way solenoid valves 52, 60 and 68 of the pressure control valve means 42 is controlled by the duty ratio (%) and the open loop or the closed loop.

Further, as shown in Table 2, a plurality of temperature ranges for the oil temperature are set in the control unit 90, and a drive frequency is set for each of these temperature ranges.

Then, the control unit 90 controls the first, second, and third three-way solenoid valves 5
The drive frequencies 2, 60 and 68 are switched stepwise in accordance with the respective temperature ranges in the above-mentioned separate table 2 as the oil temperature decreases, and the duty ratio (%) shown in the separate table 1 is changed. Instead, the opening / closing time per cycle of the first, second, and third three-way solenoid valves 52, 60, and 68 is extended. More specifically, as shown in Table 2, the control unit 90 operates from the time when the ignition switch (not shown) is turned on to the time the vehicle starts for the first time after the start of the internal combustion engine and locks up so that the hydraulic clutch 74 is completely connected. The first, second and third three-way solenoid valves 52 and 6 are set according to the oil temperature state set in a predetermined range according to schedule 1.
In addition to switching the predetermined driving frequencies of 0, 68, and when the vehicle is not starting for the first time, the first, second, third three-way solenoid valves 52, 60, A predetermined driving frequency of 68 is switched.

Therefore, at low temperatures, the oil viscosity is higher than at high temperatures, and at the time of starting, initial friction is generated by air present in each valve and each passage, so that the clutch pressure decreases and the hydraulic clutch 74 In this embodiment, each of the drive frequencies of the first, second, and third three-way solenoid valves 52, 60, and 68 is switched stepwise as the oil temperature decreases, so that the hydraulic clutch This is to obtain an appropriate oil pressure that does not cause slip in 74.

Here, the duty ratio (%) when the oil temperature is -25 ° C
The relationship based on the experimental results of the output pressure (duty output pressure) of each solenoid valve and the drive frequency will be described with reference to FIG.

That is, the output pressure characteristics at the oil temperature of −25 ° C. depending on the drive frequency are as follows: when the drive frequency is high, the opening / closing time per cycle is short, and the viscosity of the oil is large, and the rise and fall of the output pressure Response time is long. When the duty ratio is small, the output pressure does not rise completely, and therefore the output pressure does not easily increase. On the other hand, when the duty ratio is large, the fall is delayed, and the cutoff of the output pressure becomes worse. Therefore, when the driving frequency is lowered, the opening / closing time per cycle becomes longer and the effect of the response delay of the output pressure is reduced, so that the output pressure can be controlled in one cycle.

The primary pressure control valve 44, as shown in FIG.
2 has a spool valve 104 that reciprocates in the
The diameter of the primary side 104 is configured to be larger than the diameter of the clutch side. In the main body 102, a first atmospheric opening 106, a first oil passage 38, a second oil passage 40, a second atmospheric opening 108, and a ninth oil passage 70 are respectively disposed from the left side in FIG. Has a fourth oil passage 50
Are arranged respectively.

Also, in the main body 102, the first and second springs 11 are urged from the left and right sides so that the spool valves 104 are positioned at predetermined positions, that is, in a state where the respective passages are not communicated as shown in FIG.
0 and 112 are provided respectively.

Since the first, second and third three-way solenoid valves 52, 60 and 68 have the same structure, only the schematic structure of the first three-way solenoid valve 52 will be described in detail with reference to FIG.

As shown in FIG. 6, the first three-way solenoid valve 52 is
And two electromagnetic coils 116 in the case 114, a plunger 118 moving between the electromagnetic coils 116, and a plunger 118
A steel sphere 120 at the end of the sphere, a sheet part 122 surrounding the sphere 120, an input port 124 provided in the seat part 122,
It has an output port 126, an atmosphere port 128, and a spring 130 for urging the plunger 118 in the direction of preventing the atmosphere from being released. That is, when power is not supplied to the electromagnetic coil 116, the plunger 118 is moved downward by the urging force of the spring 130, the input port 124 is closed by the sphere 120, and the output port 126 communicates with the atmosphere port 128. At the time of energization, a magnetic field is generated in the electronic coil 116 to move the plunger 118 upward against the urging force of the spring 130, to close the atmosphere port 128 by the sphere 120, and to connect the input port 124 and the output port 126. Be composed.
Also, the sphere 120 when energized is usually in a free state,
The air pressure from the input port 124 is pressed to close the atmosphere port 128.

 Next, the operation of this embodiment will be described.

In the continuously variable transmission 2, as shown in FIG. 4, an oil pump 30 provided on the drive shaft 18 operates according to the rotation of the drive shaft 18. Is absorbed through the oil filter 34. The line pressure, which is the pump pressure of the hydraulic circuit 36, is controlled by a line pressure control valve 54.If the amount of leakage from the line pressure control valve 54, that is, the amount of relief of the line pressure control valve 54 is the first, the line pressure is low. On the contrary, if it is small, the line pressure becomes high.

The operation of the line pressure control valve 54 is controlled by a dedicated second three-way solenoid valve 60.
Is controlled. The line pressure control valve 54 is operated following the driving of the second three-way solenoid valve 60. As shown in Table 1, the second three-way solenoid valve 60 is controlled at a predetermined duty ratio (%) according to various control modes.

That is, when the duty ratio is 0%, the second three-way solenoid valve 60 is not driven at all, the output side is connected to the atmosphere side, and the output hydraulic pressure (duty output pressure) becomes zero.

When the duty ratio is 100%, the second three-way solenoid valve 60 is driven, the output side is connected to the atmosphere side, and the output oil pressure equal to the control pressure is maximized. That is, the output oil pressure (duty output pressure) is varied by the duty ratio (%) of the second three-way solenoid valve 60.

Therefore, the characteristic of the second three-way solenoid valve 60 is the line pressure control valve
Thus, the line pressure can be controlled by arbitrarily changing the duty ratio (%) of the second three-way solenoid valve 60. Also, a second three-way solenoid valve
The drive of 60 is controlled by the control unit 90.

The primary pressure for speed change control is the primary pressure control valve 44
Is controlled by The operation of the primary pressure control valve 44 is controlled by a dedicated first three-way solenoid valve 52, similarly to the line pressure control valve 54.

As shown in Table 1, the first three-way solenoid valve 52 is controlled at a predetermined duty ratio (%) in accordance with various control modes to conduct the primary pressure to the line pressure or to conduct the primary pressure to the atmosphere. The belt ratio is shifted to the full overdrive side by conducting to the line pressure, or is shifted to the full low side by conducting to the atmosphere side.

The clutch pressure control valve 62 for controlling the clutch pressure is connected to the line pressure side when the maximum clutch pressure is required, and is connected to the atmosphere side when the minimum clutch pressure is required.

The operation of the clutch pressure control valve 62 is controlled by a dedicated third three-way solenoid valve 68 in the same manner as the line pressure control valve 54 and the primary pressure control valve 44, and therefore, the description thereof is omitted here. The third three-way solenoid valve 68 is controlled at a duty ratio (%) shown in Table 1 below.

The clutch pressure varies within a range from a minimum atmospheric pressure (zero) to a maximum line pressure.

There are five patterns in various clutch pressure control modes.

In this pattern, (1) neutral mode... When the shift position is N or P and the hydraulic clutch 74 is completely disengaged, the clutch pressure is the minimum pressure (zero). (2), hold mode. When releasing the throttle at R and there is no intention to drive, or when it is desired to decelerate during running and cut off the engine torque, the clutch pressure is low enough to connect the hydraulic clutch 74 lightly (3), start mode ... Alternatively, when the hydraulic clutch 74 is to be engaged again after the clutch is disengaged, the engine pressure generated by the clutch (clutch input torque) can prevent the engine from blowing up and operate the vehicle smoothly.
(4), special start mode …… (b), when the vehicle speed is 8km / h or more, shift lever from D to N
→ D: Repeated use, or (B), deceleration operation, 8km / h <vehicle speed <15km / h, brake state released, (5), drive mode …… complete driving state When the hydraulic clutch 74 is fully engaged, there are five high clutch pressure levels that can afford to withstand engine tonks.

(1) in this pattern is performed by a dedicated switching valve (not shown) that is interlocked with the shift operation. The other (2), (3), (4), and (5) are controlled by the control unit 90 by controlling the first, second, and third three-way solenoid valves 52, 60, and 68 based on the duty ratio (%). Is being done.

In particular, in the state (5), the clutch pressure control valve 62
As a result, the seventh oil passage 64 and the tenth oil passage 72 are communicated with each other, so that the maximum oil pressure is generated, and the clutch pressure becomes equal to the line pressure.

The primary pressure control valve 44, the line pressure control valve 54, and the clutch pressure control valve 62 are first, second, and third three-way solenoid valves 52,
Output pressure from 60, 68 (duty output pressure: output oil pressure)
, Respectively. These first, second and third
The control oil pressure for controlling the three-way solenoid valves 52, 60, 68 is
The constant oil pressure is adjusted by the constant pressure control valve 48. This control oil pressure is always lower than the line pressure, but is a stable and constant pressure. The control oil pressure is
Each control valve 44, 54, 62 is also introduced, these control valves 44, 5
4, 62 are being stabilized.

Next, electronic control of the continuously variable transmission 2 will be described.

The continuously variable transmission 2 is hydraulically controlled, and in accordance with a command from the control unit 90, an appropriate line pressure for holding the belt and transmitting the torque, a primary pressure for changing the gear ratio, and the hydraulic clutch 74 are surely controlled. Clutch pressure for engaging each is secured.

Next, a hydraulic control method in this embodiment will be described based on the flowchart of FIG.

When the ignition switch is turned on and the program starts (step 201), first, it is determined whether or not the vehicle is starting for the first time (step 202).

If step 202 is YES at the first start, step
At 203, the oil temperature is detected, the value of the oil temperature is replaced with ETEMP, and the count of the FLG register shown in FIG. 2 is set to "00000001".

Then, the process proceeds to step 204.Since the ignition switch is turned on and the vehicle is started after the internal combustion engine is started and the hydraulic clutch 74 is completely connected, the process proceeds to step 204. As shown in FIG. 2, the driving frequency of each of the first, second, and third three-way solenoid valves 52, 60, and 68 is switched according to the set schedule 1. In this step 204, the oil temperature of 0 ° C. is replaced by TEMP1, the oil temperature of −10 ° C. is replaced by TEPM2, and the oil temperature of −20 ° C. is replaced by TEMP3.

Next, in step 205, ETEMP and TEMP1 are compared. In step 205, if ETEMP ≧ TEMP1 and the oil temperature is equal to or higher than the predetermined value of 0 ° C., the viscosity of the oil is relatively small, so the count of the FLG register is left as it is (the count is “00000001”). (Step 21
1), end (step 212), first, second, third
The three-way solenoid valves 52, 60, and 68 are driven at a drive frequency of 10 Hz.

In step 205, if ETEMP <TEMP1 and the oil temperature is 0
If the temperature is lower than ° C., the viscosity of the oil is slightly large, so that the count of the FLG register is shifted left by one (count is “00000010”) (step 206).

Then, in step 207, ETEMP and TEMP2 are compared. In this step 207, if ETEMP ≧ TEMP2 and the oil temperature is between 0 ° C. and −10 ° C., the count of the FLG register is left as it is (the count is “00000010”) (step 211), and after the end (step 212), Each of the first, second, and third three-way solenoid valves 52, 60, and 68 is driven at a drive frequency of 50 Hz, and the hydraulic pressure is increased slightly to obtain a predetermined hydraulic pressure.

In step 207, when ETEMP <TEMP1, the oil temperature becomes −1.
If the temperature is lower than 0 ° C., the viscosity of the oil is further increased.
The count of the LG register is further shifted left by one (count is “00000100”) (step 208).

Then, in step 209, ETEMP and TEMP3 are compared. In this step 209, if ETEMP ≧ TEMP3 and the oil temperature is between −10 ° C. and −20 ° C., the count of the FLG register is left as is (count is “00000100”) (step 211), and First, second,
The third three-way solenoid valves 52, 60, and 68 are operated at a drive frequency of 25 Hz to further increase the oil pressure to obtain a predetermined oil pressure.

In step 209, if ETEMP <TEMP3, the oil temperature becomes −2.
If the temperature is lower than 0 ° C., the viscosity of the oil becomes larger than the above case, so the process proceeds to step 210, where the count of the FLG register is shifted left by one again (the count is “00001000”) (step 211). After the end (step 212), the first, second and third three-way solenoid valves 52, 60 and 68 are driven at a driving frequency of 25 Hz.
And a predetermined oil pressure is obtained by increasing the oil pressure.

On the other hand, if the vehicle is not starting for the first time,
If 2 is NO, the process proceeds to step 213, and as shown in Table 2, each of the first, second,
The drive frequency of the third three-way solenoid valves 52, 60, 68 is switched. In this step 213, the detected oil temperature is replaced with TEMP, the oil temperature -5 ° C. is replaced with TEMP2, and the oil temperature -15 ° C. is replaced with TEMP3, and the count of the FLG register shown in FIG.
00001 ”.

Then, in step 214, TEMP and TEMP2 are compared. In this step 214, if TEMP ≧ TEMP2 and the oil temperature is -5 ° C. or higher, the process proceeds to step 215, where TEMP is replaced with code A in this step 125, and this code A is replaced with ETEMP in step 225. Later, the step
A jump is made to 207, and the same processing is performed as described above. As described above, when the oil temperature is equal to or higher than the predetermined value of −5 ° C. in this case, the count of the FLG register remains unchanged (the count becomes “0”).
0000001 ", and the first, second and third three-way solenoid valves 52 and 6
0 and 68 are driven at a driving frequency of 100 Hz.

In step 214, if TEMP <TEMP2 and the oil temperature is -5
If it is lower than C, the process proceeds to step 216.

In step 216, TEMP is compared with a temperature value obtained by adding, for example, −3 ° C. as a hysteresis to TEMP3. If it is determined in step 216 that the temperature value is obtained by adding -3 ° C. as a hysteresis to TEMP ≦ TEMP3, the process proceeds to step 215, where TEMP is replaced with a symbol A in this step 215, and this symbol A is replaced with ETEMP in step 225. And the process jumps to the step 207 to perform the same processing as described above. As described above, when the oil temperature is low, the count of the FLG register is shifted to “0000100”, and each of the first, second, and third three-way solenoid valves 52, 60, and 68 is driven at a drive frequency of 25 Hz. To get the hydraulic pressure.

In step 216, if the temperature value is obtained by adding -3 ° C. as a hysteresis to TEMP> TEMP3, the process proceeds to step 217. In this step 217, TEMP ≧ TEMP
In the case of 3, the process proceeds to step 218. This step 21
In Fig. 8, ETEMP and TEMP2 have a hysteresis of-
Compare the temperature value with the addition of 3 ° C. This step 21
At 8, ETEMP ≤ TEMP2 with hysteresis of -3 ° C
In the case of the added temperature value, TEMP is replaced with the code A in step 215, and this code A is replaced with ETEMP in step 225.
And the process jumps to the step 207, where the processing is performed as described above. In this case, the first, second, and third three-way solenoid valves 52, 60, and 68 are driven at a drive frequency of 50 Hz.

If it is determined in step 218 that ETEMP> TEMP2 is a temperature value obtained by adding −3 ° C. as a hysteresis, the process proceeds to step 219, where TEMP and TEMP2 are compared. If it is determined in step 219 that TEMP <TEMP2 and the oil temperature is lower than −5 ° C., the process proceeds to step 220. In this step 220, the temperature value obtained by adding -3 ° C. to TEMP2 as a hysteresis is replaced with a symbol A. The code A is replaced with ETEMP in step 225, and the process jumps to step 207, where the processing is performed as described above.

In step 219, if TEMP ≧ TEMP2 and the oil temperature is −5
If the temperature is equal to or higher than ℃, TEMP2 is replaced with code A in step 221 and this code A is replaced with ETEMP in step 225, and the process jumps to step 207, where the processing is performed as described above.

In step 217, if TEMP <TEMP3, ETEM
If P is less than −15 ° C., the process proceeds to step 222, where ETEMP and TEMP3 are compared. In this step 222, if ETEMP <TEMP3, step 233
In step 225, a temperature value obtained by adding -3 ° C. to TEMP3 as a hysteresis is replaced with a code A.
Instead of TMP, the process jumps to step 207, and the same processing is performed as described above.

In step 222, if ETEMP ≧ TEMP3, TEMP3 is replaced with code A in step 224, and this code A is replaced with ETEMP in step 225, and
A jump is made to 207, and the same processing is performed as described above.

As a result, the drive frequency of the first, second, and third three-way solenoid valves 52, 60, and 68 can be switched without changing the duty ratio (%) for each predetermined oil temperature range, and a predetermined oil pressure can be obtained. Even at low temperatures when the viscosity of the oil is large or air exists in various valves and passages, it is possible to prevent the disadvantage that the hydraulic pressure of the hydraulic clutch 74 does not operate correctly due to a decrease in clutch pressure. , The starting state is improved, and the drivability can be improved.

Further, since the drive frequency of the first, second, and third solenoid valves 52, 60, and 68 is merely changed for each predetermined oil temperature range without correcting the duty ratio (%), the control is simplified,
Further, it is easy to change the driving frequency.

Furthermore, fine correction of the duty ratio (%) is unnecessary,
The total opening time of each of the first, second and third three-way solenoid valves 52, 60 and 68 is the same, but the opening / closing time of the first, second and third three-way solenoid valves 52, 60 and 68 per cycle Longer, and at low temperatures, it facilitates the flow of oil, so the number of breaks in oil flow is reduced,
Therefore, while the flow of the oil becomes better, each of the first, second,
Since the third three-way solenoid valves 52, 60, 68 are driven at a low drive frequency, the durability of each of the first, second, and third three-way solenoid valves 52, 60, 68 is improved.

Furthermore, the microcomputer in the control unit 90 basically has a duty ratio (%) at a driving frequency of 100 Hz.
At low temperatures, for example, the drive frequency
To drive each solenoid valve at 25 Hz, set the FLG register to `` 0
Is 0000100 ", the output hydraulic pressure may be output calculation value 2 ² multiplied by the contents of the FLG register, the microcomputer program is simplified, it is possible to easily change the duty output value. Further, it is possible to easily change the program for switching the drive frequency of each of the first, second, and third three-way solenoid valves 52, 60, and 68.

Further, at the time of driving each of the first, second and third three-way solenoid valves 52, 60 and 68 in the drive mode and at the drive frequency of 100 Hz,
Although the line pressure and the primary pressure are controlled, it is not necessary to drive the first, second, and third three-way solenoid valves 52, 60, and 68 at a driving frequency of 100 Hz, and the driving frequency is about 50 Hz. , The first, second, and third
The functional deterioration of the three-way solenoid valves 52, 60, 68 can be prevented, and the durability can be improved.

Furthermore, after the first departure, each of the first, second,
When the drive frequency of the third three-way solenoid valves 52, 60 and 68 is switched, -3 ° C. is provided as a hysteresis, so that the drive frequency can be prevented from greatly changing.

In this embodiment, the switching of the driving frequency of each of the first, second, and third three-way solenoid valves 52, 60, and 68 can always be executed. However, in the normal start mode and the special start mode, the hydraulic clutch 74 is switched. In the case where the torque is transmitted by sliding, the driving mode can be limited to a neutral mode other than the start mode, a hold mode, and a drive mode in order to prevent occurrence of a drive or a shock.

Note that the present invention is not limited to the above-described embodiment, and various application modifications are possible.

For example, in this embodiment, the oil temperature is detected by a temperature sensor provided on the oil pan. However, the oil temperature sensor can be installed at any position in the hydraulic circuit, and the oil temperature at any position in the hydraulic circuit can be set. Temperature can be detected.

[Effects of the Invention] As is apparent from the detailed description above, according to the present invention, the pressure control valve means for controlling the hydraulic pressure of the hydraulic circuit is provided,
An oil temperature sensor that detects an oil temperature state in the hydraulic circuit is provided, and a control unit that operates and controls the pressure control valve means with a duty ratio and a drive frequency set according to various control modes is provided.
This control unit sets a plurality of temperature ranges for the oil temperature and sets a drive frequency for each of these temperature ranges,
By changing the drive frequency of the pressure control valve means to stepwise lower corresponding to each temperature range as the oil temperature becomes lower and extending the open / close time per cycle without changing the duty ratio, the oil temperature is increased. The required oil pressure can be ensured even at a low temperature when the viscosity of the clutch is large, and the drivability can be improved by appropriately maintaining the clutch pressure and the like.

Further, since the drive frequency of the pressure control valve means is simply changed depending on the oil temperature state without correcting the duty ratio, the control is simplified, and the change of the drive frequency can be facilitated.

Furthermore, fine correction of the duty ratio is not required, and the total opening time is the same. However, since the opening and closing time of the pressure control valve means per cycle is lengthened and the oil flows easily, the oil flow is divided. Since the number of times is reduced, the oil flow is improved, and the pressure control valve is driven at a low drive frequency, so that the durability of the pressure control valve can be improved.

If the drive frequency at which the oil temperature is lower than the predetermined value is lowered every 1/2 ⁿ from the basic frequency, the program can be easily changed, and the output oil pressure can be easily changed by the bit content of the frequency setting register. obtain.

[Brief description of the drawings]

1 to 6 show an embodiment of the present invention, FIG. 1 is a flowchart for explaining a hydraulic control method, FIG. 2 is a diagram for explaining counting of an FLG register, and FIG. FIG. 4 is a schematic diagram illustrating a hydraulic circuit and a control unit of the continuously variable transmission, FIG. 5 is a sectional view of a primary control valve, and FIG. 6 is a sectional view of a three-way solenoid valve. In the figure, 2 is a continuously variable transmission, 4 is a belt, 6 is a driving pulley, 12 is a driven pulley, 18 is a driving shaft, 30 is an oil pump, 38 is a first oil passage, and 40 is a second oil. Passage, 42 pressure control valve means, 44 primary pressure control valve, 46
Is a third oil passage, 48 is a constant pressure control valve, 50 is a fourth oil passage, 52 is a first three-way solenoid valve for primary pressure control, 54 is a line pressure control valve, 56 is a fifth oil passage, and 58 is a sixth oil passage. Passage, 60 is a second three-way solenoid valve for line pressure control, 62 is a clutch pressure control valve, 64 is a seventh oil passage, 66 is an eighth oil passage,
68 is a third three-way solenoid valve for controlling clutch pressure, 70 is a ninth oil passage, 72 is a tenth oil passage, 74 is a hydraulic clutch, 78 is a pressure sensor, 90 is a control unit, and 92 is an oil temperature sensor.

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Yoshinobu Yamashita 4590 Maisaka, Maisaka-cho, Hamana-gun, Shizuoka Prefecture (72) Inventor Takumi Tatsumi 840 Chiyoda-cho, Himeji-shi, Hyogo Prefecture Mitsubishi Electric Corporation Himeji Works (72) Inventor Hiroaki Yamamoto 6 Sadamotocho, Himeji-shi, Hyogo Mitsubishi Electric Control Software Co., Ltd. Himeji Office (56) References JP-A-64-24956 (JP, A) JP-A-53-86980 (JP, A)

Claims (2)

(57) [Claims] The width of a groove between a fixed pulley part and a movable pulley part detachably mounted on the fixed pulley part is reduced and increased by hydraulic pressure to be wound around the two pulleys. In a continuously variable transmission that performs speed change control to reduce and increase the radius of rotation of a belt to change a speed ratio, a pressure control valve means for controlling a hydraulic pressure of a hydraulic circuit is provided, and an oil temperature for detecting an oil temperature state in the hydraulic circuit is provided. A sensor is provided, and a control unit is provided for controlling the operation of the pressure control valve means with a duty ratio and a drive frequency set according to various control modes, and the control unit sets a plurality of temperature ranges with respect to oil temperature. The drive frequency is set for each of these temperature ranges, and the drive frequency of the pressure control valve means is switched stepwise lower in accordance with each of the temperature ranges and the duty ratio is changed in accordance with the lowering of the oil temperature. Hydraulic control method for a continuously variable transmission, characterized in that a longer opening time per cycle. 2. The control unit according to claim 1, wherein the control unit controls the drive frequency of the pressure control valve means so as to lower the drive frequency from a basic frequency every 1/2 ⁿ in accordance with a decrease in the oil temperature. 2. The hydraulic control method for a continuously variable transmission according to claim 1.