WO2018101283A1

WO2018101283A1 - Transmission oil pressure control device and control method for continuously variable transmission

Info

Publication number: WO2018101283A1
Application number: PCT/JP2017/042705
Authority: WO
Inventors: 盛弼柳; 洛鎬李; 官容申; 恩惠金; 京南金; テヨン金; 赫鎭卞
Original assignee: ジヤトコ株式会社
Priority date: 2016-12-02
Filing date: 2017-11-29
Publication date: 2018-06-07
Also published as: JP6700419B2; JPWO2018101283A1

Abstract

A variator (4) has: a primary pulley (42); a secondary pulley (43); and a pulley belt (44) that is hung and suspended on both the pulleys (42), (43), wherein the transmission gear ratio is controlled by changing a pulley width by means of transmission oil pressure that is adjusted on the basis of discharge pressure from an oil pump (70). In this engine vehicle, when the target transmission gear ratio of the variator (4) is determined during traveling, primary pressure (Pri) and secondary pressure (Psec) adjusted according to the target transmission gear ratio are respectively supplied to the primary pulley (42) and the secondary pulley (43). When the pulley rotational speed reaches to a level at which the transmission gear ratio of the variator (4) does not change even if the secondary pressure (Psec) is reduced, control for reducing the secondary pressure (Psec) is started.

Description

Variable speed hydraulic control device and control method for continuously variable transmission

The present invention relates to a transmission hydraulic pressure control device and a control method for a continuously variable transmission that supplies a transmission hydraulic pressure adjusted based on oil discharged from an oil pump to a primary pulley and a secondary pulley of a variator.

2. Description of the Related Art Conventionally, there is known a control device for an electric oil pump for a vehicle that changes the driving frequency of the electric oil pump according to the vehicle state in order to reduce noise generated when the electric oil pump is driven (for example, Patent Document 1).

The noise (noise) generated in the above prior art is generated in the electric oil pump, but is not limited to the electric oil pump, and is also generated in the oil pump driven by the engine. Moreover, although the noise (noise) generated in the above-described prior art is generated in the electric oil pump alone, the generation of noise is not limited to the oil pump alone in this way, and the oil pump and other rotating bodies (for example, This also occurs due to a resonance phenomenon with the secondary pulley.

That is, by using the fluctuation component of the hydraulic pressure passing through the secondary pressure oil passage from the oil pump driven by the engine to the secondary pulley as a vibration source, and resonating with a transmission mounting part provided near the secondary pressure oil passage Oil pump noise may occur. When this oil pump noise is generated in a state just before stopping or when the vehicle is stopped, where road noise, engine sound, etc. are small compared to when traveling, there is a problem that it is likely to be uncomfortable for the driver.

The present invention has been made paying attention to the above-mentioned problem, and aims to reduce the occurrence of oil pump noise that makes the driver feel uncomfortable while suppressing the occurrence of belt slip and unintentional shift.

Japanese Patent Laid-Open No. 2015-021512

To achieve the above object, the present invention provides an oil pump, a variator whose gear ratio is controlled by changing a pulley width by a transmission hydraulic pressure adjusted based on a discharge pressure from the oil pump, and a transmission hydraulic pressure A control unit. When the target transmission gear ratio of the variator is determined during traveling, the transmission hydraulic pressure control unit supplies the primary pressure and the secondary pressure adjusted according to the target transmission gear ratio to the primary pulley and the secondary pulley, respectively. When the pulley rotational speed at which the gear ratio of the variator does not change even when the secondary pressure is reduced, control for reducing the secondary pressure is started.

For example, if an oil pump noise occurs while the vehicle is stopped in the D range or R range, the driver feels uncomfortable. On the other hand, the present inventors have found that the cause of the oil pump noise is the fluctuation component of the secondary pressure, and reducing the secondary pressure reduces the oil pump noise and improves the sense of incongruity. Paying attention to this point, the pulley rotation speed at which the gear ratio of the variator does not change even if the secondary pressure is lowered, that is, the secondary pressure is lowered when the vehicle state is not shifted even if the balance pressure between the primary pressure and the secondary pressure collapses. Control was started. As a result, it is possible to reduce the occurrence of oil pump noise that makes the driver feel uncomfortable while suppressing the occurrence of belt slippage and unintentional shifting due to starting secondary pressure reduction control regardless of the vehicle state. .

1 is an overall system diagram showing a drive system and a control system of an engine vehicle to which a transmission hydraulic pressure control device and a control method for a continuously variable transmission according to a first embodiment are applied. It is a shift schedule figure which shows an example of the shift schedule used when shifting hydraulic pressure control is performed by the variator mounted in the drive system of the engine vehicle. It is an external appearance block diagram which shows the external appearance outline | summary of the belt-type continuously variable transmission unit mounted in the power unit chamber of an engine vehicle by the elastic support to a vehicle body. 6 is a flowchart showing a flow of a shift hydraulic pressure control process executed by the CVT control unit of the first embodiment. 6 is a time chart showing the characteristics of post-F / B SEC command pressure, SEC command pressure, and SEC actual pressure when the SEC actual pressure drop condition, which is one of the exit conditions for ending noise reduction control, is satisfied. Time chart showing characteristics of accelerator operation, brake operation, vehicle speed, gradient, engine speed, primary pulse, timer value, control approach flag, SEC command pressure, PRI command pressure, PRI lower limit pressure when noise reduction control is executed It is. It is a time chart which shows each characteristic of SEC command pressure, SEC command pressure, and SEC actual pressure after F / B which expanded the field surrounded by arrow H of Drawing 6 where noise reduction control is started.

Hereinafter, the best mode for realizing a transmission hydraulic pressure control device and a control method for a continuously variable transmission according to the present invention will be described based on Example 1 shown in the drawings.

First, the configuration will be described. The transmission hydraulic pressure control device and the control method in the first embodiment are applied to an engine vehicle equipped with a belt type continuously variable transmission mechanism called a variator. Hereinafter, the configuration of the first embodiment will be described by dividing it into an “overall system configuration”, a “secondary pressure oil passage configuration”, and a “shift oil pressure control processing configuration”.

[Overall system configuration]
FIG. 1 shows a drive system and a control system of an engine vehicle to which a transmission hydraulic pressure control device and a control method for a continuously variable transmission according to a first embodiment are applied. FIG. An example of the shift schedule used is shown. The overall system configuration will be described below with reference to FIGS.

As shown in FIG. 1, the drive system of the engine vehicle includes an engine 1, a torque converter 2, a forward / reverse switching mechanism 3, a variator 4 (belt-type continuously variable transmission mechanism), a final reduction mechanism 5, and drive wheels. 6 and 6.

The engine 1 can control the output torque by an engine control signal from the outside, in addition to the output torque control by the accelerator operation by the driver. The engine 1 includes an output torque control actuator 10 that performs output torque control by a throttle valve opening / closing operation, a fuel cut operation, and the like.

The torque converter 2 is a starting element having a torque increasing function. When the torque increasing function is not required, the torque converter 2 includes a lock-up clutch 20 that can directly connect the engine output shaft 11 (= torque converter input shaft) and the torque converter output shaft 21. Have. The torque converter 2 is provided with a turbine runner 23 connected to the engine output shaft 11 via a converter housing 22, a pump impeller 24 connected to the torque converter output shaft 21, and a case via a one-way clutch 25. The stator 26 is a component.

The forward / reverse switching mechanism 3 is a mechanism that switches the input rotation direction to the variator 4 between a forward rotation direction during forward travel and a reverse rotation direction during reverse travel. The forward / reverse switching mechanism 3 includes a double pinion planetary gear 30, a forward clutch 31 using a plurality of clutch plates, and a reverse brake 32 using a plurality of brake plates. The forward clutch 31 is hydraulically engaged by the forward clutch pressure Pfc when a forward travel range such as the D range is selected. The reverse brake 32 is hydraulically engaged by the reverse brake pressure Prb when the reverse travel range such as the R range is selected. The forward clutch 31 and the reverse brake 32 are both released by draining the forward clutch pressure Pfc and the reverse brake pressure Prb when the N range (neutral range, non-traveling range) is selected.

The variator 4 has a primary pulley 42, a secondary pulley 43, and a pulley belt 44, and changes a gear ratio (a ratio between a variator input rotation speed and a variator output rotation speed) steplessly by changing a belt contact diameter. A continuously variable transmission function is provided. The primary pulley 42 includes a fixed pulley 42 a and a slide pulley 42 b arranged on the same axis as the variator input shaft 40, and the slide pulley 42 b is slid by the primary pressure Ppri guided to the primary pressure chamber 45. The secondary pulley 43 includes a fixed pulley 43 a and a slide pulley 43 b that are arranged coaxially with the variator output shaft 41, and the slide pulley 43 b is slid by the secondary pressure Psec guided to the secondary pressure chamber 46. The pulley belt 44 is stretched between a sheave surface that forms a V shape of the primary pulley 42 and a sheave surface that forms a V shape of the secondary pulley 43. The pulley belt 44 is formed of two sets of laminated rings in which a large number of annular rings are stacked from the inside to the outside and a plurality of punched plate members, and is attached by being laminated in an annular manner by being sandwiched along the two sets of laminated rings. It is composed of elements. The pulley belt 44 may be a chain-type belt in which a large number of chain elements arranged in the pulley traveling direction are coupled by pins penetrating in the pulley axial direction.

The final deceleration mechanism 5 is a mechanism that decelerates the variator output rotation speed from the variator output shaft 41 and transmits it to the left and

right drive wheels

6 and 6 while providing a differential function. The final reduction mechanism 5 is provided as a reduction gear mechanism at the outer peripheral position of the first gear 52 provided on the variator output shaft 41, the second gear 53 and the third gear 54 provided on the idler shaft 50, and the differential case. And a fourth gear 55. The differential gear mechanism includes a differential gear 56 interposed between the left and

right drive shafts

51, 51.

As shown in FIG. 1, the engine vehicle control system includes a hydraulic control unit 7 that is a hydraulic control system and a CVT control unit 8 that is an electronic control system.

The hydraulic control unit 7 includes a primary pressure Ppri guided to the primary pressure chamber 45, a secondary pressure Psec guided to the secondary pressure chamber 46, a forward clutch pressure Pfc to the forward clutch 31, and a reverse brake pressure Prb to the reverse brake 32. And a unit for regulating the pressure. The hydraulic control unit 7 includes an oil pump 70 that is rotationally driven by the engine 1 that is a travel drive source, and a hydraulic control circuit 71 that adjusts various control pressures based on the discharge pressure from the oil pump 70. . The hydraulic control circuit 71 includes a line pressure solenoid valve 72, a primary pressure solenoid valve 73, a secondary pressure solenoid valve 74, a forward clutch pressure solenoid valve 75, and a reverse brake pressure solenoid valve 76. Each

solenoid valve

72, 73, 74, 75, 76 adjusts to each command pressure by varying the ON / OFF ratio (duty ratio) according to the duty command value output from the CVT control unit 8.

The line pressure solenoid valve 72 adjusts the discharge pressure from the oil pump 70 to the commanded line pressure PL in accordance with the line pressure command value output from the CVT control unit 8. The line pressure PL is a source pressure when adjusting various control pressures, and is a hydraulic pressure that suppresses belt slip and clutch slip against torque transmitted through the drive system.

The primary pressure solenoid valve 73 adjusts the pressure to the primary pressure Ppri commanded using the line pressure PL as the original pressure according to the primary pressure command value output from the CVT control unit 8. The secondary pressure solenoid valve 74 adjusts the pressure to the secondary pressure Psec commanded using the line pressure PL as the original pressure in accordance with the secondary pressure command value output from the CVT control unit 8.

The forward clutch pressure solenoid valve 75 adjusts the pressure to the forward clutch pressure Pfc commanded using the line pressure PL as the original pressure according to the forward clutch pressure command value output from the CVT control unit 8. The reverse brake pressure solenoid valve 76 reduces the pressure to the reverse brake pressure Prb commanded using the line pressure PL as the original pressure in accordance with the reverse brake pressure command value output from the CVT control unit 8.

The CVT control unit 8 performs line pressure control, shift hydraulic pressure control, forward / reverse switching control, and the like. In the line pressure control, a command value for obtaining a target line pressure corresponding to the throttle opening degree is output to the line pressure solenoid valve 72. In the transmission hydraulic pressure control, when the target speed ratio (target primary rotational speed Npri ^* ) is determined, command values for obtaining the determined target speed ratio (target primary rotational speed Npri ^* ) are sent to the primary pressure solenoid valve 73 and the secondary pressure solenoid valve 74. Output. In the forward / reverse switching control, a command value for controlling the engagement / release of the forward clutch 31 and the reverse brake 32 is output to the forward clutch pressure solenoid valve 75 and the reverse brake pressure solenoid valve 76 according to the selected range position.

The CVT control unit 8 includes a primary pulley rotational speed sensor 80, a vehicle speed sensor 81, a secondary pressure sensor 82, an oil temperature sensor 83, an inhibitor switch 84, a brake switch 85, an accelerator opening sensor 86, a primary pressure sensor 87, and a longitudinal G sensor. Sensor information and switch information from 89, etc. are input. Further, engine torque information is input from the engine control unit 88 to which sensor information from the engine rotation speed sensor 12 is input, and an engine torque request is output to the engine control unit 88. The primary pulley rotational speed sensor 80 is a sensor that detects the primary pulley rotational speed based on a pulse count number that is the number of pulse wave signal counts. Similarly, the vehicle speed sensor 81 is a sensor that detects the transmission output rotation speed based on the pulse count number that is the number of counts of the pulse wave signal. The inhibitor switch 84 detects the selected range position (D range, N range, R range, etc.) and outputs a range position signal corresponding to the range position.

Here, the normal shift hydraulic pressure control executed by the CVT control unit 8 is the shift of FIG. 2 specified by the vehicle speed VSP detected by the vehicle speed sensor 81 and the accelerator opening APO detected by the accelerator opening sensor 86. This is done by determining the target primary rotational speed Npri ^{* based} on the operating points (VSP, APO) on the schedule.

As shown in FIG. 2, the speed change schedule is set so as to change the speed ratio steplessly within the range of the speed ratio range by the lowest gear ratio and the highest gear ratio according to the operating point (VSP, APO). ing. For example, when the vehicle speed VSP is constant, if the accelerator depressing operation is performed, the target primary rotation speed Npri ^* increases and shifts in the downshift direction, and if the accelerator depressing operation is performed, the target primary rotation speed Npri ^* decreases. Shift in the upshift direction. When the accelerator opening APO is constant, the vehicle shifts in the upshift direction when the vehicle speed VSP increases, and the vehicle shifts in the downshift direction when the vehicle speed VSP decreases.

[Secondary pressure oil passage configuration]
FIG. 3 shows the appearance of the belt type continuously variable transmission unit 9 mounted in the power unit chamber of the engine vehicle by elastic support to the vehicle body. Hereinafter, the secondary pressure oil passage configuration will be described with reference to FIG.

As shown in FIG. 3, the belt-type continuously variable transmission unit 9 includes a transmission case 90, a side cover 91 fixed to one side opening of the case, a converter case 92 fixed to the other side opening of the case, and a bottom of the case An oil pan 93 fixed to the opening. In a space formed by the transmission case 90 and the side cover 91, the forward / reverse switching mechanism 3, the variator 4, the final reduction mechanism 5, and the hydraulic control circuit 71 are built. In addition, torque converter 2 is built in a space formed by converter case 92, and converter case 92 is coupled to engine 1.

The belt-type continuously variable transmission unit 9 is combined with the engine 1 to form a power unit. This power unit is disposed in the power unit chamber on the front side in a horizontal position and elastically moves to the vehicle body via a plurality of power unit mounts. Supported.

The side cover 91 supports the shaft end portion of the pulley shaft of the primary pulley 42 of the variator 4 and also supports the shaft end portion of the pulley shaft of the secondary pulley 43. As shown in FIG. 3, the side cover 91 is formed with a secondary pressure oil passage 94 that guides the secondary pressure Psec from the oil pump 70 to the secondary pressure chamber 46 of the secondary pulley 43 via the hydraulic control circuit 71. Yes. Further, as shown in FIG. 3, a unit side mounting bracket 95 is fixed to the side cover 91. That is, the secondary pressure oil passage 94 and the unit-side mount bracket 95 are arranged at positions close to each other in the side cover 91.

[Transmission hydraulic pressure control processing configuration]
FIG. 4 shows the flow of the shift hydraulic pressure control process executed by the CVT control unit 8 of the first embodiment. In the following, each step of FIG. 4 representing the transmission hydraulic pressure control processing configuration will be described. This shift hydraulic pressure control process is executed when a travel range (D range or R range) is selected.

In step S1, it is determined whether or not the vehicle is stopped in a situation where the accelerator is OFF and the brake is ON. If YES (stopped), the process proceeds to step S2, and if NO (running), the process proceeds to step S6. Here, accelerator OFF information is acquired from the accelerator opening sensor 86, and brake ON information is acquired from the brake switch 85. Whether or not the vehicle is stopped is determined by using vehicle speed information from the vehicle speed sensor 81 that detects the output rotation speed of the variator 4 and when the vehicle speed sensor value indicates a stop determination value.

In step S2, following the determination that the vehicle is stopped in step S1, it is determined whether or not the road surface on which the vehicle is stopped is flat. If YES (flat ground), the process proceeds to step S3. If NO (gradient ground), the process proceeds to step S6. Here, whether or not the stop road surface is flat is determined when the sensor value from the front and rear G sensor 89 satisfies the flat ground determination lower limit value ≦ the front and rear G sensor value ≦ the flat ground determination upper limit value. Judge. When the flat ground determination lower limit value> the front and rear G sensor value or the front and rear G sensor value> the flat ground determination upper limit value, it is determined that the stop road surface is a slope.

In step S3, it is determined whether or not the engine rotation speed is equal to or lower than the idle rotation determination value following the determination that the road is flat in step S2. If YES (engine rotation speed ≦ idle rotation determination value), the process proceeds to step S4. If NO (engine rotation speed> idle rotation determination value), the process proceeds to step S6. Here, information on the engine speed is acquired from the engine speed sensor 12. The “idle rotation determination value” is set to a value indicating that the rotation speed of the engine 1 has been reduced to the idle rotation speed range.

In step S4, following the determination in step S3 that the engine rotation speed is equal to or less than the idle rotation determination value, the primary pulley rotation speed is in a low rotation state by checking the pulse wave signal from the primary pulley rotation speed sensor 80. It is determined whether or not. If YES (primary pulley rotation speed is low), the process proceeds to step S5. If NO (primary pulley rotation speed is not low), the process proceeds to step S6. Here, when determining the low rotation state of the primary pulley rotation speed, when a pulse wave signal is input from the primary pulley rotation speed sensor 80, counting of the timer value is started from the down edge of the pulse wave signal. If the next pulse wave signal is not input even after the timer value has passed a threshold value (for example, 0.5 sec), it is determined that the primary pulley rotation speed has become a low rotation state. That is, if the next pulse wave signal is input before the timer value passes the threshold, it is determined that the primary pulley rotational speed is not yet in a low rotational state. The threshold value of the timer value is set to a time required to determine that the variator 4 has reached the pulley rotation speed in the pulley rotation stop state in which the gear ratio does not change to the upshift side even when the secondary pressure Psec is decreased. .

In step S5, following the determination that the primary pulley rotation speed is in the low rotation state in step S4, it is determined whether there is a restriction to reduce the secondary pressure Psec. If YES (no secondary pressure lowering restriction), the process proceeds to step S6, and if NO (secondary pressure lowering restriction is present), the process proceeds to step S6. Here, the reduction regulation determination of the secondary pressure Psec is, for example, that the secondary pressure Psec is regulated to be lower when the secondary pressure Psec is raised by the intervention of other shift hydraulic pressure control than the noise reduction control of the first embodiment. to decide. And the noise reduction control process after step S7 is not performed.

In step S6, following the determination of NO in any of steps S1, S2, S3, S4, and S5, normal shift hydraulic pressure control is executed, and the process proceeds to return. Here, the normal transmission hydraulic pressure control means feedback control of the differential pressure between the primary pressure Ppri and the secondary pressure Psec so that the actual primary rotation speed Npri converges to the target primary rotation speed Npri ^* . At this time, instead of lowering or raising only one of the primary pressure Ppri and the secondary pressure Psec, it is assumed that both the pressures Ppri and Psec are lowered or raised, so that the primary pulley 42 and the secondary pulley 43 The balance thrust is maintained.

In step S7, following the determination in step S5 that there is no secondary pressure reduction restriction, the lower limit pressure (PRI lower limit pressure) of the primary command pressure is increased to the primary lower limit pressure B, and the process proceeds to step S8. If it is determined in step S5 that there is no secondary pressure reduction restriction, it is determined that the conditions for entering the noise reduction control in steps S1, S2, S3, S4, and S5 are satisfied, and the control entry flag that starts the noise reduction control is determined. Is established. Here, the “primary lower limit pressure B” is a hydraulic pressure higher than the primary pressure Ppri set by the balance thrust between the primary pulley 42 and the secondary pulley 43 and is a torque input from the engine 1 in the idling rotation state. On the other hand, the hydraulic pressure (for example, 0.7 MPa) at which no belt slip occurs is set.

In step S8, following the determination that the PRI lower limit pressure is increased to the PRI lower limit pressure B in step S7 or that the release condition is not satisfied in step S12, the actual secondary pressure Psec is added to the secondary target pressure A by a hysteresis amount α. It is determined whether or not the value is equal to or greater than the value added. If YES (actual SEC pressure ≧ A + α), the process proceeds to step S9. If NO (actual SEC pressure <A + α), the process proceeds to step S10. Here, the information of “actual secondary pressure Psec” is acquired from a sensor signal from the secondary pressure sensor 82. The “secondary target pressure A” is set to the maximum pressure (for example, 0.8 MPa) in the secondary pressure region in which the oil pump noise confirmed by the experiment is reduced. “Hysteresis α” is set to a value that suppresses hydraulic control hunting of the secondary pressure Psec.

In step S9, following the determination that the actual SEC pressure ≧ A + α in step S8, the secondary command pressure by the secondary pressure command value output to the secondary pressure solenoid valve 74 is lowered, and the process proceeds to step S12. Here, in a region where the actual SEC pressure is a predetermined pressure or more away from (A + α), the secondary command pressure is lowered with a steep command pressure drop characteristic, and when the actual SEC pressure approaches from (A + α) to less than the predetermined pressure. The slope of the secondary command pressure drop characteristic is moderated. That is, in the actual SEC pressure decrease control, the secondary command pressure decrease gradient is determined so as to achieve both responsiveness (steep gradient) and convergence (slow gradient).

In step S10, following the determination that the actual SEC pressure <A + α in step S8, it is determined whether the actual secondary pressure Psec is equal to or lower than the secondary target pressure A. If YES (actual SEC pressure ≦ A), the process proceeds to step S11. If NO (actual SEC pressure> A), the process proceeds to step S12. “Secondary target pressure A” is the same value as in step S8.

In step S11, following the determination that the actual SEC pressure ≦ A in step S6, the secondary command pressure (SEC command pressure) at that time is maintained as it is, and the process proceeds to step S12.

In step S12, following the decrease in the SEC command pressure in step S9, or the determination that the actual SEC pressure> A in step S10, or the maintenance of the SEC pressure in step S11, the noise reduction control is terminated. It is determined whether the condition is satisfied. If YES (exit condition is satisfied), the process proceeds to step S13. If NO (exit condition is not satisfied), the process returns to step S8. Here, the determination of whether or not the missing condition is established is that the missing condition is not established while all of the following six conditions are not established, and when one of the following six conditions is established, it is determined that the missing condition is established. . Six specific conditions are:
1. Primary pulse count after starting control ≥ threshold (for example, 4 times)
In addition, when the secondary rotational speed sensor is provided, it is good also as secondary pulse count number ≥ threshold value after control start.
2.Brake off
3. Actual SEC pressure ≤ SEC required pressure a time has elapsed
4.Accelerator ON
5. Select operation outside the driving range
6. It is a fail judgment.

Here, “3. Actual SEC pressure ≤ SEC required pressure and a time has elapsed” means that the actual SEC pressure is less than the required SEC pressure (hydraulic pressure lower than the secondary target pressure A) as shown in FIG. This is the timing when a time elapses. This timing is when the SEC actual pressure continues to decrease after the SEC actual pressure has fallen below the secondary target pressure A, even though the SEC command pressure has been increased after F / B. It is the timing when it is determined that the actual SEC pressure has become insufficient for some reason. The “SEC required pressure” refers to the secondary pressure Psec corresponding to the input torque input from the engine 1 to the variator 4 via the torque converter 2. However, the input torque to the variator 4 is calculated by the equation (input torque≈τNe ² ) using the torque capacity τ of the torque converter 2 and the engine rotational speed Ne.

In step S13, following the determination that the removal condition is satisfied in step S12, the primary command pressure, which is suppressed by the PRI lower limit pressure B, is reduced and returned to the original value, and the reduced secondary command pressure is increased. Undo and proceed to return. In step S13, when it is determined in step S12 that the noise reduction control missing condition is satisfied, the control approach flag set during the control is lowered.

Next, the operation will be described. The operation of the first embodiment will be described by dividing it into “transmission oil pressure control processing operation”, “background art and problems of transmission oil pressure control”, “transmission oil pressure control operation”, and “characteristic operation of transmission oil pressure control”.

[Speed change hydraulic control processing action]
Hereinafter, the shift hydraulic pressure control processing operation will be described based on the flowchart shown in FIG. First, when traveling with the accelerator on / brake off, or when decelerating with the accelerator off / brake on, or when the accelerator is off / brake on but the stop condition is not met, go to step S1 → step S6 → return The forward flow is repeated. In step S6, normal transmission hydraulic pressure control is executed.

When the stop condition is satisfied, but the flat ground condition is not satisfied, the flow from step S1 to step S2 to step S6 to return is repeated. In step S6, normal transmission hydraulic pressure control is executed.

When the stop condition and the flat ground condition are satisfied, but the idle rotation condition is not satisfied, the flow of step S1, step S2, step S3, step S6 and return is repeated. In step S6, normal transmission hydraulic pressure control is executed.

The stopping condition, the flat ground condition, and the idle rotation condition are satisfied, but when the pulley low rotation condition is not satisfied, the flow from step S1, step S2, step S3, step S4, step S6, and return is repeated. In step S6, normal transmission hydraulic pressure control is executed.

Stop conditions, flat ground conditions, idle rotation conditions, and low pulley rotation conditions are satisfied, but when the SEC pressure reduction no restriction condition is not satisfied, step S1, step S2, step S3, step S4, step S5, step S6, and return. The flow to go to is repeated. In step S6, normal transmission hydraulic pressure control is executed.

When the stop condition, the flat ground condition, the idle rotation condition, the pulley low rotation condition, and the SEC pressure lowering no-restriction condition are satisfied, the process proceeds from step S1, step S2, step S3, step S4, step S5, and step S7. In step S <b> 7, the control for increasing the primary lower limit pressure to the primary lower limit pressure B is performed because the entry condition for the noise reduction control is satisfied.

Subsequently, the process proceeds from step S8 to step S9 to step S12. In step S8, it is determined whether or not the actual secondary pressure Psec is equal to or greater than the value obtained by adding the hysteresis amount α to the secondary target pressure A. Then, while it is determined that the actual SEC pressure ≧ A + α, the flow from step S8 → step S9 → step S12 is repeated, and in step S9, the secondary command pressure based on the secondary pressure command value output to the secondary pressure solenoid valve 74 is obtained. Control to lower is started.

If it is determined that the actual SEC pressure <A + α is established by starting the control to lower the secondary command pressure, the process proceeds from step S8 to step S10, while the actual SEC pressure> A is determined in step S10. The flow from step S8 to step S10 to step S12 is repeated. During this time, the control until then is taken over and the secondary command pressure is lowered.

If it is determined in step S10 that the actual SEC pressure ≦ A, the flow from step S8 to step S10 → step S11 → step S12 is repeated, and in step S11, the secondary command pressure at that time is maintained as it is. By maintaining the secondary command pressure, if the actual SEC pressure> A, the flow of going from step S8 → step S10 → step S12 is repeated until the actual SEC pressure ≧ A + α is determined. During this time, the control until then is taken over and the secondary command pressure is maintained. Thus, the actual secondary pressure Psec is lowered to the secondary target pressure A by repeating the control operation for lowering the secondary command pressure and the control operation for maintaining the secondary command pressure.

Thereafter, when the missing condition for ending the noise reduction control is established, the process proceeds from step S12 to step S13 → return. In step S13, the control approach flag is lowered, and the primary command pressure that is suppressed from being reduced by the PRI lower limit pressure B is controlled to return to the original value, and the reduced secondary command pressure is increased to return to the original value. Is done.

Thus, when the D range or the R range is selected, if the variator 4 reaches a pulley rotation speed that does not shift to the upshift side even if the secondary pressure Psec is reduced, the actual secondary pressure Psec is reduced to the secondary target pressure A. By controlling to reduce the actual secondary pressure Psec, noise called “oil pump noise” is reduced and the sound vibration performance is improved when the vehicle state is just before the vehicle is stopped or is stopped.

Further, by performing the control to reduce the actual secondary pressure Psec, the belt clamping force of the pulley belt 44 is reduced, and there is a concern that the belt slip may occur due to the decrease in the actual secondary pressure Psec. However, for this belt slip, the actual primary pressure Ppri, which is to be decreased as the actual secondary pressure Psec is decreased, is raised by the primary lower limit pressure B so that the actual primary pressure Ppri does not decrease below the primary lower limit pressure B. To prevent it.

[Background technology and issues of transmission hydraulic control]
First, it was pointed out by the user that oil pump noise is generated while the vehicle is stopped in the D range or the R range. In particular, when oil pump noise occurs in a state just before stopping or when the vehicle is stopped, where road noise and engine noise are low compared to when driving, there is a demand for the driver to feel uncomfortable and to improve sound vibration performance. It was.

In response to this request for improvement in sound vibration performance, the present inventors investigated the cause of the oil pump noise, and the oil pump noise originally had a dependency on the line pressure. It became clear that the line pressure dependency became weak and had a secondary pressure dependency. Therefore, attention was paid to the secondary pressure oil passage 94 from the oil pump 70 driven by the engine 1 to the secondary pulley 43 (FIG. 3). When attention is paid to the secondary pressure oil passage 94, resonance with a unit-side mount bracket 95 provided close to the secondary pressure oil passage 94 using the fluctuation component of the secondary pressure Psec passing through the secondary pressure oil passage 94 as an excitation source. It was found that “oil pump noise” occurred.

Further, the secondary pressure solenoid valve 74 that regulates the secondary pressure Psec is pulsating oil pressure that fluctuates as shown in the SEC actual pressure characteristics in FIG. Thus, since the excitation source of the oil pump noise is in the fluctuation component of the secondary pressure Psec, it has been found that when the secondary pressure Psec is reduced, the oil pump noise is reduced and the sound vibration performance is improved. Note that the reason why the oil pump noise is reduced when the secondary pressure Psec is reduced is that the fluctuation component (amplitude of the pulsating hydraulic pressure) that becomes the excitation source is suppressed to a small value by reducing the secondary pressure Psec.

However, focusing only on reducing the oil pump noise and reducing the secondary pressure Psec without considering the vehicle state, for example, belt slippage or unintentional shift occurs during traveling. There is a problem. That is, when the secondary pressure Psec is reduced during traveling, the clamping force of the pulley belt 44 by the secondary pulley 43 is reduced, the belt transmission torque exceeds the pulley clamping torque, and belt slip occurs. Further, when the secondary pressure Psec is reduced during traveling, the pulley width of the secondary pulley 43 is expanded, and the winding position of the pulley belt 44 with respect to the secondary pulley 43 moves in the pulley inner diameter direction as the pulley rotates, and an unintended upshift speed change Occurs.

[Speed change hydraulic control]
Hereinafter, the shift hydraulic pressure control operation will be described based on the time chart shown in FIG. When the accelerator is released at time t1 and then the brake is depressed at time t2 to stop the vehicle, normal shift hydraulic pressure control is executed and the operating point (VSP, APO) is set to C in FIG. The vehicle proceeds from point → D point → E point → F point → G point, and the vehicle speed VSP decreases.

That is, if the accelerator release operation is performed when the operating point (VSP, APO) is the point C in FIG. 2, the operating point (VSP, APO) is moved to the point D in FIG. Then, after moving to point D in FIG. 2, when the brake is depressed and decelerated, the operating point (VSP, APO) is maintained from point D in FIG. 2 while maintaining the highest gear ratio along the coastal shift line. Move to point E. Then, from point E in FIG. 2, the gear ratio of the variator 4 moves from the highest gear ratio to the point F while shifting in the downshift direction as the vehicle speed VSP decreases. When the point F by the lowest gear ratio in FIG. 2 is reached, the target primary rotational speed Npri ^* decreases while maintaining the lowest gear ratio, and the vehicle speed VSP moves to the point G where the vehicle speed VSP is zero.

After that, at time t3, it is determined that the vehicle is stopped based on the vehicle speed sensor value, and at time t4, it is determined that the road surface gradient is flat according to the front and rear G sensor values, and at time t5, the engine speed sensor value decreases to the idling speed range It is determined that However, these conditions are part of the conditions for entering the noise reduction control, and the noise reduction control is not started even if these conditions are satisfied.

After that, when the down edge of the pulse wave signal is detected from the primary pulley rotation speed sensor 80 at time t6, the timer value starts counting from the down edge. When the next pulse wave signal is not input even at time t7 when the timer value has passed a threshold value (for example, 0.5 sec), it is determined that the primary pulley rotation speed has become low, and noise reduction control is started. The When the control start time t7 is reached, the control approach flag is rewritten from the control approach flag = 0 to the control approach flag = 1, the control for lowering the secondary command pressure is started, and the primary lower limit pressure is increased to the primary lower limit pressure B. Control is performed.

Here, the control for reducing the secondary command pressure surrounded by the arrow H in FIG. 6 will be described in detail based on FIG. 7 in which the region surrounded by the arrow H in FIG. 6 is enlarged. Until the time t8 when the control target time t7 deviates from the secondary target pressure A, the secondary command pressure is lowered due to the steep decrease characteristic. From time t8 to time t9 when it is determined that the actual SEC pressure ≦ A, the secondary command pressure is lowered due to the gentle slope decreasing characteristic. From time t9 to time t10 when it is determined that the actual SEC pressure ≧ A + α, the secondary command pressure at time t9 is maintained as it is. From time t10 to time t11 when it is determined that the actual SEC pressure ≦ A, the secondary command pressure is lowered due to the gentle slope decreasing characteristic. From time t11 to time t12 when it is determined that the actual SEC pressure ≧ A + α, the secondary command pressure at time t11 is maintained as it is. From time t12 to time t13 when it is determined that the actual SEC pressure ≦ A, the secondary command pressure is lowered due to the gentle slope decreasing characteristic. After time t13, since A <actual SEC pressure <A + α, the secondary command pressure at time t13 is maintained as it is.

After the actual secondary pressure Psec is lowered to the secondary target pressure A, the down edge of the pulse wave signal is detected from the primary pulley rotation speed sensor 80 at time t14 (n = 1). Further, the down edge of the pulse wave signal is detected at time t15 (n = 1), the down edge of the pulse wave signal is detected at time t16 (n = 3), and the down edge of the pulse wave signal is detected at time t17. Is detected (n = 4). At time t17, the noise reduction control missing condition that the primary pulse count after starting control ≧ the threshold value is satisfied, and the noise reduction control is terminated. At the control end time t17, the control entry flag is rewritten from the control entry flag = 1 to the control entry flag = 0, the secondary command pressure is returned before the noise reduction control, and the primary lower limit pressure is changed from the primary lower limit pressure B. The pressure is returned to the primary lower limit pressure (comparative example) before the noise reduction control.

Here, the time chart shown in FIG. 6 determines that “the pulley rotation speed at which the transmission ratio of the variator 4 does not change” is determined, and the secondary pressure reduction control is started, but after the secondary pressure reduction control is started. Also depicts the situation where the pulley is rotating slightly. This is because even if it is determined that the pulley rotation is stopped, there is a scene in which the driver slightly releases the brake pedal and the vehicle moves forward at a creep vehicle speed or less. Or, even if the vehicle is not moving forward and the pulley rotation stoppage is determined, there is a scene where the pulley clamp force is insufficient, the belt slides against the input torque from the engine to the pulley, and the pulley rotates. by. Therefore, the absence of the noise reduction control (end of the secondary pressure reduction control) is the timing (time t17) when the primary pulse count number ≧ the threshold value.

On the other hand, when the brake ON → OFF operation is performed before the primary pulse count number ≧ threshold value due to pulley rotation stop, etc. after the start of noise reduction control, the noise reduction control missing condition is satisfied at time t18, and the noise is reduced. The reduction control is finished. Furthermore, after the noise reduction control is started, if the accelerator OFF → ON operation is performed before the primary pulse count number ≥ threshold without confirming the brake ON → OFF operation, the noise reduction control missing condition at time t19 Is established and the noise reduction control is terminated.

[Characteristic action of shift hydraulic control]
In the first embodiment, when the target speed ratio of the variator 4 is determined during traveling, the primary pressure Pri and the secondary pressure Psec adjusted according to the target speed ratio are supplied to the primary pulley 42 and the secondary pulley 43, respectively. When the pulley rotation speed at which the gear ratio of the variator 4 does not change even when the secondary pressure Psec is decreased, control for decreasing the secondary pressure Psec is started.

That is, the “pulley rotational speed at which the gear ratio of the variator 4 does not change even when the secondary pressure Psec is reduced” is a state immediately before stopping or a stopped state. In such a vehicle state, sounds other than oil pump noise (road noise, engine sound, etc.) are smaller than that during traveling, and the oil pump noise tends to be uncomfortable for the driver. Accordingly, by starting control for reducing the secondary pressure Psec when the vehicle is in a state where the sound other than the oil pump noise is low, the oil pump noise can be reduced and the driver can feel uncomfortable. . On the other hand, the oil pump noise is mixed with other sounds in a state just before stopping or in a driving state where the vehicle is not stopped, and the uncomfortable feeling given to the driver is reduced. In such a traveling state, it is possible to reduce the possibility of belt slippage or unintentional shifting by not unnecessarily reducing the secondary pressure Psec. As described above, when the pulley rotation speed at which the transmission ratio of the variator 4 does not change even when the secondary pressure Psec is reduced, the oil pump noise can be reduced by starting the control for reducing the secondary pressure Psec. Then, at the pulley rotational speed at which the gear ratio of the variator 4 does not change even when the secondary pressure Psec is lowered, the relative movement in the circumferential direction does not occur between the pulley belt 44 and the

pulleys

42, 43. It is possible to suppress the occurrence of shifting that does not occur. Further, in the first embodiment, the oil pump 70 is a pump that is rotationally driven by the engine 1 that is a driving source for traveling. Therefore, by reducing the secondary pressure Psec, the oil pump driving load is reduced and fuel efficiency is improved. To do.

In the first embodiment, when at least one pulley rotation speed of the primary pulley 42 and the secondary pulley 43 is stopped, it is determined that the pulley rotation speed does not change the speed ratio of the variator 4 even if the secondary pressure Psec is decreased. To do.

That is, it is also conceivable to start the secondary pressure lowering control based on “vehicle stoppage determination” rather than “pulley rotation speed becoming stopped”. However, the vehicle stoppage determination is rough, and the pulley may be slightly rotated at the timing when the stoppage determination is established. That is, “the pulley rotation speed is stopped” is determined based on the fact that the pulse wave signal from the primary pulley rotation speed sensor 80 is not detected for a predetermined time (for example, 0.5 sec). “Vehicle stop determination” is also determined based on the fact that the pulse wave signal from the vehicle speed sensor 81 is not detected for a predetermined time, but the predetermined time in the stop determination is shorter than the predetermined time for determining the stop state of the pulley rotation speed. (For example, 0.3 sec). Therefore, the noise reduction control is started not based on the vehicle stoppage determination but based on the pulley rotation speed being stopped. As a result, in the time chart shown in FIG. 6, the timing at which the control approach flag is set (time t7) is later than the vehicle stop determination timing (time t3). For this reason, when the pulley rotational speed is in a stopped state, even if the secondary pressure Psec is decreased, belt slippage or unintended shift does not occur. Therefore, when the pulley rotation speed is stopped, the control for reducing the secondary pressure Psec is started, so that it is possible to reliably prevent belt slippage and unintended shift.

In Example 1, after starting the control for reducing the secondary pressure Psec, when the number of pulse counts from the primary pulley rotation speed sensor 80 exceeds the threshold, the control for reducing the secondary pressure Psec is terminated.

That is, if it is detected that the primary pulley 42 or the secondary pulley 43 is rotating during the control for decreasing the secondary pressure Psec, the pulley belt 44 and the

pulleys

42 and 43 are relatively moved in the circumferential direction as the pool rotates. In addition, an unintended shift may occur. Therefore, the fact that both

pulleys

42 and 43 are rotating is detected by the pulse count number, and when the pulse count number becomes equal to or greater than the threshold value, the control for decreasing the secondary pressure Psec is terminated. Thereby, when the pulley rotation state is detected during the reduction control of the secondary pressure Psec, an unintended shift in the variator 4 can be prevented. Here, “to end the control for reducing the secondary pressure Psec” means to increase the secondary pressure Psec to the hydraulic pressure before starting the reduction control of the secondary pressure Psec.

In the first embodiment, when the control for reducing the secondary pressure Psec is performed, the oil pump noise that generates the secondary target pressure A, which is the target achieved by the oil pressure reduction, using the hydraulic system from the oil pump 70 as the vibration source is reduced. Set to the maximum pressure in the hydraulic range.

That is, the oil pump noise can be reduced by lowering the secondary pressure Psec. However, if the secondary pressure Psec is lowered too much, the secondary pressure Psec becomes insufficient at the time of subsequent start / acceleration. Occurrence delay). Therefore, by setting the secondary target pressure A as high as possible within a range where oil pump noise can be reduced, it is possible to reduce oil pump noise and reduce driving force deficiency and lag during subsequent start / acceleration. .

Here, how to control the SEC command pressure when the SEC actual pressure is reduced toward the secondary target pressure A will be described (FIG. 7). First, when the actual SEC pressure becomes the secondary target pressure A due to a decrease in the SEC command pressure, the SEC command pressure is maintained (the SEC command pressure at that time is maintained). That is, the SEC command pressure is not the secondary target pressure A, but the SEC actual pressure is the secondary target pressure A. Therefore, regardless of whether the SEC command pressure is higher or lower than the secondary target pressure A, the SEC command pressure is kept when the SEC actual pressure becomes the secondary target pressure A. After that, when the actual SEC pressure is lower than the secondary target pressure A, the SEC command pressure after F / B is increased, and when the actual SEC pressure is higher than the secondary target pressure A, the SEC command pressure after F / B is decreased. (The SEC command pressure is F / B controlled so that the actual SEC pressure becomes the secondary target pressure A).

In the first embodiment, when performing control to reduce the secondary pressure Psec, the primary lower limit pressure B that suppresses the decrease in the hydraulic pressure of the primary pressure Ppri is set to a higher hydraulic pressure than the hydraulic pressure set by the balance thrust between the primary pulley 42 and the secondary pulley 43. Set.

For example, if only the secondary pressure Psec is lowered, the balance of the thrust difference between the secondary pulley 42 and the primary pulley 43 is lost, resulting in a shift. Therefore, in normal transmission hydraulic pressure control, when the secondary pressure Psec is decreased, the primary pressure Ppri is also decreased. However, since the hydraulic pressure is lower than the primary pressure Ppri in the normal shift hydraulic pressure control that maintains the balance thrust during the reduction control of the secondary pressure Psec, the belt slips with respect to the input torque from the engine 1 in the idle rotation state. May occur. On the other hand, the primary lower limit pressure B that suppresses the decrease in the hydraulic pressure of the primary pressure Ppri is set to a higher hydraulic pressure than the hydraulic pressure set based on the balance thrust. Therefore, it is possible to prevent the occurrence of belt slip with respect to the torque input from the engine 1 in the idle rotation state.

In the first embodiment, when the secondary actual pressure (SEC actual pressure) is reduced with respect to the secondary command pressure (SEC command pressure) to the secondary pulley 42 and the difference between the secondary command pressure and the secondary actual pressure becomes a predetermined value or more, The control for reducing the secondary pressure Psec is terminated.

For example, if the secondary pressure solenoid valve 74 sticks due to contamination and the SEC actual pressure cannot follow the SEC command pressure, the oil pump noise can be reduced. The belt capacity may not be secured. On the other hand, when the difference between the SEC command pressure and the SEC actual pressure is equal to or greater than a predetermined value, the control for reducing the secondary pressure Psec is terminated (FIG. 5). Therefore, it is possible to secure a belt capacity that suppresses belt slip at the time of start / acceleration after the end of control.

Next, the effect will be explained. In the transmission hydraulic pressure control apparatus and control method for a continuously variable transmission according to the first embodiment, the following effects can be obtained.

(1) An oil pump 70, a variator 4, and a shift hydraulic pressure control unit (hydraulic control unit 7 and CVT control unit 8) are provided. The variator 4 includes a primary pulley 42, a secondary pulley 43, and a pulley belt 44 that spans between the

pulleys

42 and 43. The variator 4 is a pulley that is adjusted by a transmission hydraulic pressure that is adjusted based on the discharge pressure from the oil pump 70. The gear ratio is controlled by changing the width. When the target transmission gear ratio of the variator 4 is determined during traveling, the transmission hydraulic pressure control unit (hydraulic control unit 7 and CVT control unit 8) uses the primary pressure Ppri and the secondary pressure Psec adjusted according to the target transmission gear ratio as primary. It supplies to the pulley 42 and the secondary pulley 43, respectively. Then, when the pulley rotational speed at which the gear ratio of the variator 4 does not change even when the secondary pressure Psec is decreased, control for decreasing the secondary pressure Psec is started. Therefore, it is possible to provide a transmission hydraulic pressure control device for a continuously variable transmission that suppresses the occurrence of oil pump noise that makes the driver feel uncomfortable while suppressing the occurrence of belt slip and unintended shift.

(2) The transmission hydraulic pressure control unit (hydraulic control unit 7 and CVT control unit 8) may reduce the secondary pressure Psec when at least one of the primary pulley 42 and the secondary pulley 43 is stopped. It is determined that the pulley rotation speed at which the gear ratio of the variator 4 does not change has been reached. For this reason, in addition to the effect of (1), when the pulley rotation speed is stopped, it is possible to reliably prevent belt slippage or unintentional shift from occurring by starting control to reduce the secondary pressure Psec. it can.

(3) A pulley rotation speed sensor (primary pulley rotation speed sensor 80) that detects the pulley rotation speed of at least one of the primary pulley 42 and the secondary pulley 43 by the pulse count number that is the number of counts of the pulse wave signal is provided. The transmission hydraulic pressure control unit (hydraulic control unit 7 and CVT control unit 8) starts control to reduce the secondary pressure Psec, and then the pulse count from the pulley rotational speed sensor (primary pulley rotational speed sensor 80) exceeds the threshold value. Then, the control for reducing the secondary pressure Psec is terminated. For this reason, in addition to the effect of (2), when the pulley rotation state is detected during the reduction control of the secondary pressure Psec, an unintended shift in the variator 4 can be prevented.

(4) When the transmission hydraulic pressure control unit (the hydraulic pressure control unit 7 and the CVT control unit 8) performs the control to reduce the secondary pressure Psec, the secondary target pressure A that is the target achieved by the decrease in hydraulic pressure is set to the hydraulic pressure from the oil pump 70. The maximum pressure is set in the hydraulic range where the oil pump noise generated using the system as the excitation source is reduced. For this reason, in addition to the effects (1) to (3), the secondary target pressure A is set as high as possible within the range where oil pump noise can be reduced. Insufficient driving force and lag can be reduced.

(5) When the transmission hydraulic pressure control unit (hydraulic control unit 7 and CVT control unit 8) performs control to decrease the secondary pressure Psec, the primary lower limit pressure B that suppresses the decrease in the primary pressure Ppri is set to the primary pulley 42 and the secondary pulley. The hydraulic pressure is set higher than the hydraulic pressure set by the balance thrust with the pulley 43. For this reason, in addition to the effects (1) to (4), it is possible to prevent the occurrence of belt slip with respect to the torque input from the engine 1 in the idle rotation state.

(6) The transmission hydraulic pressure control unit (hydraulic control unit 7 and CVT control unit 8) decreases the secondary actual pressure with respect to the secondary command pressure to the secondary pulley 42, and the difference between the secondary command pressure and the secondary actual pressure is a predetermined value. If it becomes above, the control which reduces secondary pressure Psec will be complete | finished. For this reason, in addition to the effects (1) to (5), it is possible to secure a belt capacity that suppresses belt slipping when starting and accelerating after the end of control.

(7) An oil pump 70 and a variator 4 are provided. The variator 4 includes a primary pulley 42, a secondary pulley 43, and a pulley belt 44 that spans between the

pulleys

42 and 43. The variator 4 is a pulley that is adjusted by a transmission hydraulic pressure that is adjusted based on the discharge pressure from the oil pump 70. The gear ratio is controlled by changing the width. In this vehicle (engine vehicle), when the target gear ratio of the variator 4 is determined during traveling, the primary pressure Pri and the secondary pressure Psec adjusted according to the target gear ratio are supplied to the primary pulley 42 and the secondary pulley 43, respectively. To do. When the pulley rotation speed at which the gear ratio of the variator 4 does not change even when the secondary pressure Psec is decreased, control for decreasing the secondary pressure Psec is started. Therefore, it is possible to provide a transmission hydraulic pressure control method for a continuously variable transmission that suppresses the occurrence of belt slip and unintended shift while reducing the occurrence of oil pump noise that makes the driver feel uncomfortable.

As described above, the transmission hydraulic pressure control device and the control method of the continuously variable transmission according to the present invention have been described based on the first embodiment. However, the specific configuration is not limited to the first embodiment, and design changes and additions are allowed without departing from the spirit of the invention according to each claim of the claims.

In the first embodiment, when the pulley rotational speed is such that the gear ratio of the variator 4 does not change even when the secondary pressure Psec is reduced, the secondary pressure Psec reduction control is always executed regardless of whether oil pump noise is generated or not. Indicated. However, the presence or absence of oil pump noise is detected, and only when the rotation speed of the pulley is such that the gear ratio of the variator does not change even when the secondary pressure is reduced, and the occurrence of oil pump noise is detected. It is good also as an example which performs pressure reduction control.

In the first embodiment, since the primary pulley rotational speed sensor 80 is provided, the stop state of the pulley rotational speed of the primary pulley 42 is determined based on the pulse wave signal from the primary pulley rotational speed sensor 80. However, when determining the stop state of the pulley rotation speed, it may be determined by detecting the rotation speed of either the primary pulley or the secondary pulley, or by detecting the rotation speed of both pulleys.

In the first embodiment, an example of an oil pump 70 that is rotationally driven by the engine 1 that is a driving source for traveling is shown as an oil pump. However, the oil pump may be an electric oil pump that is rotationally driven by a motor that is independent of the travel drive source, or a mechanical oil pump that is rotationally driven by the travel drive source and an electric oil pump. A combination pump may be used.

In the first embodiment, when the control for reducing the secondary pressure Psec is performed, the secondary target pressure A, which is the target achieved by the decrease in hydraulic pressure, is set in advance to the maximum pressure in the noise reduction hydraulic pressure region. However, an example in which the secondary target pressure at which belt slip does not occur is determined by the torque input to the variator when the controlled condition is satisfied, or a preset secondary target pressure is input to the variator. An example of correcting with torque may be used.

Embodiment 1 shows an example in which the transmission hydraulic pressure control device and control method of the present invention are applied to an engine vehicle equipped with a belt type continuously variable transmission using only a variator. However, the transmission hydraulic pressure control device and the control method of the present invention may be applied to a vehicle equipped with a continuously variable transmission with a sub transmission in which a sub transmission mechanism and a variator are combined. Further, the applied vehicle is not limited to an engine vehicle, but can be applied to a hybrid vehicle, an electric vehicle, and the like.

Claims

An oil pump,
A primary pulley, a secondary pulley, and a pulley belt spanned between both pulleys;
A variator in which a gear ratio is controlled by changing a pulley width by a transmission hydraulic pressure adjusted based on a discharge pressure from the oil pump;
A shift hydraulic pressure control unit that supplies a primary pressure and a secondary pressure adjusted according to the target gear ratio to the primary pulley and the secondary pulley, respectively, when a target gear ratio of the variator is determined during travel; ,
The transmission hydraulic pressure control unit of the continuously variable transmission starts the control to reduce the secondary pressure when the pulley rotation speed at which the transmission ratio of the variator does not change even if the secondary pressure is reduced.
In the transmission hydraulic pressure control device for a continuously variable transmission according to claim 1,
When the pulley rotation speed of at least one of the primary pulley and the secondary pulley is stopped, the transmission hydraulic pressure control unit has a pulley rotation speed that does not change the gear ratio of the variator even if the secondary pressure is reduced. A transmission hydraulic control device for a continuously variable transmission.
In the transmission hydraulic pressure control device for a continuously variable transmission according to claim 1 or 2,
A pulley rotation speed sensor that detects a pulley rotation speed of at least one of the primary pulley and the secondary pulley by a pulse count number that is a count number of pulse wave signals;
The shift oil pressure control unit ends the control to reduce the secondary pressure when the pulse count from the pulley rotation speed sensor becomes equal to or greater than a threshold value after starting the control to reduce the secondary pressure. Variable speed hydraulic control device.
The transmission hydraulic pressure control device for a continuously variable transmission according to any one of claims 1 to 3,
When the shift hydraulic pressure control unit performs the control to reduce the secondary pressure, the oil pump noise that generates the secondary target pressure, which is the target achieved by the hydraulic pressure reduction, using the hydraulic system from the oil pump as the excitation source is reduced. A variable speed hydraulic control device for a continuously variable transmission that is set to the maximum pressure in the hydraulic range.
In the transmission hydraulic pressure control device for a continuously variable transmission according to any one of claims 1 to 4,
The shift hydraulic pressure control unit, when performing control to reduce the secondary pressure, has a primary lower limit pressure that suppresses a decrease in the primary pressure, higher than a hydraulic pressure set by a balance thrust between the primary pulley and the secondary pulley. Set to variable speed hydraulic control device for continuously variable transmission.
In the transmission hydraulic pressure control device for a continuously variable transmission according to any one of claims 1 to 5,
The transmission hydraulic pressure control unit performs control to reduce the secondary pressure when the secondary actual pressure is reduced with respect to the secondary command pressure to the secondary pulley and the difference between the secondary command pressure and the secondary actual pressure becomes a predetermined value or more. The hydraulic pressure control device for the continuously variable transmission to be finished.
An oil pump,
The pulley has a primary pulley, a secondary pulley, and a pulley belt spanned between the two pulleys, and the gear ratio is changed by changing the pulley width by the transmission hydraulic pressure adjusted based on the discharge pressure from the oil pump. A controlled variator,
In a vehicle comprising:
During travel, when the target speed ratio of the variator is determined, the primary pressure and the secondary pressure adjusted according to the target speed ratio are supplied to the primary pulley and the secondary pulley, respectively.
A transmission hydraulic pressure control method for a continuously variable transmission that starts control to reduce the secondary pressure when the pulley rotation speed at which the gear ratio of the variator does not change even if the secondary pressure is reduced.