JP6933698B2 - Hydraulic control device and hydraulic control method for continuously variable transmission - Google Patents

Description

INDUSTRIAL APPLICABILITY The present invention is a hydraulic control device and a hydraulic pressure that changes the groove width of both pulleys by supplying hydraulic pressure to a continuously variable transmission in which an endless transmission band is wound around a drive pulley and a driven pulley to change the gear ratio. Regarding the control method.

In Patent Documents 1 to 3, the gear ratio is determined by supplying hydraulic pressure to a continuously variable transmission in which an endless transmission band is wound around a drive pulley and a driven pulley to change the groove widths of both pulleys. The hydraulic control device and the hydraulic control method to be changed are disclosed.

Of these, Patent Document 1 states that in order to prevent an excessive increase in the integration term of feedback control due to a sudden change in the target gear ratio, the gear ratio is set without slipping the belt (endless transmission band) from each pulley. Based on the lower limit thrust required to maintain and the upper limit thrust considering the durability of the belt, the variable amount of thrust in each pulley is calculated, and the limit speed change speed (change in gear ratio) is calculated based on the calculated variable amount. It is disclosed that the speed limit value) is calculated and the target gear ratio is limited based on the calculated limit speed change speed.

In Patent Document 2, when the oil temperature is equal to or higher than the set temperature, the input torque is calculated from the throttle opening, and the pulley ratio is calculated from each rotation speed of the primary pulley (drive pulley) and the secondary pulley (driven pulley). It is disclosed that the required flow rate of the lubricating oil supplied to the belt is calculated based on the input torque, the rotation speed of the primary pulley, and the pulley ratio, and the discharge flow rate of the pump is set based on the calculated required flow rate. ..

In Patent Document 3, oil is supplied from a pump driven by an engine to an automatic transmission mechanism and a hydraulic control valve, while a part of the oil discharged from the main pump is pressurized by a sub pump driven by an electric motor. When supplying to the hydraulic control valve, if the pressure of the oil supplied to the automatic transmission mechanism is less than the predetermined pressure, the oil boosted by the sub-pump is supplied to the hydraulic control valve, while being supplied to the automatic transmission mechanism. It is disclosed that the drive of the sub-pump is stopped when the pressure of the oil is equal to or higher than a predetermined pressure.

Japanese Patent No. 5316692 Japanese Patent No. 3938897 Japanese Patent No. 6130860

In the hydraulic control of Patent Document 1, the contact state between the belt and the pulley becomes harsher than usual at the limit speed change speed, so it is necessary to consider the lubrication state of the belt. Since there are various types of belt lubrication devices, there is a demand for a hydraulic control method that lubricates the belt regardless of the method.

On the other hand, in Patent Document 2, when the discharge flow rate of the pump cannot be changed, the hydraulic control cannot be appropriately performed. Further, in Patent Document 3, if the sub pump is driven when the oil pressure is less than a predetermined pressure, the flow rate of the oil supplied from the main pump is further reduced. As a result, it becomes impossible to supply the required flow rate of oil to the lubricated portion such as the belt of the continuously variable transmission.

As described above, in the continuously variable transmission, in addition to the flow rate required for shifting, there is also a flow rate (required flow rate) required for lubrication of the belt or the like. Therefore, a large-capacity pump tends to be required for hydraulic control of a continuously variable transmission. Therefore, in a continuously variable transmission mounted on a vehicle, only a pump driven by a vehicle drive source (for example, an engine) is used, regardless of the lubrication device method, and the gear ratio or gear ratio (speed of change of gear ratio). ) Is required as a hydraulic control method.

The present invention has been made in consideration of such a problem, and the gear ratio (shift speed) is secured by the pump driven by the drive source of the vehicle while ensuring the flow rate required for lubrication of the endless transmission zone and the like. It is an object of the present invention to provide a hydraulic control device and a hydraulic control method for a continuously variable transmission capable of controlling the above.

An aspect of the present invention is to reduce the groove width of both pulleys by supplying hydraulic pressure to a drive pulley, a driven pulley, and a continuously variable transmission having an endless transmission band wound around the drive pulley and the driven pulley. The present invention relates to a hydraulic control device and a hydraulic control method for a continuously variable transmission that are changed and the gear ratio is changed.

In this case, the hydraulic control device includes a pump that supplies the hydraulic pressure, a valve portion that controls the supply of the hydraulic pressure from the pump to each portion in the stepless transmission, and rotation of the drive pulley and the driven pulley. A gear ratio detection unit that detects the gear ratio based on the number, a command value determination unit that determines a command value of a gear shift pressure that is a hydraulic pressure supplied to the drive pulley and the driven pulley, and the command value determination unit based on the command value. A valve control unit that controls the supply of the oil pressure by controlling the valve unit, and a valve control unit that controls the supply of the oil pressure based on the command value to supply the oil pressure to the endless transmission band. When it is expected that the lubrication pressure is lower than the threshold value, it has a command value changing unit that changes the command value so that the lubrication pressure becomes equal to or higher than the threshold value.

Further, in the oil pressure control method, when the oil pressure is supplied from the pump to each part in the stepless transmission via the valve part, the gear ratio detection part determines the number of rotations of the drive pulley and the driven pulley. Based on the step of detecting the gear ratio, the step of determining the command value of the shift pressure which is the hydraulic pressure supplied to the drive pulley and the driven pulley by the command value determining unit, and the step of determining the command value of the shifting pressure which is the hydraulic pressure supplied to the driven pulley, and the valve control unit based on the command value. The step of controlling the supply of the oil pressure by controlling the valve unit, and the oil pressure supplied to the endless transmission band by the valve control unit controlling the supply of the oil pressure based on the command value. When the lubricating pressure is expected to be lower than the threshold value, the command value changing unit has a step of changing the command value so that the lubricating pressure becomes equal to or higher than the threshold value.

According to the present invention, since the hydraulic control that feeds back the lubrication pressure is performed, the lubrication pressure can be secured regardless of the state of the hydraulic control for the continuously variable transmission. This makes it possible to perform hydraulic control at a gear ratio (shift speed) according to the lubrication pressure. As a result, it is possible to realize the hydraulic control of an appropriate gear ratio (shift speed) only by the pump driven by the drive source of the vehicle regardless of the system of the lubrication device.

It is a block diagram of the control device which concerns on this embodiment. It is a block diagram of a hydraulic control valve. It is a partial block diagram of the control device which shows the arrangement of a lubrication pressure sensor. It is a flowchart which shows the process of the control device of FIG. It is a flowchart which shows the detail of the process of step S8 of FIG. It is explanatory drawing which shows the relationship between the lubrication pressure and the lubrication flow rate. It is explanatory drawing which shows the relationship between the operating state of a lockup clutch, and a lubrication pressure. It is explanatory drawing which shows the relationship between the rotation speed of a drive pulley and a lubrication pressure. It is explanatory drawing which shows the relationship between the rotation speed of a driven pulley and a lubrication pressure. It is explanatory drawing which shows the relationship between ratio (gear ratio) and lubrication pressure. It is explanatory drawing which shows the relationship between the speed change pressure and the lubrication pressure.

Hereinafter, suitable embodiments of the hydraulic control device and the hydraulic control method for the continuously variable transmission according to the present invention will be illustrated and described with reference to the accompanying drawings.

[1. Configuration of this embodiment]
As shown in FIG. 1, the hydraulic control device 10 for the continuously variable transmission according to the present embodiment (hereinafter, also referred to as the control device 10 according to the present embodiment) is, for example, a vehicle 14 having an engine 12 as a drive source. It will be installed. FIG. 1 is a schematic configuration diagram of a control device 10 for hydraulically controlling a metal belt type continuously variable transmission 16 (CVT).

A torque converter 18 as a rotation transmission mechanism is connected to the output shaft 23 of the engine 12. The torque converter 18 includes a lockup clutch 20 that directly connects the engine 12 and the continuously variable transmission 16. A ring gear 24 of the forward / backward switching mechanism 22 is connected to the output side of the torque converter 18. The forward / backward switching mechanism 22 is composed of a planetary gear mechanism including a ring gear 24 connected to the output shaft 23 of the engine 12, a pinion carrier 26, and a sun gear 30 connected to the input shaft 28 of the continuously variable transmission 16. There is. The pinion carrier 26 is provided with a reverse brake 32 for fixing the pinion carrier 26 to the case of the continuously variable transmission 16 and a forward clutch 34 for integrally connecting the input shaft 28 of the continuously variable transmission 16 and the pinion carrier 26. ing.

The continuously variable transmission 16 includes a drive pulley 36 provided on the input shaft 28, a driven pulley 38, and a belt 40 (endless transmission band) wound around the drive pulley 36 and the driven pulley 38.

The drive pulley 36 has a fixed side pulley half body 36a that is rotatable relative to the input shaft 28 and a movable side pulley half body 36b that is slidable in the axial direction of the input shaft 28 with respect to the fixed side pulley half body 36a. And have. The movable side pulley half body 36b has a variable V-shaped groove width (groove width of the drive pulley 36) with the fixed side pulley half body 36a due to the hydraulic pressure acting on the hydraulic oil chamber 36c.

The driven pulley 38 is supported by the driven shaft 42. The driven pulley 38 includes a fixed side pulley half body 38a fixed to the driven shaft 42 and a movable side pulley half body 38b that is slidable in the axial direction of the driven shaft 42 with respect to the fixed side pulley half body 38a. Have. The movable side pulley half body 38b has a variable V-shaped groove width (groove width of the driven pulley 38) between the movable side pulley half body 38b and the fixed side pulley half body 38a due to the hydraulic pressure acting on the hydraulic oil chamber 38c.

A drive gear (not shown) is fixed to the driven shaft 42. The drive gear is connected to the wheel via a pinion, a final gear and a differential provided on the idler shaft. Therefore, the rotational force from the output shaft 23 of the engine 12 is transmitted to the input shaft 28 of the continuously variable transmission 16 via the torque converter 18 and the forward / backward switching mechanism 22. In the continuously variable transmission 16, the rotational force of the input shaft 28 is transmitted to the differential device via the drive pulley 36, the belt 40, the driven pulley 38, the driven shaft 42, the drive gear, the idler gear, the idler shaft, the pinion, and the final gear. Will be done.

A nozzle tube 44 is arranged between the drive pulley 36 and the driven pulley 38 along the axial direction of the input shaft 28 and the driven shaft 42. One end of the nozzle tube 44 is connected to the hydraulic control valve 46, and the other end is closed. An oil jet hole 44a that opens on the drive pulley 36 side and an oil injection hole 44b that opens on the driven pulley 38 side are formed on the peripheral wall of the nozzle pipe 44. One oil jet hole 44a opens toward the portion of the belt 40 wound around the drive pulley 36, and the other oil jet hole 44b opens toward the portion of the belt 40 wound around the driven pulley 38. doing.

Then, by moving the movable side pulley semifields 36b and 38b of the drive pulley 36 and the driven pulley 38 in the axial direction, the groove widths of the drive pulley 36 and the driven pulley 38 are changed, and the drive pulley 36 and the driven pulley 38 The rotation ratio of, that is, the gear ratio can be changed. Further, when the oil is supplied to the nozzle pipe 44, the oil is injected from one of the jet oil holes 44a toward the portion of the belt 40 wound around the drive pulley 36, and at the same time, the driven pulley 38 is injected from the other jet oil hole 44b. Oil is sprayed toward the portion of the belt 40 wound around the belt 40. As a result, the belt 40 can be efficiently lubricated and cooled.

Such a change in the V-shaped groove width and supply of oil to the belt 40 via the nozzle pipe 44 are performed by changing the CVT control unit 48 (gear ratio detection unit, command value determination unit, valve control unit, command value). The unit) controls the hydraulic control valve 46 (valve unit). The CVT control unit 48 is an electronic control device including a microprocessor or the like, and is a gear ratio detection unit, a command value determination unit, and a valve control unit by reading and executing a program stored in a memory (not shown). And the function of the command value change part is realized.

In addition to the CVT control unit 48 and the hydraulic control valve 46, the control device 10 includes a pump 50, a shift mode sensor 52, a throttle opening sensor 54, a line pressure sensor 56, a pump rotation speed sensor 58, an engine rotation speed sensor 60, and a drive pulley. It has a rotation speed sensor 62, a driven pulley rotation speed sensor 64, a pulley clamp pressure sensor 66, and a lubrication pressure sensor 68.

The pump 50 is a mechanical pump that is driven as the engine 12 rotates, and supplies oil from a tank (not shown) to the continuously variable transmission 16. The hydraulic control valve 46 is a valve unit that controls the supply of oil supplied from the pump 50 to each part in the continuously variable transmission 16, and includes various hydraulic control valves. The configuration of the hydraulic control valve 46 will be described later.

The shift mode sensor 52 detects whether the operation mode is the automatic shift mode or the manual shift mode from the state (external request) of the shift mode change switch provided on the shift lever (not shown) provided in the vehicle 14. ..

The throttle opening sensor 54 detects the opening degree (throttle opening degree, external request) of a throttle valve (not shown). The pump rotation speed sensor 58 detects the rotation speed Np of the pump 50. The engine speed sensor 60 detects the speed Ne of the engine 12. The drive pulley rotation speed sensor 62 detects the rotation speed Ndr of the drive pulley 36. The driven pulley rotation speed sensor 64 detects the rotation speed Ndn of the driven pulley 38.

The line pressure sensor 56 detects the line pressure PH, which is the pressure (flood control) of the oil regulated by the hydraulic control valve 46, with respect to the oil supplied from the pump 50. The pulley clamp pressure sensor 66 uses the pressure (hydraulic pressure) of the oil supplied from the hydraulic control valve 46 to the hydraulic oil chamber 36c of the drive pulley 36, that is, the hydraulic pressure when the drive pulley 36 clamps the belt 40 as the clamp pressure Pc. To detect. The lubrication pressure sensor 68 detects the pressure (flood control) of the oil supplied from the hydraulic control valve 46 to the lubrication portion such as the belt 40 as the lubrication pressure Pub.

The line pressure PH is the original pressure of the oil supplied from the hydraulic control valve 46 to each part of the continuously variable transmission 16. Further, the clamp pressure Pc of the drive pulley 36 is lower than the line pressure PH. On the other hand, the pressure of the oil supplied to the hydraulic oil chamber 38c of the driven pulley 38, that is, the clamping pressure Pc when the driven pulley 38 clamps the belt 40 is substantially the same as the line pressure PH. Further, the lubrication pressure Pub is a hydraulic pressure lower than the line pressure PH and each clamp pressure Pc.

The detection results of these various sensors are sequentially input to the CVT control unit 48.

The CVT control unit 48 obtains a gear ratio based on the detection results input from each of the above sensors, and is a shift pressure which is the pressure of oil supplied to the drive pulley 36 and the driven pulley 38 based on an external request such as a throttle opening. The command value Pcc of (clamp pressure Pc) is detected. Further, the CVT control unit 48 controls the oil pressure (flood control) supplied to each part of the continuously variable transmission 16 by controlling the hydraulic control valve 46 based on the command value Pcc. Further, when the lubrication pressure Pub supplied to the belt 40 is expected to be lower than the predetermined threshold value Pubth, the CVT control unit 48 changes the command value Pcc so that the lubrication pressure Pub is equal to or higher than the threshold value Pubth. Furthermore, the CVT control unit 48 includes a map 70 showing the relationship with the threshold value Plus, and executes a change process of the command value Pcc with reference to the map 70. The details of the operation of the CVT control unit 48 will be described later.

As shown in FIG. 2, the hydraulic control valve 46 includes a regulator valve 46a connected to the pump 50, an LC shift valve 46b connected to the downstream side of the regulator valve 46a, and the like. Note that FIG. 2 shows only the valves that are essential for the explanation of the present embodiment in the hydraulic control valve 46. Therefore, it should be noted that a large number of valves are actually arranged in the hydraulic control valve 46 in order to supply oil to each part of the continuously variable transmission 16.

The regulator valve 46a generates a line pressure PH by adjusting the oil pressure of the oil supplied from the pump 50. The line pressure PH oil is supplied toward the hydraulic oil chambers 36c and 38c of the drive pulley 36 and the driven pulley 38. Further, the oil having a line pressure PH is further regulated by the LC shift valve 46b, and is distributed and supplied to the torque converter 18 and the belt 40. It should be noted that the pressure of the oil supplied to the belt 40 (lubrication pressure Pub) is lower than the pressure of the oil supplied to the torque converter 18 (lockup clutch 20). Further, since the LC shift valve 46b distributes and supplies oil to the torque converter 18 and the belt 40, the lubrication pressure Pub of the belt 40 is affected by the lockup clutch 20.

As shown in FIGS. 2 and 3, the LC shift valve 46b is a valve for controlling the lockup clutch 20 of the torque converter 18, and the lubrication pressure Pub is changed by changing the position of the valve. Further, the LC shift valve 46b supplies the distributed oil to the belt 40, the driven shaft 42 of the driven pulley 38, and the like. In this case, an oil supply passage 42a is formed at the axis of the driven shaft 42. Further, the driven shaft 42 is formed with a communication hole 42b for communicating the oil supply passage 42a and the outer peripheral surface. As a result, the oil supplied from the LC shift valve 46b to the oil supply passage 42a lubricates the gear 72 and the bearing 74 arranged on the driven shaft 42 through the communication hole 42b. Further, the lubrication pressure sensor 68 detects the pressure of the oil supplied from the LC shift valve 46b to the belt 40, the driven shaft 42 and the like as the lubrication pressure Pub. When the oil supplied to the belt 40 is insufficient, a negative pressure is generated by the rotation of the driven shaft 42, so that the lubrication pressure sensor 68 detects the negative pressure lubrication pressure Pub.

[2. Operation of this embodiment]
The operation of the control device 10 according to the present embodiment (the hydraulic control method for the continuously variable transmission according to the present embodiment) configured as described above will be described with reference to FIGS. 4 to 11. Here, the CVT control unit 48 determines or changes the command value Pcc of the speed change pressure, and controls the hydraulic control valve 46 based on the determined or changed command value Pcc, thereby supplying each part of the continuously variable transmission 16. A case of controlling the oil pressure (flood control) supply will be described. In this operation description, if necessary, the description will be made with reference to FIGS. 1 to 3.

As described above, the lubrication pressure Pub of the oil supplied to the lubrication system such as the belt 40 has a lower pressure than the oil supplied to the other parts of the continuously variable transmission 16. Therefore, it is easily affected by clutch pressure and the like, which require high pressure. For example, when the clamp pressure Pc (hereinafter, also referred to as pulley pressure) is high and it is necessary to supply more oil to the drive pulley 36 and the driven pulley 38 in order to increase the speed change speed (change speed of the gear ratio). When the rotation speed Np of the pump 50 is low, the lubrication pressure Pub may become 0. Therefore, in the present embodiment, by feeding back the lubrication pressure Pub to the CVT control unit 48, it is possible to perform hydraulic control on the continuously variable transmission 16 at a speed change speed such that the lubrication pressure Pub is secured. Moreover, in the present embodiment, the hydraulic control is performed by the feedback control using the lubrication pressure Pub without requiring a special sensor.

In step S1 of FIG. 4, the CVT control unit 48 (see FIG. 1) determines whether or not the engine 12 and the continuously variable transmission 16 are connected by the operation of the lockup clutch 20. In this case, the CVT control unit 48 determines whether or not the lockup clutch 20 is operating based on the lubrication pressure Pub detected by the lubrication pressure sensor 68 (see FIGS. 1 and 3) and the map 70. ..

Various maps shown in FIGS. 6 to 11 are stored in the map 70. In step S1, the maps of FIGS. 6 and 7 are referred to.

FIG. 6 shows the relationship between the lubrication pressure Pub of the belt 40 (see FIGS. 1 to 3) and the flow rate (lubrication flow rate) of the oil supplied to the belt 40. The map of FIG. 6 is a map in which the lubrication pressure Pub and the lubrication flow rate measured in advance are plotted. The lubrication flow rate of the belt 40 depends on the lubrication pressure Pub. Therefore, if the lubrication pressure Pub is secured, the lubrication flow rate can be secured. Therefore, in the present embodiment, the lubrication pressure Pub corresponding to the minimum lubrication flow rate required for lubrication of the belt 40 is set as the threshold value Pubth.

In the following description, it should be noted that the threshold values shown in FIGS. 7 to 11 are set to the same value. Further, each map of FIGS. 7 to 11 was created by plotting a lubrication pressure Pub or the like measured in advance.

FIG. 7 is a map illustrating changes in the lubrication pressure Pub between the operating state (LC ON) and the non-operating state (LC OFF) of the lockup clutch 20 (see FIG. 1). As described above, the lubrication pressure Pub of the belt 40 (see FIGS. 1 to 3) is affected by the pressure and flow rate of the oil supplied to the lockup clutch 20, that is, the operating state and the non-operating state of the lockup clutch 20. Receive. As shown in FIG. 7, in the operating state (LC ON) of the lockup clutch 20, the lubricating pressure Pub is in a relatively low state, while in the non-operating state (LC OFF), the lubricating pressure Pub is in a relatively high state. It is in.

In the map of FIG. 7, the lower limit value of the lubrication pressure Pub according to the operating state is preset as the threshold value Plug. In step S1, when the lubrication pressure Pub detected by the lubrication pressure sensor 68 is lower than the threshold value Pubth, the CVT control unit 48 determines that the lockup clutch 20 is in the operating state (step S1: YES). On the other hand, in step S1, when the lubrication pressure Pub detected by the lubrication pressure sensor 68 is equal to or higher than the threshold value Pubth, the CVT control unit 48 determines that the lockup clutch 20 is in the non-operating state (step S1: NO). In the operating state (LC ON), when the lubrication pressure Pub is relatively low and the lower limit value of the lubrication pressure Pub is lower than the threshold value Plus, step S1 is skipped and the process of step S2 is executed. It is also possible. In this case, it basically includes that the lubrication flow rate is insufficient.

If a positive determination result is obtained in step S1 (step S1: YES), the CVT control unit 48 proceeds to the next step S2 and acquires the rotation speed Np of the pump 50 detected by the pump rotation speed sensor 58. As described above, the pump 50 is rotated by the drive of the engine 12, and the drive pulley 36 is rotated by the rotational force transmitted from the engine 12 via the torque converter 18. Therefore, in step S2, the CVT control unit 48 has the rotation speed Np of the pump 50, the rotation speed Ndr of the drive pulley 36 detected by the drive pulley rotation speed sensor 62, and the rotation speed Ne of the engine 12 detected by the engine rotation speed sensor 60. Of these, at least one rotation speed Np, Ndr, and Ne may be acquired.

In step S3, whether or not the rotation speed of the CVT control unit 48 is such that the lubrication pressure Pub is lower than the threshold value Pubth based on any one of the acquired rotation speeds Np, Ndr, Ne and the map of FIG. Is determined. As an example, the map of FIG. 8 is a map showing the relationship between the rotation speed Ndr of the drive pulley 36 and the lubrication pressure Pub. In FIG. 8, the lubrication pressure Pub is below the threshold value Pubth in the range of the predetermined rotation speed Ndr. That is, it is expected that the lubrication pressure Pub required for lubrication of the belt 40 cannot be secured in the range of the rotation speed Ndr (step S3: YES).

If a positive determination result is obtained in step S3 (step S3: YES), the CVT control unit 48 proceeds to the next step S4 and shifts gears based on the respective rotation speeds Ndr and Ndn of the drive pulley 36 and the driven pulley 38. Calculate (detect) the ratio.

In step S5, the CVT control unit 48 determines whether or not the gear ratio is such that the lubrication pressure Pub is lower than the threshold value Plus, based on the gear ratio and the map of FIG. As an example, the map of FIG. 9 is a map showing the relationship between the rotation speed Ndn of the driven pulley 38 and the lubrication pressure Pub according to the gear ratio. In FIG. 9, it is expected that the lubrication pressure Pub is below the threshold value Pubth within the range of the predetermined rotation speed Ndn, and the lubrication pressure Pub required for lubricating the belt 40 cannot be secured (step S5: YES). ).

If a positive determination result is obtained in step S5 (step S5: YES), the CVT control unit 48 proceeds to the next step S6 and determines the command value Pcc of the shift pressure based on the external request.

In step S7, the CVT control unit 48 determines whether or not the lubrication pressure Pub is a command value Pcc that is lower than the threshold value Pubth, based on the command value Pcc of the shift pressure and the map of FIG. The map of FIG. 10 is a map showing changes for each shift pressure when the horizontal axis is the gear ratio (ratio) and the vertical axis is the lubrication pressure Pub. In FIG. 10, the change in the command value Pcc of the shift pressure is illustrated by a solid line, a alternate long and short dash line, and a two-dot chain line for each shift pressure.

In this case, even if the shift pressure is the same, there is a range in which the lubrication pressure Pub falls below the threshold value Pubth and the lubrication pressure Pub required for lubrication of the belt 40 cannot be secured depending on the size of the ratio (step S7: YES). Further, as shown by the alternate long and short dash line and the two-dot chain line, it is clear that the lubrication flow rate is insufficient when the lubrication pressure becomes a negative pressure.

As described above, when a positive determination result is obtained in step S7 (step S7: YES), the CVT control unit 48 proceeds to the next step S8 and adjusts the shifting pressure so that the lubrication pressure Pub becomes equal to or higher than the threshold value Plus. Change the command value Pcc. After changing the command value Pcc, the CVT control unit 48 returns to step S6 and executes the processes of steps S6 and S7 again.

If a negative determination result is obtained in step S7, that is, if the command value Pcc is such that the lubrication pressure Pub is equal to or higher than the threshold value Pcc (step S7: NO), the CVT control unit 48 proceeds to step S9. The current lubrication pressure Pub is acquired from the lubrication pressure sensor 68.

In the next step S10, the CVT control unit 48 determines whether or not the acquired lubrication pressure Pub is equal to or higher than the threshold value Pubth based on the acquired lubrication pressure Pub and the map of FIG. FIG. 11 is a map showing changes for each ratio when the horizontal axis is the shifting pressure and the vertical axis is the lubricating pressure Pub. In FIG. 11, the change in the lubrication pressure Pub is illustrated by a solid line, a long and short dash line, and a two-dot chain line for each ratio pressure.

In this case, even if the ratio is the same, the lubrication pressure Pub may fall below the threshold value Pubth depending on the magnitude of the shifting pressure, and the lubrication pressure Pub required for lubricating the belt 40 may not be secured (step S10: NO). ). Further, as shown by the alternate long and short dash line and the two-dot chain line, it is clear that the lubrication flow rate is insufficient when the lubrication pressure becomes a negative pressure.

As described above, when a negative determination result is obtained in step S10 (step S10: NO), the CVT control unit 48 proceeds to step S8, and the command value of the shift pressure is set so that the lubrication pressure Pub becomes the threshold value Plus or more. Change Pcc.

On the other hand, when a positive determination result is obtained in step S10 (step S10: YES), the CVT control unit 48 has a lubrication pressure Pub of the threshold value Public or higher if it is the determined command value Pcc or the changed command value Pcc. It is determined that this is the case, and the process proceeds to the next step S11.

In step S11, the CVT control unit 48 controls the hydraulic control valve 46 based on the determined command value Pcc or the changed command value Pcc, and controls the supply of hydraulic pressure to the continuously variable transmission 16.

On the other hand, when a negative determination result is obtained in steps S3 and S5 (steps S3 and S5: NO), the CVT control unit 48 controls the hydraulic control valve 46 based on the currently set command value Pcc. If a negative determination result is obtained in step S1 (step S1: NO), the CVT control unit 48 skips the current hydraulic control process.

FIG. 5 is a flowchart showing the details of the process of step S8. As described above, in the case of a command value Pcc in which the lubrication pressure Pub is lower than the threshold value Pcc, if the hydraulic control is performed based on the command value Pcc, there is a possibility that the shift cannot be performed. Step S8 is a process for changing to a command value Pcc capable of shifting.

First, in step S81, it is determined whether or not the shift pressure is lower than the pressure capable of maintaining the gear ratio (ratio holding pressure).

When step S81 is a positive determination result (step S81: YES), the CVT control unit 48 determines that shifting may not be possible if the shift pressure is changed to the command value Pcc determined in step S6. The process proceeds to the next step S82.

In step S82, the CVT control unit 48 changes (limits) the input torque for the continuously variable transmission 16 so that the shifting operation is possible. Further, in step S83, the CVT control unit 48 changes (reduces) the pulley holding pressure so that the shifting operation is possible. As a result, in step S84, the CVT control unit 48 determines the changed command value Pcc as the command value Pcc for controlling the hydraulic control valve 46.

On the other hand, if the determination result is negative in step S81 (step S81: NO), the CVT control unit 48 determines that the shift operation is possible, and in step S84, the command value Pcc is not changed and step S6 The command value Pcc determined in the above is determined as the command value Pcc for controlling the hydraulic control valve 46.

[3. Modification example]
In this embodiment, the continuously variable transmission 16 in which the belt 40 is a metal belt has been described. Of course, this embodiment can also be applied to the chain type continuously variable transmission 16. Further, in the present embodiment, the case where the application is applied to the vehicle 14 having the engine 12 as the drive source has been described. It can also be applied to a vehicle whose drive source is other than the engine 12 (for example, an electric vehicle driven by a battery and a motor).

Further, in steps S9 and S10 of FIG. 4, a case where the detected value of the lubrication pressure Pub and the threshold value Pubth are compared has been described. If the lubrication pressure Pub cannot be measured, or if the lubrication pressure Pub fluctuates and the determination process in step S10 is difficult, use a map that creates a database of the lubrication pressure Pub or the like measured in advance. Judgment processing may be performed.

[4. Effect of this embodiment]
As described above, in the present embodiment, the drive pulley 36, the driven pulley 38, and the continuously variable transmission 16 provided with the belt 40 (endless transmission band) wound around the drive pulley 36 and the driven pulley 38 are hydraulically driven. The control device 10 (hydraulic control device for continuously variable transmission) and the hydraulic control method for changing the groove widths of both pulleys and changing the gear ratio by supplying the above.

In this case, the control device 10 includes a pump 50 that supplies hydraulic pressure, a hydraulic control valve 46 (valve portion) that controls the supply of hydraulic pressure from the pump 50 to each part in the continuously variable transmission 16, and a CVT control unit 48 (valve part). It has a gear ratio detection unit, a command value determination unit, a valve control unit, and a command value change unit).

The CVT control unit 48 detects the gear ratio based on the rotation speeds Ndr and Ndn of the drive pulley 36 and the driven pulley 38, respectively. Further, the CVT control unit 48 determines the command value Pcc of the shift pressure, which is the hydraulic pressure supplied to the drive pulley 36 and the driven pulley 38. Further, the CVT control unit 48 controls the supply of hydraulic pressure by controlling the hydraulic control valve 46 based on the command value Pcc. Furthermore, the CVT control unit 48 controls the supply of the oil pressure based on the command value Pcc, so that the lubrication pressure Pub, which is the oil pressure supplied to the belt 40, is expected to be lower than the threshold value Pubth. The command value Pcc is changed so that

On the other hand, the hydraulic control method has the following steps. That is, when the pump 50 supplies the flood control to each part in the continuously variable transmission 16 via the hydraulic control valve 46, the CVT control unit 48 feeds the drive pulley 36 and the driven pulley 38 to the respective rotation speeds Ndn and Ndr. A step of detecting the gear ratio based on the gear ratio (step S4), a step of determining the command value Pcc of the gear shifting pressure which is the hydraulic pressure supplied to the drive pulley 36 and the driven pulley 38 by the CVT control unit 48 (step S6), and the CVT control unit. A step (step S11) in which 48 controls the oil supply by controlling the oil pressure control valve 46 based on the command value Pcc, and a lubrication pressure Pub which is the oil pressure supplied to the belt 40 by controlling the oil supply. When is expected to be lower than the threshold Plubth, the CVT control unit 48 has a step (steps S7, S8) of changing the command value Pcc so that the lubrication pressure Plub becomes equal to or higher than the threshold Plubth.

In this way, since the hydraulic control is performed so as to feed back the lubrication pressure Pub, the lubrication pressure Pub can be secured regardless of the state of the hydraulic control for the continuously variable transmission 16. This makes it possible to perform hydraulic control at a gear ratio (shift speed) according to the lubrication pressure Pub. As a result, regardless of the system of the lubrication device, the hydraulic control of an appropriate gear ratio (shift speed) can be realized only by the pump driven by the drive source (engine 12) of the vehicle 14.

In this case, the control device 10 further includes a pump rotation speed sensor 58 (pump rotation speed detection unit) that detects the rotation speed Np of the pump 50. When the CVT control unit 48 is expected to have a rotation speed Np, a gear ratio, and a command value Pcc such that the lubrication pressure Pub is lower than the threshold value Pubth, the command value Pcc is set so that the lubrication pressure Pub is equal to or higher than the threshold value Pcc. To change. This makes it possible to more accurately control the hydraulic pressure at a gear ratio that can secure the lubrication pressure Pub.

Further, the control device 10 further includes a lubrication pressure sensor 68 (lubrication pressure detection unit) for detecting the lubrication pressure Pub. The CVT control unit 48 has a rotation speed and a gear ratio such that the lubrication pressure Pub is lower than the threshold Plus, while the lubrication pressure sensor 68 has a command value Pcc such that the lubrication pressure Pub is equal to or higher than the threshold Plus. The detected lubrication pressure Plub is compared with the threshold Plubth, and when the lubrication pressure Plub detected by the lubrication pressure sensor 68 is lower than the threshold Plubth, the command value Pcc is changed so that the lubrication pressure Plub becomes equal to or higher than the threshold Plubth. .. On the other hand, the CVT control unit 48 maintains the determined command value Pcc when the lubrication pressure Pub detected by the lubrication pressure sensor 68 is equal to or higher than the threshold value Pubth. The gear ratio can be appropriately set according to the detected lubrication pressure Pub, and the hydraulic control can be performed accurately.

Further, the CVT control unit 48 determines whether or not the lubrication pressure Pub is below the threshold value Pubth based on the map 70 showing the relationship between the lubrication pressure Pub measured in advance and the rotation speed Np, the gear ratio, and the command value Pcc. .. As a result, the command value Pcc can be determined or changed without the need for a special sensor or the like.

The hydraulic control valve 46 further supplies oil to the lockup clutch 20 that connects the engine 12 and the continuously variable transmission 16. The pump 50 is driven by the rotation of the engine 12. In this case, the CVT control unit 48 controls the hydraulic control valve 46 based on the command value Pcc when the oil pressure is supplied from the hydraulic control valve 46 to the lockup clutch 20. Since the lubrication pressure may change depending on the operating state of the lockup clutch 20, the above-mentioned hydraulic control can be efficiently performed by considering the operating state.

It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that various configurations can be adopted based on the contents described in this specification.

10 ... Control device (hydraulic control device for continuously variable transmission)
16 ... Continuously variable transmission 36 ... Drive pulley 38 ... Driven pulley 40 ... Belt (endless transmission band)
46 ... Hydraulic control valve (valve part)
48 ... CVT control unit (gear ratio detection unit, command value determination unit, valve control unit, command value change unit)
50 ... Pump

Claims (5)

By supplying hydraulic pressure to the drive pulley, the driven pulley, and the continuously variable transmission provided with the drive pulley and the endless transmission band wound around the drive pulley, the groove widths of both pulleys are changed to change the gear ratio. In the hydraulic control device of the continuously variable transmission to be changed
The pump that supplies the oil pressure and
A valve unit that controls the supply of the oil pressure from the pump to each unit in the continuously variable transmission.
A gear ratio detection unit that detects the gear ratio based on the rotation speeds of the drive pulley and the driven pulley, and
A command value determining unit that determines a command value of a speed change pressure that is a hydraulic pressure supplied to the drive pulley and the driven pulley, and a command value determining unit.
A valve control unit that controls the supply of the oil pressure by controlling the valve unit based on the command value, and a valve control unit.
When the valve control unit controls the supply of the oil pressure based on the command value and it is expected that the lubrication pressure, which is the oil pressure supplied to the endless transmission zone, is lower than the threshold value, the lubrication pressure is said to be the threshold value. A command value changing unit that changes the command value so as to be as described above,
A hydraulic control device for a continuously variable transmission. In the hydraulic control device for the continuously variable transmission according to claim 1.
Further having a pump rotation speed detection unit for detecting the rotation speed of the pump,
When the command value changing unit is expected to have the rotation speed, the gear ratio, and the command value such that the lubrication pressure is lower than the threshold value, the command value changing unit is instructed to make the lubrication pressure equal to or higher than the threshold value. A hydraulic control device for continuously variable transmissions that changes the value. In the hydraulic control device for the continuously variable transmission according to claim 2.
It further has a lubrication pressure detecting unit for detecting the lubrication pressure.
The command value changing unit
When the number of revolutions and the gear ratio are such that the lubrication pressure is lower than the threshold value, and the command value is such that the lubrication pressure is equal to or higher than the threshold value, the lubrication pressure detection unit detects the detection. Comparing the lubrication pressure with the threshold value,
When the lubrication pressure detected by the lubrication pressure detection unit is lower than the threshold value, the command value is changed so that the lubrication pressure is equal to or higher than the threshold value, while the lubrication pressure detection unit detects the said lubrication pressure. A hydraulic control device for a continuously variable transmission that maintains the command value determined by the command value determination unit when the lubrication pressure is equal to or higher than the threshold value. In the hydraulic control device for the continuously variable transmission according to claim 2 or 3.
The command value changing unit determines whether or not the lubrication pressure is below the threshold value based on a map showing the relationship between the lubrication pressure and the rotation speed, the gear ratio, and the command value measured in advance. Hydraulic control device for continuously variable transmission. By supplying hydraulic pressure to the drive pulley, the driven pulley, and the continuously variable transmission provided with the drive pulley and the endless transmission band wound around the drive pulley, the groove widths of both pulleys are changed to change the gear ratio. In the hydraulic control method of the continuously variable transmission to be changed,
A step of detecting the gear ratio based on the rotation speeds of the drive pulley and the driven pulley by the gear ratio detection unit when the oil pressure is supplied from the pump to each part of the continuously variable transmission via the valve unit. When,
A step of determining the command value of the shift pressure, which is the hydraulic pressure supplied to the drive pulley and the driven pulley, by the command value determination unit, and
A step of controlling the supply of the oil pressure by controlling the valve unit based on the command value by the valve control unit.
When the valve control unit controls the supply of the oil pressure based on the command value and it is expected that the lubrication pressure, which is the oil pressure supplied to the endless transmission zone, falls below the threshold value, the command value change unit determines the supply. The step of changing the command value so that the lubrication pressure becomes equal to or higher than the threshold value,
A method for controlling the hydraulic pressure of a continuously variable transmission.

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